Tooth Morphology - Chapter 1; Part 4

Dr. Rooban Thavarajah


Landmarks

• Cusp is an elevation on the crown portion

making up a occlusal part

• Tubercle: Small elevation of enamel

• Cingulum: Lingual lobe of anterior teeth

• Ridges: Elevated portion of tooth in a line

named for their location

– Marginal / Triangular / Transverse/ Oblique


Cusps

Marginal ridge

Triangular ridge

Transverse ridge

Oblique ridge


• Marginal Ridge: Ridge or elevation of enamel forming the margin of the surface of a tooth; specifically, mesial &distal of occlusal surfaces posterior teeth & mesial /distal margins of lingual surfaces anterior teeth


• Triangular Ridges: Main ridges on each cusp that run from the tip of the cusp to the central part of the occlusal surface

• Transverse Ridge: Union of 2 triangular ridges that cross the posterior surface of a tooth

• Oblique Ridge: ML –DB cusp max molars


• Developmental grooves: Shallow grooves that separate cusps or primary parts of teeth

• Fossa: Depression or concavity– Lingual / central / triangular

• Pit: small pinpoint depression found in fossa

• Sulcus: Long depression



Contact areas, embrasures


Proximal Contacts

Mesial or Distal – Where one tooth touches another – Prevents food from packing between them – Prevents buildup of excessive bacteria, food

or debris – Affords protection to the gum tissue – Offer support and anchorage to one another


Inter proximal Spaces

Triangular-shaped spaces between teeth, formed by the bone on one side and the proximal surfaces and their contact area on the other side. – Normally filled with gingival tissue

• Papillary gingiva • Inter dental papilla


Embrasures

• Open space

• Spillways

• Named for their location – Names:

• Facial (buccal or labial) • Lingual • Incisal or occlusal • Gingival/Cervical (if inter proximal space not

occupied by tissue or bone)


Embrasures

Function – Allow food to be forced away from contact

areas – Reduce the forces of occlusal forces – Self-cleansing – Permit a slight amount of stimulation to the

gingiva


Facial view Contact areas • Anterior teeth

– Contact areas: close incisal third

– Except Distal of Canine -middle third

• Occlusal / Incisal view Contact areas – Anterior teeth

• Contact areas in the center from a facial to lingual direction


Posterior teeth • Contacts: more facially • Middle to Cervical third • Slightly buccal to the

center • Lingual embrasure usually

larger


Height of contour

• Imaginary curved line encircling a tooth at its greatest bulge

• Afford correct amount of frictional massage to gingiva

• Cleansing mechanism • General rule:

– Contour will vary from tooth to tooth – Height of contour for both anterior and posterior

teeth is in the cervical third – Except lingual crest of curvature of posterior teeth

which is near the middle third

END OF UNIT


Education

Tooth Morphology - Chapter 1; Part 4