Morphology of the anatomic crown

Question 1

What are bumps and ridges on the crown classified as?

Answer 1

Elevations

Question 2

What are depressions and grooves on the crown classified as?

Answer 2

Depressions

Question 3

What are the types of elecations seen on a crown’s surface?

Answer 3

Cusps (elevation on chewing surface of the coronal portion of a tooth denoting a development, a calcified lobe)

Cingulum

Ridges

Tubercles

Question 4

What is a cusp?

Answer 4

A pointed or rounded elevation of enamel found on cuspids and on the chewing surfaces of pre-molars and molars.

Question 5

How many cusps do each teeth have?

Answer 5

Canines are also known as buspids and have 1 cusp.

Maxillary pre-molars and the mandibular first premolar have 2 cusps 1 buccal and 1 lingual.

Mandibular second pre-molar normally has 3 cusps, 1 buccal and 2 lingual.

The lingual cusps are subdivided into a mesiolingual and a distolingual.

Question 6

How many cusps does the mandibular second bicuspid have?

Answer 6

3 cusps 1 buccal and 2 lingual.

Question 7

What is a lobe?

Answer 7

One of the primary anatomical divisions of a crown.

Question 8

How are lobes of the teeth separated?

Answer 8

Lobes are usually identifiable because they are separated by developmental grooves.

Question 9

How many lobes are canines and premolars developed from?

Answer 9

4 lobes; 3 facial and 1 lingual

Question 10

How many lobes does the mandibular first molar have?

Answer 10

5 lobes

Question 11

How many lobes do maxillary third molars typically have?

Answer 11

Some have as few as 3 lobes

Question 12

What is a cingulum?

Answer 12

The lingual lobe of an anterior tooth (incisors and canines) makes up the bulk of the cervical third of the lingual surface

Question 13

What are cusp ridges?

Answer 13

Any linear elevation on the surface of a tooth. It is named according to its location and form (buccal ridge, incisal ridge, marginal ridge, etc)

Question 14

What are marginal ridges?

Answer 14

Linear elevated rounded borders of enamel which forms margins of occlusal surfaces of premolars and molars mesially and distally.

Question 15

What is a triangular ridge?

Answer 15

Those ridges which descend from the tips of the cusps of molars and premolars towards the central part of occlusal surfaces.

They are named after the cusp to which they belong

Question 16

What is a transverse ridge?

Answer 16

When a buccal and a lingual triangular ridge join they form a transverse ridge.

The union of 2 triangular ridges facing each other and crossing transversely the occlusal surface of posterior teeth

Question 17

What is the oblique ridge?

Answer 17

It is found on maxillary molars, especially the maxillary first molar.

It is formed by the union of triangular ridge of the mesiopalatal cusp that crosses the occlusal surface obliquely and the disto-buccal cusp

Question 18

What is the lingual ridge?

Answer 18

Ridge of enamel that extends from the cingulum to the cusp tip of the lingual surface of most cuspids

Question 19

What is the labial ridge?

Answer 19

Ridge running cervico-incisally in approximately the center of the labial surface of the canines.

Question 20

What is the buccal ridge?

Answer 20

Ridge running cervico-occlusally in approximately the center of the buccal surface of premolars.

Question 21

What is the cervical ridge?

Answer 21

Ridge running mesiodistally on the cervical one third of the buccal surface of all permanent molars

Question 22

What are tubercles?

Answer 22

Small elevations present on some parts of the coronal tooth enamel. Produced by excessive growth of enamel only

Question 23

What are the 2 types of tubercles?

Answer 23

Mamelons: 1 of 3 tubercles sometimes present on the incisal edge of an incisor tooth that has not been subjected to wear.

The tubercle of carabelli which is a smaller occasional cusp or susplet which is sometimes attached to the palatal surface of the mesio-lingual cusp

Question 24

What are the types of depressions that can be seen on teeth?

Answer 24

Sulcus

Grooves

Fissures

Fossa

Pits

Question 25

What is a tooth sulcus?

Answer 25

The tooth sulcus is a long and broad depression of valley on the occlusal surface of posterior teeth between ridges and cusps, the inclines of which meet in a developmental groove.

Question 26

What are developmental grooves?

Answer 26

Considered as long or short, narrow “V” shaped linear depressions, separating the normal developmental cusps, denoting evidence of merging between primary lobes of the crown.

Question 27

What are the supplementary grooves?

Answer 27

Small shallow linear depressions irregularly placed, less distinct, and not at the junction between primary lobes.

Question 28

What are the triangular grooves?

Answer 28

Separate a marginal ridge from a triangular ridge; their terminations form the triangular fossa.

Question 29

What is the central groove?

Answer 29

Groove that generally travels mesiodistally and separates occlusal table into buccal and lingual halves.

Question 30

What is a fissure?

Answer 30

A very narrow linear cleft or crevice at the depth of any groove caused by the incomplete fusion of enamel during tooth development.

Decay often begins in the deepest parts of these fissures.

Question 31

What is a fossa?

Answer 31

A fossa is an irregular small rounded Depression or concavity found on the
surface of a crown

Question 32

How are fossae formed?

Answer 32

Usually by a complete union between 3 enamel lobes

Question 33

What are the types of fossae?

Answer 33

Lingual fossae

Central fossae

Triangular fossae

Question 34

Where is the lingual of the maxillary incisor located?

Answer 34

Found on the lingual surface of incisors particularly maxillary incisors

Question 35

Where is the central fossa located?

Answer 35

Found on the occlusal surface of molars. Formed by the approach of the ridges in the direction of each other and terminating at the central point in the bottom of the depression

Question 36

Where is the triangular fossa located?

Answer 36

Found on the occlusal surface of molars and premolars mesial or diistal to the marginal ridge.

Question 37

What are pits?

Answer 37

Small pinpoint depressions located at the junction of developmental grooves or at terminals of those grooves

They are abnormal due to failure to complete union between 3 enamel lobes