Moderate Nonskeletal Problems in Preadolescent Children
Preventive and Interceptive Treatment in Family Practice
For a dentist seeing a young patient with a malocclusion, the first question is whether orthodontic treatment is needed. If so, the next question is: when should it be done? Finally, who should do it? Does this patient need referral to a specialist?
In military and emergency medicine, triage is the process used to separate casualties by the severity of their injuries. Its purpose is twofold: to separate patients who can be treated at the scene of the injury from those who need transportation to specialized facilities and to develop a sequence for handling patients so that those most likely to benefit from immediate treatment will be treated first. Since orthodontic problems almost never are an emergency, the process of sorting orthodontic problems by their severity is analogous to medical triage in only one sense of the word. On the other hand, it is very important for the primary care dentist to be able to distinguish problems that generally need to be treated soon, as opposed to more routine problems that can wait for later comprehensive care. Along the same lines, sorting out moderate from complex problems is essential because this process determines which patients are appropriately treated within family practice and which are most appropriately referred to a specialist.
As with all components of dental practice, a generalist’s decision of whether to include orthodontic treatment as a component of his or her services is an individual one, best based on education, experience, and ability. The principle that the less severe problems are handled within the context of general practice and the more severe problems are referred should remain the same, however, regardless of the practitioner’s interest in orthodontics. Only the cutoff points for treating a patient in the general practice or referral should change.
This section presents a logical scheme for orthodontic triage for children. It is based on the diagnostic approach developed in Chapter 6 and incorporates the principles of determining treatment need that have been discussed. An adequate database and a thorough problem list, of course, are necessary to carry out the triage process. A cephalometric radiograph is not required since a facial form analysis is more appropriate in the generalist’s office, but appropriate dental radiographs are needed (usually, a panoramic film; occasionally, bitewings supplemented with anterior occlusal radiographs) as are dental casts and photographs. A space analysis (see later in this chapter) is essential. A flow chart illustrating the steps in the triage sequence accompanies this section.
The first step in the triage process is to separate out patients with facial syndromes and similarly complex problems (Figure 11-1) so they can be treated by specialists or teams of specialists. From physical appearance, the medical and dental histories, and an evaluation of developmental status, nearly all such patients are easily recognized. Examples of these disorders are cleft lip or palate, Treacher Collins syndrome, hemifacial microsomia, and Crouzon’s syndrome (see Chapter 3). Complex medical treatments, such as radiation, bisphosphonates, and growth hormones, can affect dentofacial development and responses to treatment. Patients who appear to be developing either above the 97th or below the third percentiles on standard growth charts require special evaluation. Growth disorders may demand that any orthodontic treatment be carried out in conjunction with endocrine, nutritional, or psychologic therapy. For these patients and those with diseases that affect growth, such as juvenile rheumatoid arthritis, the proper orthodontic therapy must be combined with identification and control of the disease process.
FIGURE 11-1 Orthodontic triage, step 1.
Patients with significant skeletal asymmetry (not necessarily those whose asymmetry results from only a functional shift of the mandible due to dental interferences caused by crossbites) always fall into the severe problem category (Figure 11-2). These patients could have a developmental problem or the growth anomaly could be the result of an injury. Treatment is likely to involve growth modification and/or surgery, in addition to comprehensive orthodontics. Timing of intervention is affected by whether the cause of the asymmetry is deficient or excessive growth (see Chapter 13), but early comprehensive evaluation is always indicated.
FIGURE 11-2 At age 8, this boy has a noticeable mandibular asymmetry with the chin several millimeters off to the left. A problem of this type is likely to become progressively worse and is an indication for referral for comprehensive evaluation by a facial deformities team. (From Proffit WR, White RP, Sarver DM. Contemporary Treatment of Dentofacial Deformity. St. Louis: Mosby; 2003.)
