Use these selected concepts to connect diagnostic findings with treatment objectives, interpret progress records and critique orthodontic outcomes. Each concept pairs a focused principle with an original example and a specific error to avoid. The guide follows the four domains of the American Board of Orthodontics Scenario-based Clinical Examination.
Clinical diagnosis and record selection
1. Separate oral health, occlusion and facial proportions
Diagnostic orthodontic evaluation addresses three distinct categories: health of the teeth and oral structures, occlusal relationships and tooth alignment, and proportions of the face and jaw. A favorable finding in one category does not establish favorable findings in the others.
Worked example: A nine-year-old has well-aligned incisors, untreated molar caries, and a chin deviating to one side. Record the alignment, the oral disease, and the facial asymmetry as separate findings; straight incisors resolve neither the caries nor the asymmetry.
Mistake to avoid: Describing the case as normal solely because the anterior teeth look straight.
Reference: [9]
2. Choose models for the diagnostic question
Diagnostic casts support assessment of occlusal relationships, arch length requirements for tooth size discrepancies and interarch tooth size relationships, and the location and extent of arch asymmetry. Select and interpret casts according to the specific diagnostic question being investigated.
Worked example: A patient shows apparent unilateral crowding. On the casts, compare space requirements tooth by tooth and locate where the arch asymmetry lies, rather than reporting only a single whole-arch crowding total.
Mistake to avoid: Treating photographs alone as a complete substitute for the required space assessment.
Reference: [9]
3. Justify imaging after clinical assessment
Radiographic selection should follow a thorough clinical examination and reflect each patient's individual diagnostic or management need. Make a good-faith attempt to use suitable radiographs from previous dental exams instead of automatically obtaining another complete set.
Worked example: A new patient brings recent diagnostic images from the referring dentist. Review their adequacy for the current clinical questions first, and order additional exposures only for what those images leave unanswered.
Mistake to avoid: Ordering repeat images solely because the patient is new to the practice.
Reference: [13]
4. Reserve CBCT for information lower-exposure imaging cannot provide
Incorporate CBCT only when lower-exposure options cannot provide the necessary diagnostic information. Three-dimensional localization can be useful, but technological detail alone does not justify the higher exposure; apply an individual benefit-risk assessment, particularly for children.
Worked example: An eruption problem remains insufficiently localized after appropriate lower-exposure assessment. Consider whether CBCT would answer the specific unresolved question and change management before exposing the child to the higher dose.
Mistake to avoid: Making CBCT a routine requirement for every new orthodontic patient regardless of diagnostic need.
Reference: [13]
5. Distinguish painless joint sounds from symptomatic dysfunction
Clicking or popping in the temporomandibular joints without pain is common, considered normal, and does not by itself require treatment. Painful sounds, jaw stiffness, limited movement, or locking instead signal possible dysfunction needing assessment.
Worked example: During screening, one adolescent opens widely with a painless click and full range of motion, while a classmate's click occurs with pain and brief locking; only the second presentation calls for symptomatic dysfunction assessment.
Mistake to avoid: Recording both a painless click and a painful locking click as identical findings requiring the same intervention.
Reference: [15]
6. Keep a differential diagnosis for jaw and facial pain
Jaw or facial pain may or may not relate to TMD, and no widely accepted standard test exists for diagnosis. A detailed history and examination are required, with other overlapping conditions ruled out before labeling a TMD.
Worked example: A patient describes cheek pain that worsens with chewing but also reports sinus pressure and tooth tenderness; the clinician documents history and examines these structures before considering whether a TMD explains the symptoms.
Mistake to avoid: Accepting a patient's mention of 'my TMJ' as confirmation of an established temporomandibular disorder diagnosis.
Reference: [15]
7. Interpret cephalometric values in the patient's context
Cephalometric interpretation requires familiarity with measurement norms, standard deviations, and ethnic variations. Measurements presented in an examination describe the scenario patient specifically, so they cannot be converted into universal treatment targets or appliance justifications.
Worked example: A scenario patient's lower incisor-to-NB reading falls beyond the familiar range; the examinee relates the value to that patient's facial profile and dental arrangement instead of prescribing correction toward an assumed universal number.
Mistake to avoid: Treating any single measurement outside a mean as automatic justification for extraction or an appliance.
Reference: [8]
Developing dentition and space assessment
8. Identify dentition stage from the teeth present
Dentition stages are defined by which teeth are present: mixed dentition shows primary and permanent teeth together, while adolescent dentition shows permanent teeth other than third molars erupted or erupting. Approximate ages remain secondary to observed eruption status.
