Mammal Tooth Structure and Function

Mammal Dentition Structure

  • Heterodont Dentition

    • Definition: Different types of teeth with varied structures and functions.
    • Hetero = different, dont = tooth.

  • Types of Teeth: From mesial (front) to distal (back):

    • Incisors:
    • Function: Cutting food.
    • Canines:
    • Function: Grasping and piercing.
    • Premolars:
    • Function: Chopping food.
    • Molars:
    • Function: Grinding food.

Tooth Anatomy

  • Parts of a Tooth:

    • Crown: The visible part above the gums (gingiva).
    • Roots: Embedded in the socket (alveolus).
    • Movement: Slight movement occurs during chewing if the periodontal ligament is healthy.
    • Occlusal Surface: Biting surface with elevations called cusps.

  • Tissues:

    • Dentin:
    • Description: Hard substance resembling bone, composing the bulk of the tooth.
    • Alternative spellings: Dentine or Dentin.
    • Enamel:
    • Description: Hard white outer coating made of calcium.
    • Pulp Cavity:
    • Description: Central core with jelly-like connective tissue, blood vessels, and nerves.

Dental Formulas

  • Definition: Represents the number and type of teeth in maxilla (upper jaw) and mandible (lower jaw) by counting one side due to bilateral symmetry.

  • Hominoidia and Cercopithecoidia (Old World monkeys and apes):

    • Dental formula: 2-1-2-3 (two incisors, one canine, two premolars, three molars).

  • New World Monkeys (Suboidia):

    • General Formula: 2-1-3 (two incisors, one canine, three premolars, and three molars).
    • Notable Variation: Some have fewer molars, specifically a formula of 2-1-3-2 or 2-1-2-0 (with zero molars).

Deciduous Dentition (Baby Teeth)

  • Description:
    • Also called milk teeth; they are temporary and fall out.
    • Formula: Typically 2-1-2-0; two incisors, one canine, and two back teeth (often considered premolars).
    • Comparison: Adults have a different structure with more molars.

Diastema (Gap)

  • Definition: Gap between front teeth and enlarged canines, facilitating the closing of the mouth.

Sectorial Teeth Function

  • Sectorial Premolar:
    • Function: Designed for honing and slicing, typically sharp for efficient chewing.

Comparative Anatomy of Molars

  • Occlusal Surface: The chewing surface of molars with different cusp arrangements across primate evolution.

  • Early Primates: Insectivorous diet requiring sharp teeth for crunching.

  • Characteristics:

    • Upper and lower molars distinct in shape with cusps designed for processing food.

Primate Evolution in Teeth

  • Old World Monkeys:

    • Bilophodont Structure: Double ridged, specialized for slicing leaves, teeth show morphological adaptation.

  • Apes and Hominoids:

    • Y-5 Structure: Four cusps on top, five on the bottom, adaptable for a fruit-based diet.

  • Relevance: Helps in distinguishing fossil records of Old World monkeys (bilophodont) from apes (Y-5 structure) based on tooth morphology.