Skeletal Class II and Class III problems and vertical deformities of the long-face and short-face types, regardless of their cause, require thorough cephalometric evaluation to plan appropriate treatment and its timing and must be considered complex problems (Figure 11-4). Issues in treatment planning for growth modification are discussed in Chapter 13. As a general rule, Class II treatment can be deferred until near adolescence and be equally effective as earlier treatment, while Class III treatment for maxillary deficiencies should be addressed earlier. Class III treatment for protrusive mandibles appears equally ineffective whenever it is attempted. Treatment of both long- and short-face problems probably can be deferred, since the former is due to growth that persists until the late teens and outstrips early focused intervention, and the latter usually can be managed well with comprehensive treatment during adolescence. As with asymmetry, early evaluation is indicated even if treatment is deferred, so early referral is appropriate.
FIGURE 11-3 Orthodontic triage, step 2.
FIGURE 11-4 Patients with a skeletal problem of even moderate severity should be identifiable clinically. A, Skeletal Class II due to mandibular deficiency. B, Skeletal Class III with a component of both maxillary deficiency and mandibular excess. Both types of problems can easily be picked up from examination of the profile. A cephalometric radiograph at this age is not needed for diagnosis, but would be indicated if early treatment is planned.
Severe dental protrusion or retrusion, which also are complex treatment problems, should be recognized during the facial profile analysis. The urgency for treating these problems usually depends on the esthetic impact or in the case of protrusion, the potential for traumatic injury. Otherwise, they should be treated as noted above.
Some individuals with good skeletal proportions have protrusion of incisor teeth rather than crowding (Figure 11-5). When this occurs, the space analysis will show a small or nonexistent discrepancy because the incisor protrusion has compensated for the potential crowding. Excessive protrusion of incisors (bimaxillary protrusion, not excessive overjet) usually is an indication for premolar extraction and retraction of the protruding incisors. This is complex and prolonged treatment. Because of the profile changes produced by adolescent growth, it is better for most children to defer extraction to correct protrusion until late in the mixed dentition or early in the permanent dentition. Techniques for controlling the amount of incisor retraction are described in Chapter 15.
FIGURE 11-5 A, Bimaxillary dentoalveolar protrusion. Note the lip strain to bring the lips together over the teeth. The lips were separated at rest by the protruding incisors. B and C, Occlusal views show the spacing in the upper arch and very mild crowding in the lower arch. For this girl, potential crowding of the teeth is expressed almost completely as protrusion.
Unlike the more complex skeletal problems and problems related to protruding incisors, problems involving dental development often need treatment as soon as they are discovered, typically during the early mixed dentition, and often can be handled in family practice. Considerations in making that decision are outlined in Figure 11-6, and treatment of the less severe problems of this type is presented in detail in this chapter.
FIGURE 11-6 Orthodontic triage, step 3.
Treatment for an abnormal sequence of dental development should be planned only after a careful determination of the underlying cause. Asymmetric eruption (one side ahead of the other by 6 months or more) is significant. It requires careful monitoring of the situation, and in the absence of outright pathology, often requires early treatment such as selective extraction of primary or permanent teeth. A few patients with asymmetric dental development have a history of childhood radiation therapy to the head and neck or traumatic injury. Surgical and orthodontic treatment for these patients must be planned and timed carefully and may require tooth removal or tooth reorientation. Some of these teeth have severely dilacerated roots and will not be candidates for orthodontics. These situations definitely fall into the complex category and usually require early intervention.
The permanent teeth most likely to be congenitally missing are the maxillary lateral incisors and the mandibular second premolars. Maxillary central and lateral incisors are the teeth most likely to be lost to trauma.
The treatment possibilities differ slightly for anterior and posterior teeth. For missing posterior teeth, it is possible to (1) maintain the primary tooth or teeth, (2) extract the overlying primary teeth and then allow the adjacent permanent teeth to drift, (3) extract the primary teeth followed by immediate orthodontic treatment, or (4) replace the missing teeth prosthetically or perhaps by transplantation or an implant later. For anterior teeth, maintaining the primary teeth is often less of an option due to the esthetics and the spontaneous eruption of adjacent permanent teeth into the space of the missing tooth. Also, extraction and drift of the adjacent teeth is less appealing because anterior edentulous ridges deteriorate quickly. As with other growth problems, early evaluation and planning is essential. Treatment of missing tooth problems in mixed dentition children is discussed in more detail in Chapter 12.
