# ADAT practice questions: Dental anatomy and occlusion Ten original ADAT practice questions on dental anatomy and occlusion, each answered on this page with a rationale and a source. Last updated: 2026-09-18. ## Question 1 An original frontal arch diagram initially places the patient's right on the page's left. The entire diagram is then rotated 180°, without reflection. A marked permanent mandibular second premolar is now on the page's left. Which patient-side identification and ISO/FDI designation fit the marked tooth? - A. Patient's left; ISO/FDI 45. - B. Patient's right; ISO/FDI 35. - C. Patient's left; ISO/FDI 35. - D. Patient's right; ISO/FDI 45. **Answer C:** Patient's left; ISO/FDI 35. Before rotation, the marked tooth was on the page's right, which represented the patient's left. Rotation preserves that anatomical side. In ISO/FDI, permanent mandibular left is quadrant 3 and a second premolar is fifth from the midline, giving 35. Both the view transformation and the named-system encoding are required. Why the other choices do not fit: A: The patient side is correctly tracked, but 45 encodes the permanent mandibular right second premolar. It uses the wrong quadrant digit for the identified side. B: The designation 35 encodes the correct anatomical tooth, but the accompanying right-side identification treats the rotated page position as though the original view were unchanged. D: The right-side name and 45 agree with one another, but both refer to the opposite patient side from the marked tooth after the stated rotation. Source: [Radlanski](https://api.pageplace.de/preview/DT0400.9780867159066_A38511739/preview-9780867159066_A38511739.pdf) ## Question 2 A fictional unworn maxillary incisor record shows a relatively broad facial crown, a more angular mesioincisal corner and a more rounded distoincisal corner. The lingual view labels X on a rounded cervical prominence below the fossa, rather than on either bordering ridge. Which tooth-type interpretation and landmark name best fit this combination? - A. Central-incisor form; X is the cingulum. - B. Lateral-incisor form; X is the cingulum. - C. Central-incisor form; X is a marginal ridge. - D. Lateral-incisor form; X is a marginal ridge. **Answer A:** Central-incisor form; X is the cingulum. The facial combination favors a maxillary central-incisor form over its generally narrower, rounder lateral neighbor. The specified cervical lingual prominence is the cingulum; the marginal ridges border the fossa. Tooth-type comparison and cross-view landmark localization are separate required decisions. The record supports a conventional form, not an invariant identity rule. Why the other choices do not fit: B: The cingulum is localized correctly, but the stated broad crown and corner contrast favor a central form. A lateral is variable, yet it is the less fitting comparison in this supplied feature set. C: The central-form interpretation fits, but X lies on the cervical prominence rather than the mesial or distal border of the lingual fossa. Those locations distinguish cingulum from marginal ridge. D: This selects both the less fitting neighboring tooth form and the wrong lingual landmark. The two errors concern different views and cannot be resolved by crown size alone. Source: [Radlanski](https://api.pageplace.de/preview/DT0400.9780867159066_A38511739/preview-9780867159066_A38511739.pdf) ## Question 3 Two isolated permanent mandibular incisor models are available. X retains a nearly symmetric crown and modest lingual relief. Y has a preserved incisal edge that turns distolingually. Neither model has a recorded patient side. Which comparison best fits these features? - A. X favors central and Y lateral; X's symmetric crown is sufficient to recover its patient side. - B. X favors lateral and Y central; X's symmetric crown is sufficient to recover its patient side. - C. X favors lateral and Y central; X's recorded crown features leave its patient side unresolved. - D. X favors central and Y lateral; X's recorded crown features leave its patient side unresolved. **Answer D:** X favors central and Y lateral; X's recorded crown features leave its patient side unresolved. X's near symmetry fits the central comparison, whereas Y's distolingual turn favors a lateral. Symmetry supplies no directional asymmetry from which to recover X's side. Modest lingual relief is compatible with mandibular incisors but does not supply that missing side cue. Why the other choices do not fit: A: The central/lateral comparison fits. The laterality conclusion does not: symmetric crown features do not identify a distal side or the patient's left versus right. B: It reverses the