anatomy of permanent teeth

systematic identification of teeth

human permanent dentition

incisors

• 4 maxillary (upper) and 4 mandibular (lower)

• no cusps

permanent maxillary central incisor

• distal outline > convex

• > rounded distoincisal angle (vs sharp mesioincisal)

• incisal ridge straight

lingual aspect of maxillary central incisor

• crown has smooth convex proximal surfaces

• cervical line curved incisally

  • > curved on mesial side

maxillary lateral incisor compared with central (labially)

• smaller

• central > squarish

• crown > rounded outline

• mesioincisal + distoincisal angles and mesial + distal crown margins > rounded

• root curved distally

permanent maxillary lateral incisor palatal aspect

elevations

• marginal ridges (mesial + distal)

• cingulum (> cervically)

• incisal ridge

depressions

• palatal fossa: > concave and circumscribed (> clearly bounded)

maxillary central vs lateral incisors (palatally)

maxillary central vs lateral incisors

maxillary vs mandibular incisors

• root flat along m-d direction

mandibular central incisor labial

• trapezoid

• symmetrical mesio-distally

• disto-incisal margin rounded

mandibular central incisor lingual

• cingulum: centered, < developed vs maxillary incisor

mandibular central incisor mesial vs distal

mesial

• triangular

distal

• cervical line < curved

• developmental groove on root

mandibular lateral incisor labial

• slightly larger than central

• M side longer than D as incisal edge inclined

• D angle < rounded

• D contact point located closer to cervical (neck)

mandibular lateral incisor lingual

• mesial marginal ridge longer than distal

• cingulum deviated distally

mandibular lateral incisor M+D vs central

• distal surface shorter

• both cervical line curvatures < pronounced

• distal contact point > cervical

• root depressions on both surface

mandibular lateral incisor incisal/ lingual aspect

• incisal ridge tilted distally and lingually (+ whole tooth)

• cingulum shifted ditally

• allows tooth to follow dental arch curvature

mandibular central vs lateral incisors

maxillary canine

• longest root

• labial-palatal crown dimension greatest of anterior teeth

• distal bulge (side trait)

  • pinched/ stretched distally

• cusp tip located toward front side

• cingulum/ palatal ridge size largest

mandibular canine

• smaller, > slender

  • > symmetrical (vs maxillary)

• longest crown dimension

maxillary vs mandibular canines (buccal)

• crown dimensions both pentagon-shaped

• mandibular cusp < pointed

• incisal part of crown occupies 1/3 of crown height in maxillary canine

  • 1/5 of crown heights in mandibular

• cusp ridge lengths

  • mesial cusp ridge shorter in mandibular

• maxillary longest root length

maxillary vs mandibular canines (lingual)

• cingulum

  • > well defined and central in maxillary

• marginal ridge prominance

  • significant in maxillary

• lingual ridge

  • prominent in maxillary, insignificant in mandibular

• lingual fossae depth prominent in maxillary

maxillary vs mandibular canines (incisal)

• crown symmetry

  • maxillary - asymmetrical

  • mandibular - > symmetrical

• distal bulge

  • maxillary - well prominent

  • mandibular - insignificant

• incisal edge

  • maxillary - thicker than in mandibular

• facial/ labial ridge

  • prominent in maxillary

right vs left canines

1. distal cusp ridge

• longer and > sweeping/ oblique

• mesial shorter, steeper/ vertical

2. distal labial outline

• S-curve (convex middle third, slight cervical concavity)

• vs mesial: straighter line

3. distal root depression

• deeper developmental groove

general features of premolars

• at least 2 cusps

  • 1 large bucal

  • smaller lingual

  • = bicuspid

• lower 2nd premolar may have 3 cusps (1 buccal + 2 lingual)

maxillary 1st premolar

maxillary 1st premolar (buccal)

elevations

• convex surface (max at cervical ridge

• prominent ‘buccal ridge’

depressions

• shallow depressions - mesial and distal to buccal ridge

maxillary 1st premolar (lingual)

• lingual convergence

  • lingual surface narrower than buccal

• M and D outlines convex

• L cusp shorter by 1mm than B

• D slope of L cusp longer than m

• cervical line: convex root-wise (towards root)

maxillary 1st premolar (occlusal - geometric outline)

• polygonal/ hexagonal

• 2 equal buccal sides (MB, DB)

• M side shorter than D

• ML side shorter than DL side

• B-L dimension > M-D

• crown wider bucally than lingually (lingual convergence)

maxillary 1st premolar (occlusal - surface anatomy)

• 2 cusps

elevations

• 1 buccal triangular ridge

• 1 palatal triangular ridge

• mesial and distal marginal ridges

depressions

• central developmental groove

• mesial and distal triangular fossae

• mesial marginal developmental groove (side trait)

most characteristic feature of maxillary 1st premolar (side and type trait)

