Anatomy Of Incisors

Front 1

Function of Incisors

Back 1

-help cut food
-articulate speech
-support lip

Front 2

How many incisors are in each arch and what are the two types?

Back 2

4 incisors, there are centrals (8,9,24,25) and laterals (7,10,23,26)

Front 3

What are the 5 surfaces of incisors?

Back 3

mesial, distal, lingual, facial and incisal

Front 4

How many developmental lobes do incisors form from?

Back 4

4

Front 5

Which side is move convex on incisors? Are they longer or wider?

Back 5

Distal is more convex (except mandibular centrals)

Incisors are longer than wider

Front 6

Where is the contact area on incisors?

Back 6

Incisal 1/3rd on mesial, more cervical on D (except mandibular central which is symmetrical)

Front 7

Which root measurement is widest for incisors?

Back 7

roots are wider Facial-lingual that mesial-distal. (except maxillary centrals). Roots are longer than crowns-distal root depression is great than mesial

Front 8

For all incisors where is the height of contour on the lingual and facial aspects?

Back 8

cervical 1/3rd

Front 9

From the lingual view of an incisor where to the mmr and dmr converge?

Back 9

the cingulum (4th lobe)

Front 10

For incisors, the cervical line curves ___ for the proximal views and ___ on the facial/lingual.

Back 10

The cervical line curves towards the incisal edge proximally (m/d) and apically on the facial/lingual

Front 11

From the proximal view, incisors are ____ shaped lingual and ____ shaped labial. This makes them look like a shovel.

Back 11

incisors are concave lingually and convex labially from a proximal view.

Front 12

From an incisal view, incisors are narrower on which side and why is this necessary?

Back 12

incisors are more narrow lingual than labial. This is to allow all the teeth to fit into the arch.

Front 13

What is the shape of the lingual fossa on incisors?

Back 13

concave (incisal to the cingulum)

Front 14

For maxillary incisors, where is the interproximal contact mesially? where is it distally?

Back 14

mesially the contact is on the incisal 1/3rd very close to the incisal edge. Distally it is located more cervically at the junction of the incisal 1/3rd and the middle 1/3rd

Front 15

For max incisors which marginal ridge is longer? What does this do the the incisal edge?

Back 15

The mesial marginal ridge is longer than the distal. This makes the crown less symmetrical and makes the incisal edge slope cervically towards the distal.

Front 16

What shape (or alphabetical letter) are maxillary incisors said to exhibit and why?

Back 16

"S" due to the concavity of the lingual fossa incisal to the cingulum and the concavity of the labial aspect of the tooth.

Front 17

How are the roots of the max central incisors different from the roots of the max lateral incisors?

Back 17

Roots are cone shaped on the centrals and for the laterals they are narrower M-D and often exhibit a distal bend towards the apex.

Front 18

Where is the incisal edge in relation to the root axis line for maxillary incisors?

Back 18

On the root axis line or just labial to axis (for proper occlusion with mandibular incisors)

Front 19

Describe the difference between max and mand incisors for the following:
-over all shape
-proximal contact
-root to crown ratio
-width of crown
-lingual fossa
-marginal ridges

Back 19

-MN are more uniform and flatter (less lingual anatomy)
-MN proximal contacts are closer to the incisal edge
-MN roots are longer in relation to crown (greater crown to root ratio)
-MX wider m-d than MN
-MX deeper lingual fossas
-MX more defined marginal ridges/more lingual anatomy

Front 20

Where are the attrition/wear facets on the MX vs. MN incisors?

Back 20

on the facial of MN and on the lingual of MX

Front 21

Which incisors are the widest m-d

Back 21

Maxillary centrals (8&9)

Front 22

Which teeth have the longest CROWN?

Back 22

Maxillary centrals (8, 9)

Front 23

When do Max. central erupt?

Back 23

ages 7-8

Front 24

Which teeth have the smallest crown to root ratio?

Back 24

maxillary centrals (shortest roots)

Front 25

Are max centrals wider m-d or fa-ln?

Back 25

Wider M-D than FA-LN

Front 26

Where is the cingulum located on each of the incisors?

Back 26

The cingulum is always on the lingual surface at the cervical third, for maxillary centrals (8,9) and mandibular laterals (23,26) it is offset distally. For maxillary laterals (7,10) and mandibular centrals (24,25) the cingulum is centered.

Front 27

What frames the lingual fossa of maxillary incisors?

Back 27

the mesial and distal marginal ridges.

Front 28

How many developmental lobes are there for incisors? What is the fate of these lobes?

Back 28

4 developmental lobes-3 labially/facially and one lingually. The 3 facial lobes form mamelons on the incisal edge. The lingual lobe forms the cingulum.