useful central/lateral tendencies and treats symmetry as directional evidence. Neither part matches the supplied crown record. C: It correctly leaves X's side unresolved but reverses the type comparison. Y's preserved distolingual turn is the lateral-favoring feature. Source: [Radlanski](https://api.pageplace.de/preview/DT0400.9780867159066_A38511739/preview-9780867159066_A38511739.pdf) ## Question 4 A fictional permanent canine has an intact cusp, a bulky facial–lingual crown, a pronounced lingual ridge separating two fossae and a prominent cingulum. The mesial cusp ridge is shorter than the distal. Which weighting of the external features best supports an arch comparison? - A. Favor mandibular: give greatest weight to the shorter mesial cusp ridge, with the lingual relief as secondary evidence. - B. Favor maxillary: give greatest weight to crown bulk and lingual relief, with the cusp-ridge relation compatible with either arch. - C. Favor maxillary: give greatest weight to the shorter mesial cusp ridge, with crown bulk and lingual relief compatible equally with either arch. - D. Favor mandibular: give greatest weight to the pronounced lingual ridge and fossae, with the cusp-ridge relation compatible with either arch. **Answer B:** Favor maxillary: give greatest weight to crown bulk and lingual relief, with the cusp-ridge relation compatible with either arch. The bulk and prominent lingual ridge/cingulum combination favor a maxillary canine form. A shorter mesial than distal cusp ridge is a shared conventional tendency of both permanent canine types, so it contributes less to arch discrimination. These are external comparisons, not internal canal evidence. Why the other choices do not fit: A: It treats a shared cusp-ridge relation as a mandibular discriminator and discounts the stronger maxillary-type lingual relief. C: The arch conclusion fits, but its evidence ranking is reversed. The ridge-length relation is shared; the bulk and relief are the more useful comparative features. D: It handles the shared ridge relation correctly but assigns pronounced lingual ridge/fossae to the less fitting arch. Conventional mandibular canines have less pronounced lingual relief. Source: [Radlanski](https://api.pageplace.de/preview/DT0400.9780867159066_A38511739/preview-9780867159066_A38511739.pdf) ## Question 5 A maxillary premolar model has nearly equal buccal and lingual cusp heights, a rounded occlusal outline and a short central groove with numerous supplemental grooves. A root view shows one external root. Which explanation best supports a type comparison? - A. Favor second premolar: the combined crown pattern is more informative here than the single root, which can occur in either type. - B. Favor first premolar: the combined rounded outline and supplemental grooves are more informative here than the nearly equal cusp heights. - C. Favor second premolar: the single root is more informative here than the crown pattern because the first type is characteristically two-rooted. - D. Favor first premolar: the short central groove and nearly equal cusps are more informative here than the rounded outline and single root. **Answer A:** Favor second premolar: the combined crown pattern is more informative here than the single root, which can occur in either type. The crown combination favors the maxillary second-premolar comparison: near-equal cusp heights, rounder outline and a shorter central groove with supplemental relief. External root variation permits a single root in either type, making it compatible evidence rather than a decisive identifier. Why the other choices do not fit: B: Rounded outline and supplemental groove complexity also favor the second comparison; they do not counterbalance the cusp heights toward the first. C: A second-premolar conclusion fits, but prioritizing root number underuses the stronger crown combination. First premolars can be single-rooted, so a characteristic two-root description does not uniquely exclude them. D: It assigns the short groove and near-equal cusps to the wrong neighboring type. These features reinforce, rather than oppose, the second-premolar comparison. Source: [Radlanski](https://api.pageplace.de/preview/DT0400.9780867159066_A38511739/preview-9780867159066_A38511739.pdf) ## Question 6 Two unworn mandibular premolar models have paired views. In X, the occlusal view shows a strong buccolingual transverse ridge and a notch at the mesiolingual margin; its proximal view shows marked lingual crown inclination and a low lingual elevation. In Y, three developmental groove arms meet at a central pit, with one arm continuing onto the lingual surface; the lingual view shows the