Dental Anatomy and Tooth Morphology

Dental Anatomy

• Studies the external and internal structure of teeth, their functions, and how they erupt
• Important to understand normal tooth development and recognize abnormalities
• Allows for correct diagnosis and appropriate treatment

Tooth Morphology

• Teeth arranged in two arches: upper arch (maxilla) and lower arch (mandible)
• Each arch has a midline that divides the arch into quadrants: upper right, upper left, lower right, and lower left
• Four classes of teeth: incisors, canines, premolars, molars
• Incisors: two per quadrant: central and lateral incisors
• Canines: one in each quadrant
• Premolars: two per quadrant: first and second premolars
• Molars: three per quadrant: first, second, and third molars

Functions of Teeth

• Mastication: chewing and grinding food
• Aesthetics: contributing to facial appearance
• Speech: phonation (sound production)
• Growth of jaws: play a role in development
• Protection: biting in some animals (not humans)
• Other functions: using teeth as tools

Human Dental Formula

• Represents the number and type of teeth in each side of the mouth
• Primary dentition (deciduous): 20 teeth, 10 in each arch, 5 per quadrant: two incisors, one canine, two molars
• Permanent dentition (adult or succedaneous): 32 teeth, 16 in each arch, 8 per quadrant: two incisors, one canine, two premolars, and three molars
• Permanent molars are not preceded by deciduous teeth and are considered "non-succedaneous"

Tooth Numbering Systems

• Palmer Notation: most widely used system, uses a numbered representation of the four quadrants and tooth number
• FDI System (Two-Digit): two-digit system where the first digit represents the quadrant and the second digit represents the tooth number
• Universal Numbering System (American): uses numbers 1-32 for permanent teeth and letters A-T for deciduous teeth
• Dane (Hederup): using symbols (+) and (-) to indicate the quadrant and tooth number

Parts of a Tooth

• Macro-anatomy: four anatomical parts: crown, neck, root(s), and pulp cavity
• Clinical crown: portion of the tooth visible above the gum line
• Anatomical crown: entire portion of the tooth covered by enamel
• Clinical root: portion of the root visible below the gum line
• Anatomical root: entire portion of the root below the CEJ

Dental Tissues

• Micro-anatomy: consists of three calcified tissues (enamel, dentin, cementum) and one specialized connective tissue (pulp)
• Enamel: hardest tissue, covers the crown and is yellowish white
• Cementum: covers the root, dull yellow, medium for attachment
• Dentin: underlies enamel and cementum, surrounds the pulp cavity, yellow
• Pulp: soft tissue housed in the pulp cavity, provides vascular and neural supply

The Pulp

• Divided into coronal pulp (pulp chamber and horns) and radicular pulp (root canal, apical foramen, accessory canals)

The Periodontium

• The investing and supporting attachment system of teeth
• Includes two soft tissues (gingiva and periodontal ligament) and two hard tissues (cementum and alveolar bone)
• Gingiva: oral mucous membrane that covers the neck of the tooth and a portion of the alveolar bone
• Periodontal ligament: strong ligament that attaches the tooth to the alveolar bone
• Cementum: covers the anatomical root of the tooth
• Alveolar bone: bone of the jaw that surrounds the root of the tooth

Tooth Surfaces

• Each tooth has five surfaces
• Facial (labial or buccal): towards the lip or cheek, for anterior or posterior teeth
• Lingual (palatal): towards the palate (for maxillary teeth) or tongue (for mandibular teeth)
• Proximal: mesial (towards the midline) and distal (away from the midline)
• Masticatory: incisal (for anterior teeth) or occlusal (for posterior teeth)