Know What

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Creating! DENTAL ANATOMY

Identify and differentiate between individual characteristics of all permanent teeth – including:

Lobes

Grooves

Cusps

Fossae

Define the following terms:

Marginal Ridge

Triangular Ridge

Transverse Ridge

Oblique Ridge

Fossa

Developmental Grooves

Spillway

Embrasure

Contacts

Objectives

Convex:

curving or bulging

outward

rounded outward

Concave:

curving inward like a

cave or the inside of a

spoon.

hollowed out

Terminology – Overview

Linear, convex elevations on the surfaces of the

crowns of all teeth. Ridges are named

according to their location or form.

There are several types of ridges:

marginal ridges

triangular ridges

transverse ridge

oblique ridge

cusp ridges

Terminology – Ridges

Triangular Ridges

Convex Linear ridges which descend from the CUSP

TIPS of posterior teeth toward the central groove

of the occlusal surface.

In cross section they are more or less triangular in

shape.

A union of 2 linear, triangular ridges that meet

at the central groove, in the form of the

lingual spillway, found at the mesial and distal

borders of the occlusal table of posterior

teeth.

Marginal Ridges

Marginal Ridges – Height

The height of the marginal ridges of adjacent

teeth should be at the same level (unless the

teeth are malpositioned)

Note how the central grooves are CONTINUOUS

TRANSVERSE RIDGES

A transverse ridge is a union of

2 triangular ridges that face each other;

and are parallel with the marginal ridges

on the occlusal table of a posterior tooth.

OBLIQUE RIDGES

An oblique ridge is a union of

2 triangular ridges that face each other;

and are oblique with the marginal ridges

on the occlusal table of a posterior tooth.

They are only found on the maxillary molars in an oblique direction from

the distobuccal to mesiolingual cusps.

Each CUSP has FOUR cusp

ridges. They extend

mesially, distally, facially,

and lingually from the

cusp tip.

In this picture, the

LINGUAL cusp ridge, which

extends toward the central

groove, is also a

triangular ridge.

CUSP RIDGES

A peak or pointed part and are present on the occlusal surfaces of posterior teeth and incisal edges of canines

Each include 4 cusp ridges

Canines = 1 cusp

Premolars = 2-3 cusps

Molars = 4-5 cusps (or more)

In the posterior teeth,

# enamel lobes = # of cusps.

Terminology – Cusps

Lobe — one of the

primary divisions of

a crown; all teeth

develop from four or

five lobes.

Lobes are usually

separated by readily

identifiable

developmental

grooves

TERMINOLOGY REVIEW - LOBES

Cusp tips are the initial site where enamel develops. As the enamel develops and spreads laterally, it touches enamel developing from other cusps. This junction forms a developmental groove.

TERMINOLOGY REVIEW– DEVELOPMENTAL

GROOVE

TERMINOLOGY REVIEW– CENTRAL

GROOVE

The central developmental groove of posterior teeth aligns

into a continuous valley dividing the teeth approximately in

half.

TERMINOLOGY REVIEW - SUPPLEMENTAL

GROOVE

• An auxiliary groove which branches from a primary

developmental groove.

Its location is not related to the junction of primary tooth parts,

and is normally not as deep as a developmental groove.

TERMINOLOGY REVIEW –

FOSSA/FOSSAE

• An irregular, depression or concavity, on the

occlusal table of a tooth.

• Premolars: normally have two: mesial & distal

• Molars: have three: mesial, distal, & central

central distal / mesial distal/mesial distal/central/mesial

TERMINOLOGY REVIEW – PIT

• A pit is the deepest portion of a fossa.

• A small depressed area where developmental

grooves/lobes often join or end.

Distal pit

TERMINOLOGY REVIEW – ADDITIONAL

TERMS

Contact Area

Embrasures

• Occlusal

• Gingival

• Buccal

• Lingual

TERMINOLOGY REVIEW – CONTACT

AREA

• The area on a proximal surface of the crown of a tooth

that contacts the adjacent tooth.

• The contacts appear lower on each tooth as you move

posteriorly.

TERMINOLOGY REVIEW -

EMBRASURES

The open space (negative space) between the proximal

surfaces of two adjacent teeth in the same arch.

There are four types: Buccal, Lingual, Occlusal

and Gingival

TERMINOLOGY REVIEW – INTERPROXIMAL

EMBRASURES

Viewed from the occlusal aspect.

There are buccal and lingual embrasure spaces.