mesial elevation broader and taller than the distal elevation. Which pair of conventional forms best reconciles both records? - A. X: two-cusp second-premolar form; Y: three-cusp second-premolar form. - B. X: two-cusp second-premolar form; Y: two-cusp second-premolar form. - C. X: first-premolar form; Y: three-cusp second-premolar form. - D. X: first-premolar form; Y: two-cusp second-premolar form. **Answer C:** X: first-premolar form; Y: three-cusp second-premolar form. X combines the first-premolar mesiolingual groove/transverse-ridge organization with a small lingual region and greater lingual inclination. Y's central three-arm groove system and lingual separation match the three-cusp second-premolar variant, including the larger mesiolingual component. The answer requires reconciling both models; one transverse ridge alone is not a unique type identifier. Why the other choices do not fit: A: Y fits, but X's mesiolingual notch and low lingual region with marked crown inclination favor first-premolar architecture. A transverse ridge can occur in a two-cusp second, so it should not be used in isolation. B: It misweights X's shared transverse ridge and misses Y's central pit with a groove extending between distinct lingual elevations. The two-cusp second variant does not fit that complete Y record. D: X fits. Y's central pit and lingual developmental separation instead favor the three-cusp second variant; a generic rounded or bicuspid premolar label would omit those observations. Source: [Radlanski](https://api.pageplace.de/preview/DT0400.9780867159066_A38511739/preview-9780867159066_A38511739.pdf) ## Question 7 Two mandibular molar models have preserved occlusal surfaces. X has an elongated crown with MB, DB, distal, ML and DL cusps. Y has four principal cusps organized around a cross-like groove pattern. Position in the original arch is unavailable; compare conventional forms without treating them as invariant specimen identities. Which pair best fits? - A. X favors a second-molar form; Y favors a first-molar form. - B. X favors a third-molar form; Y favors a second-molar form. - C. X favors a first-molar form; Y favors a third-molar form. - D. X favors a first-molar form; Y favors a second-molar form. **Answer D:** X favors a first-molar form; Y favors a second-molar form. Five cusps including a distal cusp in an elongated crown fit the conventional mandibular first-molar comparison. Four principal cusps with a cross-like groove pattern fit a common second-molar form. Third molars and other variants can resemble these forms, but that variability does not make a third-molar assignment the best-supported conventional comparison. Why the other choices do not fit: A: It reverses the conventional first/second cusp and groove combinations. The additional distal cusp in X is part of the first-molar comparison, not a reason to reverse it. B: Y fits, but X already matches a conventional first-molar architecture. A distal cusp alone does not favor third-molar identity over that combination. C: X fits, but Y matches the conventional second-molar cross-groove form. Third-molar variability does not provide a stronger positive identification for Y. Source: [Radlanski](https://api.pageplace.de/preview/DT0400.9780867159066_A38511739/preview-9780867159066_A38511739.pdf) ## Question 8 An isolated mandibular molar model has an elongated mesiodistal crown, a conspicuous mesiobuccal cervical bulge and a relatively upright lingual contour. Its mesial and distal roots are slender and sharply divergent. No dentition label or arch position is supplied. Which conventional comparison best accounts for the crown and cervical combination as well as the roots? - A. Primary second molar, emphasizing its resemblance to the permanent first-molar crown. - B. Permanent first molar, emphasizing its elongated crown and mesial/distal root arrangement. - C. Primary first molar, emphasizing its distinctive crown form and mesiobuccal cervical prominence. - D. Permanent second molar, emphasizing its cervical contour and mesial/distal root arrangement. **Answer C:** Primary first molar, emphasizing its distinctive crown form and mesiobuccal cervical prominence. The unusual elongated crown, pronounced mesiobuccal cervical convexity and relatively upright lingual surface are the decisive primary first mandibular molar combination. Divergent roots support the comparison but are not sufficient by themselves. The primary second more closely resembles the permanent first in crown organization. Why the other choices do not fit: A: The divergent roots are compatible with a primary second, but its permanent-first-like crown is a poorer match for