Subject Wise MCQs › Dental Anatomy
Dental Anatomy: High-Yield Notes & Practice Questions
Tooth notation, crown and root morphology, pulp anatomy, eruption chronology, occlusion and common anomalies — condensed for ADC written examination revision, followed by 100 practice questions with worked answers.
Tooth Notation Systems
| System | Format | Example — Max R1 |
|---|---|---|
| FDI / ISO (used in Australia) | Two digits: quadrant (1-4 perm, 5-8 primary) + tooth (1-8) | Permanent maxillary right central incisor = 11 |
| Universal (US) | 1-32 continuous, starts upper right 3rd molar | Upper right 3rd molar = 1; upper right central incisor = 8 |
| Palmer notation | Quadrant bracket symbol + tooth number/letter | ┐ 1 (permanent) or ┐ A (primary) |
FDI is the system used and expected on the ADC written and practical exams. Quadrants: 1 = upper right, 2 = upper left, 3 = lower left, 4 = lower right (permanent); 5-8 for primary in the same rotation.
Permanent Dentition — Crown & Root Morphology
Incisors
| Feature | Max Central | Max Lateral | Mand Central | Mand Lateral |
|---|---|---|---|---|
| Mesio-distal width | Widest anterior crown (~8.5mm) | Narrower, more rounded incisal angle | Smallest tooth in arch | Slightly larger than central |
| Cingulum / lingual fossa | Prominent, may form lingual pit (caries risk) | Prominent, higher caries risk pit | Faint | Faint |
| Root form | Single, conical, longest anterior root | Single, may curve distally near apex | Single, flattened mesio-distally | Single, slight distal curve |
| Key anomaly | Talon cusp (rare) | Peg lateral / hypodontia most common site | Often crowded/rotated first | — |
Canines
Longest root of any tooth in the mouth (anchors the arch — 'cornerstone of the arch').
Single prominent labial ridge dividing mesial/distal fossae; cusp tip usually offset toward mesial.
Most resistant tooth to periodontal bone loss due to root length and bone support.
Maxillary canine root often relates closely to the canine fossa/infraorbital region — relevant to infection spread (canine space).
Premolars
| Tooth | Cusps | Roots | Canals | Clinical pearls |
|---|---|---|---|---|
| Max 1st PM | 2 (buccal larger) | Usually 2 (buccal+palatal), bifurcated apical 1/3 | 2 (occasionally 3) | Most likely premolar to have 2 roots/canals; mesial marginal groove — caries/perio trap |
| Max 2nd PM | 2 (more equal size) | Usually 1 | 1 (may bifurcate) | Root canal often single, oval canal — watch for missed 2nd canal |
| Mand 1st PM | 2, buccal dominant, lingual cusp small (non-functional) | 1 | 1 | Lingual cusp small — crown tilts lingually; mesiolingual developmental groove |
| Mand 2nd PM | 2 or 3 cusps (Y or U groove pattern) | 1 | 1 | 3-cusp type has 2 lingual cusps; most stable/predictable mandibular PM anatomy |
Molars
| Tooth | Cusps | Roots | Canals (typical) | High-yield clinical point |
|---|---|---|---|---|
| Max 1st Molar | 4 + Cusp of Carabelli (mesiolingual) | 3 (2 buccal, 1 palatal) | 4 (MB1, MB2, DB, P) — MB2 present in majority | Most commonly missed canal in endo = MB2; roots relate closely to maxillary sinus floor |
| Max 2nd Molar | 4, more variable, oblique ridge prominent | 3, often fused/converging | 3-4 | Roots closer together than 1st molar — higher fusion rate |
| Max 3rd Molar | Highly variable (3-5 cusps) | Variable, often fused | Variable | Most variable tooth in the mouth |
| Mand 1st Molar | 5 (2 buccal, 2 lingual, 1 distal) | 2 (mesial, distal) | 3-4 — mesial root almost always 2 canals (MB, ML) | Largest tooth; mesial root canals may join apically (type II/IV Vertucci) |
| Mand 2nd Molar | 4 (cross/+ groove pattern) or 5 | 2 (mesial, distal) — closer together than 1st molar | 3 | Roots may show C-shaped canal configuration (more common here than 1st molar) |
| Mand 3rd Molar | Variable, 4 cusps common | Variable, often fused/conical | Variable | Close relation to inferior alveolar canal — key for extraction risk assessment |
Root Canal / Pulp Anatomy — Key Facts
Vertucci's classification (Types I-VIII) describes canal configurations from foramen to chamber — Type I (1 canal, 1 foramen) is simplest; higher numbers indicate branching/merging.