For all practical purposes, ankylosed permanent teeth at an early age or teeth that fail to erupt for other reasons (like primary failure of eruption) fall into the same category as missing teeth. These severe problems often require a combination of surgery (for extraction or decoronation) and orthodontics, if indeed the condition can be treated satisfactorily at all. After surgical intervention, the ultimate choices are orthodontic space closure, transplantation into the affected area, or prosthetic replacement.
Ninety percent of all supernumerary teeth are found in the anterior part of the maxilla. Multiple or inverted supernumeraries and those that are malformed often displace adjacent teeth and cause problems in their eruption. The presence of multiple supernumerary teeth indicates a complex problem and perhaps a syndrome or congenital abnormality like cleidocranial dysplasia. Early removal of the supernumeraries is indicated, but this must be done carefully to minimize damage to adjacent teeth. If the permanent teeth have been displaced or severely delayed, surgical exposure, adjunctive periodontal surgery, and possibly mechanical traction are likely to be required to bring them into the arch after the supernumerary has been removed.
Single supernumeraries that are not malformed often erupt spontaneously, causing crowding problems. If these teeth can be removed before they cause distortions of arch form, extraction may be all that is needed.
Ectopic eruption (eruption of a tooth in the wrong place, or along the wrong eruption path) often leads to early loss of a primary tooth, but in severe cases, resorption of permanent teeth can result. Repositioning of the ectopically erupting tooth may be indicated, either surgically or by exposing the problem tooth, placing an attachment on it, and applying traction. A dramatic variation of ectopic eruption is transposition of teeth. Early intervention can reduce the extent to which teeth are malpositioned in some cases. These severe problems often require a combination of surgery and orthodontics and may be genetically linked to other anomalies. They are discussed in Chapter 12.
Orthodontic problems in a child with good facial proportions involve crowding, irregularity, or malposition of the teeth (Figure 11-7). At this stage, regardless of whether crowding is apparent, the results of space analysis are essential for planning treatment. The presence or absence of adequate space for the teeth must be taken into account when other treatment is planned.
FIGURE 11-7 Orthodontic triage, Step 4.
In interpreting the results of space analysis for patients of any age, remember that if space to align the teeth is inadequate, either of two conditions may develop. One possibility is for the incisor teeth to remain upright and well positioned over the basal bone of the maxilla or mandible and then rotate or tip labially or lingually. In this instance, the potential crowding is expressed as actual crowding and is difficult to miss (Figure 11-8). The other possibility is for the crowded teeth to align themselves completely or partially at the expense of the lips, displacing the lips forward and separating them at rest (see Figure 11-5). Even if the potential for crowding is extreme, the teeth can align themselves at the expense of the lip, interfering with lip closure. This must be detected on profile examination. If there is already a degree of protrusion in addition to the crowding, it is safe to presume that the natural limits of anterior displacement of incisors have been reached.
FIGURE 11-8 In some patients, as in this young adult (A), potential crowding is expressed completely as actual crowding (B and C) with no compensation in the form of dental and lip protrusion. In others (see Figure 11-5) potential crowding is expressed as protrusion. The teeth end up in a position of equilibrium between the tongue and lip forces against them (see Chapter 5).
Depending on the circumstances, the appropriate response to space deficiencies varies. For space loss of 3 mm or less, lost space can be regained. For space shortage of 4 mm or less or crowding with adequate space, repositioning incisors labially or space management during the transition are appropriate. Of these procedures, only treatment to regain space and manage transitional space is critical in terms of timing. Treatment planning for these moderate problems is outlined below in this chapter. Space discrepancies of 5 mm or more, with or without incisor protrusion, constitute complex treatment problems. In these children, if teeth are not extracted, maximum anchorage or robust mechanics must be employed, and if teeth are extracted, the anchorage considerations are critical. Severe crowding of 10 mm or more also requires careful and complex planning and often early intervention, so that permanent teeth are not impacted or deflected into eruption paths that affect other permanent teeth or bring them into the oral cavity through nonkeratinized tissue.
