1 Which key points should be clarified in the patient’s medical and dental history?

It is important to note the patient’s chief concern and specify whether treatment is sought for functional reasons, esthetic improvement, or both.¹ Medical conditions, diseases, hospitalizations, and current medications should be recorded. Drugs that may trigger hyperplastic gingival response such as phenytoin, calcium channel blockers, and immunosuppressives² as well as medications that may inhibit orthodontic tooth movement, such as bisphosphonates³ or prostaglandin-inhibitors,⁴ are important to document on the patient’s problem list.⁵ Allergies, especially to nickel or latex, should be noted by the orthodontist. Any facial or dental trauma, extractions, and habits should be listed and the oral hygiene regimen assessed. Possible familial patterns of malocclusion should be explored by collecting information about whether parents or siblings have undergone orthodontic treatment.⁶ Finally, voice change in boys and menarche in girls can be used to assess the stage of the patient’s development.⁷

2 Which aspects should be covered in the clinical examination?

In general, the face, oral cavity, and surrounding areas (including dentition) and TMJs should be examined. This specifically includes assessment of asymmetries, lip position in closure and repose, classification of the perioral musculature, and measurement of the incisor display at rest (see following cephalometric and photographic analysis questions). The health of all oral tissues and the patient’s periodontal status, especially in adults, should be evaluated. Periapical and bitewing radiographs are essential in evaluating all adult patients.⁸ It is imperative to test probing depths for adult patients and document a periodontal screening index (PSI) to document the status of the periodontium prior to any orthodontic treatment.⁹ The condition of the teeth with detailed recording of caries as well as dental and occlusal anomalies in the transverse, sagittal, and vertical plane should be noted along with assessment of the maxillary and mandibular apical bases, determination of facial and dental maxillary and mandibular midlines, and palpation of unerupted teeth.

3 Which aspects of jaw and occlusal function should be evaluated?

There are five main areas of interest to the orthodontist: mastication, speech, breathing mode, orofacial dysfunctions, and TMJ function. Mastication, including swallowing patterns as well as the presence of speech problems such as articulation distortion, stuttering, or dyslexia, requires evaluation. Depending on the severity, this may necessitate referral to a specialist. The patient should also be asked about the prevalent respiration mode, mouth versus nasal breathing, and possible sleep disorders or problems with restricted airways, such as snoring. These may be associated with such conditions as tonsillar or adenoid enlargement, nasal obstruction, allergies, and retruded mandible. However, the etiologic significance of respiration mode in relationship to facial growth and development of malocclusions remains controversial throughout the literature.^10,11 Deleterious habits (i.e., lip biting or thumb or finger sucking [Fig. 4-1, A]), cheek biting, bruxism, nail biting, and tongue thrusting [Fig. 4-1, B]) are imperative to document. They might be partially etiologic to open bite¹² and posterior crossbite¹³ or, in case of tongue thrusting, compensatory factors of a presenting malocclusion.¹⁴

FIG 4-1 A, Open bite malocclusion caused by a thumb-sucking habit. B, Malocclusion caused by a tongue-thrusting habit.

4 How is the TMJ function examined?

The patient should be initially questioned about existing TMJ problems and the history of symptoms verified through manipulation and auscultation of the TMJ for sounds such as clicking, popping, or crepitus. Palpation of the TMJ and masticatory muscles is necessary to detect tenderness or pain. In addition, the patient’s range of motion (ROM) should be recorded by observing and measuring maximal mouth opening, right and left lateral excursions, and protrusive movement.¹⁵ Ideally, mandibular movements should be painless and, for adults, within a normal range of 50 mm maximal opening and 10 mm lateral excursions. The amount of maximal mouth opening is age related and therefore generally less than 50 mm for children. Functional shifts between centric occlusion (CO) and centric relation (CR) outside the normal range of 1.5 mm need to be recorded, since they have been correlated with increased temporomandibular disorders (TMDs).¹⁶ CO-CR discrepancy may result in a false bite commonly referred to as Sunday bite, which is the forward postural position of the mandible adopted by patients with Class II profiles in order to enhance their appearance. Shifts can also be related to occlusal interferences, requiring posturing into pseudo Class III malocclusions.¹⁷ TMD is subdivided into true pathologies of the TMJ (TMJ disorders) and myofacial pain dysfunction (MPD),¹⁸ which affects masticatory and cervical muscles.¹⁹ Any clinical diagnosis should be substantiated by radiographic evidence, as well as CT and/or MRI scans as needed. However, most patients presenting with MPD usually lack clinical or radiographic evidence of pathologic TMJ changes.¹⁸

