teeth, jaws, and their movements Flashcards
Teeth used for
- Prehension
- Offense
- Defense
- Mastication
origin of teeth
from dermal scales
structure of brachydont tooth
- root embedded in a socket/ alveolus
- crown; protrudes above the gingiva
- neck; bulges at level of gingiva
enamel
- harder than bone
- arranged into rids
- wears slower than dentine
- no nerve supply
- cannot undergo repair
enamel is formed by
ameloblasts, which disintegrate after enamel is formed; cannot undergo repair
dentine (which is similar to bone) is formed from
odontoblasts at the base of dentine layer
remain alive for life of tooth
primary dentine is
laid down before eruption
secondary dentine is
produced as the tooth develops
how does dentine respond to trauma
by forming tertiary dentine: has few tubules and is more dense and darker in colour
dentine consists of
microtubules within a 70% hydroxyapatite matrix
why is dentine sensitive to pain if enamel layer is breached
because the dentine
consists of microtubules within a 70% hydroxyapatite matrix, which contains fluid.
Stimuli including heat, cold, air, drilling and mechanical which causes a rapid flow of
fluid within the dentine tubules will transmit pain.
cementum
thin, calcified covering of roots, similar om composition to woven bone
cementum is capable of
formation, destruction and repair, remodels continually throughout life
where does cementum attach
periodontal ligament
periodontal ligament
network of collagenous fibers and fibroblasts embedded in cementum and into alveolar bone, must break it down to remove tooth
pulp cavity
- brain and heart of tooth
- contain blood supply and nerves
- exact location may vary tooth to tooth
- connected to alveolus via root canal
brachydont teeth
- stop growing at maturity
- firmly anchored in jaw
- enamel is not replaced
- NOT built for grinding
Which part of the tooth is embedded in a socket/alveolus?
root
The anatomic crown is the part of the tooth containing:
Enamel
Which of the following structures is harder than bone, and cannot undergo repair?
Enamel
Which part of the tooth contains blood vessels and nerves?
pulp cavity
The crown is covered in cementum as well as enamel, with enamel extending into the root in which type of teeth?
Hypsodont
Which type of tooth is used for slicing, grinding, or crushing?
Cheek teeth (molars and premolars)
Which type of tooth does not have a deciduous tooth that precedes the adult tooth?
Molars
When the jaws come together, how does the lower canine sit in relation to the upper canine?
rostral or caudal
rostral
The dental formula counts each type of tooth in each half of the jaw. The first number is the number of that type of tooth in which jaw?
upper
The premature loss of deciduous teeth can lead to which of the following?
Malocculsion due to disorganised permanent teeth
Which surface of the tooth faces towards the cheek?
buccal
Which surface of the tooth faces towards the tongue?
Lingual
Quadrant 2 of a dental chart refers to which of the following?
Left upper quadrant
Which bone are the upper incisors embedded in?
incisive
Which of the following muscles opens the jaw when it contracts?
Digastric muscle
simple tooth
one root
hypsodont teeth have a ____ crown in relation to roots
high
hypsodont teeth eruption time
can take a long time to fully erupt
may display continual eruptions
hypsodont teeth crown is covered in
cementum and enamel, and enamel also extends into the root; enables more wear and tear on the teeth
hypsodont teeth; as surface wears, pulp cavity may become exposed, this is sealed with
secondary/ tertiary dentine
function of incisors
- cutting off pieces of food
- typically 3/3
- brachydont in most species
- important for grooming
function of canines
- grasping and/or offence and defence
- very deep rots
- lower is rostral to upper
- brachydont
function of cheek teeth (molar and premolars)
- often have a complex surface area, for slicing, grinding or crushing
- brachydont in carnivores and omnivores
- hypsodont in herbivores
difference between premolars and molars
premolars have a deciduous, molars do not
dental formula for dogs U/L
2( I 3/3 C1/1 P 4/4 M 2/3)= 42
dental formula for cats
2( I 3/3 C 1/1 P 3/2 M 1/1) = 30
carnassial teeth
used for cutting and sheering
in cats and dogs it is the last premolar in upper jaw and first molar in lower jaw
so dogs P4/ M1
cats P3/ M1
dog deciduous teeth dental formula
2 ( i 3/3 c 1/1 p 3/3) = 28
cat deciduous teeth dental formula
2( i 3/3 c 1/1 p 3/2) = 26
are there deciduous molars
no
which side does the developing permanent tooth grow on
on lingual side of deciduous tooth
what happens to deciduous teeth roots when the permanent teeth grow in
odontoclasts resorb the root of deciduous teeth, breaking down the hard tissue and releasing the minerals
describe how ankyloses of deciduous tooth can cause issues
If the repair process of
prevails over resorption process of deciduous teeth, the deposition of cementum‐like tissue may cause the tooth
to ankylose or fuse to the surrounding bone, resulting in the loss of the periodontal ligament. This prevents the tooth from falling out and impedes proper growth of the
permanent tooth. This process – ankyloses ‐ may also occur with adult teeth and
impede extractions.
