Teeth, Mastication and Sinuses Flashcards
What is ondontogenesis
The process of tooth formation
What specifically initiates the development of individual teeth?
Dental placodes
What structure initiates a bud-to-cap transition in ondontogenesis?
Primary enamel knot
The epithelial covering of deciduous teeth is continuous with the gums upon eruption, how is this epithelium removed later on?
Through wear and tear
Where does a permanent tooth migrate to?
The socket of the temporary tooth
What causes the tooth root to be absorbed/ reabsorbed as the permanent tooth grows through?
The increase of temperature and pressure within the tooth root
What happens once the tooth root of the deciduous tooth has been reabsorbed?
The deciduous tooth loosens and sheds so the permanent tooth can replace it?
Why is cementum important?
Cementum gives attachment to the periodontal ligament
What does the term brachydont mean?
Low crowned teeth that have a neck at the gumline and a root embedded at the jaw bone
What does the term hypsodont mean?
High crowned teeth that extend unusually far below the gum line and have continual eruption.
What does radicular mean?
The root closes after eruption
What does aradicular mean?
Open rooted, tooth grows continually
Where are elodont teeth found?
- Rabbits
- Guinea Pigs
- Chinchillas
- Degus
What does heterodonty mean?
Teeth are differentiated into incisors, canines, molars etc.
What does homodonty mean?
Teeth are all the same form.
What is the contact surface of teeth?
Where adjacent teeth touch.
What is the occlusal surface?
Where adjacent teeth touch.
How many roots does an incisor have?
One
What is unique about canine teeth?
The root is longer than the crown
Where are the carnassial teeth found
- Last pre-molar in the upper jaw
- First molar in the lower jaw
Why are carnassial teeth laterally flattened
To provide a shearing action for cutting food
What structure helps to determine the location of tooth cusps?
Secondary enamel knot
What is the embryonic period?
The time period between fertilisation and the earliest organ development.
What is the foetal period?
The time period between the end of the embryonic period and parturition (birth)
What is the gestation period?
The sum of the embryonic and foetal periods
What are deciduous teeth?
Temporary baby teeth
What is the function of each of the cells below:
1) Ameloblasts
2) Odontoblasts
3) Cementoblasts
1) Ameloblasts secrete enamel matrix
2) Odontoblasts produce dentine
3) Cementoblasts secrete cementum
How is a tooth formed?
1) Thickenings of oral epithelium form dental lamina
2) Underlying mesenchyme condenses
3) Dental lamina invaginates to form the dental bud
4) Dental bud expands and forms an enamel organ to surround the dental papilla
5) Cells in the tooth (prev slide) differentiate.
A lingual extension of successional lamina that develops superficial and medial to the deciduous bud helps to form what?
The bud for the permanent tooth that will succeed the deciduous tooth.
When is the deciduous dentition complete in dogs and cats
When they are 2 months old
By what age are all of the adult teeth present in dogs and cats?
6 months
What teeth erupt first in dogs?
Canines
When is the equine deciduous dentition complete?
By 6 months
What teeth can be useful for aging a horse?
Incisors - Galvayne’s Groove
What is the infundibulum?
The infolding of the enamel
Where is the cup found?
In the centre of the infundibulum
What is the enamel space?
In the deepest part of the infundibulum
When does the dental star become visible?
When tooth is 8 years old
What is different about rodent dentition?
- No canines
- No pulp cavity in teeth
- Very large diastema = interdental space
What is special about the canines in pigs?
They continuously erupt to form tusks
What is unique about cattle dentition?
They have no upper canines or molars - hard fibrous dental pad
What are the 3 different types of teeth present in reptiles?
- Acrodont
- Pleurodont
- Thecodont
What is mastication?
The process of chewing and breaking down food prior to swallowing.
How does mastication vary between carnivores and herbivores?
- Carnivores use their carnassial teeth and canines for cutting and tearing of food
- Herbivores chew with a horizontal movement and have cutting ridges in their teeth for grinding grass.
Which part of the lower jaw articulates with the temporomandibular joint?
The condylar and coronoid processes of the mandible.
Where does the masseteric muscle sit in relation to the mandible bone?
In the massenteric fossa.
What type of joint is the mandibular symphysis and where is it found?
A fibrous joint, found between the left and right halves of the mandible.
What is the function of the mandibular symphysis?
- It allows fine compensatory adjustment to ensure precise occlusion.
- Allows independent rotation of the mandibular bones.
The diagastricus muscle is used to help open the jaw, where are the origin and insertion points?
Origin = Paracondylar process of the occipital bone
Insertion = At the angle of the mandible
The masseter muscle is used to help close the jaw, where are its origin and insertion points?
Origin = Zygomatic arch
Insertion = Caudal mandible
Where are the origin and insertion points of the temporal muscle?
Origin = Lateral surface of the cranium
Insertion = Coronoid process.
Where are the origin and insertion points of the lateral and medial pterygoid muscles.
Lateral
Origin - Pterygopalatine part of the skull
Insertion - Lateral mandible
Medial
Origin - Pterygopalatine part of the skull
Insertion - Medial mandible
What muscles are enlarged in herbivores?
The masseter and pterygoid muscles, this allows for extensive chewing and lateral movement of the jaw.
What muscle is enlarged in carnivores?
Temporalis muscle, helps to snap the jaw shut.
What are the 3 compartments of the nose?
1) External nose
2) Nasal cavities
3) Paranasal sinuses
What is the correct scientific name for nostrils?
Nares
What structure separates the two nasal cavities?
The nasal septum
What unique structure do horses have in their nostrils?
Nasal diverticulum.
What bone is found at the caudal boundary of the nasal cavity?
Ethmoid bone
What type of bones are found within the nasal cavity?
Turbinate bones
What is the name of the mucosa that covers the turbinate bones?
Conchae
What are paranasal sinuses?
Air spaces surrounding certain bones bordering the nasal cavity.
Complete the sentence = where you can’t find conchae, you will find…
Meatus
What is the function of conchae?
Conchae increase respiratory area and create turbulence (this filters/ warms/ cools incoming air)
What are the 3 nasal meatuses?
Dorsal, middle, ventral
How many paranasal sinuses does a dog have? What are they?
2; frontal sinus and maxillary sinus.
Which species have the most complex paranasal sinuses?
Cattle