5 Which areas should be explored in the patient’s social and behavioral evaluation?

The patient’s motivation to seek orthodontic treatment should be assessed, since attitude and expectations concerning treatment are closely related to motivation. In general, internally as opposed to externally motivated patients show better cooperation.²⁰ Progress in school and reaction to past medical or dental treatment may also be indicative of the patient’s compliance level. A history of prolonged sucking habits, poor educational advancement, sleepwalking in younger children, and enuresis in older children may be related to emotional problems. In addition, patients affected by conditions such as autism and attention deficit disorder (ADD)/attention deficit hyperactivity disorder (ADHD) should be identified to determine the best mode of treatment.

6 What are the ages that need to be considered in orthodontic care?

Chronologic, skeletal, dental, mental, and emotional age are differentiated in the assessment of the development of a patient. Chronologic age does not correlate well with the other ages; thus, assessment of the skeletal or physiologic age helps to determine the biologic age.²¹ This is most commonly done by evaluation of a hand-wrist radiograph of the non-working hand or both hands in children under 6 years of age.²² It is indicated in children above the 95^th or under the 5^th percentile of somatograms and prospective orthognathic surgery patients. The method determines developmental and somatic maturity with a variability of ± 1 year, although in patients less than 10 years of age, poor correlation to chronologic, dental, or mental age has been observed. Understanding the timing and sequence of formation of both the primary and permanent dentition is essential for diagnosis of the dental age. It is best determined by the stages of individual tooth mineralization, since this process is not affected by early tooth loss. Various tests have been developed to assess the mental and emotional age of a patient that may not closely correlate with the developmental age. The latter can be roughly determined by evaluation of the secondary sexual characteristics. A child is considered an early or late developer if a difference of ± 2 years is found between chronologic and dental age.

7 What methods can be applied to assess the physical growth and maturation status of an individual?

Evaluation of the skeletal maturity of a patient is important to maximize efficiency and effectiveness of orthodontic treatment through proper timing. If a treatment plan demands a skeletal dentofacial orthopedic modification, the patient should be treated as close as possible to the peak velocity of growth.²³ The use of headgear or functional appliances, like the Twin Block or Herbst appliance, appears more effective if applied at or slightly after the onset of the pubertal growth spurt in the late mixed dentition.^24,25 Information regarding active growth cessation is crucial, especially in patients undergoing orthognathic surgery. Gender-specific growth curves classify a child under a height and weight percentile to establish norms for chronologic age. Currently, hand-wrist radiographs are the gold standard of growth assessment. The skeletal age is evaluated by analysis of a predictable ossification sequence of long bones of the wrist and carpal bones of the hand in children up to 9 years and metacarpals after 9 years of age.^26,27 Specific skeletal maturational events can then be linked to identify the patient’s progression on the pubertal growth curve.²⁸ Application of this method is indicated in orthognathic surgery patients ranging in age from 16 to 20 years and in patients with marked discrepancy between chronological and dental age.

