Alveolar bone – Cancellous bone directly surrounding the tooth roots.
Alveolar crest – The ridge of bone between two adjacent teeth or between the roots of a tooth.
Alveolar mucosa – Less densely keratinized gingival tissue covering the bone.
Alveolus – The cavity or socket in either jaw bone that surrounds and supports the root of the tooth.
Anterior teeth – The canine and incisor teeth.
Apex – Terminal portion of the root.
Apical delta – The diverging branches of the root canal at the apical end of the tooth root.
Apical foramen – The opening(s) in the apex of the root through which nerves and vessels pass into the root canal.
Attached gingiva – The gingiva that extends from the free gingival groove to the mucogingival line.
Attachment apparatus – The periodontal ligament, cementum, and alveolar bone that hold the tooth in place.

Canine tooth - Large, single-root tooth designed for tearing and grasping.
Carnassial tooth - Shearing tooth. Upper P4 and lower M1 in the dog and cat.
Cementoenamel junction - Found at the neck of the tooth where the enamel and the cementum meet.
Cementum - Bony layer covering the root surface.
Cingulum - The cervical third of the palatal surface of the anterior teeth.
Crown - The portion of the tooth covered with enamel.

Deciduous teeth - Teeth of the primary dentition ("baby teeth").
Dental arch - Formed by the curve of the crowns of the teeth in their normal position or by the residual ridge if the teeth are missing.
Dental Quadrant - Half of each dental arch when divided at the midline.
Dentin - The main component of the tooth. It consists of multiple tubules that extend from the pulp to its outer surface. The tubules contain sensory nerve fibers that register various degrees of pain. Harder than bone, dentin is covered by enamel on the crown and by cementum on the root.
Diastema - The space between two adjacent teeth that are not in contact with each other in an arch.

Enamel - The hard, shiny outer layer of the crown composed of hydroxyapatite crystalline components.
Epithelial attachment - Tissue attaching the gingiva to the tooth.

Free gingiva - Portion of the gingiva not directly attached to the tooth that forms the gingival wall of the sulcus.
Free gingival groove - On the surface of the gingiva a slight concavity or line separating free from attached gingiva.
Free gingival margin - The free edge of the gingiva on the tooth surface.
Furcation - The space between tooth roots where they join the crown.

Gingiva - Soft tissue surrounding the teeth.
Gingival sulcus - The normal space created by the free gingiva and the tooth.
Gnathic - Referring to the jaw.

Halitosis - Foul, offensive, or unpleasant breath.

Incisal edge - The cutting edge of the incisors.
Incisor - Small anterior tooth with a single root.
Infrabony pocket - A periodontal pocket in the alveolar bone.
Interdental - The area between the proximal surfaces of adjacent teeth in the same arch.
Interproximal - Between adjoining surfaces of teeth in the same arch.
Interradicular - Between roots of multirooted teeth.

Juga - The depressions between the ridges of bone formed by roots in the alveolar process on the mandible or the premaxilla and maxilla.

Lamina dura - The dense cortical bone forming the wall of the alveolus next to the tooth. It appears on a radiograph as a white line next to the dark line of the periodontal ligament.
Lateral or accessory canal - Small canal leading from the root canal to the outer surface of the root.
Line angle - The imaginary intersection of two tooth walls.

Mental foramen - Openings in the mandible through which nerves and vessels pass.
Molar - Large, multicusp teeth designed for grinding. Upper (two) molars have three roots and lower (three) molars have two roots in dogs.
Mucogingival line - Definite line of demarcation where the attached gingiva and alveolar mucosa meet.

Neck (cervical line) - The junction of the crown and root.

Odontoblast - The cells in the pulp that produce dentin.

Palate - The structure that separates the oral and nasal cavities.
Periodontal ligament - A network of fibers connecting the tooth to the bone.
Periodontium - The supporting structures of the teeth including the periodontal ligament, gingiva, cementum, and alveolar and supporting bone.
Posterior teeth - The premolar and molar teeth.
Premolar - The teeth distal to the canine and mesial to the molars with one to three roots.
Primary teeth - The first teeth to erupt; they are replaced by adult teeth.
Proximal - The surface of a tooth that is adjacent to another tooth.
Pulp - Soft tissue component of the tooth consisting of blood and lymphatic vessels, nerve tissue, and loose connective tissue.
Pulp chamber - Portion of the crown containing the pulp.

Radicular - Pertaining to the root.
Root - The portion of the tooth normally covered by cementum.
Root canal - Portion of the root containing the pulp.
Ruga palatina - The irregular ridge in the mucous membrane covering the anterior part of the hard palate.

Dental Positioning or Surface Terms:

Apical - Towards the apex.

Buccal - Surface of the tooth nearest the cheek (posterior teeth).

Coronal - Towards the crown.

Distal - Away from the midline in the dental arches.

Facial - Surface of the tooth nearest the face. Buccal and labial are more accurate.

Incisal - Biting surface of anterior teeth.
Interproximal - Between adjoining surfaces of the teeth.

Labial - Surface of the tooth nearest the lips (anterior teeth).
Line angle - Imaginary line formed by the junction of two adjacent surfaces/walls of a tooth.
Lingual - Surface of the tooth nearest the tongue.

