Tooth Morphology - Primary Dentition

Question 1

Primary Maxillary Central Incisor - Labial Aspect

Answer 1

Labial Surface: Very smooth.
Mesiodistal (MD) diameter is greater than the Crown Incisal (CI) length.
Incisal edge is straight.
Root is cone-shaped with tapered sides.

Question 2

Primary Maxillary Central Incisor - Lingual Aspect

Answer 2

Well-developed marginal ridges and a highly developed cingulum.
Root is narrow.

Question 3

Primary Maxillary Central Incisor - Mesial & Distal Aspects

Answer 3

Similar to labial aspect; the labiolingual width at the cervical third of the crown is only 1mm less than its cervico-incisal height.
The curvature of the cervical line (Cemento-Enamel Junction) is distinct and curves toward the incisal ridge.

Question 4

Primary Maxillary Central Incisor - Incisal Aspect

Answer 4

Incisal edge is straight.
Labial Surface is much broader and smoother than the Palatal Surface.
Lingual Surface tapers toward the cingulum; Mesial Surface and Distal Surface are broad.

Question 5

Primary Maxillary Canine - Labial Aspect

Answer 5

Crown has a narrow neck.
Mesial Surface and Distal Surface are convex.
Incisal edge is long and well-developed.
Sharp cusp and long root.

Question 6

Primary Maxillary Canine - Palatal Aspect

Answer 6

Prominent enamel ridge forms the cingulum, Mesial and Distal marginal ridges, and cusp tip.
Palatal ridge divides the cingulum into Mesial Palatal and Distal Palatal fossae.

Question 7

Primary Maxillary Canine - Mesial & Distal Aspects

Answer 7

Similar to central incisor, except labio-palatally at the cervical third is much greater.

Question 8

Primary Maxillary Canine - Incisal Aspect

Answer 8

Shape is diamond.
Cingulum: Mesial cusp slope is longer than the Distal cusp slope.

Question 9

Primary Mandibular Central Incisor - Labial Aspect

Answer 9

Crown is flat with no developmental groove.
Mesial and Distal sides are tapered.
Root is long with a pointed apex.

Question 10

Primary Mandibular Central Incisor - Lingual Aspect

Answer 10

Features cingulum, marginal ridge, and lingual fossa.

Question 11

Primary Mandibular Central Incisor - Mesial Aspect

Answer 11

Shows the typical outline of an incisor tooth.
Cervical line is convex.
Small tooth; labiolingual dimension is 1mm less than maxillary central incisor.
Root is flat and tapered with a blunt apex.

Question 12

Primary Mandibular Central Incisor - Distal Aspect

Answer 12

Similar to the mesial aspect, except the cervical line has less convexity in the incisal direction.

Question 13

Primary Mandibular Central Incisor - Incisal Aspect

Answer 13

Incisal edge is straight.
Labial Surface is slightly convex.
Lingual Surface is slightly concave.

Question 14

Primary Mandibular Canine

Answer 14

Similar to the maxillary canine, except:
Smaller tooth dimension.
Distal cusp ridge is longer than the Mesial cusp ridge.

Question 15

Primary Maxillary First Molar - Buccal Aspect

Answer 15

Smooth surface.
Crown is narrow cervically.
Mesial and Distal contact areas have the greatest crown length.
Occlusal surface is scalloped with no definite cusp form.
Root is thin, long, and widely divergent with 3 roots (2 labially and 1 lingually).
Distal root is smaller than the Mesial root.
Furcation area is close to the cervical line.

Question 16

Primary Maxillary First Molar - Lingual Aspect

Answer 16

Similar to the buccal aspect.
Mesial Palatal cusp is more prominent, longest, and sharpest.
Distal Palatal cusp is poorly defined, if present, small and round.
Distal Buccal cusp may be seen from this aspect and is longer.
All 3 roots can be seen.

Question 17

Primary Maxillary First Molar - Mesial Aspect

Answer 17

Surface has convexity.
Cervical third dimension is greater than occlusal third.
Mesial Palatal cusp is longer and sharper than the Mesial Buccal cusp.
Mesial Buccal and Palatal roots are visible.

Question 18

Primary Maxillary First Molar - Distal Aspect

Answer 18

Crown is narrower.
Distal Buccal cusp is long and sharp.
Distal Palatal cusp is poorly developed.
All 3 roots are visible.

Question 19

Primary Maxillary First Molar - Occlusal Aspect

Answer 19

Shape is rectangular.
Features 2 fossae: central and mesial triangular fossae, pits.
Buccal developmental groove divides Mesial Buccal and Distal Buccal cusps.
Oblique ridge is well developed.

Question 20

Primary Maxillary Second Molar

Answer 20

Resembles the first permanent maxillary molar, except smaller in all dimensions.
Cusp of Carabelli is also present.

Question 21

Primary Mandibular First Molar - Buccal Aspect

Answer 21

Mesial outline is straight.
Distal outline is convex.
Distal portion of the crown is smaller than the mesial portion.
Cervical line curves in the apical direction.
Mesial cusp is larger than the Distal cusp; root is long and slender.

Question 22

Primary Mandibular First Molar - Lingual Aspect

Answer 22

Crown and root converge lingually.
Mesial Lingual cusp is longer and sharper than the Distal Lingual cusp.
Part of 2 Buccal cusps may be seen; cervical line is straight.

Question 23

Primary Mandibular First Molar - Mesial Aspect

Answer 23

Curved buccally at the cervical third.
Mesial Buccal crown length is greater than Distal Buccal crown length; Mesial Buccal and Mesial Lingual cusps are visible.
Mesial marginal ridge is well developed.
Root drops straight down from the crown and is parallel for more than half its length, tapering slightly at the apical third; root end is flat and almost square.

Question 24

Primary Mandibular First Molar - Distal Aspect

Answer 24

Not curved buccally; crown length is uniform.
Distal Lingual and Distal Buccal cusps are short; Distal marginal ridge is not well developed.
Root is short and round, tapering apically.

Question 25

Primary Mandibular First Molar - Occlusal Aspect

Answer 25

Shape is rhomboidal. Mesial Lingual cusp is the largest and best developed. Buccal developmental groove divides Buccal Surface into 2 Buccal cusps. Lingual developmental groove divides Lingual Surface into 2 Lingual cusps. Central and Mesial/Distant triangular fossae are present.

Question 26

Primary Mandibular Second Molar

Answer 26

The primary mandibular second molar has characteristics that resemble those of the permanent mandibular first molar, although its dimensions differ and are smaller.

Question 27

Major Contrasts Between Primary & Permanent Teeth

Answer 27

Primary teeth are smaller in overall size and crown dimensions. Buccolingual diameter of primary molar teeth is less than that of permanent teeth. Primary teeth are usually less pigmented and whiter in appearance than permanent teeth. Crowns of primary anterior teeth are wider mesiodistally than permanent teeth. Roots of primary anterior teeth are narrower and longer.

Question 28

Major Contrasts Between Primary & Permanent Teeth (Continued)

Answer 28

Roots of primary molars are longer, more slender, and flare. Cervical ridges buccally on primary molars are much more pronounced. Crowns and roots of primary molars at their cervical portions are more slender mesiodistally. Buccal and lingual surfaces of primary molars are flatter above the cervical curvatures than those of permanent molars. Cervical ridges of the enamel of primary anterior teeth are more prominent.