in dogs incisors have how many roots
a single long root
in dogs how do the incisor crowns differ in upper and lower jaw
- upper incisor crown is tricupsid (have 3 points)
- lower incisor crown is bicupsid (have 2 points)
canine teeth in dogs have how many roots
one single root, much longer than the crown, curved into alveolus and laterally compressed
cusps of premolars in dogs
form a discontinuous serrated cutting edge
cusps of molars in dogs
have cutting potential but mostly for crushing
cheek teeth have how many roots in dogs
- first premolars and lower thirds molars have 1 root
- P4 (large carnassial tooth) and upper M1 and M2 have 3 roots; mesiolingual, mesiovestibular and distal
- rest of cheek teeth including lower carnassial (M1) have 2 roots; mesial and distal
summary:
Upper cheek teeth:
One tooth with one
root, two teeth with two
roots, three teeth with
three roots
Lower cheek teeth:
First and last tooth
with one root, rest with
two roots
how to remove a tooth
you release the gum from the neck of the tooth, then use a bur to cut the tooth all the way down to the fornication.
You can then extract each root individually. It’s also important to know the location of
the facial nerves and blood vessels that run through both the mandible and maxilla,
as you want to avoid causing nerve damage.
cheek teeth in cats roots
- first premolars have 1 root
- rest have 2 roots
- except P3 the upper carnassial has 3 roots
brachycephalic teeth
tooth root abnormalities, overcrowding, missing teeth, malocclusion, compaction
tooth surfaces;
- occlusal; chewing surface of tooth
- lingual/ palatal faces inward towards tongue
- vestibular/ buccal/ labial; towards cheek
- mesial; forward side of tooth, found on in between surface of tooth next to it
- distal; back side of tooth
dental chart (dogs)
jaws divided into 1,2,3,4 (clockwise as you look at animal so right upper is 1, left upper is 2, left lower is 3, and right lower is 4)
next 2 numbers refer to position; central incisor is 01, canines are 04, premolars are 05-08, molars are 09-11
which bones are the teeth in
- upper incisors are in incisive bone
- all other upper teeth are in maxilla
- all lower teeth in mandible
brachygnathic
mandible too short ie overbite
parrot-mouthed
prognathic
mandible too long ie underbite
angle of the mandible should lie directly ventral to the
temporomandibular joint
mandible can move in ___ planes
3
most movement in herbivores for grinding
canines have most movement in vertical plane for shearing and crushing
digastric muscle function
opening the jaw
digastric muscle origin and insertion
- origin; paracondylar process of the
occipital bone, - insertion; Medial and ventral mandible
4 pairs of muscles needed for closing jaw and chewing food
temporalis, masseter, lateral and medial pterygoid muscles
temporali origin and insertion
origin; temporal fossa
insertion; coronoid process of mandible
masseter origin and insertion
- origin; zygomatic arch
- insertion; masseteric fossa
medial and lateral pterygoid origin and insertion
- origin; pterygopalatine fossa
- insertion; medial mandible
innervation of the jaw; which nerve controls opening of mouth and muscles responsible for facial expression
facial nerve (CN VII)
which nerve controls closing of mouth, and is main facial sensory nerve
trigeminal nerve (CN V)
digastric muscle is innervated which 2 nerves;
The rostral portion is innervated by
the mandibular nerve, whereas the caudal belly has innervation from the facial nerve (CN VII)
