A: OJ is the measure of horizontal (anteroposterior) distance between the maxillary and mandibular incisors (Figure 4.1a, left). Ideal OJ is minimal, or zero OJ (Figures 4.1a, right and 4.1b–d). Ideal OJ is found when the mandibular incisal edges contact the maxillary incisor lingual surfaces with about 10–20% (1–2 mm) overbite (OB).

A: Factors influencing the magnitude of OJ include:

• Canine anteroposterior relationship (Class I, Class II, or Class III)
• Maxillary and mandibular incisor inclinations in the sagittal plane
• Maxillary and mandibular incisor alignments, spacing, crowding, and rotations
• Sum of the mesiodistal widths of the maxillary anterior teeth compared to the sum of the mesiodistal widths of the mandibular anterior teeth (presence or absence of an anterior Bolton discrepancy)

A: Excessive OJ results when:

• Canines are in a Class II relationship (Figure 4.2a) due to an underlying skeletal Class II discrepancy – either mandibular anteroposterior deficiency and/or maxillary anteroposterior excess
• Dentally, maxillary incisors are proclined too far labially and/or mandibular incisors are too upright (Figure 4.2b)
• Maxillary anterior teeth are severely spaced or mandibular anterior teeth are severely crowded
• A severe maxillary anterior Bolton tooth size excess exists or a severe mandibular anterior Bolton deficiency exists
• Discrepant maxillary and mandibular arches form; maxillary arch forms narrow and tapering toward the anterior (“V‐shaped”) and mandibular arch forms square anteriorly

A: Yes, children with OJ exceeding 3 mm have twice the risk for dental injuries as children with OJ less than 3 mm [1, 2].

A: Other variables include:

• Presence or absence of lip incompetence (exposed maxillary incisor crowns are more likely to suffer trauma than incisors with lip coverage)
• History of dental trauma
• History of risk‐taking behavior
• Sports participation
• Attention deficit hyperactivity disorder (ADHD)
• Cognitive psychomotor issues
• Teasing
• Family values

A: Yes. In cases of excessive OJ, mandibular incisors can erupt, bite into, and damage lingual periodontal or palatal soft tissues.

A: One option to reduce her OJ is to close interdental spaces between her maxillary anterior teeth (Figure 4.4). This reduces the length of the arc described by the incisal and cuspal edges of the anterior teeth (Figures 4.4a and 4.4b). However, this procedure is not without risk if fixed edgewise brackets are used to accomplish the incisor retraction. Why? Look at a similar case of severe OJ in Figures 4.4e–4.4g. Note that the developing maxillary permanent canine crowns are in the proximity of the maxillary lateral incisor roots (Figure 4.4g). When presented with this scenario, you must be careful not to cause root resorption by driving the maxillary permanent lateral incisor roots into the canine crowns. When you place fixed appliances on the maxillary lateral incisors in such cases, consider positioning the brackets in such a way that the lateral incisor roots are tipped mesially and not driven into the canine crowns. Also, proceed slowly and keep your forces light.

Another option to reduce her OJ would be to place her on a removable Class II functional appliance (e.g. a twin‐block, bionator, mandibular anterior repositioning appliance (MARA), or activator appliance). Her OJ would diminish through a combination of maxillary incisor uprighting and mandibular incisor proclination. Of course, we must consider other factors before placing her on a Class II functional appliance, including her lower anterior face height (LAFH), her mandibular incisor inclination, and her periodontal biotype. Ideal patient characteristics for treatment with Class II functional appliances are presented in detail in our next patient, Alana.

A:

A: No, we feel that her maxillary incisor angulation is WRN. Although it is true that the measured U1 to SN is less than the normal range of 101–104°, Sella appears low which reduces this angle.

An alternative estimate is to compare, on the cephalometric tracing, the line describing the long axis of the maxillary central incisors with the most posterior aspect of the lateral margin of the orbit. As an approximation, if the extended long axis line is significantly posterior to the lateral orbital margin, then the maxillary incisors are proclined. Conversely, if the extended long axis is significantly anterior to the lateral orbital margin, then the maxillary incisors are retroclined. In Alana’s case, her maxillary central incisor‐extended long axis lies just in front of the traced lateral orbital margin (Figure 4.5e), suggesting a maxillary central incisor angulation WRN.

A: Alana’s OJ resulted from the skeletal Class II discrepancy between her jaws. Her maxilla is mildly deficient anteroposteriorly, but her mandible is severely deficient.

A: Alana’s OJ is less than what it would be with normal mandibular incisal inclination. Why? Her mandibular incisors are proclined – which reduces her OJ.

Alana’s proclined mandibular incisors are dental compensations reflecting her underlying Class II skeletal discrepancy. In other words, with her severely deficient mandible, her tongue proclined her mandibular incisors during eruption.

A: High‐pull headgear effects during growth include (Figure 4.7a): [6, 7]

• Distalization of maxillary molars (correcting the Class II molar relationship dentally and creating space mesial to the maxillary molars for distalization/alignment of more anterior teeth)
• Restricting maxillary forward growth (correcting the Class II relationship skeletally as the mandible continues to grow forward)
• Reducing descent of the maxillary corpus. High‐pull headgear application in monkeys demonstrated maxillary corpus displacement posteriorly and superiorly [8]. This effect, theoretically, permits the mandible to rotate upward and forward, helping correct the Class II relationship.
• Reducing maxillary first molar eruption. This effect, theoretically, permits the mandible to rotate upward and forward, helping correct the Class II relationship.
  

  
  

High‐pull headgear effects, combined with favorable mandibular growth, facilitate correction of a Class II skeletal discrepancy, correction of Class II dental relationship, straightening of a convex profile, and increased chin projection.

A: A benefit of high‐pull headgear wear in growing patients is the reduction in maxillary first molar eruption – which permits the mandible to rotate upward and forward helping correct the Class II relationship. However, if the maxillary first molar eruption is impeded, then the mandibular first molar may overerupt (compensatory molar eruption), negating the beneficial high‐pull headgear vertical effect. To reduce mandibular first molar eruption by 1–2 mm over a one‐ to two‐year period (compared to controls), a lower lingual holding arch (LLHA) may be placed in a mixed dentition child [9].

A: We reported that one‐phase treatment for Class II malocclusions with high‐pull headgear followed by fixed orthodontic appliances resulted in correction to Class I molar through restriction of maxillary horizontal growth with continued mandibular horizontal growth. The anteroposterior molar correction and skeletal effects of this treatment were stable long term [10].

A: Cervical‐pull headgear effects in growing children include (Figure 4.7b): [3, 11]

• Distalization of maxillary molars (correcting the Class II molar relationship dentally and creating space mesial to the maxillary molars for distalization/alignment of more anterior teeth)
• Restricting maxillary forward growth (correcting the Class II relationship skeletally as the mandible continues to grow forward)
• Anterior palatal plane is tipped down
• Increasing maxillary first molar eruption slightly (compared to controls, less than 1 mm of additional maxillary first molar eruption).

Cervical pull‐headgear effects, combined with favorable mandibular growth, will facilitate correction of Class II skeletal discrepancy, correction of Class II dental relationship, straightening of a convex profile, and increased chin projection.

We use high‐pull and cervical‐pull headgears interchangeably, whichever the patient is most comfortable wearing, with the understanding that maxillary molar eruption is restricted with a high‐pull headgear but increased very slightly with a cervical‐pull headgear. Furthermore, because the anterior palatal plane is tipped down with a cervical‐pull headgear, we would generally not recommend using a cervical‐pull headgear in a patient who exhibits excess maxillary anterior gingival display.

Finally, a straight‐pull headgear consists of wearing a high‐pull and cervical‐pull headgear together. Consequently, the skeletal and dental effects of a straight‐pull headgear lie somewhere between the effects of a high‐pull and a cervical‐pull headgear (depending upon the resultant force vector magnitude and direction of each).

A: Benefits of using an occlusal bite plate for Class II correction include:

• Bite plate effect – the thick plastic between the maxillary and mandibular posterior teeth stretches the masseter/medial pterygoid musculature resulting in a reactive occlusal force that tends to reduce posterior tooth eruption. The result is a relative intrusion of posterior teeth compared to controls, and it aids mandibular upward and forward growth and Class II correction.
• Occlusal disarticulation – during adolescence, the mandible grows forward an average of 4 mm more than the maxilla (Figure 4.7e) [13]. However, because of interocclusal locking, the mandibular molars are held back by the maxillary molars – maintaining the Class II molar relationship. By disarticulating the dentition during growth (Figure 4.7f), for example with a flat bite plate (Figure 4.7g), the mandibular molars can move forward with the mandible instead of being held back by the maxillary molars – which helps correct the Class II molar relationship to Class I (Figure 4.7h).

A: In our opinion, start the patient wearing a headgear for only two–three hours each evening with a very light force (the lightest force possible to keep the headgear on). After one week, increase wear to four hours in the evening. The goal is to develop a habit of nightly wear. Then, have the patient begin wearing the headgear from 7–8 pm each evening until the next morning (when most growth is thought to occur). After the first few weeks, gradually increase the force to 250 gm per side.

A: Disagreement exists regarding the answer to this question. On the one hand, it has been suggested that the Herbst appliance is not recommended in the deciduous or mixed dentition stages. Why? Because a stable dental intercuspation is difficult to achieve during these stages and because the desired orthopedic effects are maximized only when a stable intercuspation is achieved. Instead, it has been suggested that the Herbst appliance is indicated in the permanent dentition at, or just after, the pubertal peak of growth [14, 20]. On the other hand, another study reported that a significant Class II correction with Herbst therapy was maintained throughout the transitional dental period [21]. So, disagreement exists regarding what stage of dental development is best to use a Herbst appliance.

A: Ideal candidate characteristics include:

• Class II growing child.
• Short lower anterior face height (hypodivergent, vertical skeletal deficiency with mandibular condyles growing more vertically). Why? As the Herbst appliance postures the mandible forward, condylar growth will be directed into a more normal posterior‐superior direction). In a hyperdivergent patient, condylar growth may be directed into an excessively posterior‐superior direction.
• Deep bite (not open bite).
• Proclined maxillary incisors (because they will tend to be uprighted).
• Upright mandibular incisors (because they will be proclined).
• Thick mandibular anterior labial periodontal biotype (because the mandibular incisors will be proclined, stressing the anterior periodontal tissue).