More recently, it has been shown that the peak pubertal growth can also be estimated by evaluation of the maturation level of the cervical vertebrae pictured on a cephalographic radiograph.^29,30 Shape as well as concavity of the inferior border of C2 through C6 is sequentially assessed in this method,³¹ thereby eliminating the need for an additional hand-wrist radiograph, since a cephalogram is routinely taken for every prospective orthodontic patient.^32–34

8 How is the malposition of individual teeth classified?

A malposed tooth can be inclinated, centrically or eccentrically malpositioned, totally displaced, rotated, transposed, or localized by various combinations thereof. According to Liescher’s nomenclature, the malposition of a tooth is termed mesioversion if it is displaced toward the facial midline (Fig. 4-2, A); it is classified as distoversion if it is located further away from the midline (Fig. 4-2, B).

FIG 4-2 A, Mesioversion of maxillary right central incisor. B, Distoversion of maxillary right lateral incisor. C, Labioversion of maxillary left central incisor. D, Linguoversion of maxillary central incisors. E, Infraversion of mandibular left second deciduous molar. F, Transposition of maxillary right cuspid and first premolar.

If an incisor or canine is misplaced outside the arch form toward the lip, this is described as labioversion (Fig. 4-2, C); if a posterior tooth is dislocated toward the cheek, it is described as buccoversion. A tooth is known to be linguoverted if it is inclined toward the tongue (Fig. 4-2, D). The term infraversion is applied if a tooth is not erupted to the occlusal plane (Fig. 4-2, E) whereas supraeruption describes an overerupted tooth. A tooth rotated on its own axis is classified as torsiversion. Transposition or transversion denotes a positional interchange of two adjacent teeth,³⁵ which is found most commonly in the maxilla with an incidence described as high as 1 in 300 patients.^36,37 The transposition of an upper canine with the first premolar is shown in Fig. 4-2, F.

9 Which tooth most often displays an anomaly?

In general, third molars are most commonly affected by size and shape variations, followed by upper lateral incisors and lower second premolars. Anomalies can result from genetic factors as well as environmental influences such as nutrition or diseases during the prenatal period of tooth development. Upper lateral incisors have been described as absent, peg-shaped, hypoplastic, dens evaginatus or invaginatus. Peg-shaped laterals are found in 1% to 2% of the population and are characterized as being small, conical, and tapered toward the incisal (Fig. 4-3, A).

FIG 4-3 A, Maxillary peg lateral incisors and retained left deciduous cuspid. B, Cusp of Carabelli on maxillary first molars. C, Gemination of mandibular central and lateral incisors. D, Dens in dente with talon cusp. E, Microdontia of maxillary tooth with generalized spacing. F, Macrodontia of maxillary lateral incisors. G, Amelogenesis imperfecta.

Shovel-shaped incisors mark another morphological variant. These teeth show pronounced lingual ridges and cingula and are more common in the Asian, Eskimo, and Native American populations.³⁸ In contrast, cusps of Carabelli on permanent molars have the greatest incidence among Caucasians (Fig. 4-3, B).³⁹

The term taurodontia describes a tooth whose crown and pulp chamber is elongated with little or no constriction at the cementoenamel junction (CEJ), resulting in a short root. The incomplete division of a single tooth germ is known as gemination (Fig. 4-3, C).

These teeth clinically appear as fused with a notch in the crown but generally display a single root and pulp chamber. Truly fused teeth, however, result from union of the dentin of two adjacent tooth buds. Consequently, tooth count will normally reveal one less individual tooth in the affected arch. Twinning is the complete division of one tooth germ into two teeth, resulting in one more individual tooth than the normal complement. If two adjacent teeth are joined only at the cementum, they are described as being concrescent.

A dens evaginatus is characterized by a talon cusp (Fig. 4-3, D). Invagination of the enamel organ into the crown, thereby extending into the dentin and root of a tooth, is known as dens invaginatus or dens in dente. It is more common in the permanent dentition with an incidence of about 2% and usually affects the upper lateral incisor.⁴⁰

The teeth can be hypoplastic (microdontia) (Fig. 4-3, E) or hyperplastic (macrodontia) (Fig. 4-3, F) in size, and discolorations can be of intrinsic or extrinsic origin.