Worked example: A twelve-year-old presents with retained primary second molars alongside erupted permanent incisors and first molars; the record describes an observed mixed dentition rather than labeling adolescent dentition based on chronological age alone.
Mistake to avoid: Classifying a patient's dentition stage from birthdate without checking which teeth have actually erupted.
Reference: [9]
9. Recognize ankylosis as loss of normal periodontal attachment
Ankylosis occurs when root cementum fuses directly to surrounding bone and the periodontal ligament is replaced by osseous tissue, so the tooth cannot erupt. In a growing child it appears increasingly infraoccluded as neighboring teeth continue to erupt.
Worked example: Serial records show a primary molar remaining at the same vertical level while adjacent teeth erupt further, supporting clinical and radiographic investigation for ankylosis rather than assuming the molar physically descended.
Mistake to avoid: Labeling every infraoccluded tooth ankylosed without clinical and radiographic assessment or considering other eruption disorders.
Reference: [9]
10. Distinguish primary failure of eruption from obstruction
Primary failure of eruption is partial or complete non-eruption of permanent teeth without a mechanical obstruction or syndrome. Posterior open bite and infraocclusion can raise suspicion, but diagnosis combines clinical, radiographic, and genetic information.
Worked example: Posterior teeth are infraoccluded and imaging shows no obstructing lesion, so the clinician pursues the broader clinical, radiographic, and genetic assessment for primary failure of eruption instead of assuming a removable barrier.
Mistake to avoid: Diagnosing primary failure of eruption from a posterior open bite without evaluating competing explanations.
Reference: [9]
11. Calculate tooth size and arch space discrepancy
Tooth size/arch length discrepancy is the difference between the space required to align teeth and the space available in each arch. State the subtraction convention explicitly so the numerical sign cannot obscure crowding versus excess space.
Worked example: Required space measures 75 mm and available space 69 mm; required minus available equals 6 mm, indicating a 6 mm shortage under the stated convention.
Mistake to avoid: Reporting a signed discrepancy number without explaining whether it represents crowding or excess spacing.
Reference: [9]
12. Interpret crowding alongside facial and skeletal relationships
A crowding measurement must be interpreted alongside esthetic, dental, skeletal, and soft tissue relationships. The same measured space shortage can occur in patients whose treatment limitations and objectives differ, so the number alone does not determine treatment.
Worked example: Two patients each show 5 mm of crowding but have different facial profiles and skeletal findings; the shared measurement identifies a space problem, not an identical treatment plan.
Mistake to avoid: Selecting extraction, expansion, or incisor movement from the crowding total while ignoring the remaining diagnosis.
Reference: [9]
13. Measure the greatest anterior overjet consistently
Under the 2015 DI convention, positive overjet uses the incisor pair with the greatest overjet, measured from the most lingual mandibular incisor's facial surface to the maxillary incisor's incisal-edge middle, in maximum intercuspation for plaster casts or the specified standard 3D orientation for digital models.
Worked example: In maximum intercuspation, one incisor pair shows 3 mm overjet and another shows 7 mm; record the 7 mm pair, measured from the most lingual mandibular incisor's facial surface to the maxillary incisal-edge middle.
Mistake to avoid: Measuring an arbitrarily chosen incisor pair instead of the pair with the greatest overjet.
Reference: [5]
Treatment objectives and sequencing
14. Prioritize problems and anticipate interactions
A diagnostic summary establishes the relative soft tissue, dental and skeletal contributions to the malocclusion, prioritizes the problems by relative severity according to the individual diagnosis, and detects favorable or unfavorable interactions that treatment options for each problem area may produce.
Worked example: A summary ranks severe crowding above a mild facial concern; one option resolves the crowding but leaves the facial concern unresolved, so the crowding is prioritized and the remaining concern recorded when comparing options.
Mistake to avoid: Treating resolution of one problem as resolution of the whole diagnostic summary.
Reference: [9]
15. Set treatment objectives in three planes
Enter a succinct treatment objective for each relevant area of analysis, organized across horizontal, vertical and transverse planes; objectives state intended patient-specific changes, and naming only an appliance does not satisfy this, nor does organizing objectives establish a correction's feasibility.
Worked example: For a diagnosed transverse deficiency, the objectives space records the intended maxillary width change in the transverse plane rather than simply naming an expansion appliance.
Mistake to avoid: Writing only an appliance name where a patient-specific objective in three planes is required.
