test 3: teeth and jaws Flashcards
back of the oral cavity
palatoglossal arch
functions of the mouth
threat display, defense, vocalization, food acquisition, and processing
tongue is used for
food prehension and repositioning, separation of waste
types of taste buds
vallate, foliate and fungiform
what papillae do not have tastebuds
filiform and conical
functions of saliva
Keeps the mouth moist
Antibacterial: protects teeth
Lubricates swallowing
Begins carbohydrate breakdown
– Saliva also deposits tartar on teeth
position of salivary glands
what type of animals have small salivary glands
carnivores- meat wet doesn’t need help to swallow
saliva contains ___ that starts carb breakdown
ptyalin (α-amylase)
Saliva production is affected by___
: 1) mental state; 2) hydration; 3) presence of objects in the mouth
sympathetic innervation will do what to saliva?
decrease (fight ot flight)
increase (rest and digest)
mastication
- Chewing divides food into smaller pieces & prepares it for swallowing
- Particle size reduction ↑ surface area & facilitates digestion (chemical)
___ includes the teeth; jaws & jaw joints; & jaw muscles
Masticatory apparatus
teeth can provide information about
age, diet and sex
__ teeth are used for food acquisition
incisors and canines
___are used for food processing
premolars and molars
Tooth development involves interactions between epithelium & ___
mesenchyme
6 dental tissues
enamel
dentine
cement
pulp
periodontal ligament
gingiva
what three dental tissues are not mineralized
pulp
periodontal ligament
gingiva
what three dental tissues are mineralized
enamel
dentine
cement
enamel
hard & brittle. Resists abrasion.
Covers anatomical crown
97% hydroxyapatite
Acellular – damage can’t be repaired*
Formed by ameloblasts (ectodermal)
dentine
elastic. ‘Tough’ zone just below EDJ.
Absorbs & distributes stresses
70 - 80% hydroxyapatite
Formed by odontoblasts (derived from neural crest)
Four types:
Primary dentine (formed before tooth erupts)
Secondary (slowly fills pulp cavity after eruption)
Tertiary dentine (repairs cracks, etc.)
So-called “intermediate cement” (at the CDJ)
cement
attachment for periodontal ligament
Covers root (and sometimes also covers crown)
50-65% hydroxyapatite
Formed by cementoblasts
Can be cellular or acellular
Annual layers (# of layers – age estimate)
pulp
Pulp (located within the tooth)
Living core of tooth
Includes vessels, nerves, lymphatics, loose CT, & odontoblasts
Vessels & nerves enter & exit via root canal
Odontoblasts are at pulp surface. Have cellular processes that extend to EDJ and CDJ
periodontal ligament
(lies outside of tooth)
Connects tooth to alveolus (socket) in jaw
Supports the tooth against bite force
Assists in eruption (periodontal traction)
Sensory: temperature; tension / pressure; pain
gingiva
(lies outside of tooth)
Covers jaw bone, & forms a “cuff” around teeth
Two types:
attached – to jaw bone or tooth cement
free – overlaps crown; forms ‘gingival pocket’
Derived from oral mucosa
what part of the tooth is acellular
enamel- can not be repaired
how does dentine repair itself
odontoblasts processes reach out into the EDJ(enamel-dentine junction) and secrete new dentine (tertiary dentine) to repair itself
___ covers the root of the tooth
cement
living core of the tooth
pulp
___ attaches root of tooth to the alveolus
periodontal ligament
gums or ___
gingiva
what are the pockets around a tooth
gingival pockets
4 parts of a tooth
crown
neck
root
alveolus
anatomical crown vs clinical crow
- Crown (height rel. to root length can vary)
a. Anatomical crown – enamel-covered
b. Clinical crown – visible above gums
where to grip a tooth to extract it
neck
tooth socket
alveolus
any part of the tooth that has an enamel covering
crown (anatomical crown)
what kind of animal has very big difference between clinical and anatomical crown?
horse (high crowned teeth)
tooth development
- Oral epithelium (DE) invaginates into jaw mesoderm (DM) to form the “dental lamina” (see E13.5)
- Tooth buds form on the lamina. Each bud includes:
Dental cap – ectoderm (from oral epithelium)
→ ameloblasts (produce enamel)*
cap includes root sheath (at bottom of cap)
Dental papilla – ectomesenchym (cranial neural crest)
→ odontoblasts (produce dentine) (DP in E14.5)
tooth pulp = remnant of dental papilla
Dental follicle – ectomesenchym; surrounds the dental cap and dental papilla.
→ cementoblasts (produce later cement layers)
→ periodontal ligament (CT connection to alveolus)
Oral epithelium (DE) invaginates into jaw mesoderm (DM) to form the ___
“dental lamina”
Tooth ___ form on the lamina
buds
tooth buds include
dental cap
dental papilla
dental follicle
dental cap
ectoderm (from oral epithelium)
→ ameloblasts (produce enamel)*
cap includes root sheath (at bottom of cap)
dental papilla
ectomesenchym (cranial neural crest)
→ odontoblasts (produce dentine)
tooth pulp = remnant of dental papilla
dental follicle
§ectomesenchym; surrounds the dental cap and dental papilla.