TERMINOLOGY REVIEW - OCCLUSAL & GINGIVAL

EMBRASURES

• The space between the teeth as viewed from the direct

Buccal AND Lingual aspects.

Defined as: “The occlusal surfaces of the premolars and

molars; the basic collective topography, including the form of

the cusps, inclined planes, marginal ridges, and central

fossae and grooves of the teeth .” (Mosby’s Dental Dictionary)

It can also be said that the occlusal table is the perimeter of

the biting surface of the tooth where the mesial, distal,

facial/buccal and lingual surfaces meet the occlusal surface.

TERMINOLOGY – OCCLUSAL TABLE

INDIVIDUAL TOOTH ANATOMY

THE MAXILLARY ARCH

Molar crowns are wider buccolingually than mesiodistally.

Molar occlusal surfaces contain an oblique ridge and a distolingual groove that sets them apart from mandibular molars.

Molars, from the occlusal view, are rhomboidal or heart shaped where mandibular crowns are rectangular or pentagonal shaped.

MAXILLARY FIRST MOLARS

• The maxillary first molar is the largest tooth in

the maxillary arch; and has the largest crown of

all the teeth.

The buccal margin is divided into two (unequal, mesial is larger) parts by the concavity of the buccal groove

Buccal groove extends apically halfway to the cervical margin where it may end with a buccal pit;

or split into two slanting grooves which extend a short distance then fade out.

MAXILLARY FIRST MOLARS

MAXILLARY FIRST MOLARS

The occlusal-lingual view contains the

distolingual groove that separates the occlusal

margin into two distinctly unequal parts.

The lingual groove often ends in a pit, which is

very prone to caries.

MAXILLARY FIRST MOLARS

There are four major cusps and one minor cusp which is

the cusp of Carabelli.

The occlusal table includes the oblique ridge due to its

height.

MAXILLARY FIRST MOLARS

• Oblique ridge: The oblique ridge is created by the union

of the distal cusp ridge of the mesiolingual cusp and the

lingual cusp ridge of the distobuccal cusp.

MAXILLARY FIRST MOLARS

• Transverse ridge: The lingual cusp ridge of the

mesiolingual cusp and lingual cusp ridge of the

mesiobuccal cusp form a transverse ridge.

MAXILLARY FIRST MOLARS

• Marginal ridges: The mesial marginal ridge is longer

and more pronounced than the distal marginal ridge.

D M

MAXILLARY FIRST MOLARS –

FOSSAE

• Central fossa: The central fossa is located

mesial to the oblique ridge in the central portion

of the occlusal surface. The central fossa is

always the largest and deepest of the fossae.

Distal fossa: Is divided into

two parts: the (1) distal

fossa and the (2) distal

triangular fossa :

(1) The distal fossa is

located distal and parallel to

the oblique ridge.

The distal triangular fossa

is located mesial to the distal

marginal ridge and is

continuous with the distal

fossa.

MAXILLARY FIRST MOLARS –

FOSSAE

Mesial fossa: The

mesial fossa is

located distal to the

mesial marginal ridge.

MAXILLARY FIRST MOLARS –

FOSSAE

Central Groove:

The central groove

extends in a

mesiodistal direction

connecting the

mesial, central and

distal pits.

MAXILLARY FIRST MOLARS –

GROOVES

Spillways are grooves that extend over the marginal ridge.

Each marginal ridge has its corresponding spillway located slightly lingual of center

Their function is to drive food lingually to the tongue.

MAXILLARY FIRST MOLARS –

SPILLWAYS

MAXILLARY SECOND MOLARS

• This tooth closely resembles the first molar

except for the following differences: • There is (usually) no cusp of Carabelli

• The distolingual cusp and oblique ridge are also smaller then

that of the first molar.

THE MANDIBULAR ARCH

• Crowns are wider mesiodistally than

buccolingually

• Mandibular molars have two lingual cusps of

approximately the same size with 2 to 3 buccal

cusps.

MANDIBULAR FIRST MOLARS

• The first mandibular molar is the largest and strongest

tooth in the lower arch.

• It normally has five cusps.

• The crown is wider mesiodistally then any other tooth in

the mouth, with the buccal lateral surface being the

largest.

#30 #19

MANDIBULAR FIRST MOLARS

• The buccal surface is divided into three parts by

two grooves. The mesiobuccal groove and the

distobuccal groove.

• These three parts decrease in size from mesial to distal.