16. Require a comprehensive plan before extraction for crowding
Extraction of primary or permanent teeth to alleviate crowding should not be undertaken without a comprehensive space analysis and both short-term and long-term orthodontic treatment planning; a visible alignment problem alone is insufficient justification, and this prerequisite does not itself determine which teeth to extract.
Worked example: A parent requests immediate removal of primary canines for lower incisor crowding; the clinician completes a comprehensive space analysis plus short- and long-term planning before deciding whether extraction is appropriate.
Mistake to avoid: Extracting primary canines solely because one crowded segment looks misaligned, without any space analysis.
Reference: [9]
17. Account for variable self-correction in mixed dentition
A systematic review found mandibular incisor crowding tended to decrease from early mixed to permanent dentition, but with great variability and some patients worsening, so group findings cannot forecast an individual child's trajectory.
Worked example: When a family asks whether their child's early incisor crowding will certainly disappear, explain that improvement can occur but observation and individualized assessment are needed because some children's crowding worsens.
Mistake to avoid: Promising spontaneous resolution of crowding or assuming every early crowding finding requires immediate active alignment.
Reference: [9]
18. Weigh alignment gains against arch length loss
Extracting mandibular primary canines reduces incisor irregularity, but at the expense of significant arch length loss, up to 2.7 mm; any extraction still requires comprehensive space analysis and short- and long-term planning.
Worked example: After primary canine removal, incisors look less irregular but measured arch length has decreased; describe both outcomes rather than declaring the child's space problem solved, since straighter incisors do not mean more space.
Mistake to avoid: Confusing improved incisor appearance with an increase in available space for the remaining permanent teeth.
Reference: [9]
19. Link leeway space management to eruption milestones
The AAPD identifies holding arches as a mixed-dentition option for managing leeway space until all premolars and permanent canines erupt; planning should specify that developmental endpoint, though this is a consideration, not a mandate for every patient.
Worked example: For a child considered for leeway space management while premolars remain unerupted, connect the holding strategy to monitoring permanent canine and premolar eruption, without promising that space holding alone resolves all crowding.
Mistake to avoid: Assuming successful space holding automatically establishes sufficient space for every permanent tooth in the arch.
Reference: [9]
20. Monitor an ankylosed primary molar with a successor
For an ankylosed primary molar with a successor, AAPD guidance supports maintaining the tooth until eruption interference or tipping or drifting of adjacent teeth occurs; these complications change the management assessment and require ongoing clinical evaluation.
Worked example: An ankylosed primary molar initially shows no eruption interference, but later records reveal adjacent tooth tipping; reassess management at that point because the complication the maintenance plan was contingent upon has now appeared.
Mistake to avoid: Continuing an unchanged observation plan after eruption interference or adjacent drifting has already developed.
Reference: [9]
21. Plan differently when an ankylosed molar lacks a successor
When an infraoccluded primary molar has no permanent successor, management decisions must weigh the patient's age, the tooth's condition, the comprehensive orthodontic plan including future prosthodontic needs, and parental preferences. The successor-present retention pathway cannot simply be transferred, and specialist consultation may assist decision making.
Worked example: Imaging confirms an infraoccluded primary second molar in a 12-year-old has no premolar successor. The orthodontist and pediatric dentist jointly discuss the child's age, the tooth's condition, long-term space and restoration objectives, and the family's preferences before coordinating any specialist plan.
Mistake to avoid: Discussing long-term consequences of keeping or removing the tooth while ignoring the missing permanent successor entirely.
Reference: [9]
Prognosis, consent and stability planning
22. Avoid routine early orthodontic eruption attempts in PFE
In primary failure of eruption, affected teeth are not initially ankylosed but may become ankylosed when orthodontic forces are applied. Because the evidence does not support early orthodontic intervention of affected teeth, it should be avoided; diagnosis relies on clinical, radiographic, and genetic assessment, and later multidisciplinary options are individualized.
Worked example: A confirmed PFE case is referred for early traction of unerupted posterior teeth. The clinician explains that routine early traction is inappropriate because forced eruption may promote ankylosis, and instead pursues coordinated longer-term planning with reassurance and education.
Mistake to avoid: Responding to failed eruption by simply increasing the orthodontic force on the affected teeth.
Reference: [9]
23. Treat informed consent as an ongoing discussion
For developing-dentition care, a thorough discussion of existing problems, treatment options, alternatives, and outcomes is necessary not only at the beginning of treatment but ongoing during later stages. Including the patient and parent in treatment planning is critical for informed consent, and a changed clinical situation can require renewed discussion.
Worked example: At a progress assessment, unfavorable mandibular growth leads to a substantially revised plan. The orthodontist explains the new options, their alternatives, and expected outcomes to the patient and parent rather than relying only on the initial pretreatment consent conversation.