Mandibular 1st molar mesial root: 2 canals in ~90%+ of cases (MB & ML), may exhibit isthmus / mid-root fin.
Maxillary 1st molar MB root: MB2 canal present in a majority of teeth (reported up to ~60-90% depending on method) — most frequently missed canal clinically.
C-shaped canal systems are most classically associated with mandibular 2nd molars (fused distolingual + distobuccal roots).
Pulp chamber size and pulp horns reduce with age via secondary/tertiary dentine deposition — relevant to cavity preparation depth in older patients.
Apical foramen frequently exits slightly off the anatomic (radiographic) apex — important for working length determination.
Primary (Deciduous) Dentition
Differences from permanent teeth
Smaller overall crown size but crown width is proportionally larger relative to crown height (bulbous crowns).
Enamel and dentine are thinner and less mineralised → faster caries progression, more translucent/whiter appearance.
Pulp chambers are proportionally larger with pulp horns closer to the surface → higher risk of pulp exposure during cavity prep.
Cervical constriction is more pronounced with a bulbous crown contour (pronounced cervical ridge), especially on molars.
Roots are more slender, flare out (divergent) to accommodate the developing permanent tooth bud below/between them.
Enamel rods at the cervical margin run occlusally (not gingivally as in permanent teeth) — relevant to cavosurface margin design.
Primary molars: mandibular 1st, mandibular 2nd, maxillary 1st, and maxillary 2nd — resemble permanent premolars/molars in position but with distinct morphology (e.g., primary mandibular 1st molar has a very distinct mesiobuccal cervical bulge).
Notation for primary teeth
FDI: quadrants 5 (UR), 6 (UL), 7 (LL), 8 (LR), teeth numbered 1-5 mesial to distal (e.g., primary maxillary right central incisor = 51).
Eruption Chronology (high-yield for exam recall)
Primary dentition (approx. age of eruption)
| Tooth | Maxillary | Mandibular |
|---|---|---|
| Central incisor | 8-12 months | 6-10 months |
| Lateral incisor | 9-13 months | 10-16 months |
| Canine | 16-22 months | 17-23 months |
| 1st molar | 13-19 months | 14-18 months |
| 2nd molar | 25-33 months | 23-31 months |
General rule: mandibular teeth usually erupt before their maxillary counterparts, except lateral incisors (maxillary lateral tends to erupt earlier than mandibular in some references — know both patterns but mandibular-first is the dominant exam rule).
Permanent dentition (approx. age of eruption)
| Tooth | Maxillary | Mandibular |
|---|---|---|
| Central incisor | 7-8 yrs | 6-7 yrs |
| Lateral incisor | 8-9 yrs | 7-8 yrs |
| Canine | 11-12 yrs | 9-10 yrs |
| 1st premolar | 10-11 yrs | 10-12 yrs |
| 2nd premolar | 10-12 yrs | 11-12 yrs |
| 1st molar | 6-7 yrs | 6-7 yrs |
| 2nd molar | 12-13 yrs | 11-13 yrs |
| 3rd molar | 17-21 yrs | 17-21 yrs |
First permanent tooth to erupt overall: mandibular 1st molar (or mandibular central incisor, depending on reference) at ~6 years — the '6-year molar' is the classic exam answer for first permanent tooth.
Mandibular canine erupts notably earlier than maxillary canine — a common trick question.
