RD 1 Lecture 1 (8/20)

What does the term dentition refer to?

all of the the teeth in the mouth

What are homodonts?

Animals that have all the same teeth in their dentition

All teeth are exactly the same

What is the typical anatomical shape of homodont dentition?

conical and interdigitate

What are heterodonts?

mammals that have teeth of different types/classes

How many classes of teeth are in the human permanent dentition?

four

How many classes of teeth are in the human primary dentition?

three

What is another word for primary?

deciduous

What is a monophyodont?

has one set of teeth

ex. beluga whale, dolphin

What is a Polyphyodont?

has an endless succession of teeth

constantly exfoliated and replaced

ex. sharks, frogs

What is a diphyodont?

has two sets of teeth

ex. humans

what is another term for permanent?

secondary

succedaneous (besides premolars)

What are the two types of dentition that humans have?

Diphyodont and Heterodont

What is the top arch of teeth called?

Maxillary arch

What is the lower arch of teeth called?

Mandibular arch

What else can the arches be divided into?

quadrants

What age is the primary/deciduous dentition normally found?

2-6 years

What are the classes of teeth that the primary dentition has?

incisors, canines, and molars

How many teeth are in the entire primary dentition?

20

By what age is the primary dentition usually shed?

12 or 13

What is the formula used to represent the teeth in the primary dentition?

I 2/2, C 1/1, M 2/2

How many teeth are in the secondary/permanent/succedaneous dentition?

32

What are the classes of teeth in the permanent dentition?

incisors, canines, premolars, molars

What is a key difference between the primary and permanent dentition?

Only permanent has premolars

What is the formula that can be used for the permanent dentition?

I 2/2, C 1/1, PM 2/2, M 3/3

Which dentition are the anterior teeth present in?

both primary and permanent

What are the anterior teeth?

incisors and canines

What are the posterior teeth?

premolars and molars

Which teeth are present only in the permanent/not in the primary dentition?

premolars

What is the universal numbering system?

1-32 secondary, A-T primary

What is the FDI numbering system

• PERMANENT DENTITION

1 = maxillary, right quadrant

2 = maxillary, left quadrant

3 = mandibular, left quadrant

4 = mandibular, right quadrant

• PRIMARY DENTITION

5 = maxillary, right quadrant

6 = maxillary, left quadrant

7 = mandibular, left quadrant

8 = mandibular, right quadrant

The second number starts at midline and go back the quad (1-8 perm, 1-5 prim)

What is the palmer system?

uses a bracket for each quad and 1-8 or number (A-E) starting at midline and going back

What are the four tissues of the tooth

enamel, dentin, cementum, and pulp

What tooth tissues are calcified?

enamel and dentin

What tooth tissues are relatively hard and in what order?

enamel > dentin > cementum

what are the only visible tooth tissues?

enamel and cementum

What is the hardest substance in the body? (herder than bone)

enamel

What is the composition of enamel?

95% calcium hydroxyapatite (calcified) and 5% water and enamel matrix

What does the enamel develop from?

enamel organ (ectoderm)

What is enamel the product of?

specialized epithelial cells called ameloblasts

What does cementum look like?

dull yellow

external layer of root

How thick is the cementum on the tooth root?

very thin

What is the composition of cementum?

65% calcium hydroxyapatite (mineralized and calcified) and 35% organic matter (collagen fibers)

What is cementum about as hard as?

Bone

softer than enamel!

Where does the cementum develop from?

dental sac (mesoderm)

What is the cementum produced by?

cells called cementoblasts

What does dentin look like?

hard(sticky) yellowish tissue

What is dentin composed of?

70% calcium hydroxyapatite, ~18% organic matter (collagen fibers), and water

How hard is dentin?

harder than cementum but softer and less brittle than enamel

Where does dentin develop from?

embryonic dental papilla (mesoderm)

what cells form the dentin?

odontoblasts

What is the softest tooth tissue?

pulp

what is pulp?

connective tissue in the cavity or space in the center of the crown and root called the pulp cavity

What does the pulp contain?

rich supply of blood vessels and nerves

what is the coronal portion of the pulp called?

pulp chamber

what is the root portion of the pulp called?

pulp canal or root canal

what is the pulp cavity surrounded by?

dentin

where is the only spot the pulp cavity is not surrounded

root tip (apex) called apical foramen

where do nerves and blood vessels enter the pulp?

apical foramina

what is the only way pulp is visible (like dentin)

xrays or sectioned tooth

where does the pulp develop from?

dental papilla (mesoderm)

What is the anatomical crown?

part of the tooth (in the mouth or handheld) normally covered by an enamel layer

What is the anatomical root?

part of a tooth covered by cementum

What is the clinical crown?

amount of tooth visible in the oral cavity

What is the clinical root?

amount of tooth that is not visible since it is covered with gingiva (gum tissue)

What is the facial surface?

surface of a tooth in the mouth resting against or next to the cheeks or lips

can be used for all teeth

posterier facial surface can also be called

buccal

anterior facial surface can also be called

labial

what is the lingual surface?

surface of a maxillary or mandibular tooth nearest the tongue

in the maxillary the lingual surface can also be called

palatal

on posterior teeth the chewing surface is called

occlusal

on anterior teeth the chewing surface is called

incisal edge or ridge

what are proximal surfaces

sides of a tooth generally next to an adjacent tooth

where is the mesial

close to the midline

where is the distal

surface further away from the midline

what is an exception to the fact that a mesial of one tooth touches a distal of the tooth next to it?

central incisors (mesial to mesial) and last tooth in back

proximal surfaces are not

naturally cleaned by the action of the cheeks, lips and tongue

what surfaces are usually more slef-cleaning?

facial and lingual

What is a line angle?

junction line where two tooth surfaces meet

what is the guideline to combining terms for line angles?

mesial → distal → facial → lingual → occlusal or incisal

what are point angle?

junctions of three tooth surfaces at a point

To describe a dimension of a tooth, for example, the length of an incisor crown from the incisal edge to the cervical line is called

incisocervically

Label the line and point angles

a tooth can be divided into

thirds

divide the tooth crown into the following thirds (horizontally from any side)

cervical, middle, and occlusal (or incisal)

horizontal lines can divide the root into thirds

cervical, middle, and apical (toward the root tip or apex)

tooth from the facial (or lingual) surface, vertical lines can be used to divide the crown or root into

mesial, middle, and distal thirds

tooth from the proximal (mesial or distal) surface, vertical lines can be used to divide the crown or root into

facial, middle, and lingual thirds

tooth from the occlusal (or incisal) surface, lines running mesiodistally can be used to divide the crown into

facial, middle, and lingual

lines running faciolingually can be used to divide the tooth into

mesial, middle and distal thirds

Root-to-crown ratios for teeth are normally

>1.00

why is it significant to know root-to-crown ratios?

A tooth with a small root-to-crown ratio (closer to 1) is not the best choice for attaching and supporting false teeth

morphological structures can be divided into two broad sections based on:

1. Elevations & Ridges

2. Depressions & Grooves

Elevations =

rounded

ridges =

linear

what is a cusp?

pyramidal elevation or peak

where are cusps located?

occlusal surfaces of molars and premolars, and on the incisal edges of canines

how many cusp ridges does each cusp have?

four, converge towards the cusp tip

(rounded pyramid)

cusps are named based on

location on tooth

On a two-cusped premolar, the two cusps are named

after the surface adjacent to each cusp: buccal or lingual

On a four-cusped molar, the four cusps are named

after the adjacent line angles: mesiobuccal, distobuccal, mesiolingual, and distolingual