Oral Ana Part 2: Parts of the tooth and its supporting structures

enamel
dentin
coronal pulp

• Crown

cementum
dentin
radicular pulp

• Root

periodontium
gingiva
periodontal ligaments
alveolar bone

• Supporting structures

• collectively known as the _______

crown
root
supporting structures

• what are the parts of the tooth (clinically)

enamel

• hardest, outermost layer of the tooth

• strongest tissue in the human body
  
  

• Composition: - 95% HYDROXYAPATITE - crystalline structure made of calcium and phosphate - 4% water - Organic material

• Function: - Protection - shield from external forces and acids - Insulation - prevent sensitivity to hot and cold temperature changes - Appearance - translucence, contributes to overall color

dentin

• hard, mineralized connective tissue that forms the bulk of the tooth
  location: - under the enamel of the crown and the cementum of the root sandia ‘26
  Composition: - 70% inorganic material, CRYSTALLINE HYDROXYAPATITE - 20% organic material, Type I collagen fibers and non-collagenous proteins - 10% water
  Function: - Protection - protect the pulp from external stimuli - Support - supports the harder enamel layer - Flexibility - absorbs impact of chewing and prevent enamel from fracturing

cementum

• histologically and chemically similar to bone; nourished by the periodontal ligaments
  
  Location: - Acellular cementum - cervical (neck) of the root - Cellular cementum - apical (tip) end of root; thicker
  
  Composition: - 65% inorganic material, mainly HYDROXYAPATITE CRYSTALS and trace elements - 35% organic material, primarily collagen fibers and water
  
  Function: - anchors the tooth to the jaw bone provide stability and support during tooth function

dental pulp

• soft, inner connective tissue containing blood vessels, nerves, and specialized cells

gingiva

• pink-colored, keratinized mucosal tissue that surrounds and protects the teeth

periodontal ligaments

• dense, fibrous, specialized connective tissue which supports and attaches the tooth to the alveolar bone

alveolar crest fibers

• Originate from the cervical part of the root and run coronally to the alveolar bone crest

horizontal fibers

• attached apical to the alveolar crest fibers; run perpendicular to the root connecting to the bone

oblique fibers

• most numerous; run from cementum in oblique direction, inserting coronally into the bone

apical fibers

• radiate from the cementum around the apex of the root, forming the base of the socket

interradicular fibers

• found only between the roots of multi-rooted teeth

transeptal fibers

• interdental ligament; run from cementum of one tooth to the cementum of adjacent tooth at the interdental area

interradicular group
alveolar crest
apical fibers
horizontal group
oblique group
transeptal

• what are the principle fibres of PDL
  Mnemonics “I am HOT"

alveolar bone

• specialized bone tissue of the jaw; dual structure of cortical and cancellous bone layers

• not static, continuously remodeled and adapts to the forces exerted on the teeth during function.

labial surface

• side that faces the lip, anterior teeth

buccal surface

• side that faces the cheeks, posterior teeth

lingual surface

• surface towards the tongue

occlusal surface

• chewing or biting surface of posterior teth

incisal surface

• incisal edge or cutting edge of anterior teeth for cutting and biting

proximal or proximate surface

• side surface adjacent to another tooth in the same dental arc

mesial

• surface towards the midline

distal

• surface away from the midline

contact area

• specific part of the proximal surface where two adjacent teeth touch each other

labial surface
buccal surface
lingual surface
occlusal surface
incisal surface
proximal or proximate surface
mesial surface
distal surface
contact area

• what are the surfaces of the teeth

cusp

• rounded or pointed projection on occlusal or incisal surface

• found in molars, premolars (bicuspid) and canine (cuspid)

• designed to stamp into the grooves of opposing teeth

• susceptible to wear and fractures over time

tubercle

• small, rounded prominence on the crown of a tooth formed by extra enamel deposits

• accessory cusp, i.e. cusp of carabelli; variable in size and occurence

• distinct extra formation or enamel, similar to a cusp but smaller

cingulum

• small, rounded ridge or convexity on the lingual surface of the crown of anterior teeth near the gum line (cervical third)

• represents the lingual developmental lobe

marginal ridge

• rounded, raised edges of enamel

• mesial and distal borders of occlusal surface of posterior teeth

• lingual surfaces of anterior teeth

triangular ridge

• raised, linear elevation of enamel on the occlusal surface of posterior teeth

• descends from tip of a cusp towards center of tooth, resembling two slopes of a triangle

transverse ridge

• union of two triangular ridges

• runs from buccal to lingual side; provides tooth with increased strength and stability

oblique ridge

• raised, slanting ridge of enamel on the occlusal surface of permanent Mx molars

• connects the ML cusp to the DB cusp

• increase mastication area and distribute forces evenly

marginal ridge
triangular ridge
transverse ridge
oblique ridge

• what are the 4 types of ridges

fossa

• Irregular depression or concavity on the surface of a tooth

lingual

• large, shallow depression on lingual/palatal surface of anterior teeth

central

• found in the center of occlusal surface of posterior teeth

triangular

• located mesially or distally to the marginal ridges on occlusal of posterior teeth

lingual
central
triangular

• what are the 3 types of fossa

sulcus

• long, narrow depression on the occlusal surface of posterior teeth

developmental groove

• shallow, linear depression; fusion of the developmental lobes

• serves as anatomical landmarks

• increase risk for caries and periodontal disease

supplemental groove

• minor, shallow, linear depressoin; auxilliary to a more prominent developmental groove

• located on various surfaces of the tooth

• can provide additional retention and stability to restorations

pits

• small, pinpoint depressions on occlusal surfaces of molars and premolars and lingual surfaces of maxillary CI and LI; convergence of developmental grooves

central pit

• central fossa of posterior teethl; where multiple developmental grooves intersect

triangular pit

• deepest part of the triangular fossa; where developmental grooves meets the marginal ridge

buccal and lingual pit

• where grooves on the buccal or lingual terminate

central pit
triangular pit
buccal and lingual pit

• what are the 3 types of pits

lobes

• primary sections of the crown during formation

• - Anterior teeth - four lobes - - - - - - - - -

• Labial lobes - mesiofacial, centrofacial, and distofacial lobes

• Lingual lobe - cingulum

• Premolars - four or five lobes

• First premolars - four lobes

• Mandibular second premolars - five

• lobes; two lingual lobes

• Mx Molars - four or five lobes

• Mx 1 molar - five lobes; major and minor buccal cusps, two lingual cusps and supplemental cusp (cusp of Carabelli)

• Mx 2 and 3 molars - four lobes; fewer, less developed cusps

• Md molars - five lobes

mamelons

• rounded eminences on the incisal ridge of unworn incisors

• formed by the incisal termination of labial lobes