Mistake to avoid: Treating the first consent conversation as sufficient coverage for every subsequent change in the plan.
Reference: [9]
24. Include cooperation in prognosis and option selection
Patient compliance is an important consideration during treatment planning and informed consent because it can significantly affect the outcome. Cooperation, parental support, and the patient's chronological, mental, and emotional age and ability to understand and cooperate should be assessed rather than presumed, without attributing every unfavorable outcome to patient behavior.
Worked example: A proposed growth-modification option depends on reliable daily wear, but the family reports difficulty following previous appliance instructions. The clinician discusses this adherence limitation openly when comparing feasible options and documents the conversation as part of informed consent.
Mistake to avoid: Giving the same prognosis regardless of whether the plan's participation requirements can realistically be met.
Reference: [9]
25. Do not infer that braces caused a TMD
Research summarized by NIDCR does not support the belief that a bad bite or orthodontic treatment such as braces causes TMD. Symptoms arising during treatment still require proper assessment, because timing alone never establishes causation for a particular patient's pain.
Worked example: A patient reports new jaw pain five months after fixed appliances were placed. The clinician records the symptoms, performs an appropriate assessment, and explains to the patient that the sequence of events alone does not establish that the braces caused a temporomandibular disorder.
Mistake to avoid: Telling a patient that braces definitely caused the jaw pain because it appeared during treatment.
Reference: [15]
26. Do not promise a TMD cure through bite correction
Evidence is insufficient that occlusal treatments, including using orthodontics to change tooth position, treat TMD, and in some cases they worsen the problem. Experts recommend conservative care and avoiding permanent changes to the jaw joints, teeth, or bite.
Worked example: A patient requests braces solely to cure longstanding jaw pain. The clinician explains that evidence does not support bite alteration as a TMD treatment, arranges appropriate evaluation, and separately discusses the patient's independent orthodontic indication without guaranteeing pain relief through alignment.
Mistake to avoid: Presenting irreversible bite change as a proven first-line treatment for the patient's TMD symptoms.
Reference: [15]
27. Discuss lower incisor alignment as a long-term stability issue
The 2013 BOS guideline describes increases in lower incisor irregularity throughout life in a large proportion of treated and untreated patients, with most change by the middle of the third decade. Posttreatment alignment should therefore be discussed with realistic retention expectations.
Worked example: At debond, a patient expects her lower incisors to stay perfectly aligned forever after stopping retention. The clinician explains that irregularity can increase over time in treated and untreated people, and they discuss an individualized stability plan reflecting her willingness to accept change.
Mistake to avoid: Promising that finishing active treatment removes any possibility of later lower incisor crowding.
Reference: [12]
28. Recognize spacing closure as a distinct retention consideration
The 2013 BOS guideline recommends permanent retention after orthodontic closure of generalized spacing or a midline diastema in an otherwise normal occlusion. This carries SIGN Grade C evidence, meaning expert opinion rather than directly applicable high-quality studies, and requires individual interpretation.
Worked example: Treatment has closed a midline diastema in an adult with an otherwise normal occlusion. During the stability discussion, the clinician includes the guideline's consideration of long-term retention for spaced dentitions, noting the Grade C evidence level and that no appliance choice guarantees against recurrence.
Mistake to avoid: Assuming incisor contact at debonding makes the closed diastema permanently stable without retention.
Reference: [12]
Biomechanics and biological limits
29. Relate a single force to the center of resistance
In the simplified center-of-resistance model for single-rooted teeth, a single force whose line of action passes through the center of resistance produces bodily movement, while an offset line produces tipping; the line of action, not just direction, determines the movement.
Worked example: Two schematic retraction forces on a modeled incisor point the same way, but only one line passes through the modeled center of resistance; that force predicts bodily movement, while the offset line predicts tipping.
Mistake to avoid: Assuming two parallel forces must produce the same tooth movement regardless of where their lines pass.
Reference: [11]
30. Treat the center of resistance as patient dependent
The center of resistance is not a fixed universal point: root morphology and mass distribution, periodontal attachment structure, alveolar bone level, adjacent teeth and force direction all contribute. Considering it as a clinically useful region, rather than an exact point, is valid and useful.
Worked example: A finite element model places a modeled incisor's center of resistance at a particular fraction of root length; treat this as a model-dependent estimate for that configuration, not an exact location valid for every clinical incisor.
Mistake to avoid: Transferring one experimental center-of-resistance location unchanged to teeth with different support or anatomy.
