Mandibular Incisors

Question 1

What are the mandibular incisors?

Answer 1

central = #24 and #25
lateral = #23 and #26

Question 2

What is interproximal contact?

Answer 2

where two adjacent teeth contact

Question 3

What is an embrasures?

Answer 3

the spaces/spillways that widen out from the contact

Question 4

What are the embrasures?

Answer 4

anterior have 4: incisal, gingival (cervical), facial, lingual

posterior have 4: occlusal, gingival (cervical), facial, lingual

Question 5

What are the differences in sizes of the anterior and posterior embrasures?

Answer 5

anterior
incisal < gingival
facial = lingual

posterior
occlusal = gingival
facial < lingual

Question 6

What are the general characteristics of mandibular incisors?

Answer 6

used to incise or cut food
4 in number: 2 central incisors and 2 lateral incisors
have smaller mesiodistal diameters than any other tooth
central incisor is the smallest tooth
broader buccolingually (BL) than mesiodistally (MD)

Question 7

What are the mandibular central incisor facial view characteristics?

Answer 7

trapezoidal in outline (tapers cervically)
incisal outline is straight (mamelons present when the tooth erupts)
crown is approximately 2x as long (IG) as wide (MD)
90 degree MI and DI line angles

Question 8

What is an interesting fact about mandibular central incisor?

Answer 8

the only symmetrical tooth in the mouth because 90 degree MI and DI line angles and contact points are the same

Question 9

What are the contact areas of the central incisor?

Answer 9

incisal 1/3

Question 10

In most teeth, the distal contact area is positioned?

Answer 10

more cervically than the mesial contact even if it is located in the same 1/3 of the tooth

Question 11

What is the size of the crown and root?

Answer 11

9mm
12.5mm

Question 12

Describe the labial surface of the mandibular central incisor

Answer 12

smooth - no developmental depressions
is flat in incisal 1/3 and becomes more convex cervically

Question 13

Describe the root of the mandibular central incisor

Answer 13

single root - narrow mesiodistally, curves distally in some cases
root in longer than the crown length

Question 14

Describe the lingual view of the mandibular central incisor

Answer 14

trapezoidal in outline
smooth and rounded, slightly concave but no distinct lingual fossa
mesial and distal marginal ridges are only minor elevations
cingulum is much less distinct than in the maxillary incisor
no developmental grooves

Question 15

Describe the mesial view of the mandibular central incisor

Answer 15

triangular in outline
labial outline is curved (convex)
the height of contour of the labial surface is in the cervical 1/3
incisal edge lies lingual to line bisecting the root
when worn, the incisal edge angles to the facial
CEJ curves incisally about 1 mm more than on the distal

Question 16

On the mandibular central incisor, the cervical line extends

Answer 16

1 mm more apically on the lingual than on the labial
these teeth are broader labiolingually than mesiodistally

Question 17

Describe the crown and root characteristics on a mandibular central incisor

Answer 17

crown may have a concavity below middle 1/3 above the cervical line
root extends straight from CEJ and tapers apically from middle 1/3
root may have a broad developmental depression along its length

Question 18

Describe the distal view of the mandibular central incisor

Answer 18

cervical lines currves incisally 1 mm less than on the mesial
developmental depression on distal of root is greater than on the mesial

Question 19

Describe the incisal view of the mandibular central incisor

Answer 19

symmetry of tooth is obvious
mesial 1/2 and distal 1/2 of the tooth are almost identical
incisal edge is at right angles to a line bisecting the crown labiolingually
incisal edge lies lingual to center of the tooth
tooth converges lingually
the MD width of the labial surface is wider than the MD width of the lingual surface
contact areas aer centered faciolingually

Question 20

Describe the rooth and pulp of the mandibular central incisor

Answer 20

single rooted tooth
root is broader FL than MD
developmental depressions run longitudinally down root on mesial and distal
distal depression usually deeper than mesial
root is round/ovoid in cross section with depressions on the mesial and distal
usually one pulp canal (narrow MD, broad FL)
some have two pulp canals (40% of the time)
if two, called facial and lingual canals

Question 21

General characteristics of the mandibular lateral incisor

Answer 21

resembles the central incisor
larger than the central incisor
wider MD than the central incisor
all extra width appears to be added to the distal aspect of the tooth

Question 22

Describe characteristics of the facial view of the lateral incisor

Answer 22

distal crown height is often shorter than the mesial crown height
incisal edge slopes downward distally
mesioincisal angle is 90 degrees
distoincisal angle is rounded
lateral is wider MD than central
mesial and distal contacts are in the incisal 1/3 (distal contact is more cervical than mesial)

Question 23

Describe characteristics of the lingual view of the lateral incisor

Answer 23

same as the lingual surface of the mandibular central incisor

trapezoidal in outline
smooth and rounded, slightly concave but no distinct lingual fossa
mesial and distal marginal ridges are only minor elevations
cingulum is much less distinct than in the maxillary incisor
no developmental grooves

Question 24

Describe characteristics of the mesial and distal views of the lateral incisor

Answer 24

similar
the developmental depressions on the rooth of the mandibular lateral incisor are more pronounced (deeper) than on the mandibular central incisor
distal developmental depression is more marked than the mesial
the distal aspect is twisted lingually. The lingual surface (marginal ridge). is not visible when viweed from the distal

Question 25

Describe characteristics of the incisal view of the lateral incisor

Answer 25

incisal edge of the lateral is lingual to the center of the tooth
tooth is not symmetrical - the distal part of the crown appears to be curved lingually like as if the distal part is twisted on the tooth
DF line angle is positioned more lingual

Question 26

Describe characteristics of root and pulp of lateral incisor

Answer 26

similar to the central incisor but slightly larger
root is ovoid/round
depression on the distal is deeper than the central
typically one pulp canal but can have 2 canals (40% of the time)