the specifically described first-primary cervical and lingual contours. B: The elongated crown and two named roots are compatible broad features. They underuse the distinctive cervical bulge/upright lingual combination and slender divergence that favor the primary first. D: A conventional permanent second has a more nearly square four-cusp/cross-groove crown. Its general two-root arrangement does not explain this distinctive elongated cervical/crown combination as well. Source: [Radlanski](https://api.pageplace.de/preview/DT0400.9780867159066_A38511739/preview-9780867159066_A38511739.pdf) ## Question 9 A before-and-after educational model shows adjacent posterior crowns with the same CEJs. The later model has flattened cusp tips and a broader proximal contact area. Gingival margins and the spaces below the contacts are outside both views. Which report preserves the observed changes and the limits of those views? - A. The cusp/contact contours changed; the CEJs retain the anatomical boundaries, and the present gingival embrasure is not fully described. - B. The cusp/contact contours changed; the CEJs retain the anatomical boundaries, and broader contact establishes loss of the gingival embrasure. - C. The cusp/contact contours changed; the contact's cervical edge now supplies the anatomical boundary, and the gingival embrasure remains unmeasured. - D. The cusp/contact contours changed; the CEJs retain the anatomical boundaries, and the clinical crown boundary coincides with them in the later view. **Answer A:** The cusp/contact contours changed; the CEJs retain the anatomical boundaries, and the present gingival embrasure is not fully described. The model directly shows surface wear, a broader contact and unchanged CEJs. CEJs still define the anatomical crown/root boundary. A contact view that omits gingival margins and the spaces below it does not fully describe the gingival embrasure or determine the clinical crown boundary; neither observation follows simply from contact width. Why the other choices do not fit: B: It retains the correct anatomical boundary but converts contact broadening into complete loss of an unshown space. Contact extent alone does not describe the entire gingival embrasure. C: The missing-space limit is reasonable, but the cervical contact edge is not the enamel–cementum junction. It cannot replace the CEJ as the anatomical boundary. D: The anatomical boundary is correct, but the clinical crown depends on the gingival margin, which was excluded from the views. Coincidence with the CEJ is not demonstrated. Source: [Radlanski](https://api.pageplace.de/preview/DT0400.9780867159066_A38511739/preview-9780867159066_A38511739.pdf) ## Question 10 In an original section model, X is a chamber extension toward a cusp. Two separate openings in the chamber floor lead into pathways inside one external root; the pathways later unite before one external exit. Which identification and count report fit? - A. X is an orifice; there are two chamber orifices and one external root. - B. X is a pulp horn; there are two chamber orifices and one external root. - C. X is a pulp horn; there are one chamber orifice and two external roots. - D. X is an orifice; there are one chamber orifice and two external roots. **Answer B:** X is a pulp horn; there are two chamber orifices and one external root. A cusp-directed chamber extension is a pulp horn. The floor openings are the two orifices; the complete model separately specifies one external root. Later union explains how two entry pathways can reach one exit. Identifying X and distinguishing the external/root-entry counts are both required. Why the other choices do not fit: A: The counts are right, but a chamber extension toward a cusp is not the floor opening into a root pathway. That opening is an orifice. C: X is identified correctly, but the report reverses the observed opening/root counts. Two internal entries do not create two external roots. D: It combines the chamber-landmark error with the reversed counts. The model provides separate evidence for each distinction. Source: [AAE](https://www.aae.org/specialty/clinical-resources/glossary-endodontic-terms/) ## Next step [Take the free 25-question ADAT practice test](https://dentovio.com/adat/free-practice-test) Official reference: [ADA 2026 ADAT Candidate Guide](https://www.ada.org/-/media/project/ada-organization/ada/ada-org/files/education/2026_adat_candidate_guide.pdf). Original exam-style questions written for study, never recalled exam content. Independent educational preparation, not affiliated with or endorsed by the American Dental Association. Practice results are not calibrated ADAT scores.