Occlusion
Angle's Classification (molar relationship)
| Class | Definition |
|---|---|
| Class I | Mesiobuccal cusp of max 1st molar occludes in buccal groove of mand 1st molar (normal A-P relationship) |
| Class II | Mand molar positioned distally relative to max molar (mesiobuccal cusp occludes mesial to buccal groove) — Div 1 (proclined incisors) / Div 2 (retroclined central incisors) |
| Class III | Mand molar positioned mesially relative to max molar — mesiobuccal cusp occludes distal to buccal groove |
Other key occlusal concepts
Overjet: horizontal overlap of maxillary over mandibular incisors (normal ~2-4mm).
Overbite: vertical overlap of maxillary over mandibular incisors (normal ~2-4mm / up to 1/3 crown coverage).
Curve of Spee: anteroposterior curvature of the occlusal plane (mandibular arch).
Curve of Wilson: mediolateral curvature across posterior teeth.
Centric relation vs centric occlusion (maximum intercuspation) — key distinction for prosthodontic/restorative exam questions.
Tooth Development
Stages of tooth germ development: Bud stage → Cap stage → Bell stage (early & late) → Apposition → Maturation.
Enamel formed by ameloblasts (ectodermal origin); dentine formed by odontoblasts (ectomesenchymal/neural crest origin).
Hertwig's epithelial root sheath initiates root formation and dictates root number/shape; its fragmentation forms epithelial rests of Malassez (can give rise to radicular cysts).
Enamel knot: signalling centre controlling cusp pattern/number — key in cusp morphogenesis.
Amelogenesis imperfecta = defect in enamel formation (hypoplastic, hypomineralised, or hypomature types); dentinogenesis imperfecta = defect in dentine (associated with COL1A1/2 or DSPP mutations, translucent/opalescent teeth).
Clinically Relevant Applied Anatomy
Maxillary posterior teeth (especially 1st & 2nd molars) — roots frequently in close proximity to, or projecting into, the maxillary sinus floor; risk of oro-antral communication on extraction.
Inferior alveolar nerve (IAN) canal — runs close to mandibular molar (esp. 3rd molar) roots; radiographic signs of close proximity include darkening of root, interruption of the white line of the canal, and deflection of the canal.
Mental foramen — typically located near the apex of the mandibular 2nd premolar; important landmark for mental nerve block and avoiding nerve damage during apical surgery/implant placement in that region.
Lingual nerve — runs close to the lingual plate at the level of the mandibular 3rd molar, at variable and sometimes very superficial position — key risk during 3rd molar surgery (lingual flap retraction).
Nasopalatine canal — located behind the maxillary central incisors (incisive fossa); relevant to anaesthesia and implant planning in the anterior maxilla.
Greater palatine foramen — usually located palatal to the maxillary 2nd/3rd molar; landmark for greater palatine nerve block.