Reference: [11]
31. Reassess biomechanics when periodontal support is reduced
In studies summarized by the review, reduced palatal alveolar bone height during anterior tooth retraction was associated with a more apical center of resistance. Reduced support can therefore invalidate biomechanical assumptions based on an intact periodontium, so individual assessment is more reliable.
Worked example: Before planned retraction, an incisor shows reduced palatal alveolar support; reassess the assumed resistance region for this patient instead of adopting the geometry of an intact-support model unchanged.
Mistake to avoid: Prescribing unchanged retraction mechanics without accounting for the patient's altered periodontal support.
Reference: [11]
32. Connect orthodontic movement with periodontal remodeling
The compression-tension model links orthodontic loading to osteoclast formation on the compression side and bone formation on the tension side. Tooth movement reflects biological remodeling of the periodontium stimulated by force, not displacement through inert bone; detailed mechanisms remain incompletely understood.
Worked example: A diagram labels one periodontal region around a moving tooth as compressed and another as under tension; in this model, associate the compressed region with osteoclast-mediated remodeling and the tense region with bone formation.
Mistake to avoid: Describing orthodontic tooth movement as purely mechanical sliding through inert, unresponsive bone.
Reference: [10]
33. Avoid a universal optimal force prescription
The biological review reports no consensus on the exact optimal orthodontic force magnitude. Movement type, periodontal condition, aging, hormonal readiness and genetic variation prevent any single experimental force value from becoming a universal clinical prescription.
Worked example: A finite element simulation proposes 30 g for tipping one modeled maxillary canine. Its value reflects that model and movement, so it should not be adopted for every tooth and patient.
Mistake to avoid: Converting a laboratory optimum into a general treatment rule.
Reference: [10]
34. Evaluate acceleration claims against uncertain evidence
The 2021 review describes the acceleration effects of nearly all existing methods as uncertain and controversial. A plausible mechanism or one favorable study cannot establish dependable clinical acceleration across patients and protocols.
Worked example: A family is offered guaranteed shorter treatment based on one acceleration study. Explain instead that evidence is uncertain, describe that method's specific findings and risks, and avoid promising outcomes.
Mistake to avoid: Equating a biological rationale with proven treatment-time reduction.
Reference: [10]
35. Reassess active force when root resorption is obvious
The review advises discontinuing orthodontic forces when root resorption is obvious, noting that root repair occurs after force cessation. Recognizing this adverse response should prompt reassessment rather than automatic continuation of the same mechanics.
Worked example: A progress assessment identifies obvious root resorption during active movement. The supported response is identifying force discontinuation and case reassessment, not continuing unchanged or promising recovery of lost root length.
Mistake to avoid: Promising that a fixed rest interval will reverse the structural loss.
Reference: [10]
Progress evaluation, retention and safety
36. Keep initial, progress and final records distinct
The Case Management Form separates pretreatment, progress and posttreatment measurements into the PRE TX, PROG and POST TX columns. Preserve each stage rather than replacing the initial baseline, so recorded values remain available for comparison.
Worked example: An initial arch width is 34 mm and a progress width is 36 mm. Keep 34 mm in PRE TX and 36 mm in PROG, so the recorded increase is 2 mm.
Mistake to avoid: Overwriting the baseline with the latest measurement and losing the ability to evaluate change.
Reference: [7]
37. Refine automated cephalometric tracings
Automated tracings must be checked against the image, using cursor placement with hide-and-show toggling to confirm accuracy, and refined wherever they deviate; this verifies tracing quality only and does not endorse any particular software product.
Worked example: A prepared tracing shows the program's mandibular border outline running outside the cortical shadow. The clinician toggles the line off, re-traces the cortex against the image, then proceeds to superimposition.
Mistake to avoid: Trusting software-drawn contours for measurement simply because no error message appeared.
Reference: [8]
38. Maintain consistent tooth template dimensions
Tooth templates should match in size within a single tracing and across serial tracings, since a size mismatch can create apparent crown or root changes unrelated to actual tooth movement; consistency does not substitute for accurate calibration or anatomical tracing.
Worked example: A final incisor template appears visibly larger than the initial one for the same tooth. The clinician standardizes template size first, then re-evaluates the apparent incisor displacement before reporting change.
Mistake to avoid: Describing an enlarged template outline as biological growth of the tooth.
Reference: [8]
39. Check head position before interpreting serial changes
Head position variation can displace landmarks lateral to the sagittal plane and introduce superimposition error, so inconsistent positioning is a possible, not automatic, explanation for apparent change; image quality and tracing accuracy also need checking.
