Veterinary Dental Anatomy and Nomenclature

Technician Responsibilities in Veterinary Dentistry

• The professional duties attributed to the veterinary technician include:

  • Conducting oral examinations and detailed recording of findings.

  • Managing anesthesia during dental procedures.

  • Performing dental radiography.

  • Executing dental scaling and polishing.

  • Providing comprehensive dental hygiene instruction to clients.

Anatomy of the Tooth

• The physical structure of a tooth comprises the crown (visible portion above the gumline) and the root (portion below the gumline).

• The apex refers to the deepest terminal part of the root.

• The apical foramen consists of small openings at the apex through which nerves and blood vessels enter the tooth.

Enamel

• This is the hardest and most mineralized tissue found in the body.

• It contains no nerve or blood supply.

• Compared to human teeth, the enamel in animals is thinner.

• It is normally present only on the crown, above the gumline.

• Ameloblasts are the specific cells responsible for producing enamel.

Dentin(e)

• This tissue constitutes the bulk of the mature tooth.

• It is produced by cells called odontoblasts.

• Dentin functions to protect the underlying pulp.

• Unlike enamel, dentin is continuously deposited throughout the lifetime of the animal.

Pulp

• The pulp is composed of connective tissue, nerves, and blood vessels.

• Within the crown, the section containing the pulp is designated as the pulp chamber.

• Within the root, the pulp is contained within the root canal.

• The pulp chamber is lined by odontoblasts.

Anatomy of the Periodontium

• The periodontium is the suspensory apparatus that functions to attach the tooth to the jaw.

• It is composed of four distinct structures: the gingiva, periodontal ligament, cementum, and alveolar bone.

Gingiva

• This tissue surrounds the tooth and the marginal parts of the alveolar bone.

• It forms a protective cuff around each individual tooth.

• The gingiva comprises several parts, including the gingival margin and the free gingiva.

Gingival Sulcus

• This is a shallow groove surrounding each tooth, formed by the margin of the free gingiva and the tooth surface.

• Sulcus depth is assessed by inserting a periodontal probe until resistance is encountered.

• Normal sulcus depths are:

  • In the dog: $1-3\,mm$

  • In the cat: $0.5-1\,mm$

Periodontal Ligament

• This is a specialized connective tissue that attaches the root cementum to the alveolar bone.

• It acts as a suspensory ligament for the tooth within the socket.

Alveolar Bone and Cementum

• The alveolar bone supports the teeth; the roots are contained within alveolar sockets in the bone.

• Alveolar bone undergoes atrophy if tooth loss occurs.

• Cementum is the tissue covering the root of the tooth, providing an attachment point for the periodontal ligament.

Tooth Morphology Classification

• Furcation: This term identifies the area where the roots of a multirooted tooth begin to diverge.

Brachydont Teeth

• Characterized by small crowns and elongated roots.

• They have closed apices that stop growing after a certain period.

• Species with brachydont teeth include felines, canines, and humans.

Hypsodont Teeth

• These are long-crowned teeth that continue to grow and erupt throughout the animal's lifetime.

• Species with hypsodont teeth include horses and ruminants.

Dental Pad

• In ruminants, a firm dental pad replaces the upper incisors.

Diphyodont Dentition and Dental Formulas

• Diphyodont refers to animals having two successive sets of teeth (deciduous and permanent).

• Note: There are NO deciduous molars in either dogs or cats.

Canine Dental Formulas

• Puppy (Deciduous): $2 \times (i\,3/3, c\,1/1, p\,3/3) = 28$ teeth.

• Adult Dog (Permanent): $2 \times (I\,3/3, C\,1/1, P\,4/4, M\,2/3) = 42$ teeth.

Feline Dental Formulas

• Kitten (Deciduous): $2 \times (i\,3/3, c\,1/1, p\,3/2) = 26$ teeth.

• Adult Cat (Permanent): $2 \times (I\,3/3, C\,1/1, P\,3/2, M\,1/1) = 30$ teeth.

Equine Dental Formulas

• Horse (Deciduous): $2 \times (i\,3/3, c\,0/0, p\,3/3) = 24$ teeth.

• Horse (Permanent): $2 \times (I\,3/3, C\,1/1 \text{ or } 0/0, P\,3 \text{ or } 4/3 \text{ or } 4, M\,3/3) = 36 \text{ to } 44$ teeth.

