Chapter 16.12 Incisors

Masticatory function of Incisors

B.C. (Biting and Cutting)

Name of biting surface of anterior tooth

Incisal ridge

Name of biting surface of anterior tooth after attrition

Incisal edge

Vertical labial lines of separation

Developmental depressions

Number of developmental lobes and their names

Four; Mesiolabial, distolabial, middlelabial and lingual lobes.

T/F All permanent anterior teeth are succedaneous.

True

Which deciduous teeth do the permanent maxillary incisors replace?

D, E, F and G

Which deciduous teeth do the permanent mandibular incisors replace?

N, O, P, and Q

How many total permanent incisors does a fully dentulous mouth have?

8

T/F An edentulous patient has 32 teeth.

False; An edentulous patient has no teeth.

What does succedaneous mean?

When a permanent tooth replaces a primary tooth.

What shape is an anterior tooth when viewed proximally? When viewed from labial/lingual?

Triangular; Trapezoidal

Height of contour on anteriors labially/lingually

Cervical third

T/F Posterior CEJ curvature is greater than that of anteriors

False; Anteriors have greater CEJ curvature.

Where are developmental pits located?

In the deepest part of the fossa.

V-shaped linear depression on lingual surface

Developmental or primary groove

Shallow, irregular linear depression on lingual surface

Supplemental or secondary groove

Direction of roots of maxillary anterior teeth

Great lingual and slight distal inclination

Direction of roots of mandibular anterior teeth

Vary in angulation from nearly vertical to great lingual inclination

Incisor Functions

1. Bite and cut food during mastication
2. Involved during articulation of speech
3. Assist in guiding jaw closed
4. Support lips and face to maintain vertical dimension

Reason behind presence of mamelons

Where the three labial lobes come together

T/F Mamelons never go away

False; Mamelons wear away on teeth in occlusion due to attrition

T/F The incisal surface of an anterior tooth after attrition is called an incisal ridge

False; It is called an incisal edge

How many incisal angles does an incisor have and what are their names?

2; Mesioincisal angle and distoincisal angle

How many surfaces does an anterior tooth have and what are they called?

5; Mesial, distal, facial (labial), lingual, incisal

T/F Mandibular incisors are larger than maxillary incisors

False; Maxillary incisors are larger

T/F Lateral maxillary incisors are smaller than the centrals

True

T/F Lateral mandibular incisors are smaller than the centrals

False; Centrals are smaller than laterals

Increased prominence of lingual marginal ridges and a deeper lingual fossa

Shovel-shaped

Projection from cingulum

Talon cusp

Reasons lingual pit has an increased risk of caries

Increased biofilm retention and weakness of the enamel forming the walls of the pit

Vertically placed groove that originates in lingual pit and extends cervically and slightly distal to cingulum

Linguogingival groove

How many roots do central incisors have; How many pulp horns?

1; 3

Lines that run MD in cervical third of incisors

Imbrication lines

What are between the imbrication lines?

Grooved perikymata

T/F Mesial angles are rounder than distal angles in maxillary central incisors

False; Distal angles are slightly rounded while mesial angles are sharp

Mesial contact of maxillary central incisors location

Incisal third

Distal contact of maxillary central incisors location

Junction of incisal and middle third

T/F Mesial marginal ridge is longer and straighter than distal marginal ridge on maxillary incisors

True

T/F Distal CEJ curvature is deeper incisally on incisors

False; Mesial CEJ curvature is deeper

Most often missing or peg shaped teeth in adult dentition

Lateral incisors

Incisors with root 1.5x longer than the crown

Maxillary lateral incisors, mandibular lateral incisors and mandibular central incisors

How many roots do maxillary lateral incisors have; How many pulp horns?

1; 2-3

T/F MI angle of maxillary lateral incisor is sharper than DI angle, but still rounder than those of central.

True

Mesial contact of maxillary lateral incisor

Junction of incisal and middle third

Distal contact of maxillary lateral incisor

Middle third

T/F Lingual fossa and pit of maxillary lateral incisors more shallow than those of central incisors

False; Deeper

Most symmetrical teeth in the permanent dentition

Mandibular incisors

T/F Lingual anatomy on mandibular incisors less prominent than that of maxillary incisors

True

Teeth where overlapping and crowding are common

Mandibular incisors

Has straight incisal edge

Mandibular central incisor

T/F MI and DI angles of mandibular central incisors are sharp and nearly identical

True

Distal root bend

Mandibular central and lateral incisors

How many roots do mandibular central incisors have; How many pulp horns?

1; 3

Mesial contact of mandibular central incisors

Incisal third

Distal contact of mandibular central incisors

Incisal third

Barely noticeable lingual fossa and marginal ridges

Mandibular central incisors

Location of cingulum of mandibular central and maxillary lateral incisors

Centered

Asymmetrical

Mandibular lateral incisors

T/F Mandibular lateral incisors are larger than mandibular central incisors

True

How many roots do mandibular lateral incisors have; How many pulp horns?

1; 3

T/F Lateral incisors have longer roots than central incisors

True

Incisal edge of mandibular lateral incisor

Slopes toward distal

T/F DI angle of mandibular lateral incisor sharper than MI angle

False; MI angle sharper

Mesial contact of mandibular lateral incisor

Incisal third

Distal contact of mandibular lateral incisor

Incisal third but more cervical than mesial contact

Cingulum distal to long axis

Mandibular lateral and maxillary central incisors

T/F Marginal ridges and and lingual surface of mandibular lateral incisors more prominent than those of centrals

True

What is attrition?

Wearing away of tooth surface from tooth to tooth contact

Eruption age of mandibular central incisors

6-7 years

Eruption age of mandibular lateral incisors

7-8 years

Eruption age of maxillary central incisors

7-8 years

Eruption age of maxillary lateral incisors

8-9 years