Mineralization abnormalities can also be observed sporadically or as part of a syndrome such as dentinogenesis and amelogenesis imperfecta (Fig. 4-3, G), characterized by deficient calcification as in hypermineralization or deficient matrix formation as in hyperplasia of the affected tooth component.

10 What are the significant areas of cast analysis?

Dental casts obtained from impressions that extend far enough into the sulcus to allow accurate reproduction of the soft tissue anatomy should accurately represent the dentition and immediate supporting structures. The objective of study cast analysis is the 3D assessment of the maxillary and mandibular dental arches and their occlusal relationships. This encompasses the metric analysis of arch width, length, symmetry, and palatal height as well as tooth size and space analysis in relation to the apical bases and examination of the interarch occlusion. The apical base arch is the area of alveolar bone on the level of the root apices of the teeth, whereas the basal arch is formed by the maxillary and mandibular corpus. Its dimensions are stable and unaffected by tooth loss or alveolar resorption. The dental arch perimeter is measured through the contact points of the teeth and ideally should be congruent to the sizes of the alveolar and basal arches. It should be noted that the mandibular arch is often referred to as the diagnostic arch because of the cortical bone on the facial and lingual surfaces. In contrast to the intermolar width, which significantly increases in the maxillary arch between 3 and 13 years of age, the mandibular intercanine distance increases during the transition of primary to permanent dentition⁴¹ (see Chapter 2), then decreases slightly until adulthood.

As part of the cast analysis, the individual arch shape should be appreciated. It has been shown that the most common arch form is the ovoid arch, followed by tapered and squared arch shapes (Fig. 4-4).⁴²

FIG 4-4 Arch forms. A, ovoid; B, tapered; C, square.

Arch length discrepancy, also referred to as arch circumference discrepancy, is identified as the difference between the available arch length and the required arch length. It is determined by measuring the mesiodistal tooth widths of the permanent teeth from the mesial of the permanent mandibular first molars for the mandibular arch and permanent maxillary first molars for the maxillary arch.

11 What is the Bolton analysis?

The Bolton analysis offers a method to determine the ratio of the mesiodistal widths of the maxillary versus the mandibular permanent teeth, also known as tooth size discrepancy, and its interarch effects. When looking at interarch relationships, it is essential to treat the anterior teeth separately from the posterior units. Tooth size discrepancies in the anterior region can be corrected only with compensations in the anterior region and not through treatment changes in the posterior teeth. Thus, the Bolton analysis consists of an anterior ratio analysis, designed to identify incompatibilities in anterior teeth, or a whole dentition ratio, which, when compared to the anterior ratio, determines the discrepancies of the posterior teeth. The anterior ratio is calculated by dividing the sum of the mesiodistal widths of the mandibular six anterior teeth by the sum of the mesiodistal widths of the maxillary anterior teeth and then multiplying the result times 100. The mean anterior ratio is 77.2, whereas the mean overall ratio is 91.3. The latter is calculated according to the same principle as the anterior ratio but is calculated by dividing the sum of the mesiodistal widths of the mandibular right first molar tooth to the left first molar tooth by the sum of the mesiodistal widths of the maxillary first molar to first molar teeth.^43,44 Studying the Bolton ratios using standardized tables for comparison of the anterior and overall ratio relationship helps to estimate the overbite and overjet relationship that will likely be obtained through orthodontic treatment as well as to identify occlusal discrepancies produced by interarch tooth size incompatibilities. It has been found that there is a high incidence of tooth size discrepancies throughout all malocclusion groups.⁴⁵ Statistically, about 5% of the population display some disproportion among individual tooth sizes, with the upper lateral incisor being most commonly affected. However, application of the Bolton analysis should be handled with care, since arch length discrepancies seem to be specific for gender and ethnicity.⁴⁶

12 What represents the basis for Angle’s dental classification?

The Angle classification, first published in the 1890s, is based on the anteroposterior occlusal relationship of the permanent first molar that was termed the key to occlusion. According to Angle, a Class I normal occlusion is defined by the interlocking of the mesiobuccal cusp of the upper first molar into the mesiobuccal g/>