Worked example: Paired lateral structures sit at visibly different positions between serial cephalograms. The clinician questions head-position comparability, and also reviews image quality and tracing accuracy, before attributing the difference to treatment.
Mistake to avoid: Reading every contour discrepancy between serial tracings as growth or appliance effect.
Reference: [8]
40. Use regional anatomy for maxillary superimposition
ABO maxillary regional superimposition registers on the zygomatic processes, superior surfaces of the orbital floors and the superior palatal floor; the anterior zygomatic surface guides anteroposterior orientation, while vertical interpretation must account for remodeling of the orbital, nasal and palatal regions.
Worked example: A regional maxillary tracing is registered on the incisor itself. The clinician re-checks it against the zygomatic processes, orbital floors and palatal floor before interpreting the incisor's movement within the maxilla.
Mistake to avoid: Registering a maxillary superimposition on the very incisor whose movement is being measured.
Reference: [8]
41. Include maintenance in fixed retention
The 2013 BOS guideline notes that fixed retainers reduce demands on patient compliance but are associated with greater plaque and calculus deposition than removable retainers, so they require long-term maintenance.
Worked example: A patient selects a bonded retainer because remembering removable wear is difficult. The plan records hygiene review and continuing retainer checks, since reduced compliance demands do not remove monitoring needs.
Mistake to avoid: Describing a bonded retainer as maintenance-free once it is fitted.
Reference: [12]
42. Check posterior coverage of vacuum-formed retainers
The 2013 BOS guideline advises full posterior occlusal coverage for vacuum-formed retainers, including second molars when present, to reduce the risk of those teeth overerupting during retention.
Worked example: At retainer assessment, a vacuum-formed retainer covers the first molars but leaves erupted second molars uncovered; the guideline's coverage advice identifies this as a risk for overeruption.
Mistake to avoid: Checking only the anterior fit while ignoring posterior occlusal coverage.
Reference: [12]
43. Consider posterior settling when comparing retainers
The 2013 BOS guideline reports that Hawley retainers facilitate posterior settling in the first three months, while one study found less settling with vacuum-formed retainers; this matters less when good posterior intercuspation already exists.
Worked example: Two patients finish treatment with different degrees of posterior interdigitation; the settling difference between Hawley and vacuum-formed retainers matters more for the poorly interdigitated one.
Mistake to avoid: Applying a study's average retainer comparison without assessing the existing occlusion.
Reference: [12]
44. Apply Standard Precautions regardless of infection status
Per the CDC, Standard Precautions are the minimum infection prevention practices for all patient care regardless of suspected or confirmed infection status; Transmission-Based Precautions are always added to them, never substituted.
Worked example: A patient reports no known infection, so Standard Precautions continue unchanged; if transmission-based measures were needed, they would supplement, not replace, the baseline practices.
Mistake to avoid: Reserving routine infection precautions for patients identified as infectious.
Reference: [14]
Occlusal outcome assessment
45. Use arch-specific alignment landmarks
The manual cast assessment scores anterior alignment from the incisal edges and lingual incisal surfaces in the maxilla and the incisal edges and labial incisal surfaces in the mandible; posteriorly it uses maxillary central grooves and mandibular mesiobuccal and distobuccal cusp alignment.
Worked example: A cast shows orderly maxillary posterior buccal cusp heights, yet the central grooves sit at differing mesiodistal levels; the examiner scores posterior alignment from the central grooves, not the cusp appearance.
Mistake to avoid: Applying the mandibular posterior buccal-cusp convention when assessing maxillary posterior alignment.
Reference: [6]
46. Interpret marginal ridges with their anatomical limitations
Marginal ridges assess vertical positioning of posterior teeth. Equal ridge heights indicate matching underlying levels only when restorations are absent, attrition is minimal, and periodontal bone loss is absent; these factors are evaluated separately. Manual scoring excludes the canine-premolar contact and the distal of the lower first premolar.
Worked example: A restored premolar's marginal ridge sits lower than the adjacent unrestored tooth's ridge. The examiner records the discrepancy for scoring but does not conclude that the ridge relationship alone establishes differing bone levels between the teeth.
Mistake to avoid: Treating apparently level marginal ridges as proof of periodontal health beside a restored tooth.
Reference: [6]
47. Assess posterior buccolingual inclination with the correct cusp reference
The manual straightedge assessment reverses its reference between arches: it contacts mandibular buccal cusps and reads the lingual cusps against the surface, while in the maxillary arch it contacts lingual cusps and reads the buccal cusps. Mandibular first premolars and second molar distal cusps are not scored.