• The final count depends on the presence of canine teeth and "wolf teeth" (the first premolar).

Tooth Eruption Schedules (in weeks)

Osteology of the Skull

• Key bones involved in the dental and cranial structure include:

  • Incisive bone (premaxilla) and Incisive foramen.

  • Maxilla (containing upper teeth).

  • Mandible (containing lower teeth), featuring the Coronoid process and Angular process.

  • Nasal bone.

  • Lacrimal bone.

  • Frontal bone.

  • Parietal bone.

  • Zygomatic bone and Zygomatic arch.

  • Temporal bone and Mandibular fossa.

  • Occipital bone, Occipital condyle, and Foramen magnum.

  • Palatine bone.

  • Basisphenoid and Basioccipital bones.

  • Tympanic bulla and External acoustic meatus.

  • Jugal and Squamosal bones.

  • Eustachian tube.

Functional Types of Teeth

• Incisors: Located rostrally; used for gnawing and grooming.

• Canines: Long teeth used for prehending (grasping) and holding objects/prey.

• Premolars and Molars (Cheek Teeth): Used for shearing and grinding food.

• Incisal edges: The cutting edges of the incisor teeth.

• Occlusal surface: The grinding surface of the cheek teeth where the upper and lower teeth meet.

Positional Terminology

• Rostral: Toward the nose.

• Caudal: Toward the tail/back of the head.

• Vestibular: The surface facing the vestibule (includes Buccal and Labial).

• Buccal: Surface toward the cheek (premolars/molars).

• Labial: Surface toward the lips (incisors/canines).

• Facial: Term that can refer to the vestibular surfaces of the anterior teeth.

• Lingual: The surface of the lower (mandibular) teeth facing the tongue.

• Palatal: The surface of the upper (maxillary) teeth facing the hard palate.

• Mesial: The surface of the tooth directed toward the midline of the dental arch.

• Distal: The surface of the tooth directed away from the midline of the dental arch.

• Apical: Toward the root tip.

• Coronal: Toward the tooth crown.

• Interproximal spaces / Interdental space: The area between adjacent teeth.

• Cingulum: A ridge on the palatal/lingual side of the incisors.

• Interradicular: The area between the roots of a single tooth.

• Cervical area / Gingival area: The region near the neck of the tooth where the crown meets the root.

Triadan Numbering System

• This system uses three digits to identify specific teeth.

• First Digit (Quadrant/Dentition):

  • $100$ Series: Right upper (maxillary) quadrant (Permanent).

  • $200$ Series: Left upper (maxillary) quadrant (Permanent).

  • $300$ Series: Left lower (mandibular) quadrant (Permanent).

  • $400$ Series: Right lower (mandibular) quadrant (Permanent).

  • $500-800$ Series: Used for deciduous teeth (500=UR, 600=UL, 700=LL, 800=LR).

• Second and Third Digits:

  • Together, these denote the specific tooth within the quadrant, starting from the midline and moving caudally.

The Rule of 4 and 9

• The Canine tooth is always numbered as tooth $04$.

• The First Molar is always numbered as tooth $09$.

• Consequently, the fourth premolar is $08$ and the third premolar is $07$.

Root Morphology and Tooth Counts

Feline Root Counts (Upper/Maxillary)

• Incisors: One root.

• Canine: One root.

• Second Premolar ($106/206$): One to three roots.

• Third Premolar ($107/207$): Two roots.

• Fourth Premolar ($108/208$): Three roots.

• First Molar ($109/209$): One root.

Feline Root Counts (Lower/Mandibular)

• Incisors: One root.

• Canine: One root.

• Third Premolar ($307/407$): Two roots.

• Fourth Premolar ($308/408$): Two roots.

• First Molar ($309/409$): Two roots.

Canine Root Counts (Upper/Maxillary)

• Incisors: One root.

• Canine: One root.

• First Premolar: One root.

• Second & Third Premolars: Two roots.

• Fourth Premolar: Three roots.

• Molars: Three roots.

Canine Root Counts (Lower/Mandibular)

• Incisors: One root.

• Canine: One root.

• First Premolar: One root.

• Second, Third, & Fourth Premolars: Two roots.

• First & Second Molars: Two roots.

• Third Molar: One root.