Generally, minor midline diastemas will close and cause little esthetic or developmental problems. Large diastemas, over 2 mm, can be esthetic concerns and inhibit adjacent teeth from erupting properly. They are cause for heightened concern and early treatment.
Whether crossbite and overbite/open bite should be classified as moderate or severe is determined for most children from their facial form (Figure 11-9). Mixed dentition treatment for all of these problems must be discussed in the context of “should be treated” versus “can be treated.”
FIGURE 11-9 Orthodontic triage, step 5.
As a general guideline, posterior crossbite in a preadolescent child falls into the moderate category if no other complicating factors (like severe crowding) are present. It should be treated early if the child shifts laterally from the initial dental contact position. Although it can be treated early if there is no shift, often it is better to delay until the late mixed dentition so the erupting premolars and second molars can be guided into position. If a skeletal posterior crossbite is treated in adolescence, it will require heavier forces and more complex appliances.
Anterior crossbite usually reflects a jaw discrepancy but can arise from lingual tipping of the incisors or crowding as they erupt. Treatment planning for the use of removable versus fixed appliances to correct these simple crossbites early is discussed below.
Excessive overjet, with the upper incisors flared and spaced, often reflects a skeletal problem but also can develop in patients with good jaw proportions. If adequate vertical clearance is present, the teeth can be tipped lingually and brought together with a simple removable appliance when the child is almost any age, and the timing of treatment often depends on child and parent preference.
Anterior open bite in a young child with good facial proportions usually needs no treatment because there is a good chance of spontaneous correction with additional incisor eruption, especially if the open bite is related to an oral habit like finger sucking. A complex open bite (one with skeletal involvement or posterior manifestations) or any open bite in an older patient is a severe problem. A deep overbite can develop in several ways (see Chapter 6) but often is caused by or made worse by short anterior face height. This is seldom treated in the mixed dentition.
Traumatically displaced erupted incisors pose a special problem because of the resulting occlusal problems. There is a risk of ankylosis after healing occurs, especially after traumatic intrusion. If the apex is open and root development is incomplete, waiting for spontaneous re-eruption is warranted. If the injuries are more severe or in older patients, either immediate orthodontic or surgical treatment is needed, and the long-term prognosis must be guarded. Treatment planning after trauma is discussed in Chapter 13.
This triage scheme is oriented toward helping the family practitioner decide which children with orthodontic problems to treat and which to refer. Treatment for children with moderate nonskeletal problems, those selected for treatment in family practice using the triage scheme, is discussed later in this chapter. Early (preadolescent) treatment of more severe and complex nonskeletal problems is discussed in Chapter 12, and treatment for skeletal problems is discussed in Chapter 13.
Posterior crossbite in mixed dentition children is reasonably common, occurring in 7.1% of U.S. children aged 8 to 11.1 It usually results from a narrowing of the maxillary arch and often is present in children who have had prolonged sucking habits. The crossbite can be due to a narrow maxilla (i.e., to skeletal dimensions) or due only to lingual tipping of the maxillary teeth. If the child shifts on closure or if the constriction is severe enough to significantly reduce the space within the arch, early correction is indicated. If not, treatment can be deferred, especially if other problems suggest that comprehensive orthodontics will be needed later.
It is also important to determine whether any associated mandibular asymmetry is the result of a shift of the lower jaw due to dental interferences or is due to a true maxillary or mandibular asymmetry. Another critical question is whether the posterior crossbite is related to skeletal maxillary retrusion or mandibular protrusion. In these cases, the anteroposterior position of the maxilla or mandible is contributing to the crossbite, and the actual transverse dimension of the palate may be normal.
Correcting posterior crossbites in the mixed dentition increases arch circumference and provides more room for the permanent teeth. On the average, a 1 mm increase in the inter-premolar width increases arch perimeter values by 0.7 mm.2 Total relapse into crossbite is unlikely in the absence of a skeletal problem, and mixed dentition expansion reduces the incidence of posterior crossbite in the permanent dentition, so early correction also simplifies future diagnosis and treatment by eliminating at least that problem from the list.
