Chapter 2: The tooth - functions and terms

cementoenamel junction (CEJ) or cervical line

where is the crown and root joined?

anatomical crown

the whole crown of the tooth that is covered by enamel (regardless of whether it is erupted)

clinical crown

the part of the crown which is visible above the gingiva

eruption

moving of tooth through its surrounding tissues so that the clinical crown gradually appears longer

bifurcation

division of a root into 2 segments

trifurcation

division of a root into 3 segments

furcal region

between the roots

alveolar process

portion of the jaw that supports the teeth

alveolus

bony socket in which the tooth fits

enamel, dentin, cementum, dental pulp

what are the 4 tooth tissues?

enamel

outer surface of the anatomic crown; hardest tissue in human body, most densely mineralized; thickest at tip of crown, thinnest at cervical line; colour varies with thickness and mineralization

dentin

forms the main portion or body of the tooth; hard, dense, calcified tissue; softer than enamel, harder than cementum and bone; yellow in colour and elastic in nature; capable if adding to itself

secondary dentin

grows very slowly and is initiated by normal attrition and wear, normal aging process; formed after tooth erupts

reparative dentin

laid down in response to caries or trauma

cementum

covers the root in a non perfect layer; voids expose dentin; main function to provide a medium for attachment of the tooth to the alveolar bone; thin at cervical line, thicker at apex

dentinocemental junction (DEJ)

what is union of cementum and dentin called?

cellular cementum

apical 1/3 of root; can reproduce itself, compensating for attrition, no sharpeys fibers or bare spots

acellular cementum

covers most of anatomic root; primary function be part of the attachment system of tooth (sharpeys fibers)

pulp

housed in center of the tooth with dentin surrounding the tissues; nourishing, sensory, dentin-reparative system of tooth; composed of blood vessels, lymph vessels, connective tissue, nerve tissue (pain) and special dentin-forming cells

odontoblasts

special dentin forming cells that surround pulp

lay down primary, secondary and reparative dentin

what is the main function of odontoblasts?

pulp chamber, pulp canals

what are the 2 divisions of the pulp?

pulp chamber

in coronal portion of tooth

pulp canals

in root portion of tooth

pulp horns

in each cusp of tooth

incisors, canines, premolars, molars

what are the 4 types of teeth?

cutting, holding/grasping, grinding

what are the 3 basic food processing functions of the teeth?

incisors

designed to cut; lingual surface is shovel shaped to guide food into mouth

canines

designed to hold or grasp; functions to protect TMJ during side jaw movements, only teeth touching

canines

which is the longest teeth in human dentition?

maxillary canines

which teeth have the longest root?

premolars

designed to hold and grind food; pointed buccal cusps hold the food while lingual cusps grind it; not as long as canines; can have 2 or 3 cusps

molars

designed to chew or grind food; cusps are designed to interlock the upper and lower to form a crushing mechanism; max differ from mand; can have 4 or 5 cusps

tubercles

small elevations of enamel on some portion of the crown of the tooth; doesn’t always occur on lingual surface but can occur on an area like labial or occlusal surface

fossa

depression or concavity on a tooth

cingulum

lingual lobe of max anterior teeth

pits

small pinpoint hole anywhere in enamel; usually occur along the developmental grooves or in the fossae

cusps

mound on crown of tooth that makes up major division of its occlusal surface

ridge

elevated portion of a tooth that runs in a line; all cusps have 4

marginal ridges

rounded borders of enamel forming the mesial and distal shoulders of occlusal surfaces of posterior teeth and the mesial and distal shoulders of the lingual surfaces of anterior teeth

triangular ridges

the main ridges on each cusp that run from the tip of the cusp to the central part of the occlusal surface

transverse ridges

union of 2 triangular ridges, a buccal and lingual that cross the occlusal surface of a posterior tooth

concavity

carved-out section of area, like a cave

convexity

opposite of concavity; bulging out

lingual fossa

separates the lingual lobe from the other 3 lobes

line angle

junction of 2 surfacess (distal meets buccal)

point angle

point where 3 surface meet (mesialingualincisal)