Maxilla - The bone that forms most of the upper jaw.
Mesial - Toward the midline of the dental arch.

Occlusal - The chewing surfaces of the caudal teeth.

Palatal - Surface of the tooth towards the hard palate.

Sublingual - The structures and surfaces beneath the tongue.

Endodontics - The diagnosis and treatment of diseases inside the tooth that affect the tooth pulp and apical periodontal tissues.
Exodontics - Branch of dentistry that deals with extraction of teeth.

Oral Surgery - Pertaining to surgery of the oral cavity.
Orthodontics - Branch of dentistry that deals with the prevention and correction of irregularities of the teeth and malocclusion.

Periodontics - Branch of dentistry dealing with the study and treatment of periodontal diseases.
Prosthodontics - Branch of dentistry that deals with the construction of appliances designed to replace missing teeth and/or other oral structures.

Restorative/operative dentistry - Branch of dentistry dealing with restoring the form and function of teeth.

Oral Diseases/Conditions:

Abrasion - The wearing away of teeth due to abnormal contact with structures other than teeth.
Acquired Pellicle - The thin film composed mostly of protein that forms on the surface of teeth. It forms with or without bacteria and can be removed by abrasive action.
Anodontia - The absence of teeth.
Anterior crossbite - An orthodontic condition in which canine, premolar, and molar occlusion is normal but one or more mandibular incisors are anterior to the maxillary incisors.
Attrition - The wearing away of teeth by tooth-against-tooth contact during mastication.
Avulsion - The separation of the tooth from its alveolus.

Brachygnathia - The lower jaw is markedly shorter than the upper jaw.

Calculus - Hard, mineralized plaque on the tooth surface.
Caries - A demineralization and loss of tooth structure due to action of microorganisms on carbohydrates.

Edentulous - Without teeth.
Embedded tooth - A tooth that has not erupted into the oral cavity and is not likely to erupt.
Erosion - Loss of tooth structure by chemical means not involving bacteria.

Facet - A flattened or worn spot on the surface of a tooth.
Freeway space - The space between the opposing mandibular and maxillary premolar cusps when the mouth is closed.
Fused teeth - The joining of two teeth in development where they have developed from different tooth buds.

Gemini tooth - The partial division of a tooth bud attempting to form two teeth.
Gingival hyperplasia - A pathological increase in the amount of normal gingival tissue in a normal arrangement.

Horizontal bone loss - Loss of crestal alveolar bone along an arch secondary to periodontal disease.

Impacted tooth - An unerupted or partially erupted tooth that is prevented from erupting further by any structure.

Level bite - Occlusion where the upper and lower incisors meet incisal edge to incisal edge.
Luxation - The displacement or partial displacement of a tooth from its alveolus.

Odontalgia - Pain in a tooth.
Oligodontia - Reduced number of teeth.
Open bite - The failure of the upper and lower incisors to contact each other when the mouth is closed.
Oronasal fistula - An abnormal opening between the oral and nasal cavity.
Overbite - Layman's term for the upper jaw overlapping the lower jaw.

Periapical abscess (or apical abscess) - An abscess at the apex of the root, involving the pulp and surrounding apical tissues.
Periodontal abscess - An abscess involving the periodontium.
Periodontal pocket - Pathologic increase in the depth of the gingival sulcus with loss of epithelial and periodontal ligament attachments.
Plaque - A thin film covering the teeth, composed of bacteria, salvia, food particles, and sloughed epithelial cells.
Posterior cross bite - An abnormal occlusion where one or more mandibular premolars or molars occlude buccal to their occlusal partner.
Pulpitis - Inflammation of the pulp.
Pyorrhea - A discharge of pus from the periodontium.

Resorption - The loss of substance by a physiologic or pathologic process.
Reverse scissor bite - Occlusion where all the lower incisors occlude anterior to the upper incisors.
Root fenestration - A window-like opening of bone and gingiva over the root.

Stomatitis - Inflammation of the soft tissues of the mouth.
Supernumerary teeth - Teeth in excess of the normal number.

Vertical bone loss - Bone loss at an acute angle to the root surface, forming an infrabony pocket.

Wry bite - A malocclusion in which the midline of the lower jaw does not oppose the midline of the upper jaw.

Dental Devices:

Abutment - A tooth or implant that is used for the support or anchorage of a prosthesis or appliance.
Anchorage - Used orthodontically, it is the resistance to unwanted tooth movement.

Bite impression - Used to align casts to the occlusion of the patient.

Cast - A replication of the teeth and tissues made from an impression.
Crown or Cap - A cast metal covering of the crown of the tooth.

Impression - A negative replication of the teeth and tissues used to make a cast.

Orthodontic appliance - A device used to apply force to the teeth for tooth movement or to maintain tooth position.

Prosthesis - An artificial part that replaces part of the body.

Splint - An apparatus designed to prevent motion or displacement.

References:

1. Cohen S, Burns RC. Pathways of the Pulp. St Louis: C.V. Mosby Co., 1984:302.
2. Rateitschak KH, et al. Periodontology. Stu Hgart: George Thieme Medical Publishers, 1989:35-37