Although it is important to determine whether the crossbite is skeletal or dental, in the early mixed dentition years the treatment is usually the same, since relatively light forces will move teeth and bones. An expansion lingual arch is the best choice at this age—heavy force from a jackscrew device is needed only when the midpalatal suture has become significantly interdigitated during adolescence (Figure 11-10; also see Chapter 13). Heavy force and rapid expansion are not indicated in the primary or early mixed dentition. There is a significant risk of distortion of the nose if this is done in younger children (see Figure 7-8).
FIGURE 11-10 In young children, lingual arch type maxillary expansion devices (W-arches and quad helixes) deliver enough force to open the midpalatal suture as demonstrated in this maxillary occlusal radiograph.
In a few cases, mostly observed in the primary or early mixed dentition, a shift into posterior crossbite will be due solely to occlusal interference caused by the primary canines or (less frequently) primary molars. These patients can be diagnosed by carefully positioning the mandible in centric occlusion; then it can be seen that the width of the maxilla is adequate and that there would be no crossbite without the shift (Figure 11-11). In this case, a child requires only limited equilibration of the primary teeth (often, just reduction of the primary canines) to eliminate the interference and the resulting lateral shift into crossbite.3
FIGURE 11-11 Minor canine interferences leading to a mandibular shift. A, Initial contact. B, Shift into centric occlusion. The slight lingual position of the primary canines can lead to occlusal interferences and an apparent posterior crossbite. This sole cause of posterior crossbite is infrequent and is best treated by occlusal adjustment of the primary canines.
More commonly, a lateral shift into crossbite is caused by constriction of the maxillary arch. Even a small constriction creates dental interferences that force the mandible to shift to a new position for maximum intercuspation (Figure 11-12), and moderate expansion of the maxillary dental arch is needed for correction. The general guideline is to expand to prevent the shift when it is diagnosed, but there is an exception: if the permanent first molars are expected to erupt in less than 6 months, it is better to wait for their eruption so that correction can include these teeth, if necessary. A greater maxillary constriction may allow the maxillary teeth to fit inside the mandibular teeth—if so, there will not be a shift on closure (Figure 11-13), and there is less reason to provide early correction of the crossbite.
FIGURE 11-12 Moderate bilateral maxillary constriction. A, Initial contact. B, Shift into centric occlusion. Moderate bilateral maxillary constriction often leads to posterior interferences upon closure and a lateral shift of the mandible into an apparent unilateral posterior crossbite. This problem also is best treated by bilateral maxillary expansion.
FIGURE 11-13 Marked bilateral maxillary constriction. A, Initial contact. B, Centric occlusion (no shift). Severe constriction often produces no interferences upon closure, and the patient has a bilateral posterior crossbite in centric relation. This problem is best treated by bilateral maxillary expansion.
Although it is possible to treat posterior crossbite with a split-plate type of removable appliance, there are three problems: this relies on patient compliance for success, treatment time is longer, and it is more costly than an expansion lingual arch.4 The preferred appliance for a preadolescent child is an adjustable lingual arch that requires little patient cooperation.
Both the W-arch and the quad helix are reliable and easy to use. The W-arch is a fixed appliance constructed of 36 mil steel wire soldered to molar bands (Figure 11-14). It is activated simply by opening the apices of the W and is easily adjusted to provide more anterior than posterior expansion, or vice versa, if this is desired. The appliance delivers proper force levels when opened 4 to 6 mm wider than the passive width and should be adjusted to this dimension before being cemented. It is not uncommon for the teeth and maxilla to move more on one side than the other, so precise bilateral expansion is the exception rather than the rule, but acceptable correction and tooth position are almost always achieved.
FIGURE 11-14 The W-arch appliance is ideal for bilateral maxillary expansion. A, The appliance is fabricated from 36 mil wire and soldered to the bands. The lingual wire should contact the teeth involved in the crossbite and extend not more than 1 to 2 mm distal to the banded molars to eliminate soft tissue irritation. Activation at point 1 produces posterior expansion and activation at point 2 produces anterior expansion. B, The lingual wire should remain 1 to 1.5 mm away from the marginal gingiva and the palatal tissue. C, This W-arch is being used to correct a bilateral constriction in the primary dentition.