Common Dental Anomalies (frequently tested)
| Anomaly | Definition / key point |
|---|---|
| Dens invaginatus | Infolding of enamel organ into the tooth (‘tooth within a tooth’); commonly max lateral incisor; predisposes to pulp necrosis via invagination communicating with pulp |
| Talon cusp | Accessory cusp-like projection from cingulum of anterior teeth, mimics eagle talon on radiograph |
| Taurodontism | Elongated pulp chamber with apical displacement of furcation ('bull-like' tooth); pulp floor is apically positioned — molars |
| Dilaceration | Abnormal root curvature/angulation, often from trauma to primary predecessor or developmental disturbance |
| Fusion | Union of two normally separate tooth germs — results in reduced total tooth count; may share one pulp chamber |
| Gemination | Single tooth germ attempts to divide — normal tooth count maintained (count teeth to distinguish from fusion) |
| Concrescence | Union of two teeth via cementum only, after root formation is complete |
| Dens evaginatus | Extra tubercle on occlusal surface (classically mandibular premolars in Asian populations); risk of pulp exposure on wear/fracture |
| Hypodontia | Congenital absence of teeth; most common missing teeth (excluding 3rd molars) = mandibular 2nd premolar and maxillary lateral incisor |
| Supernumerary — mesiodens | Most common supernumerary tooth; located between maxillary central incisors, may cause delayed eruption/displacement |
| Enamel pearl | Ectopic nodule of enamel on root surface, usually at furcation of molars — can complicate periodontal therapy |
| Turner's tooth / hypoplasia | Localised enamel defect from infection/trauma to overlying primary tooth affecting the permanent successor |
Exam-Style Quick Recall Table
| Question | Answer |
|---|---|
| Longest tooth root overall | Maxillary canine |
| Smallest tooth in the mouth | Mandibular central incisor |
| Tooth most likely to have 2 canals among premolars | Maxillary 1st premolar |
| First permanent tooth to erupt | Mandibular 1st molar (‘6-year molar’) |
| Tooth most associated with C-shaped canals | Mandibular 2nd molar |
| Most common site for a peg-shaped/missing tooth | Maxillary lateral incisor |
| Most common supernumerary tooth | Mesiodens |
| Cusp most associated with Carabelli trait | Mesiolingual cusp of maxillary 1st molar |
| Nerve at risk during lingual flap in 3rd molar surgery | Lingual nerve |
| Landmark near mandibular 2nd premolar apex | Mental foramen |
Practice questions
Select an option to check your answer. Each answer includes a short explanation.
Which permanent tooth is described as the 'cornerstone of the arch'?
- ACentral incisor
- BCanine
- CFirst premolar
- DFirst molar
Which tooth most commonly has two root canals in its single root?
- AMaxillary 2nd premolar
- BMandibular 1st premolar
- CMaxillary 1st premolar
- DMandibular canine
The 'six-year molar' refers to which tooth?
- AMaxillary 1st molar
- BMandibular 1st molar
- CMaxillary 2nd molar
- DMandibular 2nd premolar
An extra canal frequently missed during root canal treatment of a maxillary first molar is:
- ADB2
- BMB2
- CP2
- DDL
Which tooth is most frequently congenitally absent (excluding 3rd molars)?
- AMaxillary lateral incisor / mandibular 2nd premolar
- BMaxillary canine
- CMandibular central incisor
- DMaxillary 1st molar
The most common supernumerary tooth is the:
- AParamolar
- BMesiodens
- CDistomolar
- DParapremolar
Which cusp is associated with the Carabelli trait?
- AMesiobuccal cusp of mandibular 1st molar
- BMesiolingual cusp of maxillary 1st molar
- CDistobuccal cusp of maxillary 2nd molar
- DDistolingual cusp of mandibular 2nd molar
Taurodontism primarily affects which dental structure?
- AEnamel thickness
- BPulp chamber size and furcation position
- CRoot canal number
- DCrown morphology
C-shaped root canal systems are most classically found in:
- AMaxillary 1st premolar
- BMandibular 2nd molar
- CMaxillary central incisor
- DMandibular canine
Which nerve is at greatest risk during lingual flap retraction in mandibular 3rd molar surgery?
- AInferior alveolar nerve
- BLingual nerve
- CBuccal nerve
- DMylohyoid nerve
The mental foramen is typically located near the apex of which tooth?
- AMandibular 1st molar
- BMandibular canine
- CMandibular 2nd premolar
- DMandibular 1st premolar
Which root sheath structure initiates root formation?
- AEnamel knot
- BHertwig's epithelial root sheath
- CStellate reticulum
- DDental lamina
Epithelial rests of Malassez arise from fragmentation of:
- ADental lamina
- BHertwig's epithelial root sheath
- CStratum intermedium
- DEnamel organ
Dentinogenesis imperfecta is most commonly linked to a defect in which gene?
- ACOL1A1/DSPP
- BAMELX
- CENAM
- DMMP20
Amelogenesis imperfecta primarily affects:
- ADentine formation
- BCementum formation
- CEnamel formation
- DPulp vascularity
Which tooth is the most common site for dens invaginatus?