Worked example: An examiner rests the straightedge on maxillary buccal cusps and notes a lingual cusp discrepancy. Before interpreting the finding, the setup is corrected so the straightedge contacts the maxillary lingual cusps and the buccal cusps are read instead.
Mistake to avoid: Transferring the mandibular buccal-cusp straightedge setup unchanged to the maxillary arch.
Reference: [6]
48. Assess contact of functional posterior cusps
Manual ABO contact assessment targets functional cusps: mandibular buccal cusps and maxillary lingual cusps. Diminutive maxillary distolingual cusps and mandibular first premolar lingual cusps are excluded, and each tooth is scored with a maximum of two points rather than an unrestricted per-cusp sum.
Worked example: A maxillary molar's mesiolingual cusp contacts its opponent while the small distolingual cusp does not. The examiner scores only the functional mesiolingual cusp's status, capped at two points, and does not penalize the excluded diminutive cusp.
Mistake to avoid: Scoring a diminutive noncontacting distolingual cusp as a contact deficiency like a functional cusp.
Reference: [6]
49. Judge posterior relationships against the intended extraction finish
The manual ABO cast evaluation describes ideal Class I landmarks, yet it also accepts Class II or Class III posterior finishes when the extraction pattern makes them appropriate, so the final molar label alone cannot determine success.
Worked example: A case finished Class II by design after maxillary premolar extractions is assessed by whether the maxillary first molar's buccal cusp aligns with the mandibular second premolar–first molar embrasure, not by its Class label.
Mistake to avoid: Failing any case whose molars are not Angle Class I, regardless of the intended extraction finish.
Reference: [6]
50. Distinguish anterior and posterior overjet assessment
In manual ABO outcome assessment, overjet covers both the anterior anteroposterior relationship and the posterior transverse relationship, so a mandibular buccal cusp's buccolingual position within the opposing occlusal surface is part of this criterion.
Worked example: Incisor contacts look acceptable, but a mandibular first molar's buccal cusp sits more than 1 mm buccal to the center of the opposing maxillary molar's occlusal surface, so a posterior overjet discrepancy is scored.
Mistake to avoid: Checking only the incisor contacts and overlooking displaced mandibular buccal cusps transversely.
Reference: [6]
51. Score residual interproximal spaces by contact
The manual ABO interproximal assessment scores each contact once: no points at 0.50 mm or less, one point for greater than 0.50 mm through 1 mm, two points beyond 1 mm, with a maximum of two points per contact.
Worked example: On the occlusal view, one contact shows a 0.8 mm residual space and another shows 1.3 mm; they contribute one and two points respectively, giving three points for the two contacts.
Mistake to avoid: Scoring one residual space twice by counting it separately for each adjacent tooth.
Reference: [6]
52. Respect panoramic limitations in root angulation assessment
Because panoramic radiographs are frequently distorted, the manual omits scoring the canine's relationship with adjacent roots on final panoramics and excludes dilacerated roots from grading, though clinically indicated evaluation remains the clinician's responsibility.
Worked example: A final panoramic image suggests an unusual canine-adjacent root relationship; the examiner applies the manual's canine exclusion, notes possible distortion, and avoids a routine angulation penalty without ordering extra imaging.
Mistake to avoid: Treating every apparent panoramic root convergence as an accurate anatomical finding.
Reference: [6]
Growth interpretation and case appraisal
53. Register overall superimposition on cranial base anatomy
Register superimposition on the workshop's stable cranial base anatomy using its complete set: the anterior sella wall below the anterior clinoid processes, planum sphenoidale, greater sphenoid wings, cribriform plate, ethmoidal crests, and cerebral surfaces of the orbital frontal bone, traced consistently across images.
Worked example: An examinee matches overlapping incisor outlines for an overall comparison; before interpreting total tooth and jaw displacement, the tracings are re-registered on the specified cranial base structures instead.
Mistake to avoid: Choosing registration points only because they make the dental outlines coincide.
Reference: [8]
54. Use internal mandibular anatomy for regional registration
Register the mandibular regional superimposition on internal symphyseal anatomy—the most anterior inferior symphyseal portion and inferior internal cortical plate—together with the inferior alveolar canal, considering these regional structures as a set.
Worked example: A later record shows a third molar with formed roots; its bud outline no longer meets the workshop's pre-root-development condition, so registration relies on the symphysis and canal alone.
Mistake to avoid: Assuming every visible third molar bud is a suitably stable regional landmark.