The quad helix (Figure 11-15) is a more flexible version of the W-arch, although it is made with 38 mil steel wire. The helices in the anterior palate are bulky, which can effectively serve as a reminder to aid in stopping a finger habit. The combination of a posterior crossbite and a finger-sucking habit is the best indication for this appliance. The extra wire incorporated in it gives it a slightly greater range of action than the W-arch, but the forces are equivalent. Soft tissue irritation can become a problem with the quad helix. Both the W-arch and the quad helix leave an imprint on the tongue. Both the parents and child should be warned about this (Figure 11-16). The imprint will disappear when the appliance is removed but can take up to a year to totally do so.
FIGURE 11-15 The quad helix used to correct bilateral maxillary constriction. A, The appliance is fabricated from 38 mil wire and soldered to the bands. The lingual wire should contact the teeth involved in the crossbite and extend no more than 1 to 2 mm distal to the banded molars to eliminate soft tissue irritation. Activation at point 1 produces posterior expansion, while activation at point 2 produces anterior expansion. B, The lingual wire should remain 1 to 1.5 mm away from the marginal gingiva and palatal tissue. C, This quad helix is being used to correct a bilateral maxillary constriction in the primary dentition.
FIGURE 11-16 W-arches, quad helixes, and habit appliances often leave indentations in the superior surface of the tongue (arrows). These often remain after appliance removal for up to 1 year. No treatment is recommended, but patients and parents should be warned of this possibility.
With both types of expansion lingual arches, some opening of the midpalatal suture can be expected in a primary or mixed dentition child, so the expansion is not solely dental. Expansion should continue at the rate of 2 mm per month (1 mm on each side) until the crossbite is slightly overcorrected. In other words, the lingual cusps of the maxillary teeth should occlude on the lingual inclines of the buccal cusps of the mandibular molars at the end of active treatment (Figure 11-17). Intraoral appliance adjustment is possible but may lead to unexpected changes. For this reason, removal and re-cementation are recommended at each active treatment visit. Most posterior crossbites require 2 to 3 months of active treatment (with the patients seen each month for adjustments) and 3 months of retention (during which the lingual arch is left passively in place). This mixed dentition correction appears to be stable in the long term.5
FIGURE 11-17 A, Posterior crossbites should be overcorrected until the maxillary posterior lingual cusps occlude with the lingual inclines of the mandibular buccal cusps, as shown here, and then retained for approximately 3 months. B, After retention, slight lingual movement of the maxillary teeth results in normal occlusion.
Some children do have a true unilateral crossbite due to unilateral maxillary constriction of the upper arch (Figure 11-18). In these cases, the ideal treatment is to move selected teeth on the constricted side. To a limited extent, this goal of asymmetric movement can be achieved by using different length arms on a W-arch or quad helix (Figure 11-19), but some bilateral expansion must be expected. An alternative is to use a mandibular lingual arch to stabilize the lower teeth and attach cross-elastics to the maxillary teeth that are at fault. This is more complicated and requires cooperation to be successful but is more unilateral in its effect.
FIGURE 11-18 True unilateral maxillary posterior constriction. A, Initial contact. B, Full occlusion (no shift). True unilateral constriction has a unilateral posterior crossbite in centric relation and in centric occlusion, without a lateral shift. This problem is best treated with unilateral posterior expansion.
FIGURE 11-19 An unequal and asymmetric W-arch used to correct a true unilateral maxillary constriction. The side of the arch to be expanded has fewer teeth against the lingual wire than the anchorage unit. Even with this arrangement, both sides can be expected to show some expansion movement and the extent cannot be predicted.
All of the appliances described above are aimed at correction of teeth in the maxillary arch, which is usually where the problem is located. If teeth in both arches contribute to the problem, cross-elastics between banded or bonded attachments in both arches (Figure 11-20) can reposition both upper and lower teeth. The best choice is a latex elastic with a -inch (5 mm) lumen generating 6 ounces (170 gm) of force. The force from the elastics is directed vertically as well as faciolingually, which will extrude the posterior teeth and reduce the overbite. Therefore cross-elastics should be used with caution in children with increased lower face height or limited overbite. Crossbites treated with elastics should be overcorrected, and the bands or bonds left in place immediately after active treatment. If there is too much relapse, the elastics can be reinstated without rebanding or rebonding. When the occlusion is stable after several weeks without elastic force, the attachments can be removed. The most common problem with this form of crossbite correction is lack of cooperation from the child.