A: Headgears and functional appliances are equally effective in correcting Class II malocclusions before comprehensive orthodontic treatment [22–33]. Short‐term skeletal effects include a small restriction in forward maxillary growth with headgears (SNA decreases 0.5–3°) and a small forward positioning of B‐Point with functional appliances (1–2°), resulting in an A‐point – Nasion – B‐point angle (ANB) improvement in Class II patients of about 1° with headgears or functional appliances. A significant portion of the Class II correction is a distal maxillary molar movement with headgears and mesial mandibular molar movement (along with mandibular incisor proclination) with functional appliances. Higher levels of evidence are needed to answer the question of whether headgear and functional appliance effects following comprehensive treatment are equal.

A: We found that headgear and Herbst treatments result in significantly improved profiles that are judged to be similarly attractive [34]. Treatment with activators or Twin‐block appliances (followed by fixed orthodontic appliances) led to slight improvements in patients’ convex profiles – a difference that was relatively small and clinically questionable [35].

A: Since Class II functional appliances procline mandibular incisors, using a Class II functional appliance may not be desirable if the incisors are already proclined (dental compensations frequently observed in skeletal Class II patients). The initial presence of proclined mandibular incisors is one reason we often choose to treat a Class II patient with headgear (no mandibular incisor effects) versus a Class II functional appliance (additional mandibular incisor proclination).

A: We recommend overcorrecting. If you are using headgears/functional appliances to treat a Class II skeletal discrepancy, don’t just treat to Class I molars and stop. Instead, overcorrect slightly to Class III (1–2 mm). Then, slowly taper off the headgear or functional appliance wear over a period of months while you monitor stability.

A: In our clinical opinion, yes – first create OJ before treating a child using headgear. Why? We recommend first creating OJ under the assumption that upright maxillary incisors could restrict forward mandibular growth. Proclining upright maxillary incisors first may permit forward mandibular growth. Of course, with a Herbst appliance, you must either create OJ before activating the appliance or place the child in an anterior crossbite with the appliance.

A: Proclining maxillary incisors (unlocking the bite) plus correcting the deep bite with a removable plate does not result in mandibular anterior positioning [36]. However, the effect of unlocking the bite on future mandibular growth is unknown. We did find a recent case report of SNB increase after deep bite correction [37], but future research is needed to fully answer this question. Until then, we recommend unlocking the bite in Class II division 2 children prior to orthopedic treatment for its potential benefit on future mandibular forward growth.

A: Neither appliance is ideal. We love the effects of headgears and have had many amazing outcomes using them. However, patient compliance can be a real problem. If you attempt headgear treatment, then try using it for a fixed test period (three or four months). If the patient is not cooperating fully, then consider other options.

We love cemented Herbst appliances because, in large measure, you remove patient compliance. However, the ideal Herbst patient (Class II growing child, short lower anterior face height/hypodivergent, deep‐bite, proclined maxillary incisors, upright mandibular incisors, thick mandibular anterior labial periodontal biotype) is somewhat uncommon which limits their ideal application. Furthermore, most skeletal Class II patients present with proclined mandibular incisors (dental compensations), and all Class II functional appliances procline mandibular incisors even further. Finally, using a Herbst appliance in a hyperdivergent patient results in the chin position worsening (rotating down and back) which is just the opposite effect from what we desire.

In summary, neither headgears nor Class II functional appliances are a panacea for Class II skeletal correction. We discuss both options with parent and child. If a child will wear a headgear, then we will usually first attempt treatment with a headgear (it is inexpensive). If a child is an ideal Herbst patient, or nearly ideal, then we will use a Herbst appliance if the child would prefer that option.

A: First, let’s decide whether to attempt orthopedic correction. This decision is based upon two factors: the magnitude of her skeletal discrepancy and the time remaining to correct it orthopedically. Looking at Alana’s lateral cephalometric tracing (Figure 4.5e), we see that her anteroposterior skeletal discrepancy is severe (ANB angle of 6° with a retrusive mandible and maxilla), but her dental Class II molar relationship is moderate (only 3–4 mm Class II). Further, she is only nine years old, so you should have years of adolescent growth left to attempt Class II correction. Therefore, if Alana is cooperative, we have a good chance to fully correct her to a Class I molar relationship (or overcorrect to a slight Class III) plus a good chance to improve her skeletal discrepancy and chin projection. Even if Alana does not fully correct her skeletal discrepancy, at least she may be able to improve it to the point where we can acceptably mask it (camouflage). We conclude that we should attempt Class II orthopedic treatment for Alana. On the other hand, if Alana had been older (had reached puberty years earlier), then we would not attempt orthopedics to correct her severe Class II skeletal discrepancy because we would not anticipate much remaining growth.

Second, let’s decide when to begin Class II orthopedic treatment. Alana is just entering her late mixed dentition stage of development, so now is a good time to start. Starting sooner, in the early mixed dentition, is generally ill‐advised. Why? The strongest scientific evidence finds no advantage to beginning Class II treatment in the early mixed dentition (except for a possible decrease in incisal trauma as a result of excess OJ) [22–24, 29,38–40]. However, this is a general guideline and not a fixed rule. The dental stage is poorly correlated with skeletal growth – so use your judgment in deciding when to initiate orthopedic treatment. The average onset of statural growth spurt is a little more than nine years of age for girls and a little less than twelve years for boys; peak statural growth spurt is about one and a half to two years later; facial skeletal growth peaks later; and there is considerable variation in these times [41]. If Alana had been in the early mixed dentition, but her parents told you she had good statural growth (regular incremental change in stature), then we would recommend initiating Class II orthopedic treatment immediately.

To summarize, considering her severe skeletal Class II discrepancy, moderate dental Class II discrepancy, age, and stage of dental development, Alana is a good candidate for initiating orthopedic treatment now. Even if Alana had been in the early mixed dentition stage of development, if her parents told you she had good statural growth (regular incremental change in stature), then we would recommend initiating Class II orthopedic treatment.

By way of review, the term “good statural growth” or “regular incremental change in stature” refers to a relatively constant growth velocity in stature over time, as opposed to mildly declining growth velocity, which is often seen in advance of the pubertal period of growth acceleration. Remember, some individuals, particularly females, may not experience a true acceleration during puberty, but rather show good, relatively constant growth velocity during their years of growth in stature.

But what about the incidence of incisal trauma, specifically? Should we institute Class II treatment in the early mixed dentition if the child is experiencing incisor trauma?

A: The evidence suggests that early orthodontic treatment for children seven–eleven years old with prominent upper front teeth is more effective in reducing incisal trauma than later orthodontic treatment. Early treatment reduces the risk of trauma by 33% and 41% when patients are treated with functional appliances and headgears, respectively. However, these data should be interpreted with caution because of the high degree of uncertainty. Further, the authors concluded that there are no other advantages in providing two‐phase treatment compared with one‐phase in early adolescence [44, 45], and they have subsequently reported that the only effect of early Class II treatment was a 12% reduction in the incidence of incisal trauma. At the end of all treatment, 19% of the early treatment group had experienced trauma. Whereas, 31% of those that did not have early treatment had trauma [2]. Finally, the dental injuries tend to be minor, and the cost of incisor trauma treatment small, compared with the expected additional cost of a two‐phase orthodontic intervention [46].

So, should we institute Class II treatment in the early mixed dentition patient with a history of incisal trauma and prominent maxillary incisors? We feel that this decision must be made on a case‐by‐case basis. It must be made after considering the following factors:

• OJ magnitude
• Lip competence or lip incompetence
• History of incisal trauma (frequency/severity)
• History of risk‐taking behavior
• Sports participation
• ADHD
• Cognitive psychomotor issues

Based upon these factors, we will consider early Class II treatment or other, simpler, treatments (e.g. sports mouthguard wear).

A: Check for lip competence (Figure 4.1a). Thankfully, Alana exhibits lip competence – her incisors are covered by soft tissue which should act as a cushion and reduce any likelihood of dental trauma.

A: You need to inquire about the following (all of which her parents deny): history of dental trauma, risk‐taking behavior, participation in sports, ADHD, cognitive psychomotor issues, and teasing. Further, they are not overly concerned with her appearance at this age.

Discussions with her parents should include:

• Treatment options – tell them that orthopedic treatment to correct Alana’s Class II relationship may reduce the possibility of incisal trauma, but that dental injuries resulting from excess OJ tend to be minor. Tell them that Alana could still have incisal trauma even with treatment, or that she may not have incisal trauma without treatment. Finally, explain that Alana is entering the late mixed dentition stage of development, and now is a good time to begin orthopedic treatment.
• Your confidence in reducing OJ with each orthopedic option – tell them that, with Alana’s cooperation, treatment with either headgear or a Class II functional appliance will reduce her OJ.
• Other (nontreatment) options to reduce the likelihood of dental trauma (e.g. Alana wearing a sports mouthguard, as needed).

A: We decided to place Alana on an LLHA and an high pull headgear (HPHG). The LLHA would utilize mandibular “E‐space” (not leeway space since the mandibular primary canines were exfoliated) to help align incisors spontaneously. The LLHA would also reduce/prevent mandibular permanent first molar mesial drift and force Class II molar correction to be made with the HPHG. Finally, an LLHA would reduce mandibular first permanent molar eruption (and compensatory mandibular first permanent molar eruption) – thereby helping the mandible to rotate forward‐aiding Class II correction.

A: Masking (camouflage) is an attempt to improve a malocclusion with dental movements only – not by addressing an underlying skeletal discrepancy. With masking, you are trying to get the teeth together without orthopedics or surgery. Masking (e.g. use of Class II elastics or extraction of maxillary first premolars to permit canine relationship improvement, etc.) would be considered a fallback option or contingency plan if Alana does not respond to orthopedic treatment.