→ cementoblasts (produce later cement layers)
→ periodontal ligament (CT connection to alveolus)
Ameloblast basal lamina = position of ___
Enamel-Dentine Junction (EDJ)
___ will become the pulp of the tooth
dental papilla
dental papilla will produce odontoblasts which produce ___
dentine
dental cap will produce ameloblasts if ___ is present
stellate reticulum
ameloblast build need enamel
EDJ
enamel dentine junction
why does dental papilla get smaller
puts on more and more layers of dentine
odontoblasts
Odontoblasts add dentine layers, at dental papilla
New layers form on pulp side of older dentine layers
Odontoblasts move away from cap & EDJ as layers added
dental papilla = future tooth pulp
Ameloblasts
Ameloblasts – add enamel layers to outer crown surface
New layers form outside older enamel layers
Ameloblasts move outward, away from papilla & EDJ
why no enamel at root?
no stellate reticulum= no ameloblasts = no enamel
root sheath
root sheath
lower edge of dental cap (see “HERS”)
Zone of cap without ameloblasts; makes no enamel
Odontoblasts facing the sheath produce root dentine
Produces thin, highly calcified layer of outer root dentine (sometimes called ‘Intermediate cement’)
Root sheath disintegrates as tooth erupts (except in open-rooted teeth, which keep growing throughout life)
dental follicle
Derived from ectomesenchyme
Inner cells become cementoblasts that make dental cementum (new layer added every year)
Outer cells give rise to periodontal ligament
Top half of follicle resorbs bone above tooth; bottom half builds alveolar bone below tooth.
dental follicle will produce ____
cementoblasts → cement
periodontal ligament
tooth eruption
- Erupting teeth travel along the dental lamina to the jaw surface
- The follicle is essential for eruption. If the follicle is missing, eruption fails.§Creates pathway for erupting tooth by resorbing overlying bone / tooth roots§Fills the emptied crypt with new bone (which helps push tooth toward jaw surface)§Produces the periodontal ligament (which pulls the erupting tooth toward jaw surface)
- Enamel deposition ceases as the tooth erupts (except in open-rooted teeth)
- Dentine & cement continue to form after tooth erupts, in all teeth
ever growing teeth
hypselodont (rodent)
what happens to teeth after they erupt
§The pulp cavity narrows as dentine gradually fills it
§Root canal also narrows, but remains open (for nerves & vessels)
§Pulp cavity remains wide in open-rooted teeth (+ no roots), continue to grow & erupt throughout life, hypselodont
septae between teeth
interalveolar septae
septae between roots
interradicular septae
what type of teeth attachment do mammals have
gomphodont attachment. One or more roots; alveoli (sockets) fit root tightly
set of teeth that are identical
homodont dentition
animals with no teeth
adontia (bird)
set of teeth that are different
heterodont dentition
when an animal looses its teeth
edentulous
why does a tooth not make enamel once it has erupted?
broken follicle- no more stellate reticulum = no ameloblasts = no enamel
there is still odontoblasts on inside of tooth making dentine
when teeth are replaced many times
polyphyodont
when teeth are replaced once
diphyodont
mesial surface
front of tooth closest to midline
distal side of tooth
back of tooth, opposite of mesial
labial side of tooth
outer, toward the lips
occlusal
where teeth overlap each other
inside of teeth are ___
lingual or palatal (upper or lower jaw)
TMJ
Temporomandibular joint (TMJ) – between skull & jaw
A wide condylar joint with menisci
Hinge motion allows jaw to open and close
May also allow side-to-side or rostral-to-caudal motion
where left and right mandible meet
mandibular symphysis
dogs do not have a fused mandibular symphysis. True or false
true- some motion between left and right mandibles
carnivores the occlusal surface is not in line with the TMJ. True or false
false
in line. out of line for herbivores
jaw adductor muscles
temporalis
massester
pterygoids
jaw abductor
digastricus (close jaw)
___ closes jaw by pulling up & back: hinge-like closure on TMJ
temporalsis
___ closes jaw; can also pull jaw rostrally or laterally at TMJ
massester
___ close jaw; can also pull jaw rostrally or medially
pterygoids
why two CN for digastricus
developmental biology- two bronchial arches
what type of animal has the larges temporalis
carnivores (need to slice food)
what kind of animal has the largest masseter
rodent (gnawing) sideways motion
high crowned tooth
hypsodont
ever growing tooth
hypselodont
diet is reflected in
. Shapes of the animal’s teeth
- Position of its TMJ relative to occlusal surface
- Relative sizes of its adductor muscles
omnivore
teeth, jaw and adductor
carnivore
teeth, jaw and adductor
herbivore
teeth, jaw and adductor