Reference: [8]
55. Separate movement within the jaws from growth displacement
Compare total change on the cranial base superimposition with tooth movement on regional superimpositions; subtracting regional tooth movement from total change along a consistent coordinate direction estimates growth-related displacement.
Worked example: Along one stated axis, total displacement measures +5 mm and movement within the jaw measures +2 mm; the remaining +3 mm represents growth-related displacement under this interpretation.
Mistake to avoid: Subtracting unsigned distances measured in different directions or from incompatible superimpositions.
Reference: [8]
56. Read the CMF difference as an absolute magnitude
The CMF DIFF column records the absolute difference between initial and final measurements, so it shows the amount of change but cannot by itself identify whether a measurement increased or decreased.
Worked example: Initial and final values of 8 and 3 give an absolute difference of 5; values of 3 and 8 also give 5, although the direction of change is reversed.
Mistake to avoid: Reading an absolute difference of 5 as proof of an increase or a decrease.
Reference: [7]
57. Judge objective suitability separately from result acceptability
The Case Management Form asks two separate questions for each subdivision: whether the pretreatment skeletal, dental, and facial objectives were appropriate, and whether the post-treatment change was acceptable. Each judgment scores 0 or 1, the two values are summed, and the rationale must be defensible.
Worked example: Appraisal finds the original sagittal skeletal objective appropriate but the resulting sagittal skeletal change unacceptable; that subdivision records 0 for the objective and 1 for the result, totaling 1, with any facial outcome assessed separately.
Mistake to avoid: Combining a skeletal objective and a facial result in one subdivision.
Reference: [7]
58. Use reproducible landmarks for arch width comparisons
Molar and canine arch widths may be measured between any conveniently measurable tooth points, but the chosen anatomical landmarks must be described in the case report and applied identically to pretreatment and post-treatment casts, so differences reflect true change rather than shifted endpoints.
Worked example: Pretreatment maxillary width was measured between molar cusp tips, while the final cast was measured between gingival margins; the examinee remeasures both casts using the same defined cusp-tip landmarks before recording the treatment difference.
Mistake to avoid: Reporting arch expansion from measurements taken between different anatomical points on each cast.
Reference: [7]
59. Measure the deepest unilateral curve of Spee
On the mandibular cast, evaluate each side independently and record the deeper value. Per side, build a horizontal reference from that side's most distal-buccal molar cusp tip and its central incisor edge, then measure vertically, in millimeters, down to the most gingivally positioned premolar or deciduous molar buccal cusp tip. This describes cast geometry only and does not by itself dictate leveling mechanics.
Worked example: Using the same-side molar cusp and incisor edge landmarks, the right mandibular side measures 2 mm and the left 3 mm; the Case Management Form entry is 3 mm, the deeper side, rather than the 2.5 mm mean.
Mistake to avoid: Averaging the two sides, or mixing the molar reference from one side with the incisor edge from the other.
Reference: [7]
60. Document arch form change independently of width
Mandibular arch form is documented as ovoid, round, tapered, or square, with SAME recorded when the initial form was maintained and CHG when it changed; a single width measurement alone cannot substitute for this documented form comparison.
Worked example: A tapered pretreatment arch form becomes ovoid after treatment, so the difference column records CHG; the examinee appraises this change against the treatment objectives rather than recording SAME because one intermolar width is unchanged.
Mistake to avoid: Equating one unchanged linear width measurement with preservation of the entire mandibular arch form.
Reference: [7]
Sources
- ABO Scenario-based Clinical Examination: Components and Criteria
- ABO Scenario-based Clinical Examination Study Guide 2026
- ABO Certification FAQs: Current Clinical Examination and Removal of e-CRE
- AAO: American Board of Orthodontics Reports Success with New Clinical Examination Format
- ABO Discrepancy Index Scoring Instructions
- ABO Grading System for Dental Casts and Panoramic Radiographs: Manual Outcome Assessment
- ABO Case Management Form Instructions: Measurements, Treatment Objectives and Outcome Evaluation
- ABO Cephalometric Review Workshop, March 14, 2025
- AAPD: Management of the Developing Dentition and Occlusion in Pediatric Dentistry
- Biomechanical and biological responses of periodontium in orthodontic tooth movement: up-date in a new decade
- The center of resistance of a tooth: a review of the literature
- British Orthodontic Society Clinical Guidelines: Orthodontic Retention, 2013
- ADA: X-Rays/Radiographs—Patient Selection, Digital Imaging and Radiation Safety
- CDC: Standard Precautions in Dental Settings
- NIDCR: Temporomandibular Disorders—Diagnosis and Treatment