A: Changes include the following:

• Facial and smile esthetic improvement – Alana is now a beautiful young woman with a beautiful smile.
• Straighter profile with good chin projection.
• Maxilla grew downward but not forward (Figure 4.9l).
• Mandible grew downward and forward.
• Differential jaw growth as a result of the HPHG restraining maxillary forward growth but permitting mandibular forward growth (ANB angle decreased from 6° to 3°).
• Increase in skeletal LAFH (LAFH/total anterior face height [TAFH] × 100% increased from 52 to 55%).
• Maxillary and mandibular molars erupted and moved mesially, lower incisors proclined.
• Class I occlusion has been achieved.
• Mandibular left permanent canine and second premolar are rotated (Figure 4.9i).
• OJ has been reduced from 4–5 mm to minimal, and Alana has been free of maxillary incisor trauma.
  

  
  
  

A: “Take‐home pearls” include the following:

• Alana presented when she was nine years old and entering the late mixed dentition stage of development. Her parents were concerned that her top teeth stuck out (4–5 mm OJ), and that she might break them if she fell. Her first permanent molars were Class II bilaterally by 3–4 mm secondary‐to‐mandibular skeletal anteroposterior deficiency (ANB = 6° with maxillary anteroposterior deficiency). She was successfully treated non‐extraction to Class I molars with minimal OJ via HPHG orthopedics in conjunction with an LLHA and fixed orthodontic appliances.
• Children with an OJ exceeding 3 mm are at twice the risk for dental injuries as children with an OJ less than 3 mm. However, the dental injuries tend to be minor.
• Early treatment to reduce OJ can reduce the possibility of incisal trauma, but research supporting this decision should be interpreted with caution, and there are no other advantages to early Class II treatment.
• In addition to the presence of an interlabial gap (ILG) (exposed maxillary incisor crowns), other factors that weigh into your decision to treat excessive OJ early include a history of past dental trauma, history of risk‐taking, participation in sports, ADHD, cognitive psychomotor issues, and teasing.
• Before deciding to treat or not treat, you and the parents should discuss options, your confidence in each option to reduce the child’s OJ, and other (nontreatment) options to reduce the likelihood of dental trauma.
• Parents should be informed that their child may still have incisal trauma even with treatment, or that their child may not have incisal trauma without treatment.
• Excessive OJ in children can be reduced by closing spaces between maxillary anterior teeth (retracting maxillary incisors), proclining mandibular incisors, moving all maxillary teeth distally, moving all mandibular teeth mesially, or via Class II orthopedic treatment resulting in differential jaw growth (mandible growing forward more than the maxilla).
• In our opinion, neither headgears nor Class II functional appliances are a panacea for early Class II skeletal correction. Headgears can be effective, but patient cooperation can be problematic. Class II functional appliances can be effective, especially Herbst appliances, but lower incisors are proclined and functional appliance use in hyperdivergent patients can be problematic.
• Class II orthopedic treatment (headgear or functional appliance treatment) should generally begin no earlier than the late mixed dentition stage of development unless the patient demonstrates good statural growth in the early mixed dentition (displaying regular incremental change in stature).

A: In general terms, Class II molar relationships can be of dental origin (e.g. early loss of maxillary primary second molars with mesial drift of maxillary first permanent molars) or of skeletal origin (inadequate mandibular forward growth and/or excessive maxillary forward growth).

A: Inadequate anterior OJ/anterior crossbite/underbite occurs when:

• A skeletal Class III discrepancy (Class III apical base discrepancy, Figure 4.10a) exists between the jaws – either mandibular anteroposterior excess and/or maxillary anteroposterior deficiency. Such a skeletal discrepancy places the molars and canines in a Class III relationship.
• Dentally, maxillary incisors are too upright and/or mandibular incisors are too proclined (Figure 4.10b). Such a situation can exist with severe maxillary anterior crowding, severe mandibular anterior spacing, severe mandibular anterior Bolton excess, or severe maxillary anterior Bolton deficiency.
• A combination of both.

A: A pseudo Class III malocclusion (Figures 4.11a and 4.11b) exists when a child has a Class I molar relationship in CR but, because of premature occlusal contacts, shifts forward into a Class III molar relationship in CO. The child’s posterior teeth occlude in CO but usually do not occlude in CR because the incisors are in edge‐to‐edge contact.

A: Nakasima [47] reported the following etiologic factors:

• Dental factors – ectopic eruption of maxillary central incisors and premature deciduous molar loss.
  

  

  

• Functional factors – anomalies in tongue position, neuromuscular features, and airway problems.
• Skeletal factors – minor transverse maxillary discrepancies.

A: The patient has a pseudo Class III malocclusion. He is really Class I but presents as Class III when his mandible shifts forward into CO. According to one study, pseudo Class III patients usually have a mesial step (in CO) that is less than 3 mm, retroclined maxillary incisors, and mandibular incisors that are proclined and spaced [48].

A: Once the anterior crossbite (CR‐CO shift) has been corrected in pseudo Class III children, they become Class I and can complete orthodontic treatment as Class I patients. Future anteroposterior growth is usually not a concern.

However, even after an anterior crossbite has been corrected in skeletal Class III children, they will probably remain Class III and their future Class III growth pattern (excessive mandibular growth and/or deficient maxillary growth) is a major concern that impacts future treatment success. Our point is that you must carefully differentiate whether you are dealing with a pseudo Class III or skeletal Class III malocclusion.

A: Some authors feel that anterior crossbites resulting from CR‐CO shifts should be treated very early [49], but we generally recommend waiting at least until the permanent incisors erupt. We suggest that you make this decision on a case‐by‐case basis. Let’s examine the factors which will influence your decision:

• Presence of an underlying skeletal discrepancy – determining whether the patient is truly Class I in CR (skeletally normal) or is skeletally Class III. If you correct an anterior crossbite in a child with normal skeletal growth by advancing the maxillary primary incisors with a removable appliance or fixed appliances, then the crossbite should remain corrected. However, if you correct an anterior crossbite in a child with a Class III skeletal discrepancy (maxillary anteroposterior deficiency and/or mandibular anteroposterior excess), then you need to begin orthopedic treatment to address the skeletal discrepancy (e.g. high‐pull chin cup, reverse pull headgear (RPHG), TAD‐supported Class III elastics) – or, you will end up chasing a recurring anterior crossbite as the child continues the same Class III growth pattern.
• Permanent incisor eruption status – if the maxillary permanent incisors are close to erupting, then anterior crossbite correction should probably be postponed. As the primary central incisors exfoliate, the CR‐CO shift may disappear, and the permanent incisors may erupt normally and resolve the crossbite. Also, advancing the primary incisor crowns out of crossbite could result in their roots being tipped distally into the crowns of the erupting permanent incisors causing primary incisor root resorption and premature primary incisor exfoliation. Note: Algorithms to predict permanent incisor crossbites based upon primary incisor crossbites have been formulated [50] but are unproven.
• Damage to permanent incisors or to soft tissue – ongoing trauma to permanent anterior teeth is a compelling reason to correct anterior crossbites due to functional shifts. This could be either hard tissue (enamel) trauma or soft tissue (gingival) trauma.
• Compliance or lack of compliance – at what age will a child take an interest in correcting an anterior crossbite? The answer depends upon their maturity and desire.
• Psychosocial issues – is the patient being teased because of the crossbite?
• Magnitude of CR‐CO shift – a child shifting the mandible forward into an anterior crossbite is analogous to a child wearing a Class II functional appliance. The result should be analogous – accelerated mandibular growth, maxillary forward growth restriction, uprighting of maxillary incisors, and proclination of mandibular incisors. The greater the magnitude of the CR‐CO shift, the more pronounced these changes should be. This notion, originally put forward by Charles Tweed [51], is intuitively plausible, but is unproven.

Based upon the above factors, and after benefit/risk discussions with parents, a mutual decision can be made to correct the primary incisor anterior crossbite or to recall the child until permanent incisors erupt. We generally recommend waiting to correct the anterior crossbite until the permanent incisors erupt. However, we will correct an anterior crossbite in the primary dentition if we wish to proceed with Class III orthopedics.

A: Not necessarily. In the absence of a CR‐CO shift, tissue damage, or esthetic concerns, you may decide to monitor the anterior crossbite until later comprehensive orthodontic treatment. Figures 4.13a–4.13f illustrate an example of such an occlusion – where a decision was made to monitor the crossbite until comprehensive treatment. And Figure 4.13g–4.13h illustrates a sixteen‐year‐old girl who waited until comprehensive treatment to correct her anterior crossbite without any harmful effects.

On the other hand, Figure 4.13i–4.13o illustrates an eight‐year‐old boy who complained of repeated trauma to his maxillary left central incisor as he bit into anterior crossbite. In this patient, we recommended early crossbite correction. Figure 4.13p shows another child with developing gingival recession labial to her mandibular central incisors presumably due to trauma from the anterior crossbite. We noted fremitus of the mandibular central incisors during closure and recommended early correction of this crossbite.

A: Although he has a slightly convex profile (Figure 4.14c), Tomas is dentally Class I and has an anterior crossbite of his primary incisors. His mandibular permanent central incisors are erupting into the oral cavity.

A: We would not recommend correcting his crossbite now. Why? A CR‐CO shift is absent, and no tissue damage has occurred.

Notice the proximity of the maxillary primary incisor root apices to the crowns of the erupting maxillary permanent incisors (Figure 4.14d). Proclining his maxillary primary incisor crowns out of crossbite could drive their roots reciprocally into the permanent incisor crowns – initiating primary root resorption.

We recommend monitoring Tomas for one year to see if his permanent incisors erupt normally or into an anterior crossbite. If the permanent incisors erupt into crossbite, then a decision can be made to correct the crossbite.

A: Ramus has a mildly convex profile and Class I malocclusion. He has maxillary and mandibular anterior spacing with an anterior crossbite of his primary teeth.

A: The factors include:

• Presence of an underlying skeletal discrepancy (i.e. will he grow Class III and develop recurring anterior crossbites?) – Ramus does not appear to have a Class III skeletal discrepancy. He is dentally Class I and has a mildly convex profile.
• Permanent incisor eruption status – without a radiograph, we do not know the eruption status of his permanent incisors.
• Damage to hard or soft tissue – the maxillary right primary central incisor appears worn/damaged (Figure 4.15e), but his permanent incisors have not erupted. There does not appear to be damage to his soft tissue as a result of the crossbite.
• Compliance or lack of compliance – Ramus’ parents state that he is compliant.
• Psychosocial issues – none noted.
• CR‐CO shift magnitude – his CR‐CO shift is slight.