MANDIBULAR FIRST MOLARS

• The mesial buccal groove extends from the central pit

buccally onto the buccal surface where it travels in a

straight line to a point midway between the gingival and

occlusal margins ending in a buccal pit.

MANDIBULAR FIRST MOLARS

• The distobuccal groove extends in a distobuccal

direction from the central pit onto the buccal surface.

• The distobuccal groove also extends straight cervically

and usually ends in a pit.

MANDIBULAR FIRST MOLARS

• The lingual groove extends from

the central pit on the occlusal

surface onto the lingual surface

slightly to the distal of center,

dividing the lingual surface into two

parts.

• It extends cervically, and

terminates in the occlusal third

near its junction with the middle

third.

MANDIBULAR FIRST MOLARS: “CHAIR

TEETH”

• The central groove takes a “jog” where the distal cusp’s

triangular ridge crosses over the central groove to the

lingual.

Also note: the buccal groove and lingual groove DO NOT

LINE UP ON THE OCCLUSAL! They form a “chair”

shape at the central groove.

MANDIBULAR FIRST MOLARS

Cusps: There are normally five cusps, with the mesiobuccal

cusp being the largest and the distal buccal cusp being the

smallest.

MANDIBULAR FIRST MOLARS

Transverse ridges: There are

NO TRANSVERSE RIDGES

on mandibular first molars.

MANDIBULAR SECOND MOLARS

• The second molar has only four cusps which are

almost equal in size.

• The buccal groove divides the buccal surface into two

almost equal parts and the lingual groove does the same

for the lingual surface.

MANDIBULAR SECOND MOLARS

• The central groove forms almost a straight line through

the center of the occlusal surface.

• The intersection of the central groove with the buccal

and lingual groove forms the central fossa.

• The central pit is the deepest, with the mesial and distal

pits being of equal depth but shallower than the central.

MANDIBULAR SECOND MOLARS

Two transverse ridges are formed by the union of the

lingual triangular ridges with the buccal triangular ridges.

MANDIBULAR SECOND MOLARS

Mandibular second molars are “Double K” teeth

MAXILLARY PREMOLARS

Maxillary first and second premolars are more similar to each

other than the mandibular premolars, with 2 nearly equal

sized cusps.

2nd 1st

The maxillary first premolar is slightly larger than the second

premolar;

The crowns of maxillary premolars are normally wider

buccolingually than mesiodistally

MAXILLARY FIRST PREMOLARS

• There are two cusps; one buccal and one lingual. The

buccal cusp tip is wider and higher than the lingual cusp

tip.

• The buccal and lingual triangular ridges of the tooth meet

in the central groove forming a transverse ridge.

The mesial marginal

ridge is normally

slightly shorter than

the distal ridge.

MAXILLARY SECOND PREMOLARS

• The second premolar closely resembles the first

premolar except for the following:

• The crown is smaller

• The buccal cusp is rounder

• The buccal and lingual cusps are of almost equal height.

• The central groove is shorter and more irregular.

• The mesial and distal pits are located closer to each

other and more toward the middle of the tooth.

MANDIBULAR PREMOLARS

• The mandibular premolars are about same size

buccolingually and mesiodistally.

1st 2nd (2-cusp) 1st 2nd (3-cusp)

• The mandibular premolars may have more than

two cusps, and the lingual cusps are smaller

than the facial cusps.

MANDIBULAR FIRST PREMOLARS

The mandibular first premolars are closer in form

and function to the CANINE than the second

premolar.

There are two cusps, one buccal and one lingual

with the buccal being much larger.

MANDIBULAR FIRST PREMOLARS

• The buccal and lingual triangular ridges

meet in the central groove to form a

transverse ridge.

• The buccal triangular ridge is larger and

longer than the lingual ridge.

MANDIBULAR SECOND PREMOLARS: “Y-

TYPE”

The three cusp type has a mesiolingual and a distolingual cusp.

Between the two lingual cusps is a lingual groove that extends a short distance onto the lingual surface.

The mesiolingual cusp is wider and longer while the distolingual cusp is smaller.

The main groove pattern takes on

the form of a Y and is named

the Y type.

This is the most common form for the second premolar.

MANDIBULAR 2ND PREMOLARS: “H - OR U-

TYPE”

• The two cusp type has a single lingual cusp with no lingual groove.

• The lingual cusp is directly opposite the buccal cusp forming a

transverse ridge.

• The main groove pattern on the two cusp type resembles an H or U

resulting in H - type and U - type second premolars.

least common type.

QUESTIONS?