- AMaxillary central incisor
- BMaxillary lateral incisor
- CMandibular canine
- DMaxillary 1st premolar
Dens evaginatus classically presents on which teeth?
- AMaxillary incisors
- BMandibular premolars
- CMaxillary molars
- DMandibular incisors
Fusion differs from gemination in that:
- AFusion increases total tooth count, gemination decreases it
- BFusion results in a reduced tooth count, gemination maintains
- CBoth always reduce tooth count
- DThere is no clinical difference
Concrescence refers to union of adjacent teeth via:
- AEnamel
- BDentine
- CCementum
- DPulp tissue
An enamel pearl is most commonly found at the:
- AIncisal edge
- BCervical third of anterior teeth
- CFurcation of molars
- DRoot apex
Turner's hypoplasia of a permanent tooth is most often caused by:
- AGenetic mutation
- BInfection/trauma to the overlying primary tooth
- CFluorosis
- DVitamin D deficiency
Which classification system describes root canal configurations from foramen to chamber?
- ABlack's classification
- BVertucci's classification
- CAngle's classification
- DKennedy classification
In Vertucci Type I canal configuration:
- ATwo canals join into one
- BOne canal from chamber to apex
- CTwo separate canals throughout
- DThree canals merging
The mandibular 1st molar mesial root most commonly contains how many canals?
- A1
- B2
- C3
- D4
Which tooth's roots are most commonly in close proximity to the maxillary sinus floor?
- AMaxillary premolars and molars
- BMandibular premolars and molars
- CMaxillary anterior teeth
- DMandibular anterior teeth
A radiographic sign suggesting close proximity of a mandibular molar root to the IAN canal includes:
- AWidening of the periodontal ligament space only
- BDarkening/deflection of the root and interruption of the canal's
- CHypercementosis
- DRoot resorption of adjacent tooth
The nasopalatine canal is located:
- ABehind the maxillary central incisors
- BBehind the maxillary 2nd molars
- CBelow the mandibular incisors
- DBehind the mandibular 3rd molars
The greater palatine foramen is typically located palatal to which tooth?
- AMaxillary central incisor
- BMaxillary canine
- CMaxillary 1st premolar
- DMaxillary 2nd/3rd molar
Angle's Class II malocclusion is defined by:
- ANormal molar relationship
- BMandibular molar positioned mesial to normal
- CMandibular molar positioned distal to normal (mesiobuccal cusp
- DAnterior open bite
Which describes Angle's Class III relationship?
- AMesiobuccal cusp of maxillary 1st molar occludes in the buccal
- BMandibular molar positioned mesial to the maxillary molar
- CExcess overjet
- DDeep bite with retroclined incisors
Normal overjet is approximately:
- A0-1mm
- B2-4mm
- C5-7mm
- D8-10mm
The curve of Spee describes:
- AMediolateral curvature of posterior occlusal plane
- BAnteroposterior curvature of the occlusal plane
- CCurvature of the dental arch form
- DCurvature of root apices
The curve of Wilson refers to:
- AAnteroposterior occlusal curvature
- BMediolateral curvature across posterior teeth
- CCurvature of the maxillary arch
- DCurvature of the mandible
Centric occlusion refers to:
- AThe most retruded jaw position
- BMaximum intercuspation of the teeth
- CRest position of the mandible
- DFirst point of tooth contact only
Which primary tooth typically shows the most pronounced cervical bulge/ridge?
- APrimary maxillary central incisor
- BPrimary mandibular 1st molar
- CPrimary maxillary canine
- DPrimary mandibular central incisor
Compared to permanent teeth, primary tooth enamel and dentine are:
- AThicker and more mineralised
- BThinner and less mineralised
- CIdentical in thickness
- DOnly the enamel is thinner
Pulp horns in primary teeth are:
- ACloser to the surface than in permanent teeth
- BFurther from the surface
- CAbsent
- DOnly present in molars
In primary teeth, cervical enamel rods run:
- AGingivally
- BOcclusally
- CHorizontally
- DThere is no consistent orientation
Using FDI notation, the primary maxillary right central incisor is:
- A11
- B51
- C61
- D81
In FDI notation, quadrant '3' refers to:
- AUpper right permanent
- BUpper left permanent
- CLower left permanent
- DLower right permanent
Using Universal (US) notation, tooth #8 refers to:
- AUpper right 3rd molar
- BUpper right central incisor
- CLower left central incisor
- DUpper left 1st molar
Which primary tooth erupts first?