A: We decided not to treat him at this time. We decided to wait until his permanent central incisors erupted.

A: His maxillary permanent central incisors are erupting into crossbite, he has a large midline diastema with a low/thick maxillary labial frenum, and he is still Class I. His slight CR‐CO shift disappeared.

A: Since he lacks a CR‐CO shift and tissue damage, you could monitor his anterior crossbite until comprehensive treatment begins. However, his parents stated that Ramus was being teased about his crossbite. They request that you begin treatment now.

A: Yes. Ramus was asked to bite firmly, but gently, on a wooden tongue blade covered with gauze as often as possible during the day (Figure 4.17).

A: Repeated, and frequent, biting on the tongue blade corrected his anterior crossbite. However, the OB of his permanent central incisors was minimal, and it appears that his maxillary lateral incisors may erupt into a crossbite. At this time, we decided to monitor for six months while his lateral incisors erupted. The patient never returned for follow‐up.

A: Any number of appliances or techniques could be used, most of which require placement of a posterior bite plate to open the OB and permit the maxillary incisors to be advanced (Figures 4.19a–4.19d).

Options include:

• Placement of orthodontic cement “bite plates” on the maxillary molars [52] to open the OB and allow the tongue itself to push/procline the maxillary incisors out of the crossbite. This technique is more successful if the maxillary incisor is tipped lingually in a single tooth crossbite with an adequate room for the incisor. Drs. Herb and Justin Hughes will also advise the patient to push the tooth forward with their thumb.
• Once the OB is opened with orthodontic cement (Figure 4.20c), fixed orthodontic appliances can be placed on maxillary teeth, and compressed open coil springs trapped between the primary canines and permanent central incisors to advance the incisors out of crossbite.
• Removable maxillary appliances (Figure 4.21) incorporate an acrylic posterior bite plate to open the OB plus springs, or screws, to advance the incisors.

A:

A: Marc’s A‐Point (Figure 4.22e) lies considerably behind the Nasion‐perpendicular line. Therefore, as discussed in the Appendix, his maxilla is deficient (retrusive) anteroposteriorly.

A: B‐Point should normally lie behind the Nasion‐perpendicular line. Marc’s B‐Point lies slightly ahead of the Nasion‐perpendicular line. Therefore, his mandible is excessive anteroposteriorly.

A: The cause is skeletal – a combination of maxillary anteroposterior deficiency (hypoplasia) combined with mandibular anteroposterior excess (hyperplasia).

A: You can correct Marc’s anterior crossbite temporarily by proclining his maxillary incisors, but the underlying cause is skeletal and not dental. So, even if you correct his crossbite dentally, chances are that it will recur as he continues to grow.

Of course, once you correct his crossbite dentally, you could ask Marc to wear a high‐pull chin cup to inhibit forward mandibular growth while permitting forward maxillary growth. If he cooperated with high‐pull chin cup wear, then his anterior crossbite would not return.

A: The root apex of his maxillary left lateral incisor appears to be superimposed on the erupting left permanent canine crown. Looking at the cephalometric radiograph, the developing maxillary permanent left canine appears to be posterior to the erupted maxillary permanent right canine (Figure 4.22d). Taken together, it appears that if you advance his maxillary left lateral incisor crown to eliminate the anterior crossbite, then you run the risk of reciprocally driving the lateral root tip into the canine crown – possibly resorbing the lateral incisor root. Before proceeding with this option, it would be best to take a 3‐D radiograph to determine the spatial relationship between these two teeth. This was not done.

A: Yes. If you advance the maxillary left lateral incisor crown, then proceed slowly with light forces and position the maxillary left lateral incisor bracket so that the lateral incisor root will be tipped mesially (Figure 4.23), away from the canine crown.

A: Orthopedics, masking (camouflage), and surgery are the three general ways to address any skeletal discrepancy whether in the anteroposterior, vertical, or transverse dimension. Specifically, for a skeletally deficient maxilla and/or skeletally excessive mandible (Class III relationship):

• Orthopedics – seeks to enhance maxillary forward growth and/or restrict mandibular forward growth (Figure 4.24a). Examples include RPHG treatment, high‐pull chin cup treatment, and Class III elastics worn between maxillary and mandibular TADs.
• Masking or camouflage – seeks to correct Class III dental relationships (Figure 4.24b) by masking the underlying skeletal discrepancy and not changing the jaws. Generally, we consider Class III masking only during comprehensive treatment in the adult dentition with patients who have completed, or nearly completed, growth.

Class III masking involves moving maxillary teeth mesially and/or moving mandibular teeth distally. Options include the use of interarch Class III elastics or springs (Figure 4.24c), RPHG to move maxillary teeth mesially, TADs used as anchorage to help move maxillary teeth mesially or mandibular teeth distally, and various combinations of permanent teeth extractions followed by space closure (e.g. extraction of mandibular first premolars in order to create space for mandibular canine retraction into a Class I canine relationship).

Class III elastics or springs are generally worn between the maxillary first permanent molars and mandibular canines. In addition to their desirable effects of moving maxillary anterior teeth mesially and mandibular teeth distally, Class III elastics can have undesirable effects such as erupting maxillary molars and mandibular incisors, rotating the occlusal plane counterclockwise (CCW), and rotating the mandibular plane clockwise (CW).

• Surgery – surgery would generally not be considered in children, other than in cases of craniofacial anomalies and/or airway problems. Depending upon his growth and compliance, future surgery for Marc may include either a maxillary advancement osteotomy and/or a mandibular setback osteotomy. Figures 4.24d–4.24e illustrate skeletal changes as a result of maxillary and genioplasty advancement osteotomies in an adult.

A: The effects of RPHG [53, 54] wear (six months, 380 gm of force per side) following RME are, on average:

• 1.8 mm forward maxillary growth.
• Labial movement of maxillary incisors (maxillary tooth movement is eliminated if miniplates are used for anchorage instead of maxillary teeth).
  

  

• Increased fullness of maxillary lip.
• 2.5 mm backward mandibular movement (chin cup effect).
• Downward and backward mandibular rotation (mandibular MPA increase of 1.5°).
• LAFH increase of 2.9 mm.
• Lingual movement of mandibular incisors.

A: Yes. A traditional guideline calls for RPHG treatment when a child’s maxillary permanent incisors are erupting. The skeletal effects of RPHGs are less in patients older than ten years of age [55–57].

A: If you plan RPHG treatment on Marc, you should do it now to achieve maximal skeletal benefit.

A: Some studies report no difference in A‐Point advancement with, or without, RME [58–60]. However, one study reported A‐point advancing more if RPHG is applied (300–500 gm/side, twelve hours per day until the anterior crossbite is corrected) during RME, less after RME, and even less without RME [60]. When using RPHG to advance a child’s maxilla, we recommend applying RPHG during RME (assuming transverse correction is needed) because there is no disadvantage in doing so.

A: Alternating rapid maxillary expansion and constriction protocol (Alt‐RAMEC) was designed to maintain sutural stimulation over a longer period of time than RME alone, thus achieving greater maxillary protraction during RPHG treatment [61]. What is the protocol? The RME appliance is opened 1 mm per day (four turns per day), alternating one week of expansion with one week of constriction for seven to nine weeks.

In a recent study [62], Alt‐RAMEC with RPHG was shown to be more effective in advancing the maxilla when compared to RME with RPHG. No significant differences were noted regarding mandibular projection, length, and vertical skeletal relationships. In another study [63] comparing the effects of facemask protraction combined with alternating rapid palatal expansion and constriction – the authors found only statistically significant differences (not clinically significant differences) when compared to RME with RPHG.

At this time, we feel that findings regarding the effectiveness of alternating rapid maxillary expansion and constriction during RPHG treatment are inconclusive.

A: Consider placing TADs in the maxilla [64]. Elastics can be worn directly from the RPHG to the TADs.

A: Compared to conventional RPHG patients, miniplate anchorage RPHG patients had more maxillary forward movement (without significant anterior rotation), less mandibular posterior rotation, less face height increase, and no dental movement [65]. In a similar study [66], a miniplate anchorage RPHG group showed more forward maxillary movement, less Frankfort horizontal to mandibular plane angle (FMA) opening, and less sagittal and extrusive maxillary molar movement compared to a bonded RME appliance anchorage RPHG group. A meta‐analysis [67] concluded that approximately 3 mm of horizontal A‐point movement is reliably attainable with skeletal (miniplate) anchorage maxillary protraction – which is 1 mm greater than that expected with tooth‐borne maxillary protraction [58].

A: Intact maxillary primary canines can be intentionally ankylosed to serve as anchors. Root canal treatment is performed on extracted primary canines (Figure 4.26a), and the periodontal ligament is scraped off. Wires are attached to the primary canines (Figure 4.26b). The canines are reinserted into their respective sockets and stabilized until they ankylose (Figures 4.26c and 4.26d). Elastics are worn from the primary canine wires to the RPHG (Figure 4.26e). We have used this anchorage technique but are not enthusiastic about it. We prefer miniplates as anchors instead.

A: While it is true that early RPHG treatment achieves short‐term positive skeletal and dental changes, there is a lack of evidence on its long‐term benefits [68] – except for the fact that early Class III protraction facemask treatment reduces the need for orthognathic surgery from 66% (control group) to 36% (facemask group) [69]. We are left with the clinical observation that once orthopedic forces are discontinued, the former Class III growth pattern returns – tending to recreate the same skeletal discrepancy. Whether the patient will eventually outgrow the correction depends on how much growth remains after orthopedics is stopped and whether (how much) you overcorrect the patient (made them Class II).

A: Any orthopedic treatment, including RPHG treatment, is unstable in the sense that the old growth pattern returns after treatment [57, 70, 71] – as long as the patient is growing. The A‐point advancement you achieve may not be lost after RPHG treatment, but the Class III growth differential between the maxilla and mandibular will return. That is, Marc’s excess mandibular growth will exceed his deficient maxillary growth.

A: The key to using RPHG on growing, maxillary deficient, Class III children is overcorrection. Do not just correct the patient to a Class I molar relationship. Instead, overcorrect to a Class II molar relationship. Also, monitor and maintain your correction until the patient is finished growing. If the patient begins to grow Class III again, then decide whether to return to the RPHG, place the patient on a high‐pull chin cup, or place the patient on TAD‐supported Class III elastics.

