Teeth 1 Flashcards
Purpose of teeth
-intake, cutting and chewing food
-grooming
-aggression
-holding objects
Loss of teeth
-main reason for starvation and dying of old animals in the wild
Dentistry practice and history
-vet dentistry practice has grown in recent decades (more than 15% of small animal practice)
-interest in horse teeth has a longer history than in small animals
-preventative tooth care is becoming more common
Word derivative of Teeth
Dens (latin) or odous (Greek)
Crown
-part encased in enamel
Enamel
-very resilient, shiny, white
- densely calcified
- 96% inorganic
-hardest substance in body
-acellular so limited reparability
Root
-part encased in cement
Cement
-softer, less shiny, yellowish
- similar in hardest to bone
-50% inorganic
-covers tooth root
-thickness increases with age
-resistant to pressure erosion
- root apex is weakest part
Neck
-where crown and root meet
-ideally covered by gums
Clinical crown
Exposed part regardless of its structure
Anatomical crown
- Enamel-covered part regardless of its location
- Includes clinical crown and reserve crown
Reserve crown
-in herbivores
-enamel covered part which continues to erupt, as exposed part wears down
Dentin
- Ivory
- Calcified
- 70% inorganic
- 2nd hardest material in body
- Rich in collagen
- Forms bulk of tooth
What makes dentin?
Made by odontoblasts that line the pulp cavity
- Lay down secondary dentin, after damage they lay down darker tertiary dentin
Cement root apex
- Weakest part
- Reason for loss of baby teeth because pressure of adult tooth from below breaks connection at apex
Pulp
-loose connective tissue
- blood vessels
- nerves
Dental (pulp) cavity
Space within a tooth containing pulp
Apical foramina
-apical opening of dental cavity and the passage of vessels, nerves, lymph
-usually multiple in animals (but single in humans)
Tooth socket
-alveolus
-where tooth implanted in margin of jaw/alveolar process
Lamina dura
-a lamina of compact bone lining tooth socket
-perforated (cribriform) for vessels, nerves
-seen as a white line in X-rays
Periodontal ligament (PDL)
-also called sharpeys fibers
-tough fibro-collagen fibers
-suspend tooth
Types of periodontal ligament (PDL)
1.gingival PDL fibers
2.trans-septal PDL fibers
3.Alveolodental PDL fibers
Gingival PDL fibers
-anchor cement to gum
Trans-septal PDL fibers
-attach neighbouring teeth
Alveolodental PDL fibers
-fasten tooth to the socket
Gingiva
-gums
-keratinized
-tough
-collagen
-rich
-protective
Interdental gingiva/papilla
-gingiva peak between adjacent teeth
Free gingiva
-forms gingiva margin
-surrounds part of the crown
Attached gingiva
-tightly adherent to subgingival connective tissue and bone
Mucogingival junction (MGJ)
-junction between attached gingiva and alveolar mucosa
Gingival sulcus
-between tooth and free gingival margin
-crevice that surrounds tooth
-rich in immunity elements
Gingival sulcus depth for cats vs dogs
-Cats: 0.5-1mm
- Dogs: 1-3mm
Junctional epithelium (JE)
-at bottom of sulcus
- protects PDL
Cemento-enamel junction (CEJ)
-junction between anatomical crown and root
Heterodonty
- In mammals
- Teeth in different parts of mouth have different form and function
o Incisors
o Canines
o Premolars
o Molars
Incisors function
-cutting food, nibbling, grooming
- max 3 on each side of jaw
Canine function
-aggression and holding
-cradle of tongue in dogs
-well developed in carnivores
- n=1 on each side of jaw
Premolars function
-holding, carrying and breaking food
- n=max 4 on each side of jaw
Molars function
-crushing, grinding food
- flat occlusal tables
-n=max 3 on each side of the jaw
-absent in milk set of teeth
Cheek teeth
-includes both premolars and molars
-better developed in herbivores
Diphyodonty
-teeth in mammals grow in 2 successions (unlike in most other vertebrates)
- deciduous teeth and then permanent teeth
Deciduous teeth
-also called milk, primary, temporary teeth
-smaller, sharper, weaker, replaced later
-lack molar teeth
Permanent teeth
-also called adult or secondary teeth
-darker, larger
Dental formula
- dentition
-standard number, type, and arrangement of teeth which is set in each mammal species
>written for one side of upper and lower jaw
>written as a fraction or in separate rows
>lower case for milk teeth; upper case for adult teeth
> order is always the same, letters can be skipped
> superscript number for upper teeth; subscript number for lower teeth
Dental formula in dog
-deciduous: i3-c1-p3/i3-c1-p3 =TOTAL 28
-permanent: I3-C1-P4-M2/I3-C1-P4-M3 = TOTAL 42
Modified triadan system
-standard method of numbering teeth in vet dentistry
-mouth divided into 4 quadrants
-each tooth given a unique 3 digit number based on quadrant and location starting from midline
>first digit denotes its general location in jaw
>second digit denotes its location from midline
Modified triadan system quadrants
-from upper right to upper left to lower left and then lower right
-quadrants 1-4= permanent teeth
-quadrants 5-8= deciduous teeth
Modified triadan system and missing teeth
If a tooth is missing, skip its number
-if premolar, numbers lost from front
- if molar, numbers lost from back
Dental directional
- Teeth follow a curved line of arcade
Surface terms
-vestibular or facial surface (includes labial and buccal surfaces)
-lingual (usually lower jaw) or palatine (usually upper jaw)
- contact surfaces (mesial-closer to front or distal-farther to back of mouth)
-occlusal=masticatory surface- chewing surface of teeth
Dentition in dog upper jaw
-Upper jaw: 3 incisors, 1 canine, 4 premolars, 2 molars
-wider and pear shaped
- missing a upper molar
Dentition in dog lower jaw
-Lower jaw: 3 incisors, 1 canine, 4 premolars, 3 molars
-narrower and triangular
Overlap of teeth/jaws in dog
Little overlap between upper and lower jaws except for molars so dental cavities (tooth decay) is less common (~7%) but when present usually at occlusal of molars
Structure of dog incisors
-Upper incisors=trifid
-lower incisors=bifid
Canine tooth of dog
- Very large root
- Difficult to extract without surgery
Dog premolars
-irregular
-increase in size to back and when jaw is closed they form a serrated cutting edge
Sectorial or carnassial teeth
-P^4 and M1 act like scissors
Dog molars
-molars are broader, decrease in size to back and can cut and crush
Masticatory force of dog
30,000-80,000 psi
Tooth roots in dog
-root number important for extractions
-multiple roots diverge and so during extractions need to cut teeth per root number
Permanent tooth roots of dog
-All incisors and canine have 1 root
-Upper premolars and molars (P1 has 1 root, P2 and P3 has 2 roots, P4 and M1 and M2 have 3 roots)
- lower premolars and molars (P1 and M3 have 1 root, P2-M2 have 2 roots)
3 roots
Means 2 are vestibular (outer) and 1 lingual (inner)