- AMaxillary central incisor
- BMandibular central incisor
- CMandibular lateral incisor
- DMaxillary lateral incisor
The last primary tooth to erupt is typically the:
- APrimary canine
- BPrimary 2nd molar
- CPrimary 1st molar
- DPrimary lateral incisor
Which permanent tooth generally erupts significantly earlier in the mandible than the maxilla?
- ACentral incisor
- BCanine
- C1st premolar
- D2nd molar
Third molars typically erupt at what age range?
- A12-13 years
- B14-16 years
- C17-21 years
- D22-25 years
Which stage of tooth development involves differentiation of ameloblasts and odontoblasts?
- ABud stage
- BCap stage
- CBell stage
- DInitiation stage
The enamel knot functions as a:
- ANutrient supply structure
- BSignalling centre controlling cusp pattern
- CRoot-forming epithelium
- DSite of dentine mineralisation
Ameloblasts are derived from which embryonic tissue?
- ANeural crest mesenchyme
- BOral ectoderm
- CMesoderm
- DEndoderm
Odontoblasts are derived from:
- AOral ectoderm
- BEctomesenchyme (neural crest origin)
- CEndoderm
- DNotochord
Which permanent tooth has the widest mesiodistal crown dimension among anterior teeth?
- AMaxillary lateral incisor
- BMaxillary central incisor
- CMandibular central incisor
- DMandibular canine
A prominent lingual pit/fossa increasing caries risk is most characteristic of the:
- AMandibular canine
- BMaxillary lateral incisor
- CMandibular 2nd premolar
- DMaxillary 1st premolar
Which tooth is most likely to be a 'peg lateral' or congenitally absent?
- AMaxillary lateral incisor
- BMaxillary central incisor
- CMandibular lateral incisor
- DMaxillary canine
Which mandibular premolar typically has a small, non-functional lingual cusp?
- AMandibular 1st premolar
- BMandibular 2nd premolar
- CBoth equally
- DNeither
The mandibular 2nd premolar 3-cusp variant has:
- A1 buccal, 2 lingual cusps
- B2 buccal, 1 lingual cusp
- C3 buccal cusps
- DNo lingual cusps
Which molar has the greatest number of major cusps typically?
- AMaxillary 1st molar (4 + Carabelli)
- BMandibular 1st molar (5)
- CMaxillary 2nd molar (4)
- DMandibular 2nd molar (4)
The oblique ridge is a distinguishing anatomical feature of which tooth group?
- AMandibular molars
- BMaxillary molars
- CMaxillary premolars
- DMandibular premolars
Which tooth is considered the most morphologically variable in the human dentition?
- AMaxillary central incisor
- BMandibular canine
- CMaxillary/mandibular 3rd molars
- DMaxillary 1st premolar
Root fusion is most commonly seen between which molar roots?
- AMaxillary 1st molar roots
- BMaxillary 2nd/3rd molar roots
- CMandibular 1st molar roots
- DMandibular canine roots
Which of the following best distinguishes centric relation from centric occlusion?
- ACentric relation is a bone-based jaw position independent of tooth
- BThey are identical terms
- CCentric occlusion refers only to the resting position
- DCentric relation depends on tooth wear
Radiographically, hypercementosis appears as:
- AThinning of the root outline
- BBulbous excess cementum deposition around the root
- CWidened pulp chamber
- DRadiolucent apical halo
External root resorption differs from internal resorption in that:
- AExternal resorption originates from the periodontal
- BExternal resorption always affects the pulp first
- CInternal resorption cannot be seen radiographically
- DThere is no clinical distinction
Dilaceration of a tooth root is most often the result of:
- AGenetic syndrome only
- BTrauma to the primary predecessor during root development
- CExcess fluoride exposure
- DVitamin deficiency
Which of the following primary teeth has no permanent successor equivalent replaced by another primary tooth (i.e., succeeded by a premolar)?