A: High‐pull chin cup effects (fourteen hours/day of wear for two years plus wear during sleep for three additional years) include: [72]

• ANB improvement
• Chin position improvement
• Inhibition of mandibular ramal height growth and inhibition of mandibular body length growth
• Backward rotation of mandible
• Closure of gonial angle
• Mandibular plane angle (FMA) flattened in high‐pull chin cup patients but opened in controls
• Maxilla continues to grow forward
• LAFH is not increased compared to controls [73, 74]

Note: Even in severe dolichofacial Class III patients who are compliant, long‐term (>five years) high‐pull chin cup therapy is effective [75]. However, wearing a chin cup (like wearing an RPHG) does not normalize growth. The changes listed above will not be maintained if chin cup wear is discontinued before facial growth is complete [72–76].

A: Yes. Anterior crossbites in skeletal Class III children result from:

• Deficient maxillary forward growth with normal mandibular forward growth
• Deficient maxillary forward growth with excessive mandibular forward growth
• Normal maxillary forward growth with excessive mandibular forward growth.

In every case, mandibular forward growth exceeds maxillary forward growth. So, restricting mandibular forward growth with a high‐pull chin cup while allowing maxillary forward growth will improve the Class III relationship and tend to correct an anterior crossbite. Of course, the magnitude of the skeletal discrepancy, the amount of growth remaining (time), and the patient’s compliance all play a role in determining success.

A: Yes, that is correct – which brings us to our recommended protocol for treating anterior crossbites in Class III skeletal children (maxillary deficiency, mandibular excess, or a combination of both). We recommend correcting the anterior crossbite first, dentally. Then, placing the child in a high‐pull chin cup, or Class III elastics supported by TADs, until they finish growing.

To illustrate our protocol, examine Alex (Figure 4.28), a five‐year‐ and six‐month‐old boy who presented with an anterior crossbite, Class I canine relationship, and negligible CR‐CO shift. Alex could not get his incisors back to an edge‐to‐edge relationship. His pediatric dentist told his parents that Alex would need jaw surgery. Mom presented to our practice crying, and begging us to help Alex without surgery. Alex had a concave profile, an ANB angle of –2 degrees, and we felt that he was beginning to grow Class III (maxillary deficiency and mandibular excess).

We first corrected his anterior crossbite using a mandibular bite plate plus fixed appliances to advance his maxillary primary incisors (Figure 4.28l). We normally wait until maxillary permanent incisors erupt to correct anterior crossbites, but we were concerned about his unfavorable growth and decided to correct it in the primary dentition.

Following crossbite correction, Alex was placed on a high‐pull chin cup (Figures 4.29a–4.29h). Alex wore the high‐pull chin cup nightly until growth was complete. He had no additional treatment. He and his mom were delighted with his outcome and elected not to perfect the alignment of his teeth with braces (Figures 4.30a–4.30i). Our point is that this treatment protocol can be very effective with a compliant patient.

Some of our friends are gifted orthodontists who never use chin cups, and they only treat Class III growing patients with RPHGs. So, why do we recommend the above approach? Our reasons are as follows:

• Jaw growth is not normalized with orthopedics – when you stop orthopedic treatment, the underlying difference between maxillary and mandibular forward growth that caused the initial Class III relationship will return. With our approach, the child and parents understand that they must be committed to wearing the chin cup every night until growth is complete. Once you achieve Class III correction with a chin cup, you must hold that correction until growth is complete. The same is true for TAD‐supported Class III elastic wear.
  

  

  

• RPHGs are not usually applied with the understanding that they must be worn until growth is complete. RPHGs are usually worn until the child’s Class III relationship is corrected. Once RPHG wear is discontinued, the Class III skeletal growth pattern returns for as long as the child grows, and the child can grow out of your correction.
• For that reason, RPHG treatment usually includes overcorrection. But, deciding how much to overcorrect with RPHG is a gamble at a young age. If you overcorrect too much, the child may end Class II. If you overcorrect too little, the child will end Class III. Getting it just right is very, very difficult. And remember, the average additional forward maxillary growth with tooth‐borne RPHG is limited, ranging from only 1–3 mm [58, 67].
  

  

• Overcorrection with RPHG can be a viable approach and it follows from our general principle for orthopedics, “overcorrect and monitor until growth is complete.” We ask only that you monitor the patient until growth is complete.
• With our approach (anterior crossbite correction – followed by high‐pull chin cup or TAD‐supported Class III elastic wear), the child is asked to comply with wearing only one orthopedic appliance (chin cup or Class III elastics). With RPHG, the child may be asked to switch over to a different appliance later (chin cup) and lose interest. Maintaining habits is generally easier than starting new habits.
• Finally, in cases of anterior crossbites due to Class III skeletal discrepancies, we suggest correcting the crossbite first, even in the primary dentition. If there was no skeletal discrepancy that needed to be addressed orthopedically, then we would generally not correct the anterior crossbite until permanent incisors erupted.

A: In our opinion, start the patient wearing a high‐pull chin cup for only two to three hours each evening with a very light force (the lightest force possible to keep the chin cup on). After one week, increase wear to four hours in the evening. The goal is to develop a habit of nightly wear. Then, have the patient begin wearing the high‐pull chin cup from 7–8 pm each evening until the next morning (when most growth is thought to occur).

After the first few weeks, gradually increase the force. The ideal force for chin cup therapy is unknown, but a force exceeding 125–250 gm, measured at the center of the chin cup, appears to be necessary. Why do we say this? In a recent study, fewer than 50% of patients treated with a light‐force chin cup had favorable clinical outcomes [77]. Therefore, we recommend an eventual chin cup force of 250 gm per side, the same force recommended for TAD‐anchored Class III elastic wear.

A: You should always be concerned about loading the TMJs – whether with chin cups, Class III elastics, or soft tissue stretching following BSSO advancements. However, there is no evidence that 500 gm or even 1000 gm orthopedic chin cup force, applied at the center of the chin, induces TMD. In a recent study of 250 chin cup‐treated female subjects [75], 5% developed transient symptoms of TMD during or after active treatment (temporary muscular pain and difficulty achieving maximum mouth opening). Their TMDs were treated using conservative measures (e.g. splint therapy).

Here are our recommendations regarding chin cups and TMD:

• Do not load TMJs using chin cups (or Class III elastics or Class III springs) in patients who initially present with TMJ pain or restricted function
• Inform patients of the possibility of transient symptoms developing during chin cup treatment
• In patients who develop TMD symptoms during chin cup treatment, discontinue chin cup wear.

A: TAD‐anchored Class III elastic patients have an average maxillary advancement of 4 mm, and B‐Point improvement of 2 mm, compared to Class III control subjects [78].

A: Class III elastics worn between miniplates resulted in over 2 mm more maxillary advancement than RME followed by RPHG [79]. The Class III elastics were initially applied with a force of 150 gm but gradually increased to 250 gm after three months, and they were coupled with a bite plate to eliminate occlusal interference in the incisor region until anterior crossbite correction was achieved.

A: When the mandibular primary canines and primary molars exfoliate, the LLHA prevents/reduces mesial drift of the permanent molars and worsening of the Class III relationship.

Further, we already stated that for Class III orthopedic treatment, the skeletal effects of RPHGs are greatest in patients 10 years of age or younger [55–57]. However, what about timing for Class III children treated with high‐pull chin cups or Class III elastics supported by TADs? What does the evidence tell us?

A: Unlike Class II treatment, we lack prospective, randomized clinical trials for Class III patients using either high‐pull chin cups or Class III elastics supported by TADs. Instead, we have weaker levels of evidence. As a recent systematic review of Class III orthopedic outcomes concluded: “high‐quality investigations are still needed to perform a definitive assessment of the effectiveness of Class III treatment at the skeletal level.” [80]

So, what recommendations do we suggest for the timing of high‐pull chin cup or TAD‐supported Class III elastic treatment?

• The greater the Class III skeletal discrepancy magnitude, the earlier we recommend you should start orthopedics (to take advantage of as much future growth as possible).
• Compliance is critical. All patients will eventually suffer “burnout.” Informing them that excellent cooperation may eliminate the need for future orthognathic surgery will motivate some patients. For others, it will not. If the child does not cooperate within a few months of starting orthopedics, discontinue and monitor them until they complete growth. At that time, re‐evaluate for masking or surgery.
• Class III orthopedic treatment (chin cup or TAD‐supported Class III elastic wear) would ideally bracket the time when the patient is growing most. However, that precise time is difficult to predict, and Class III mandibular excess patients grow longer than other patients (e.g. mandibular‐deficiency patients).
• Long‐term orthopedic use of Class III elastics supported by TADs (five to ten years until the patient has completed growth) has not been reported.

For Alex (Figure 4.28), we started orthopedics at six years and six months of age because his mother (a physician) feared that Alex would require jaw surgery someday if we did not intercede. In terms of compliance, Alex was outstanding. He wore a high‐pull chin cup for nine years – probably as a result of his mother’s influence. Most likely, she kept her son out of the operating room.

A: Because Marc was nine years old, presented with a deficient maxilla, and lacked maxillary left posterior permanent teeth, we placed him on a TAD‐supported RPHG (Figure 4.32).

This treatment alone corrected his anterior crossbite and Class III dental relationship (Figure 4.33). Note the orthopedic changes which occurred (Figure 4.33c):

• Maxilla grew downward and forward.
• Mandible rotated downward and backward (clockwise rotation) and exhibited slight condylar growth.
• Maxillary molar and incisors erupted.

Marc’s anteroposterior relationship was monitored. We were prepared to maintain his anteroposterior correction using a high‐pull chin cup if his Class III growth pattern returned, but he remained stable. His miniplates were removed, fixed orthodontic appliances were later placed, leveling/alignment of his arches attempted, and space closure attempted.

However, significant root resorption was noted on a routine panoramic image (Figure 4.34). Following discussions with Marc and his parents, a decision was made to discontinue further treatment. Final records of Marc (Figure 4.35) were made years later after cosmetic veneers had been placed. Correction of his anterior crossbite via RPHG was stable, and ideal OJ has been achieved. Marc and his parents were very happy with the treatment he received, and he will be referred for extraction of his third molars.

