Dental Anatomy and Tooth Morphology

Dental Anatomy, Physiology and Occlusion

• This topic covers the structure, function, eruption, and shedding of teeth.
• Tooth morphology is the study of the external and internal structure, function, eruption, and shedding of teeth.
• Dental anatomy knowledge is crucial for practitioners to diagnose and treat normal and abnormal cases correctly.

Tooth Morphology

• Tooth morphology encompasses the external and internal structure of all teeth.
• It includes the study of eruption and shedding mechanisms.

Importance of Dental Anatomy Study

• Practitioners need knowledge of morphology, occlusion, aesthetics, and functions of teeth.
• This helps differentiate between normal and abnormal cases, enabling accurate diagnoses and appropriate treatment.

The Surface Form of the Oral Cavity

• The oral cavity comprises several key structures: lips, roof of the mouth (palate), floor of the mouth, tongue, uvula, and cheeks.
• Gingiva, teeth, and palatine tonsils are also included in the oral cavity.

Dental Anatomy Includes

• Dentition refers to all teeth present in the upper and lower jaws.
• External morphology and internal composition of teeth are key aspects.
• The relationship of teeth to each other and the skull bone is also studied.

Teeth

• Teeth are arranged in two dental arches (one upper and one lower).
• The upper arch is called the maxilla, containing upper/maxillary teeth.
• The lower arch is called the mandible, containing lower/mandibular teeth.
• Each dental arch is divided into four quadrants by a midline.

Classes of Teeth

• Anterior teeth include incisors and canines.
• Posterior teeth (cheek teeth) include premolars and molars.
• There are four types of teeth (incisors, canines, premolars, and molars).
• Each quadrant contains one canine, two premolars, and three molars.

Dental Traits

• Set traits distinguish deciduous (baby) teeth from permanent teeth.
• Arch traits differentiate maxillary and mandibular teeth.
• Class traits categorize teeth according to their function (incisors, canines, premolars, molars).
• Type traits differentiate teeth within the same class (e.g., central vs. lateral incisors).

Dentition Periods

• Clinically, humans have two dentitions: deciduous (baby/milk/temporary) and permanent.
• The primary (deciduous) dentition consists of 20 teeth.
• Each quadrant has 5 teeth: 2 incisors, 1 canine, and 2 molars.
• The mixed dentition period, or "ugly duckling stage," occurs when deciduous teeth are replaced by permanent ones (ages 6-12).
• The permanent dentition comprises 32 teeth.
• Each quadrant has 8 teeth: 2 incisors, 1 canine, 2 premolars, and 3 molars.

Shedding

• Deciduous teeth are lost and replaced by permanent teeth.

X-Ray Showing

• X-rays show different stages of dentition—primary, mixed, and permanent.

Functions of Teeth

• Mastication (chewing) is the most important function.
• Teeth are designed for cutting, tearing, and grinding of food.
• Teeth also have an important role in esthetics, speech, and jaw growth.

Dental Functions

• Teeth also maintain facial vertical dimensions.
• Some animals use teeth for defense, and humans can use teeth for other tasks (e.g., tools).

Human Dental Formula

• Expresses the number and type of teeth per side.
• Primary teeth: 2I, 1C, 2M = 10
• Permanent teeth: 2I, 1C, 2P, 3M = 16

Tooth Numbering Systems

• Palmer Notation System (1861): numbered 1-8 for upper and lower quadrants. Deciduous teeth are lettered (A-E).
• FDI (Fédération Dentaire Internationale) Two-digit system: Each tooth is assigned a two-digit number based on its quadrant and position.
• Universal Numbering System (ADA): The teeth are numbered from 1 to 32.

Parts of a Tooth

• Crown: The visible part of the tooth above the gum line.
• Enamel: The hard, protective outer layer of the crown.
• Neck: The narrow part of the tooth where the crown meets the root.
• Cementum: The hard, bone-like tissue covering the root.
• Root: The part of the tooth below the gum line.
• Pulp: The soft tissue inside the tooth that contains blood vessels and nerves.
• Pulp Cavity: the hollow space within the tooth containing the pulp.

Anatomical and Clinical Crown and Root

• Clinical crown is the portion visible, while anatomical is the entire structure.
• Clinical root is the area of the root covered by gingiva.
• Anatomical root is the total surface of the root.
• Gingival recession is the loss of gum around teeth, exposing part of the anatomical root.

Dental Tissues

• Enamel, dentin. and cementum are calcified tissues.
• Pulp is a soft connective tissue.

Junctions of Tooth Tissues

• Cemento-enamel junction (CEJ), Dentino-enamel junction (DEJ), and Dentino-cemental junction (DCJ).

Tooth Surfaces

• The surfaces of the tooth are identified by their relationship to other structures in the oral cavity, enabling proper cleaning and assessment.

Division Into Thirds

• Teeth may be divided horizontally or vertically into thirds for anatomical analysis.

Line and Point Angles

• Both line and point angles are utilized to describe the relationship of adjacent teeth, which influences cleaning, diagnosis, and repair procedure.

Anatomical Landmarks of the Crown

• Lobe, Cusps, Cingulum, Mamelons, Tubercle, Enamel Pearl, Ridge
• These features denote the development and growth of the teeth.

Tooth Depressions

• Developmental grooves, fissures, sulci, and fossae can be found in teeth. These features are important landmarks for practitioners.

The Periodontium

• This is the investing and supporting structure of teeth.
• Comprises soft tissue (gingiva) and hard tissue (cementum and alveolar bone) and Periodontal Ligament (PDL).

Teeth May Be Divided According to Number of Roots

• Single-rooted teeth include all anterior teeth and premolars.
• Multi-rooted teeth include mandibular molars and maxillary first premolars (2 roots).
• Maxillary molars (3 roots).

Self-Cleaning Surfaces

• These surfaces are cleaned by the tongue, lips, cheeks, and mouth fluids during normal function.

Calcification

• The organic framework of a tooth becomes hard via calcium and phosphorous salts.

Life History of the Tooth

• Stages of tooth development (initiation, bud, cap, bell).
• Stages of tooth development (apposition, root formation, eruption).
• Additional developmental stages: completion of root development and shedding of deciduous teeth (baby teeth).
• Permanent teeth emergence.

Chronology of the Human Teeth

Deciduous (Milk) Teeth:

• Table summarizing the timing of each stage (appearance, calcification, eruption, root completion, resorption, and shedding)

Permanent Teeth:

• Table summarizing the timing of each stage (appearance, calcification, eruption, and root completion)

Condition of Teeth at Different Ages

Mixed Dentition

• Illustrations depicting the mixed dentition stage (eruption, root completion) over time.