Dental Anatomy Health Article

Definition

Dental anatomy is the study of the classification and morphology of teeth, as well as the study of the principles of occlusion.

Description

Dental anatomy may be considered the study of teeth at three different levels. First, teeth may be studied in terms of the elements of each individual tooth (for example, dentin and enamel). Second, teeth may be studied in terms of classification and numbering systems. Third, teeth may be studied in the larger context of the oral cavity, along with the principles of occlusion and structures that may display pathology such as the gingiva and the temporomandibular joint.

Teeth

The teeth are derived from the ectoderm and the mesoderm in the embryonic stages of development. Each tooth arises from either the maxilla (the bone that makes up the upper jaw) or the mandible (the bone that makes up the lower jaw). Teeth originating from the maxilla are considered to be in the superior dental arch, or the maxillary dental arch. Teeth arising from the mandible are considered to be in the inferior dental arch, also known as the mandibular dental arch.

Each tooth consists of:

• Crown: The visible portion of a tooth.
• Root: The portion of the tooth embedded in the gum.
• Pulp: Located in the center of the tooth, it contains the arteries, veins, nerves and lymphatic tissue.
• Blood vessels: They carry nutrients to the pulp.
• Root canal: The canal in the root of the tooth is where the nerve and blood vessels travel with nutrients to the tooth from the mandible or the maxilla.
• Ligament: The connective tissue that surrounds the root of a tooth and connects it to the maxilla or mandible.
• Bone: Alveolar bone forms tooth socket and part of the teeth.
• Cementum: The layer of tissue covering the dentin on the root of the tooth. Serves the same role as enamel.
• Dentin: The calcified tissue underlying the enamel (on the crown) and cementum (on the root), making up the main bulk of the tooth.
• Enamel: The calcified outer layer of the crown of the tooth.

Although each tooth has the same basic structure, some variation exists. Different types of teeth have variation in their roots. Incisors and cuspids have only one root. Maxillary (upper) premolar teeth commonly have two roots, whereas the mandibular premolars commonly have one. The premolars may also have two roots fused to look as one. The molars on the maxillary arch have three roots, while, on the other hand, the molars on the mandibular arch have two roots.

Tooth types

Permanent teeth are divided into four groups based on their function and placement in the jaw. Teeth are given the same name whether they are in the upper or lower jaw. From medial (middle of the mouth) to lateral, the four types of teeth are listed below:

• Incisors cut the food. They are divided into central and lateral. They are the two most medial teeth on either side (left and right) in the upper and lower jaw, for a total of eight.

• Cuspids also known as canines, cut and tear the food. They are the third teeth from the center, and there are a total of four (two upper, two lower).
• Pre-molars seize and shear the food. They are also known as bicuspids because they have two cusps, or projections on the surface of the teeth. There are eight total (four upper, four lower) between the cuspids and the molars.
• Molars grind the food. They are the most lateral teeth. There are a total of twelve, including the four "third molars" also known as wisdom teeth.

Children who still have their temporary teeth (also known as primary, deciduous, or "baby" teeth) have incisors (four upper, four lower), cuspids (two upper, two lower), and molars (four upper and four lower), but lack pre-molars. There are 20 total primary teeth.