Front 29

Describe the facial aspect of maxillary central incisors in relation to:
-width of crown cervically vs. incisally
-angle of mesial-incisal vs. distal-incisal edge
-size of pulp cavity
-width of crown and root labially vs. lingually

Back 29

-crown wider incisally
-mi angle is almost 90 degrees, di is more rounded and shorter.
-large pulp cavity
-crown and root are wider facially than lingually

Front 30

Which teeth exhibit the greatest CEJ curvature and on what aspect of the tooth?

Back 30

Max centrals (8,9) have the greatest mesial CEJ curvature of all teeth.

Front 31

Describe the roots of the mx centrals

Back 31

blunt apex, only slightly longer than the crowns of the teeth (mx centrals have smallest crown to root ratio)

Front 32

How is the shape/anatomy of the lateral max incisors different from the centrals?

Back 32

-Smaller, more rounded
-Narrower than the centrals
-marginal ridges rounder.

Front 33

Which teeth vary in form more than any other tooth?

Back 33

Maxillary laterals (and 3rd molars)
-can be missing
-can be peg shaped

Front 34

How do the roots of max. lateral incisors compare to those of the centrals?

Back 34

Lateral roots are longer
and wider LA/LN than M/D

Front 35

When do max lateral incisors erupt?

Back 35

age 8-9

Front 36

How is the lingual view of max lateral incisors different from the centrals?
-lingual fossa
-lingual pit
-cingulum
-marginal ridges

Back 36

-laterals have more defined lingual fossa and accessory ridges may be present from cingulum to center of fossa.
-lingual pit is more common
-cingulum is centered
-marginal ridges are both straight--mesial is still slightly longer, but they are more similar in length than those of the centrals

Front 37

Which tooth may exhibit a distal lingual groove of the cingulum that entends onto the root surface? Why is this important?

Back 37

max. lateral incisors. This is siginificant because this could be an area that develops perio issues due to the inaccessibility of the groove once it dips subgingivally.

Front 38

From the incisal view compare and contrast the max. centrals with the laterals.
-overall shape
-width m-d vs fa-ln
-cingulum
-incisal ridge
-FA shape

Back 38

-Centrals have a triangular shape, laterals are more round
-Both are wider M-D than FA-LN, but the laterals have much smaller differences in these measurements (the difference is less defined than it is for the centrals)
-CI-cingulum offset distally, LI-cingulum centered
-LI-incisal ridge curves distally "disto-lingual twist)
-CI more flattened on FA surface

Front 39

What are the smallest teeth in the mouth?

Back 39

Mandibular centrals

Front 40

Describe the general shape of mandibular centrals

Back 40

bilaterally symmetrical, straight incisal edge, mesial and distal marginal ridges form sharp angles, crown is triangular

Front 41

Crowns and roots of mn centrals are wider in which direction (M-D or FA-LN)

Back 41

MN centrals are wider FA-LN than M-D. (opposite of max centrals)

Front 42

Where are the proximal contacts for the M and D of the MN centrals?

Back 42

Both are at the incisal 1/3rd

Front 43

When do MN centrals erupt?

Back 43

ages 5-6

Front 44

on MN centrals the crown and root taper in which direction>?

Back 44

lingually

Front 45

Describe the crown to root ratio of MN centrals

Back 45

Larger ratio--roots are much longer than crowns.

Front 46

How are the marginal ridges and fossa depth of MN centrals different from the MX centrals?

Back 46

-minimal marginal ridges and fossa depth on the MN centrals

Front 47

What is a useful identifier in distinguishing between #24 and 25?

Back 47

Roots usually have a distal bend at the root apex.

Front 48

Where is the incisal edge in relation to the root axis for MN centrals?

Back 48

lingual to long axis (opposite from MX incisors)

Front 49

For MN centrals does the M or D root surface have a more pronounced root concavity?

Back 49

Neither, both are pronounced--makes it harder to ID tooth.

Front 50

Contrast the size of the MN lateral incisors from the central incisors

Back 50

MN lateral incisors have longer roots and bigger crowns than the MN centrals (This is opposite in the MX arch)

Front 51

When do MN lateral incisors erupt?

Back 51

age 7-8

Front 52

How is the overall shape of MN laterals different from MN centrals?

Back 52

Laterals are larger and more rounded than the centrals.

Front 53

Where is the interproximal contact for the MN lateral incisors?

Back 53

Incisal third

Front 54

From a mesial view of MN laterals, which surface of the tooth can you see more of than normal (ie. than can see from M of a central) and why?

Back 54

You can see more of the lingual surface due to the distal twist.

Front 55

Describe the characteristics of a MN lateral incisor from an incisal view
-incisal edge-shape
-MMR
-Crown LA vs. LN
-width of crn LA/LN vs. M/D
-Cingulum location
-Lingual fossa size

Back 55

-incisal edge curves distally-distolingual twist. More rounded than MN central
-MMR is longer than DMR
-Crown is narrower LN than LA
-crown is wider LA/LN than M/D
-cingulum distally offset
-small or non-existant lingual fossa