FIGURE 11-20 A, This patient has the permanent maxillary left first molar displaced lingually and the permanent mandibular left first molar displaced facially, which resulted in a posterior crossbite between these teeth. B, A short and relatively heavy cross-elastic is placed between the buttons welded on the bands. The elastic can be challenging for some children to place but should be worn full-time and changed frequently.
FIGURE 11-21 This flowchart can be used to aid decision making regarding possible options for posterior crossbite correction in the primary and mixed dentitions. Answers to the questions posed in the chart should lead to successful treatment pathways. The approaches to skeletal correction of posterior crossbites are described in Chapter 13.
Anterior crossbite, particularly crossbite of all of the incisors, is rarely found in children who do not have a skeletal Class III jaw relationship. A crossbite relationship of one or two anterior teeth, however, may develop in a child who has good facial proportions. When racial/ethnic groups in the U.S. population are combined, about 3% of children have an anterior crossbite in the mixed dentition (see Figure 1-7).
In planning treatment for anterior crossbites, it is critically important to differentiate skeletal problems of deficient maxillary or excessive mandibular growth from crossbites due only to displacement of teeth.6 If the problem is truly skeletal, simply changing the incisor position is inadequate treatment, especially in more severe cases (see Chapter 13).
Anterior crossbite affecting only one or two teeth almost always is due to lingually displaced maxillary central or lateral incisors. These teeth tend to erupt to the lingual because of the lingual position of the developing tooth buds and may be trapped in that location, especially if there is not enough space (Figure 11-22). Sometimes, central incisors are involved because they were deflected toward a lingual eruption path by supernumerary anterior teeth or overretained primary incisors. More rarely, trauma to maxillary primary teeth reorients a permanent tooth bud or buds lingually.
The most common etiologic factor for nonskeletal anterior crossbites is lack of space for the permanent incisors, and it is important to focus the treatment plan on management of the total space situation, not just the crossbite. If the developing crossbite is discovered before eruption is complete and overbite has not been established, the adjacent primary teeth can be extracted to provide the necessary space (Figure 11-23).
FIGURE 11-23 An anterior crossbite that is developing as erupting permanent incisors are deflected lingually can be treated by extracting adjacent primary teeth if space is not available for the erupting permanent teeth. A, The permanent maxillary right lateral incisor is beginning to erupt lingual to the other anterior teeth. B, Extraction of both primary maxillary canines has allowed spontaneous correction of the crossbite although all the irregularity has not been resolved.
Lingually positioned incisors limit lateral jaw movements, and they or their mandibular counterparts sometimes suffer significant incisal abrasion. In addition, when oral hygiene is less than ideal and gingival inflammation occurs, anterior teeth that are in crossbite, especially the lower incisors, are likely to have gingival recession. So, for these reasons, early correction of this type of anterior crossbite is indicated.
Only occasionally is it indicated to correct anterior crossbite in the primary dentition by moving the primary teeth because crowding severe enough to cause it is rare and the teeth often exfoliate before they can be successfully moved. Dental anterior crossbites typically develop as the permanent incisors erupt. Those diagnosed after overbite is established require appliance therapy for correction. The first concern is adequate space for tooth movement, which usually requires reducing the width of some teeth, extraction of the adjacent primary teeth, or opening space orthodontically. The diagnostic evaluation should determine whether tipping will provide appropriate correction. Often it will because the problem arose as eruption paths were deflected. If teeth are tipped when bodily movement is required, stability of the result is questionable.
In a young child, one way to tip the maxillary and mandibular anterior teeth out of crossbite is with a removable appliance, using fingersprings for facial movement of maxillary incisors (Figure 11-24) or, less frequently, an active labial bow for lingual movement of mandibular incisors. Two maxillary anterior teeth can be moved facially with one 22-mil double-helical cantilever spring. The appliance should have multiple clasps for retention, but a labial bow is usually contraindicated because it can interfere with facial movement of the incisors and would add little or no retention.