• mesial cusp ridge longer than distal

• mesial marginal developmental groove

maxillary 2nd premolar

• 1 root

• thicker marginal ridges

maxillary 1st vs 2nd premolar (buccal)

maxillary 1st vs 2nd premolar (lingual)

maxillary 1st vs 2nd premolar (mesial)

maxillary 1st vs 2nd premolar (occlusal)

maxillary 1st vs 2nd premolars: overall

mandibular 1st premolar

mandibular 1st premolar (buccal)

mandibular 1st premolar (lingual)

lingual convergence

• lingual side narrower than buccal

outlines

• M and D outlines convex

cervical line: convert root-wise

depressions

• mesiolingual developmental groove at ML line angle (side trait)

mandibular 1st premolar (m+d)

mandibular 1st premolar (occlusal)

mandibular 2nd premolar (2 cusp type)

• bulbous/ round

mandibular 2nd premolar vs 1st (buccal)

mandibular 2nd premolar vs 1st (m+d)

mandibular 2nd premolar vs 1st (occlusal) 2 cusp

mandibular 2nd premolar vs 1st (occlusal) 3 cusp type

side traits of mandibular 2nd premolar

2 cusp type

• distal fossa generally larger than mesial

• lingual cusp tip shifted mesially

3 cusp type

• lingual cusp usually subdivided into mesiolingual and distolingual cusps

• mesiolingual cusp wider and higher distolingual

mandibular 1st vs 2nd premolars

maxillary vs mandibular premolars

maxillary 1st molar

• 3 roots

• 4 cusps

maxillary 1st molar (buccal)

• mesio-buccal cusp broader, shorter, < sharp than disto-buccal

• cervical outline

  • irregular and slightly convex towards root

maxillary 1st molar (buccal - root)

• root trunk: 4mm length

• 3 roots seen from buccal aspect

• axis of roots inclined distally

• deep developmental groove extends on root trunk

maxillary 1st molar (palatal)

• ML cusp = largest

• DL cusp = spheroidal

• cusp of carabelli in 60% of lingual cusp surface of ML cusp (5th cusp/ tubercle)

• lingual developmental groove

• cervical outline: irregular and slightly convex towards root

maxillary 1st molar (occlusal)

• geometric outline: rhomboidal, reduces in MD width from 1st to 3rd molar

cusp size largest → smallest

1. ML cusp

2. rounded MB

3. sharp DB

4. small distolingual

5. tubercle of Carabelli

maxillary 1st molar (occlusal - elevations)

• 4 cusps with 4 triangular ridges and tubercle

• oblique ridge

  • between ML, DB cusps

  • distal cusp ridge of ML cup and triangular ridge of DB cusp

• mesial marginal and distal marginal ridges

maxillary 1st molar (occlusal - depressions)

• 2 major fossae (central and distal)

• 2 minor fossae (M + D triangular fossae)

• developmental grooves (central)

maxillary 2nd molar

• 3 roots

maxillary 2nd molar (buccal)

maxillary 2nd molar (buccal)

maxillary 2nd molar (mesial)

maxillary 2nd molar (occlusal)

maxillary 1st vs 2nd molars key diff

mandibular 1st molar

• 5 cusps

• 2 roots

mandibular 1st molar (buccal)

• trapezoidal with small, uneven side present cervically

• M outline: concave till contact area at junction of occlusal and middle 1/3

• D outline: straight till contact area with distal cusp ridge

mandibular 1st molar (buccal) occlusal + cervical outline

occlusal outline

• 2 cusps: MB, DB, **D

cervical outline

• straight with dipping into root bifurcation

mandibular 1st molar (buccal) anatomical landmarks

• 2 developmental grooves (MB, DB)

• (in Chinese pop, may be 2 mesial roots)

mandibular 1st molar roots

• roots ~ x2 length of crown

• axis of roots inclined distally

• root trunks 3mm

• deep developmental groove extends on root trunk

mandibular 1st molars lingual

occlusal outline

• formed by 2 lingual cusps

• ML, DL of nearly equal length

cervical outline

• irregular with dipping into root bifurcation

anatomical landmarks

• lingual developmental groove

mandibular 1st molars occlusal - elevations

anatomical landmarks

• zigzag groove pattern

elevations

• 5 cusps with 5 triangular ridges

• M marginal ridge and D marginal ridge

mandibular 1st molars occlusal - depressions

• 1 major central fossa + pit

• 2 minor fossae (M + D triangular fossae)

developmental grooves

• central groove = zigzag in its MD course

• MB groove, DB and L groove

  • **MB groove may end in buccal pit (prone to caries)

mandibular 2nd molar

• 2 roots

• 4 cusps

mandibular 2nd molar - buccal

geometric outline

• trapezoid with small, uneven side located cervically

anatomical landmarks

• buccal developmental groove may end up in buccal pit

• MB cusp longer than DB cusp

• root closer and nearly parallel with > pointed apex than 6

  • convergence

mandibular 2nd molar - lingual

crown

• lingual cusps > pointed than buccal

anatomical landmark

• lingual developmental groove never pitted

root

• short root trunk with developmental depression

mandibular 2nd molar mesial

geometric outline

• rhomboidal with lingual inclination

• M marginal ridge concave

• only M root visible (M root much longer)

• longitudinal depression on M surface M root

mandibular 2nd molar occlusal

mandibular molars 1st vs 2nd (occlusal)

mandibular molars 1st vs 2nd

(third molars)