Morphology of the anatomic crown Flashcards
What are bumps and ridges on the crown classified as?
Elevations
What are depressions and grooves on the crown classified as?
Depressions
What are the types of elecations seen on a crown’s surface?
Cusps (elevation on chewing surface of the coronal portion of a tooth denoting a development, a calcified lobe)
Cingulum
Ridges
Tubercles
What is a cusp?
A pointed or rounded elevation of enamel found on cuspids and on the chewing surfaces of pre-molars and molars.
How many cusps do each teeth have?
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.
How many cusps does the mandibular second bicuspid have?
3 cusps 1 buccal and 2 lingual.
What is a lobe?
One of the primary anatomical divisions of a crown.
How are lobes of the teeth separated?
Lobes are usually identifiable because they are separated by developmental grooves.
How many lobes are canines and premolars developed from?
4 lobes; 3 facial and 1 lingual
How many lobes does the mandibular first molar have?
5 lobes
How many lobes do maxillary third molars typically have?
Some have as few as 3 lobes
What is a cingulum?
The lingual lobe of an anterior tooth (incisors and canines) makes up the bulk of the cervical third of the lingual surface
What are cusp ridges?
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)
What are marginal ridges?
Linear elevated rounded borders of enamel which forms margins of occlusal surfaces of premolars and molars mesially and distally.
What is a triangular ridge?
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
What is a transverse ridge?
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
What is the oblique ridge?
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
What is the lingual ridge?
Ridge of enamel that extends from the cingulum to the cusp tip of the lingual surface of most cuspids
What is the labial ridge?
Ridge running cervico-incisally in approximately the center of the labial surface of the canines.
What is the buccal ridge?
Ridge running cervico-occlusally in approximately the center of the buccal surface of premolars.
What is the cervical ridge?
Ridge running mesiodistally on the cervical one third of the buccal surface of all permanent molars
What are tubercles?
Small elevations present on some parts of the coronal tooth enamel. Produced by excessive growth of enamel only
What are the 2 types of tubercles?
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
What are the types of depressions that can be seen on teeth?
Sulcus
Grooves
Fissures
Fossa
Pits
What is a tooth sulcus?
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.
What are developmental grooves?
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.
What are the supplementary grooves?
Small shallow linear depressions irregularly placed, less distinct, and not at the junction between primary lobes.
What are the triangular grooves?
Separate a marginal ridge from a triangular ridge; their terminations form the triangular fossa.
What is the central groove?
Groove that generally travels mesiodistally and separates occlusal table into buccal and lingual halves.
What is a fissure?
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.
What is a fossa?
A fossa is an irregular small rounded Depression or concavity found on the
surface of a crown
How are fossae formed?
Usually by a complete union between 3 enamel lobes
What are the types of fossae?
Lingual fossae
Central fossae
Triangular fossae
Where is the lingual of the maxillary incisor located?
Found on the lingual surface of incisors particularly maxillary incisors
Where is the central fossa located?
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
Where is the triangular fossa located?
Found on the occlusal surface of molars and premolars mesial or diistal to the marginal ridge.
What are pits?
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