FIGURE 11-24 Anterior crossbite correction with a removable appliance to tip teeth. A, The permanent maxillary left central incisor has erupted into crossbite and (B) has been corrected with a removable appliance. C, This appliance is used to tip both central incisors facially with a 22 mil double helical fingerspring activated 1.5 to 2 mm per month to produce 1 mm per month of tooth movement. Note that plastic baseplate material extends over the spring to maintain its vertical position. The appliance is retained with multiple Adams’ clasps.
An anterior or posterior biteplate, or bonded adhesive on the occlusal surfaces of posterior teeth to reduce the overbite while the crossbite is being corrected, usually is not necessary in children. Unless the overbite is exceptionally deep, a biteplate would be needed only in a child with a clenching or grinding habit. A reasonable approach is to place the removable appliance without a biteplate and attempt tooth movement. If, after 2 months, the teeth in the opposing arch are moving in the same direction as the teeth to which the force is being applied, the bite can be opened by adding orthodontic banding cement to the occlusal surfaces of the lower posterior molars. When the crossbite is corrected, the cement can be removed relatively easily, and it does not require alteration of the appliance. Using a biteplate or opening the bite risks the chance that teeth not in contact with the appliance or the opposing arch will erupt excessively.
A removable appliance of this type requires nearly full-time wear to be effective and efficient. If the lingual fingersprings are activated 1.5 to 2 mm, they will produce approximately 1 mm of tooth movement in a month. The offending teeth should be slightly overcorrected and retained until overbite is adequate to retain the corrected tooth positions. One or 2 months of retention with a passive appliance is usually sufficient. The most common problems associated with these simple removable appliances are lack of patient cooperation, poor design leading to lack of retention, and improper activation.
One of the simplest fixed appliances for correction of maxillary incisors with a moderate anterior crossbite is a maxillary lingual arch with fingersprings (sometimes referred to as whip springs). This appliance (Figure 11-25) is indicated for a child with whom compliance problems are anticipated. The springs usually are soldered on the opposite side of the arch from the tooth to be corrected, in order to increase their length. They are most effective if they are approximately 15 mm long. When these springs are activated properly at each monthly visit (advancing the spring about 3 mm), they produce tooth movement at the optimum rate of 1 mm per month. The greatest problems are distortion and breakage from poor patient cooperation and poor oral hygiene, which can lead to decalcification and decay.
FIGURE 11-25 A, An anterior crossbite caused by lingual position of the maxillary incisors can be corrected using (B) a 36 mil lingual arch with soldered 22 mil fingersprings. A guidewire can be placed between the incisors as shown here to keep the springs from moving incisally. C, After correction, the appliance can be modified to serve as a retainer by soldering the free ends of the springs to the lingual arch.
It also is possible to tip the maxillary incisors forward with a 2 × 4 fixed appliance (2 molar bands, 4 bonded incisor brackets). In the rare instance when there is no skeletal component to the anterior crossbite, this is the best choice for a mixed dentition patient with crowding, rotations, the need for bodily movement, and more permanent teeth in crossbite (Figure 11-26). When the anterior teeth are bonded and moved prior to permanent canine eruption, it is best to place the lateral incisor brackets with some increased mesial root tip so that the roots of the lateral incisors are not repositioned into the canine path of eruption, with resultant resorption of the lateral incisor roots. If torque or bodily repositioning is needed for these teeth, finishing with a rectangular wire is required even in early mixed dentition treatment. Otherwise, the teeth will tip back into crossbite again.
FIGURE 11-26 A, This patient has an anterior crossbite and irregular maxillary anterior teeth. B, A 14 mil segmental NiTi archwire was used from maxillary lateral to lateral incisors to take advantage of the archwire’s extreme flexibility for alignment. C, This was followed by a heavier stainless steel archwire that extended to the molars for more control and stability for diastema space closure with an elastomeric chain. D, Final alignment.