A: Class III molar relationships can be of dental origin (e.g. early loss of mandibular primary second molars with mesial drift of mandibular permanent first molars) or of skeletal origin (excessive forward growth of the mandible and/or inadequate forward growth of the maxilla).

A: “Take‐home pearls” include the following:

• Marc was nine years old in the late mixed dentition when he presented with a 3 mm bilateral Class III relationship and anterior crossbite secondary to maxillary skeletal anteroposterior deficiency combined with mandibular skeletal anteroposterior excess. His crossbite was corrected, skeletally, using an RPHG and maxillary (miniplate) TADs.
• When you employ Class III or Class II orthopedics, you are not normalizing growth. You can alter anteroposterior jaw growth during orthopedic force application. But once you stop orthopedics, a growing patient will return to their previous growth pattern and may grow out of your correction. We were very fortunate that Marc’s correction held without the need to place him on a high‐pull chin cup (or Class III elastics to TADs) after the crossbite correction.
• For the above reason, you should overcorrect and monitor until growth is complete. If you are using RPHG/high‐pull chin cup/Class III elastics supported by TADs to correct a Class III skeletal discrepancy, then don’t just correct the patient to Class I and stop. Instead, overcorrect slightly to Class II (1–2 mm), and maintain/monitor your correction until the patient is finished growing.

If you are using headgears or functional appliances to treat a Class II skeletal discrepancy, then don’t just correct the patient to Class I and stop. Instead, overcorrect the patient slightly to Class III (1–2 mm), and slowly taper off the headgear or functional appliance wear over a period of months while you monitor the stability of your correction.

• In our experience, Class II orthopedic correction is more stable than Class III orthopedic correction. Why? Whereas Class II skeletal discrepancies usually result from deficient mandibular growth, Class III skeletal discrepancies usually result (at least partially) from excess mandibular growth, and excessively growing mandibles grow for longer periods of time than normal.
• A decision to employ Class III or Class II orthopedics is predicated upon two factors – the magnitude of the skeletal discrepancy and the time (growth) remaining to treat it. If you have a compliant child with a mild skeletal problem and years of growth ahead, then you have a reasonable chance of correction with orthopedics. If you have a moderate skeletal problem and years of growth ahead, you have less of a chance to achieve full correction with orthopedics. If you have a severe skeletal problem with minimal future growth, then your chances of full correction are greatly reduced. However, even in the latter case, you may still be able to improve the skeletal discrepancy with orthopedics to the point where you can successfully employ masking treatments.
• We generally recommend waiting to correct an anterior crossbite until the permanent incisors erupt. We will correct an anterior crossbite in the primary dentition if we wish to proceed with Class III orthopedics.
• Once an anterior crossbite (CR‐CO shift) has been corrected in pseudo Class III children, the child becomes Class I and can complete orthodontic treatment as a Class I patient. Future anteroposterior growth is usually not a concern.

However, even after an anterior crossbite has been corrected in skeletal Class III children, they will probably remain Class III and their future Class III growth pattern will impact long‐term treatment success. You must remain vigilant in determining whether you are dealing with a pseudo Class III or a skeletal Class III. Your success will depend upon it.

• 3 mm of horizontal A‐point movement is reliably attainable with skeletal (miniplate) anchorage maxillary RPHG protraction – which is 1 mm greater than what can be expected with tooth‐borne maxillary RPHG protraction.
• For growing skeletal Class III patients, we recommend correcting the anterior crossbite first, dentally. Then, placing the child on a high‐pull chin cup, or Class III elastics supported by TADs, until they finish growing.
• Principle of Class II correction: avoid treatments that rotate the mandible down and back – worsening a convex profile and worsening a Class II relationship.
• Principle of Class II correction: you must have anterior OJ in order to correct a Class II posterior relationship.
• Timing guidelines – You should wait to begin Class II orthopedic treatment until the late mixed dentition. However, consider beginning in the early mixed dentition if the parent tells you that the child has good statural growth (displaying regular incremental increases in stature).

For Class III orthopedic correction – the more severe the anticipated Class III skeletal discrepancy, the earlier we recommend you start orthopedics (as early as six to seven years). As a rule, begin RPHG at the time the maxillary permanent central incisors are erupting, but before age ten. Begin high‐pull chin cup or TAD‐supported Class III elastics as early as the early mixed dentition.

• Compliance – if the compliance of a Class III patient wearing an RPHG or high‐pull chin cup wanes, consider offering TAD‐supported Class III elastics as an alternative. Some of our patients who refuse to wear an RPHG or chin cup successfully wear TAD‐supported Class III elastics well.

No matter which appliance you use, patients must develop a habit of wear and stick to it, possibly for years.

Whether Class III or Class II orthopedics, patients have only one cup of compliance. When it is gone, it is gone. When it is gone, consider other options. We are not here to make patients’ lives, parents’ lives, and our own lives miserable by forcing compliance.

• Although Class II and Class III masking can be performed in young children, masking is usually performed in the permanent dentition during comprehensive treatment and has not been discussed at length here. Likewise, we have only touched on maxillary or mandibular surgeries which are beyond the scope of this early treatment textbook.

However, anytime orthopedics is attempted in a child, discussions of future “fallback” options (contingency plans including masking or surgery) should be discussed with parents in the event that orthopedics fails.

A:

A:

Average mesiodistal widths of permanent teeth (mm): [81]

Average mesiodistal widths of primary teeth (mm): [81]

MAXILLARY ARCH (leeway space cannot be used since maxillary first primary molars have exfoliated)

0.0 mm of maxillary anterior crowding currently present (Figure 4.36h)

+8.2 mm mesiodistal width of maxillary right primary second molar

−7.0 mm anticipated size of maxillary right second premolar

+1 mm space distal to maxillary right primary canine

+7.0 mm mesiodistal width of maxillary right primary canine

−7.5 mm anticipated width of maxillary right permanent canine

+7.0 mm mesiodistal width of maxillary left primary canine

−7.5 mm anticipated width of maxillary left permanent canine

+1 mm space distal to maxillary left primary canine

+8.2 mm mesiodistal width of maxillary left primary second molar

−7.0 mm anticipated size of maxillary left second premolar

Balance = 0 mm + 8.2 mm − 7.0 mm + 1 mm + 7.0 mm − 7.5 mm + 7.0 mm − 7.5 mm + 1 mm + 8.2 mm − 7.0 mm = +3.4 mm

MANDIBULAR ARCH (leeway space cannot be used since the primary canines and left primary first molar have exfoliated)

0 mm of mandibular incisor crowding currently present (Figure 4.36i)

+9.9 mm mesiodistal width of mandibular left primary second molar

−7 mm anticipated size of mandibular left second premolar

+5.0 mm space between mandibular right primary first molar and mandibular right lateral incisor

−7.0 mm anticipated size of mandibular right permanent canine

+7.7 mm mesiodistal width mandibular right primary first molar

−7.0 mm anticipated size of mandibular right first premolar

+9.9 mm mesiodistal width mandibular right primary second molar

−7 mm anticipated size of mandibular right second premolar

Balance = 0 mm + 9.9 mm − 7.0 mm + 5.0 mm − 7.0 mm + 7.7 mm − 7.0 mm + 9.9 mm

7.0 mm = +4.5 mm

That is, 3.4 mm of maxillary spacing and 4.5 mm of mandibular spacing is anticipated following the eruption of all permanent teeth (if proper space maintenance is employed).

A: Although both molar classification schemes are based on the mesiodistal relationship of the maxillary first molar mesiobuccal cusp and the mandibular first molar buccal groove, the Angle classification defines Class I molar occlusal relationship as a range of values, with the range determined by mandibular molar cusp width. The Iowa classification defines Class I molar occlusal relationship as a categorical discrete value, restricted to the ideal molar occlusal relationship. Any variation from this value is defined as “Class II” or “Class III” (see Appendix for a review of the Iowa classification method).

Edward H. Angle defined Class II molar occlusion when the mandibular molars are distal to the normal Class I position “to the extent of more than one‐half the width of one cusp.” [82] As mandibular molar buccal cusps are, on average, 4–5 mm in mesiodistal width, Angle Class II molar relationship occurs on average when mandibular molars are distal to ideal Class I position by more than 2–2.5 mm.

The Iowa classification simply measures the deviation from an ideal molar relationship. Mandibular molars deviating to the distal of the ideal position are classified as Class II by the millimeter deviation.

In Jake’s case, his molar occlusal relationship is Angle Class I because he varies from ideal Class I by less than one‐half mandibular buccal cusp width. His Iowa classification molar occlusal relationship is Class II by 1 mm.

A: The Iowa classification system gives a quantitative description of molar occlusal relationships. This is especially important in the mixed dentition, where diagnosis often includes an estimate of residual leeway space available for mesial movement of permanent first molars after the loss of succedaneous teeth. Knowing the exact variation in the first permanent molar occlusal relationship allows for better treatment planning.

A:

A: In the context of the three principles:

1. The goal of early treatment is to correct developing problems – get the patient back to normal for their stage of development (including preventing complications such as resorption of adjacent tooth roots, reducing later treatment complexity, and reducing/eliminating unknowns). Obtaining bilateral Class I molar relationships, improving his convex profile/retrusive chin, and improving his deep bite would put Jake back on track.
2. Early treatment should address very specific problems with a clearly defined end point. An active treatment component should usually be completed within six to nine months (not protracted over many years, except for some orthopedic problems). Considering Jake’s primary problems:
   • His minimal Class II molar relationship could be readily corrected now with Class II orthopedics or in the permanent dentition with any number of Class II correctors (e.g. Class II elastics).
   • His convex profile/retrusive chin may not be improved with orthopedic treatment because his molars are Class II by only 1 mm. Orthopedic treatment encouraging differential mandibular forward growth will likely result in an unacceptable Class III molar relationship. Further, his Class II (1 mm) molar relationship may self‐improve with mandibular permanent first molar mesial drift when the mandibular primary second molars exfoliate.
   • His deep bite could be corrected now in six to nine months using fixed orthodontic appliances to level his arches.
3. Always ask yourself: Is it necessary that I treat the patient early? What harm will come if I choose to do nothing now? In our opinion, no harm will come if we place Jake on periodic recall. His permanent teeth should erupt normally, and his permanent mandibular molars should drift mesially (after exfoliation of his mandibular primary second molars) with his molars moving into a Class I relationship. In order to improve his chin projection with orthopedics, we would have to devise a treatment plan to provide a Class III molar occlusion.