- APrimary central incisor
- BPrimary canine
- CPrimary 1st and 2nd molars
- DPrimary lateral incisor
The permanent molars (1st, 2nd, 3rd) are best described as:
- ASuccessional teeth replacing primary molars
- BAccessional teeth with no primary predecessors
- CSupernumerary teeth
- DPrimary teeth retained into adulthood
A tooth exhibiting both a crown-root fusion and a shared pulp chamber between two adjacent tooth germs describes:
- AGemination
- BFusion
- CConcrescence
- DDens invaginatus
Which anatomical landmark should be identified before an inferior alveolar nerve block?
- APterygomandibular raphe and coronoid notch
- BIncisive papilla
- CRetromolar pad only
- DHamular notch
A greater palatine nerve block anaesthetises which region?
- AAnterior hard palate only
- BPosterior hard palate and soft tissue distal to canine
- CEntire palate including anterior teeth pulps
- DBuccal soft tissue of molars
The nasopalatine nerve block anaesthetises:
- AAnterior hard palate soft tissue from canine to canine
- BPosterior palate
- CBuccal gingiva of incisors
- DEntire maxillary arch pulps
Which tooth's extraction carries the highest risk of oro-antral communication?
- AMaxillary canine
- BMaxillary 1st/2nd molar
- CMandibular molar
- DMaxillary central incisor
Buccal object rule (SLOB rule) is used to determine:
- ACaries depth
- BRelative bucco-lingual position of a root/canal or object on two
- CBone density
- DPeriodontal pocket depth
Which canal is most likely present but unlocated in an inadequately treated maxillary 1st molar, leading to endodontic failure?
- APalatal canal
- BMB2
- CDB canal
- DAccessory apical canal in the palatal root
The apical foramen's actual exit point relative to the radiographic apex is typically:
- AExactly at the radiographic apex
- BSlightly coronal/off-centre to the radiographic apex
- CAlways 5mm short
- DAlways at the widest root point
Which statement about Hertwig's epithelial root sheath (HERS) is correct?
- AHERS forms enamel
- BHERS determines the number and shape of roots
- CHERS is part of the dental papilla
- DHERS persists as a mineralised structure into adulthood
Cementum is produced by:
- AAmeloblasts
- BCementoblasts
- COdontoblasts only
- DOsteoblasts
Which type of cementum is found in the apical third and involved in tooth attachment repair?
- AAcellular extrinsic fibre cementum
- BCellular intrinsic fibre / mixed cementum
- CEnamel cuticle
- DReduced enamel epithelium
Which structure marks the cementoenamel junction pattern where cementum overlaps enamel (most common pattern)?
- AEnamel meets cementum edge to edge (~30%)
- BCementum overlaps enamel (~60%)
- CA gap exists exposing dentine (~10%)
- DEnamel always overlaps cementum
Periodontal ligament fibres running from cementum to alveolar bone crest are called:
- AApical fibres
- BAlveolar crest fibres
- CHorizontal fibres
- DOblique fibres
The majority of periodontal ligament fibres (bulk of the ligament) are classified as:
- AOblique fibres
- BHorizontal fibres
- CApical fibres
- DInterradicular fibres
Sharpey's fibres refer to:
- ANerve fibres in the pulp
- BCollagen fibre bundles embedded in bone/cementum anchoring the PDL
- CVascular channels in dentine
- DEnamel rod boundaries
Which best explains why primary teeth roots are more divergent/flared than permanent teeth?
