Dental Anatomy: Tooth Forms, Occlusion, and Jaw Movements

mamelons

round eminences at the terminations of each labial lobe incisally

1. Haplodont class - single cone

2. Triconodont class - three cusps in line

3. Tritubercular class - three cusps in triangle

4. Quadritubercular class - four cusps in quadrangle

four phylogenetic classes of tooth forms

jaw movements and functions are governed by the forms of the teeth

jaw movements in relation to tooth forms

tubercle

an accessory projection of enamel, often considered an extra lobe

significance of the trapezoidal outline of a tooth crown

protects the periodontium, provides interproximal spaces, and allows for self-cleansing

1. Trapezoid

2. Triangle

3. Rhomboid

three geometric figures used to describe tooth crown outlines

primary function of the permanent dentition

to prepare food for swallowing and facilitate digestion

malocclusion

deviations in intramaxillary and/or intermaxillary relations of the teeth and/or jaws

interdental papilla

it fills interproximal spaces and covers part of the cervical third of the tooth crowns

occlusion

the anatomical alignment of the teeth and their relationship to the masticatory system

cervical line

the stable anatomical demarcation of teeth defined as the cementoenamel junction

1. Length and shape of the root

2. Angle of the incisal and occlusal surfaces with respect to the root bases

two important points for occlusal stability

dehiscence

a cleft type partial absence of bone over the root area of a tooth

fenestration

a window type partial absence of bone over the root area of a tooth

Curve of Spee

a curvature that begins at the tip of the canine and follows the buccal cusp tips of premolars and molars posteriorly

Curve of Wilson

a curvature due to the lingual inclination of the mandibular molars, where the curvature of mandibular teeth is concave and maxillary teeth is convex

significance of the triangular outline of anterior teeth

it keeps the axis of crowns and roots parallel and ensures proper occlusion

primary lobes of anterior teeth

1. Mesial

2. Labial

3. Distal

4. Lingual

• Mesial

• Distal

• Buccal

• Lingual

primary lobes of premolars

1. Mesial

2. Distal

3. Buccal

4. Mesiolingual

5. Distolingual.

primary lobes of mandibular second premolars

significance of the rhomboid outline of mandibular posterior teeth

it protects the periodontium and maintains proper occlusion

importance of the trapezoidal outline of maxillary posterior teeth to dental function

it provides contact between teeth at proximal areas, protecting interproximal gingival tissue

interproximal spaces

pyramidal-like spaces that extend from the alveolar bone to and around the proximal contacts of the teeth

role of contact areas between adjacent teeth

ensure mutual support and occlusal stability

relationship between tooth form and food mastication

shapes of incisal and occlusal surfaces are related to the function they perform during chewing

effect of misalignment on the gingival line

abnormalities may change the gingival line, potentially harming tissue health

• canines

• arch form

• jaw movement

primary difference in the dental anatomy of humans and anthropoid apes

purpose of the narrow occlusal surface in teeth

it facilitates the initial penetration of food materials and reduces masticatory force