A: Reasons include palatal pain or tissue damage from incisor impingement. Jake exhibits neither pain nor tissue damage.

A: Key facts include the following:

• Jake has a convex profile. Laypersons prefer an orthognathic profile [83].
• The zero‐meridian line is a vertical line drawn down from soft‐tissue Nasion perpendicular to Frankfort horizontal (Figure 4.37). Ideally, the chin should lie on the zero‐meridian line or just short of it [84]. Jake’s chin is retrusive and sits back further than this.
• Jake is essentially Class I dentally with normal OJ. Using orthopedics to encourage forward growth of Jake’s mandible relative to his maxilla would give him a Class III molar relationship and put him in anterior crossbite – unless our treatment plan included retraction of his mandibular anterior teeth. As we said previously, this is too risky and should not be attempted. Alternatively, moving his maxillary teeth distally to retract his upper lip and reduce his profile convexity is not an option because it would cause his already obtuse nasolabial angle (NLA) to become more obtuse, worsening his nose‐to‐lip relationship.
  

  

• A range of attractiveness exists. We held a thoughtful, sensitive, discussion with Jake’s parents – without Jake present. They felt that Jake was a good‐looking young man with an acceptable chin position.

A: Treatment options include the following:

• Recall (no early treatment, monitor only) – evaluate tooth eruption in one year. We feel that this is a reasonable option. Why?

1. Jake’s permanent first molars are Class II by only 1 mm. Our detailed space analysis tells us that his mandibular permanent first molars will have the space to drift to the mesial following exfoliation of his mandibular primary teeth. They will probably drift to the mesial into a bilateral Class I relationship.
2. We anticipate that his permanent teeth will erupt uneventfully (Figure 4.36d).
3. His parents are happy with Jake’s facial esthetics – including his current profile.

• Space maintenance – place an LLHA and/or Nance holding arch before exfoliation of Jake’s remaining primary canines and primary molars. We do not recommend this option. Jake currently has 0 mm of maxillary crowding and only mild (2 mm) mandibular anterior crowding. Space maintenance will provide us with spacing in both arches following the eruption of all permanent teeth, but an LLHA will greatly reduce/prevent the mandibular permanent first molars from drifting to the mesial into a Class I relationship.
• Class II orthopedic treatment – restriction of maxillary growth while allowing continued mandibular forward growth or attempting to accelerate mandibular forward growth. If you choose this option, then you should first make a lateral cephalometric radiograph/cone beam computed tomography (CBCT) to confirm that Jake has a Class II skeletal discrepancy – and not merely an ineffective Pogonion.

However, we are not enthusiastic about this option. Why? While it is true that Jake has a convex profile/retrusive chin, and while it is true that now would be the appropriate time to apply Class II orthopedic treatment (late mixed dentition), Jake is essentially Class I dentally with normal OJ, and his parents like his profile.

• Extraction of maxillary primary canines – to facilitate the eruption of Jake’s maxillary permanent canines. We do not recommend this option since Jake’s maxillary permanent canines appear to be erupting normally (Figure 4.36d).

A: We recommend recalling Jake in one year and treating him to a Class I molar relationship once his permanent teeth erupt. When he is an adult, Jake can decide whether he wants a stronger chin. If he does, then he could consider a genioplasty advancement.

A:

A: No additional records are needed in order to decide whether to recall or to initiate early treatment. However, we are certain that a lateral cephalometric radiograph would corroborate our finding of a hypoplastic mandible.

A:

Below are space estimates:

Average mesiodistal widths of permanent teeth (mm): [81]

Average mesiodistal widths of primary teeth (mm): [81]

MAXILLARY ARCH

+2.0 mm of anterior spacing (Figure 4.38h, midline diastema plus small spaces distal to central incisors)

+5.1 mm width of the maxillary right primary lateral incisor

−6.5 mm space needed for maxillary right permanent lateral incisor

+5.1 mm width of maxillary left primary lateral incisor

−6.5 mm space needed for maxillary left permanent lateral incisor

+2.0 mm of anticipated leeway space (1 mm/side)

Balance = + 2 mm + 5.1 mm − 6.5 mm + 5.1 mm − 6.5 mm + 2 mm = +1.2 mm

MANDIBULAR ARCH

−5.0 mm of incisor crowding is currently present

+3.2 mm of anticipated leeway space (1.6 mm/side)

Balance = − 5.0 mm + 3.2 mm = − 1.8 mm

That is, 1.2 mm of maxillary arch spacing and 1.8 mm of mandibular arch crowding is anticipated following the eruption of all permanent teeth (if proper space maintenance is employed).

A:

A: In the context of the three principles:

1. The goal of early treatment is to correct developing problems – get the patient back to normal for their stage of development (including preventing complications such as resorption of adjacent tooth roots, reducing later treatment complexity, or reducing/eliminating unknowns). Addressing the following problems would put Alexandra back on track:
   • Class II (6 mm) anteroposterior molar relationship and excess incisor OJ (secondary to mandibular skeletal deficiency)
   • Deep bite (secondary to overeruption of mandibular permanent central incisors, Figures 4.38d and 4.38f)
   • Large buccal corridors (narrow maxilla)
   • Moderate mandibular anterior crowding (predicted mild mandibular arch crowding if proper space maintenance is employed)
2. Early treatment should address very specific problems with a clearly defined end point, with any active treatment component usually completed within 6 to 9 months and not protracted over years (except for some orthopedic problems). Evaluating Alexandra’s problems with this in mind:
   • Her skeletal Class II relationship is a specific problem with a clearly defined end point, but it could take years to correct with orthopedics depending upon her mandibular and maxillary growth magnitude, direction, and timing.
   • Her deep bite could be corrected with fixed orthodontic appliances in six to nine months by leveling her lower arch. Mandibular incisor palatal impingement could be corrected immediately using a vacuum‐formed clear maxillary retainer that covers only her palate and maxillary incisors (allowing her posterior teeth to erupt slightly).
     

     

   • Her narrow maxilla could be readily expanded with RME.
   • Her moderate (5 mm) mandibular anterior crowding could be reduced using leeway space with an LLHA, but eruption of her mandibular permanent canines and premolars could take years.

3. Always ask yourself: Is it necessary that I treat the patient early? What harm may result if I choose to do nothing now? If we do not begin Class II orthopedic treatment now, then we may miss the opportunity to maximize orthopedic treatment effects if she begins her growth acceleration soon. However, at the age of eight years, we anticipate she is about one and a half to two years in advance of beginning her facial growth acceleration, as the average age for female peak mandibular growth velocity is ~eleven and a half years [41]. Also, she is at increased risk for damage to her maxillary incisors if we do not reduce her OJ. Finally, if we do not place an LLHA for another year, or do not expand her maxilla with RME for another year, then we anticipate no harm will result.

A: A compelling reason would be if pain or tissue damage resulted from mandibular incisor palatal impingement. However, clinical examination and discussions with Alexandra reveal neither pain nor tissue damage is present.

How do you respond? Should you extract her mandibular primary canines in order to align her mandibular incisors? Should you begin serial extraction? What do you recommend?

A: Let’s consider our options and make a recommendation:

1. Extraction of mandibular primary canines – could reduce mandibular incisor crowding (improve incisor alignment) via transeptal fiber pull. However, by extracting mandibular primary canines, you incur the risk of primary and permanent molars drifting to the mesial resulting in arch perimeter loss. Further, we see no compelling reason to put the child through unnecessary surgical procedures. If you decide to extract mandibular primary canines, then we recommend placing an LLHA to reduce mesial molar drift and arch perimeter loss.
2. Serial extraction – Alexandra is not a good candidate for serial extraction. Why?

The ideal serial extraction patient is in the early mixed dentition and normal in every way except severe anterior crowding (≥ 9 mm per arch). Specifically, the ideal serial extraction patient presents with:

• Class I permanent first molars. Alexandra is severely Class II (6 mm) secondary to mandibular skeletal deficiency. This Class II relationship should be corrected to Class I before permanent tooth extractions. Why? If we follow a serial extraction protocol and eventually extract mandibular premolars in the presence of a Class II interarch relationship, then Alexandra’s Class II canine relationship could worsen as her mandibular permanent canines move distally into the mandibular first premolar extraction spaces.
• Vertically normal to slightly long soft tissue and skeletal LAFH, with minimal OB or possibly a mild open bite, but not a deep bite. Alexandra has a 100% deep bite (palatal impingement). Retracting anterior teeth following premolar extractions could worsen her deep bite.
• Normal incisor angulation or proclined incisors, but not upright incisors. Without a cephalometric radiograph and analysis, we cannot state whether Alexandra exhibits this feature. However, based upon her intraoral photographs, we believe that her maxillary central incisors are proclined.
• Normal posterior transverse relationship (normal intermolar arch widths with good posterior interdigitation; absence of posterior crossbites; and absence of significant transverse compensations). Posterior crossbites are absent. However, Alexandra exhibits large buccal corridors, her maxilla appears narrow (Figure 4.38b), and we cannot rule out the presence of posterior transverse compensations from the records presented.
• Severe (≥ 9 mm) anterior crowding: Alexandra does not exhibit this feature because she has only moderate (5 mm) mandibular anterior crowding.

Based upon the above, Alexandra is not an ideal candidate for serial extraction. We recommend neither serial extraction nor extraction of mandibular primary canines.

A: Yes, you should question them regarding: [1, 2]

• Past dental trauma
• Risk‐taking behavior
• Participation in sports
• ADHD
• Cognitive psychomotor issues
• Teasing

Her parents deny all of these.

A: Lip soft tissue coverage acts as an incisor cushion in the event of facial trauma. Lip soft tissue coverage and negative responses to the previous question will reduce the need for early OJ reduction treatment.

A: Skeletal discrepancies (apical base discrepancies) in the anteroposterior, vertical, or transverse dimensions can be treated using orthopedics, masking (camouflage), or surgery.