- ATo accommodate the underlying permanent tooth bud
- BDue to smaller crown-root ratio
- CRandom anatomical variation
- DBecause primary roots are shorter overall
Physiologic root resorption of primary teeth is primarily mediated by:
- AOsteoblasts
- BOdontoclasts (similar to osteoclasts)
- CAmeloblasts
- DFibroblasts
Which best describes the relationship between crown formation and the Nolla stages of tooth development used for age estimation?
- ANolla stages track only root formation
- BNolla stages (0-10) track crown initiation through to apical
- CNolla stages are unrelated to radiographic assessment
- DNolla stages apply only to primary teeth
Demirjian's method for dental age estimation evaluates:
- ARoot resorption of primary teeth only
- BStages of mineralisation of specific permanent teeth (usually 7
- CEruption sequence only
- DCementum annulation rings
Enamel is composed of approximately what percentage inorganic content by weight?
- A50%
- B70%
- C96%
- D20%
Dentine is approximately what percentage inorganic content by weight?
- A96%
- B70%
- C45%
- D20%
Which dentine type is formed after tooth eruption and continues slowly throughout life?
- APrimary dentine
- BSecondary dentine
- CReparative (tertiary) dentine
- DMantle dentine
Tertiary (reactionary/reparative) dentine forms in response to:
- ANormal ageing only
- BLocalised irritation/stimuli such as caries or attrition
- CGenetic factors exclusively
- DFluoride exposure
Which best describes the direction of dentinal tubules in relation to caries susceptibility near the cervical region?
- ATubules run straight and are less numerous, reducing sensitivity
- BTubules converge more densely and can increase sensitivity/caries
- CTubules are absent near the cervical margin
- DDirection has no clinical relevance
The zone of Weil is a histological layer found in:
- AEnamel
- BThe subodontoblastic region of the pulp
- CCementum
- DAlveolar bone
Odontoblasts are directly responsible for producing:
- AEnamel
- BDentine
- CCementum
- DPeriodontal ligament
Which pulp tissue layer lies directly beneath the odontoblastic layer and is relatively cell-free?
- ACell-rich zone
- BCell-free zone (zone of Weil)
- CPulp core
- DPredentine
Reversible pulpitis is generally characterised by:
- ASpontaneous, lingering pain
- BSharp pain on stimulus that resolves quickly once stimulus removed
- CNo response to any test
- DRadiographic periapical radiolucency
Irreversible pulpitis is classically characterised by:
- APain that resolves immediately after stimulus removal
- BSpontaneous, lingering, poorly localised pain often worse at night
- CNo symptoms at all
- DPain only on percussion
A tooth with a necrotic pulp and apical radiolucency but no symptoms is best classified as:
- ASymptomatic apical periodontitis
- BAsymptomatic apical periodontitis
- CAcute apical abscess
- DReversible pulpitis
Percussion sensitivity in a tooth most directly indicates inflammation of the:
- APulp only
- BPeriodontal ligament/periapical tissues
- CGingiva only
- DEnamel
Which test is most useful to assess pulp vitality by directly stimulating nerve fibres?
- APercussion test
- BElectric pulp test
- CPalpation test
- DMobility test
Cold testing primarily assesses:
- ABlood flow directly
- BA-delta nerve fibre response (sharp, quick pain)
- CC-fibre response only
- DPeriodontal ligament status
Heat testing is more likely to elicit a response mediated by:
- AA-beta fibres
- BA-delta fibres exclusively
- CC-fibres, producing dull, lingering pain
- DNo nerve fibres, only vascular pressure
In endodontics, which canal system feature is a common cause of a 'missed canal' leading to treatment failure in mandibular incisors?
- AA second (lingual) canal not identified
- BExcess canal curvature only
- CApical delta always present
- DCementum hypertrophy
Which statement about the maxillary lateral incisor root and canal is correct?
- AIt is always straight with a single canal
- BIt commonly shows distal curvature near the apex
- CIt always has two canals
- DIt has the widest root of the anterior teeth
These notes are compiled from standard dental anatomy texts for study purposes. They are a revision aid, not a substitute for your own reading or current clinical guidelines. If you spot an error, please leave a comment.