Teeth Flashcards
Homodont
One type of tooth (many non-mammals)
Heterodont
different types of teeth (many mammals)
T/F: molars are only found in adults
True
Baby animals do not have molars
T/F: both baby and adult animals may have premolars
True
Both babies and adults have premolars
Which bones are mammal teeth found in?
- Incisive bones
- Maxilla
- Mandible
Diphyodont
has baby and adult teeth
Hypsodont
high crowns e.g. horses
Brachydont
low crowns (relative to the overall tooth) e.g. dogs
Role of incisors
- Nibbling
- Grooming
- Cutting
Role of canines
- Grasping
- Fighting/defence
- Stabbing
- Toxin injections (some shrews/voles)
Roles of premolars and molars
- Crushing
- Shearing
- Gripping
- Grinding
Diastema
Gap between incisors and cheek teeth; typically found in herbivores
Describe jaw action in carnivores
- Move jaw sideways to engage teeth
- Pterygoideus muscles
- The muscles to move jaw sideways don’t need to be strong because the food is put in the right place before biting down
- Close jaw to shear/crush
- Masseter and temporalis musles
- These muscles need to be very strong
Describe jaw action in omnivores
Combined crush/grind action
Describe jaw action in herbivores
- Opposite to carnivores:
- Jaw is closed first around herbage (masseter)
- Then jaw is moved sideways whilst being held closed
- This allows the grinding of plant material to break down cells
- Pterygoideus muscles are large as they are working under load, equalled by masseter muscles
Lophodont
Structure of teeth in odd-toed herbivores

Selenodont
Structure of teeth in even-toed herbivores

Describe secodont arrangement of teeth
- e.g. carnivores
- Staggered teeth good for gripping hard and soft round objects
- Carnassial teeth overlap as the jaw closes to create cutting/scissor action

Where is enamel in herbivore teeth?
- Enamel is inside the tooth, covered by cement.
1

Crown: visible (supragingival) region of the tooth. Consists of smooth, hard enamel and hard dentine.
2

Enamel
- Hardest known biological substance outside of limpets
- Acellular once formed so cannot be repaired if damaged
- Mostly made of hydroxyapetite
- Dissolves in acid e.g. coca cola
Dentine
living tissue within the pulp cavity. Contains odontoblasts with processes in dentinal tubules.
Primary dentine
most of dentine, formed as the tooth grows.
Mineralised collagen
Secondary dentine
Grows slowly
Formed after tooth eruption
Makes the pulp cavity smaller
Tertiary dentine
formed in reaction to damage
Has a irregular structure that helps it fill damage
What substances overlie dentine?
Enamel and cement.
Labial
Lateral/cheek side
Lingual
medial side of mandibular teeth
Palatal
Medial side of maxillary teeth
Mesial
Rostral side
Distal
Caudal side
Occlusal
meeting surface of teeth
Cusps
raised parts of the occlusal surface
Grooves
indented parts of the occlusal surface
Apical
towards the tooth root
Coronal
towards the tip of the crown of the tooth.
Periodontium and its role
- Role is to attach, support and protect the tooth and jaw

Gingiva and its role
- Squamous epithelium forming a dense fibrous layer closely bound to the periosteum
- Reflects on the CEJ to form the gingival sulchus (risky pocket that needs to be kept clear)
- This is the site where gingivitis starts
What is cementum a.k.a. cement?
- Similar to bone, peripheral to dentine or enamel
- Provides site of attachment for periodontal fibres
- Completely covers herbivores
Difference between cement in carnivores and herbivores
- In carnivores, cement does not cover enamel
- In herbivores, cement grows with the tooth (as they continuously erupt) as it left on the outside, overlying the enamel
What gets worn away slowest on herbivores teeth (dentine, cement or enamel)?
- Dentine and cement get worn away quicker than enamel
- This leaves enamel ridges on the teeth which are good for grinding
Periodontal ligament
series of angled collagen fibres that support the tooth, act like a shock absorber and spreads the load into the whole socket.
What does the tooth root consist of?
Consists of
- Cementum
- Dentine
- Root canal
- Apex-apical delta
Teeth can be single/multi-rooted.
Describe the structure of a carnivore’s tooth root
Dentine root covered by enamel
Compare to herbivores, who have enamel all the way down to the bottom
Types of tooth root
-
Closed: the root apex has closed off
- The tooth erupts slowly and continuously (horses, cattles) or erupts to a set height (dog)
- Open: the root apex is open, so the tooth continually grows and erupts e.g. rodent incisors
Remember that growth and eruption are different things.
Describe carnivores’ tooth eruption
Once teeth have finished growing, they erupt to a certain height and stop.
Describe horses’ tooth eruption
- Once teeth have finished growing, they erupt to a certain height and stop.
1

Wolf tooth
2

Diastema
3

First incisors
4

Second incisors
5

Third incisors
6

Canines
7

Second premolars
8

Fourth premolars
9

First molars
10

Third molars