• Class II orthopedics would include restricting Alexandra’s forward maxillary growth (while permitting the mandible to continue growing forward) or attempting to accelerate mandibular forward growth.
• Masking or camouflage seeks to achieve a Class I (canine) relationship, and excellent occlusion, dentally without addressing the underlying skeletal discrepancy. We generally consider masking during comprehensive treatment in adult dentition.
• Surgery would involve lengthening her mandible so that it relates properly to her maxilla. We generally consider surgery during comprehensive treatment in adult dentition.

A: We lack a cephalometric analysis of Alexandra, so we are judging her mandibular skeletal deficiency based upon a very retrusive profile (Figure 4.38c) and 6 mm permanent first molar Class II relationship (Figures 4.38e and 4.38g). However, in our clinical opinion, her mandibular deficiency appears severe.

Alexandra is only eight years old, and we have her entire adolescent growth period to attempt correction. Even if we cannot achieve full orthopedic correction to Class I with an improved profile, with good compliance, we may be able to at least improve her skeletal discrepancy to the point where we can mask/camouflage her, acceptably.

In terms of when to attempt orthopedic treatment – there is no advantage in treating Class II relationships in the early mixed dentition (except for a possible decrease in incisal trauma as a result of excess OJ) [22–24, 29,38–40]. However, even if a patient is in the early mixed dentition – if he/she exhibits good statural growth, we recommend that you consider initiating Class II orthopedic treatment. We spoke to Alexandra’s parents who stated that she had not yet entered her growth spurt and did not appear to be growing continuously.

A: Ask them to begin recording her height, monthly, and to keep you informed of changes. Or, you can recall Alexandra bimonthly or trimonthly to record her change in height yourself.

A: Closing her maxillary anterior spaces with fixed appliances would retract her maxillary incisors and reduce her OJ. However, her diastema is only a few millimeters wide (Figure 4.38h), and its closure would reduce OJ minimally.

A: Significant unknowns include future jaw growth magnitude and direction, an undetected CR‐CO shift, and patient compliance.

A: Treatment options include the following:

• Recall (no early treatment, monitor only) – recall Alexandra in one year to evaluate tooth eruption. This is an excellent option. Why? Alexandra’s primary problems are her Class II molar relationship secondary to mandibular skeletal hypoplasia, dental deep bite, narrow maxilla, and moderate mandibular anterior crowding. These problems can all be corrected later.

The highest level of scientific evidence concludes that Class II correction in two stages (early initial treatment followed by later adolescent treatment) does not offer any advantages over one stage treatment (later adolescent) [85] – except possibly a reduction in incisal trauma. Alexandra has no history of incisor trauma, she is in the early mixed dentition, and her parents state that she does not appear to be growing.

Her dental deep bite can be corrected later (she lacks pain when biting and tissue trauma), her narrow maxilla can be corrected later (before puberty), and her moderate mandibular anterior crowding can be improved later using leeway space and placement of an LLHA.

• Space maintenance – placement of an LLHA before exfoliation of Alexandra’s primary canines and primary molars. Space maintenance is reasonable at a future date because 1.8 mm of mandibular arch crowding is anticipated following the eruption of all permanent teeth if one is employed. However, there is no compelling need to place an LLHA now, since the emergence of her permanent canines and premolars is not imminent. We would not recommend a Nance holding arch since it will not improve Alexandra’s Class II molar relationship.
• Class II orthopedic treatment – since Alexandra is in the early mixed dentition and a change in her statural height is not apparent, we recommend delaying initiation of Class II orthopedic treatment.
• Mandibular space regaining – opening space for Alexandra’s mandibular permanent lateral incisors. Since we cannot say with certainty that Alexandra’s mandibular primary lateral incisors were lost prematurely or that her deep bite forced her mandibular incisors lingually (reducing arch length), we cannot say with certainty that opening these spaces would be space regaining. Also, proclining her mandibular anterior teeth by opening lateral spaces would be ill‐advised because of the very thin periodontal biotype labial to her mandibular central incisors (Figure 4.38f). Gingival recession could result if her mandibular central incisors are proclined. Finally, since we anticipate minimal mandibular arch crowding (1.8 mm) if we place an LLHA, there is no compelling reason to open space for the mandibular lateral incisors now.

• RME – to widen Alexandra’s maxilla and reduce her large buccal corridors. If Alexandra exhibited a lateral CR‐CO shift into a unilateral crossbite, then we would strongly recommend RME to reduce the likelihood of her growing into a mandibular skeletal asymmetry. However, she does not exhibit a lateral shift.

RME may eventually be recommended, especially if Alexandra exhibits significant posterior dental compensations (maxillary molar buccal crown torque, mandibular molar lingual crown torque). At that time, expanding her maxilla would increase her posterior OJ which could then be used to upright her mandibular posterior teeth transversely without putting her into posterior crossbite. Another reason to eventually consider RME would be to provide better arch coordination if differential jaw growth brings a wider part of her mandible forward relative to her maxilla.

• Extraction of maxillary primary canines (and possibly maxillary primary first molars) – to facilitate eruption of Alexandra’s maxillary permanent canines. Although such treatment may eventually be considered, Alexandra’s dental development is too early (Figure 4.38d) to consider primary tooth extractions now.
• Extraction of mandibular primary canines – to improve mandibular incisor alignment. Sometimes, parents insist on this treatment, but you must be careful about letting parents dictate treatment. It would be better to educate parents about leeway space and space maintenance which, in many cases, reduces or eliminates mandibular anterior crowding spontaneously. If you decide to extract mandibular primary canines, then place an LLHA to minimize potential arch perimeter loss due to mesial molar drift.
• Serial extraction – as discussed earlier, Alexandra is not an ideal candidate for serial extraction.

A: Since Alexandra was not exhibiting good statural growth velocity (was not growing continuously or entering her adolescent growth spurt), we decided to monitor only and recall her in one year. Her parents said they would measure her height each month and inform us of changes. We told her parents that Alexandra was at an increased risk of maxillary incisor trauma due to her OJ being >3 mm and recommended that she wear a mouthguard when playing sports.

A: We would take new records, including a lateral cephalometric radiograph. Based upon our analysis at that time, we anticipate treating her with RME to widen her maxilla and reduce her buccal corridors, with an LLHA to reduce mandibular anterior crowding using leeway space and to reduce mandibular first permanent molar eruption (thereby helping B‐point to rotate forward with mandibular growth), and with high‐pull headgear to restrict forward maxillary growth while allowing her mandible to continue growing forward. High‐pull headgear wear will also retract maxillary molars distally (helping to correct the Class II relationship) and reduce maxillary molar eruption (helping B‐point to rotate forward with mandibular growth). We may also fabricate and ask her to wear a mandibular clear retainer to disarticulate her occlusion. We would not treat her with a Class II functional appliance because we do not want her mandibular incisors to procline and stress her mandibular labial periodontal tissue.

Note: Placement of an LLHA will force Class II correction through headgear effects – and not through mandibular permanent molar mesial drift.

A: Goals will include improving her profile and smile, increasing her chin projection, achieving a Class I canine relationship, achieving a Class I molar relationship if she is treated either non‐extraction or with the extraction of two premolars in both arches, and achieving minimal OB and OJ.

A:

A: No additional records are needed in order to decide whether to recall Mark or begin early treatment.

A:

Average mesiodistal widths of permanent teeth (mm): [81]

Average mesiodistal widths of primary teeth (mm): [81]

MAXILLARY ARCH

+1.0 mm of anterior spacing (midline diastema, Figure 4.39j)

−1.0 mm of left lateral incisor crowding

+2.0 mm of anticipated leeway space (1.0 mm/side)

Balance = + 1.0 mm −1.0 mm + 2.0 mm = +2.0 mm

MANDIBULAR ARCH (leeway space cannot be included because mandibular permanent canines have already erupted)

+9.9 mm width mandibular left primary second molar

−7.0 mm anticipated width mandibular left second premolar

+7.7 mm width mandibular left primary first molar

−7.0 mm anticipated width mandibular left first premolar

−4.0 mm anterior crowding currently present

+7.7 mm width mandibular right primary first molar

−7.0 mm anticipated width mandibular right first premolar

+9.9 mm width mandibular right primary second molar

7.0 mm anticipated width mandibular right second premolar

Balance = +9.9 mm − 7.0 mm + 7.7 mm − 7.0 mm − 4.0 mm + 7.7 mm − 7.0 mm + 9.9 mm − 7.0 mm

= +3.2 mm

That is, 2 mm of maxillary spacing and 3.2 mm of mandibular spacing are anticipated following the eruption of all permanent teeth (if proper space maintenance is employed).

A: First Principle: Define the patient’s primary problems in each dimension (plus other major problems) and stay focused on these problems during treatment planning and throughout treatment delivery. At every appointment, check primary problems in CR.

A:

A: Mark’s maxillary incisors are stepped down (overerupted) by 2–3 mm relative to his maxillary posterior teeth, and his mandibular incisors are stepped up (overerupted) 4 mm relative to his mandibular posterior teeth.

A: Incisor overeruption caused Mark’s dental deep bite and palatal impingement.

A: In the context of the three principles:

1. The goal of early treatment is to correct developing problems – get the patient back to normal for their stage of development (including preventing complications such as resorption of adjacent tooth roots, reducing later treatment complexity, or reducing/eliminating unknowns). Correcting Mark’s Class II skeletal and dental relationships, excessive OJ, and dental deep bite, alleviating his moderate mandibular anterior crowding, and uprighting his mandibular incisors would get Mark back on track for his stage of development.
2. Early treatment should address very specific problems with a clearly defined end point, with any active treatment component completed within six to nine months (except for some orthopedic problems). Orthopedic correction of Mark’s Class II discrepancy and excessive OJ could take longer than six to nine months.

   His deep bite could be corrected by leveling dental arches with fixed orthodontic appliances within six to nine months, but uprighting his mandibular incisors could take longer. His moderate (4 mm) mandibular crowding could be resolved by placing an LLHA, but this correction may take longer than nine months depending upon when Mark’s permanent teeth erupt. Also, please remember that placement of an LLHA will not only prevent uprighting of his mandibular anterior teeth but will procline them slightly [86, 87].

   

3. Always ask yourself: Is it necessary that I treat the patient now? What harm may occur if I choose to recall?
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