Axial Skeleton: Mandible

Other Bones Articulated to the Skull:

§ Mandible
§ Ear Ossicles
§ Hyoid Apparatus
§ 1st Cervical Vertebrae (occipital bone)

Mandible

· bears the lower teeth and articulates with the mandibular fossa of the zygomatic process of the temporal bone

· the mandibular symphysis unites the 2 mandibles and it also divides the jaw into right and left equal halves

Divided Into Two Parts:
1. Body
2. Ramus

Mandible Body

contains the 3 Mental Foramina

1. Rostral Mental Foramen
2. Middle Mental Foramen
3. Caudal Mental Foramen

Mandible Ramus

Has Lateral Surface and Dorsal Surface

Lateral Surface:
Masseteric Fossa, Condylar Process, Angular Process and Mandibular Notch

Dorsal Surface:
Coronoid Process, Medial Surface and Mandibular Foramen

Masseteric Fossa

triangular area, it serves as the insertion of the Masseter muscle

Condylar Process

helps form the temporo-mandibular joint

Angular Process

a hooked eminence ventral to the condylar process; serves as the insertion of the pterygoid medially and masseter laterally

Mandibular Notch

it is a U-shaped depression between the condylar and coronoid process; serves as the passageway of the motor branches of the mandibular nerve in order to innervate the masseter muscle

Coronoid Process

a process that forms the dorsal half of the ramus and is located dorsal to the condylar and angular process of the mandible

Medial Surface

contains a shallow depression for the insertion of the temporalis muscle

Mandibular Foramen

it is the caudal opening of the mandibular canal; transmits the inferior alveolar artery, vein and nerve

Canine Dentition

: characters of set of teeth

Adult dogs should have 42 teeth

I= incisor. Upper 3. Lower 3
C=Canines Upper 1. Lower. 1
P=premolars. Upper 4. Lower 4
M=molars. Upper 2. Lower 3

Always times by 2

Teeth

Structures of the mouth that function as weapons of offense and defense and prehensile organ of the animal

: arranged in
[1] Superior/Upper/Maxillary Arcade and
[2] Inferior /Lower/Mandibular Arcade

: that face each other wherein the inferior arch is usually narrower than the superior arch

Parts of a Tooth

Crown
it is the exposed part of the tooth located above the gums

Neck
it is the part of the tooth formed by a slight constriction located on the gum line

Root
part of the tooth located below the gum; it is embedded in the alveolus

Layers/Substances of a Tooth

· Enamel
· Dentine
· Cementum
· Dental pulp

Enamel

Outermost substance of the tooth

: densely calcified making it one of the hardest substance in the body but there is possibility for it to be breached amd removed especially when the dog is 17 weeks of age

: mostly white in color but turns as the teeth grows old

Dentine

Calcified and collagen rich substance of the tooth making it similar to bones

: makes up the bulk of the tooth
: usually ivory and yellowish in color but is generally white

Cement

Also calcified but softer than any of the other calcified of the tooth

: a thin covering that gradually throughout life and is found at the roots of the teeth

Dental Pulp

it is the soft tissue of the tooth that is richly vascularized, containing the different blood vessels and nerves supplying the oral cavity

Surfaces of the Teeth

contain six surfaces
[1] Labial
[2] Buccal
[3] Lingual
[4] Palatine
[5] Contract
[6] Occlusal

Labial Surface

the outer surface of the teeth facing the lips

Buccal/Vestibular Surface

the outer surface of the teeth facing the cheek mucosa

Lingual Surface

the inner surface of the mandibular teeth facing the tongue

Palatine Surface

the inner surface of the maxillary teeth facing the hard palate

Contact Surface

it is the surface of the teeth that comes in contact with or faces an adjacent tooth

[1] Mesial contact surface
[2] Distal contact surface

Occlusal/Masticating surface

it is the surface of the tooth that faces the opposite dental arch

Heterodont Teeth

incisors, canines, premolars, molars

Incisors

type of teeth whose roots are embedded in the incisive bone of the skull

: consist of 3 teeth on both sides of the upper and lower jaw

: comprised of the central incisor, intermediate incisor and corner incisor

: the upper incisors are slightly placed in front of the lower incisors

: for cutting, nibbling and grooming functions

There are 12 Total Incisor

Canines

type of teeth located caudal and separated by a space from the incisors

: it is the longest among the 4 types of teeth, its roots are nearly twice as long as their length of their crown

: they are large, curved and laterally compressed

: functions for aggressive and holding purposes

Diastema

a space between incisor and canine (between two teeth)

Premolars

a component of the cheek teeth located caudal to the canines

: Consist of 4 teeth on each side of each jaw

· they are present in both temporary and permanent dentition (except PM1)

Contains
[1] 1st Premolar
[2] 2nd and 3rd Premolar
[3] 4th Premolar

1st Premolar

a small, peg-like tooth, it is the smallest of the 4 premolars

usually remaining throughout life, it erupts at 4-5 months postnatal

2nd and 3rd Premolar

possesses 2 roots

4th Premolar

it is the largest among the premolars (carnassial, shearing or sectorial tooth)

it is the largest cutting/shearing teeth of the upper jaw

it is the most commonly involved tooth in infections

Molars

the other component of the cheek teeth located caudal to the premolars

: Consist of up to 2 teeth on each side of the upper jaw and 3 on each side of the lower jaw

: like the 1st premolar, it has no deciduous predecessor

: possesses broader, more extensive occlusal surfaces

: functions in crushing or grinding the food

Contains:
[1] Lower 1st Molar
[2] 2nd and 3rd Molar

Lower 1st Molar

it is the largest cheek tooth of the mandible

also called the carnassial or sectorial tooth

2nd and 3rd Molar

the smallest among other molars

Diphyodont Teeth

two sets of teeth
[1] Deciduous Teeth
[2] Permanent Teeth

Deciduous Teeth

: Temporary set of teeth that erupt in young animals and are replaced at or near maturity

: Some are functional only until the 2nd month after birth, some remain throughout life

Deciduous Teeth Dental Formula in Dog

I [3,3]; C [1,1]; P [3,3]

: 28 Total Right and Left

Permanent Teeth

: Replaces some of the deciduous teeth and remain throughout the dog's life

: 42 in number

Permanent Teeth Dental Formula in Dog

I [3,3]; C [1,1]; P [4,4]; M [2,3]

: 42 Total Right and Left

Triadan System of Tooth Identification

Upper Right: Quadrant 1
: 101-110

Upper Left: Quandrant 2
: 201-210

Lower Left: Quandrant 3
: 301-311

Lower Right: Quadrant 4
: 401-411

Eruption of Deciduous Teeth

Incisor 1, 2 and :
3-4 Weeks

Canine:
3 Weeks

Premolar 1:
None

Premolar 2, 3, and 4:
4-6 Weeks

Molar 1, 2 and 3:
None

Eruption of Permanent Teeth

Incisor 1: 3-4 Months

Incisor 2: 4 1/2 Months

Incisor 3: 5 Months

Canine: 5-6 Months

Premolar 1: 4-5 Months

Premolar 1, 2, 3 and 4: 5-6 Months

Molar 1: 4-5 Months

Molar 2: 5-6 Months

Molar 3: 6-7 Months