Anatomical Landmarks Of The Crown 4d6aa

Anatomical Landmarks of the Crown Crown Elevations Lobes 

One of the primary centres of calcification and growth formed during the crown development.

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Each tooth begins to develop from 4 lobes or more.

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The pulp chamber has pulp horns corresponding to these lobes).

Types of Lobes 

Mamelones o

They three small round projections of enamel present in the incisal 1/3 of newly erupted incisors

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o

Ideal age to see = 6-7 years

o

Mamelones eventually wears down into a flat edge

Cingulum(cingula) o

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Enlargement or bulge on the cervical 1/3 of lingual surface of the crown in anterior teeth.

Cusps o

Pyramidal projections on the incisal portion of the canine and occlusal surfaces of the posterior teeth(premolars and molars)

Tubercles 

Small elevation due to excessive formation of enamel

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Tubercle of carabelli  found on the palatal surface of Upper E and 6 and sometimes lingual surfaces of incisors over the cingulum

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Tubercles are not cusps as it is formed of enamel only while cusp is formed of pulp horn covered by dentin and enamel  therefore tubercles are not primary centres of calcification

Ridges  It is a linear elevation on different surfaces of the crown 

Facial surfaces o

o

o

Labial ridge 

found on the labial surface of canines

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result of the overdevelopment of the middle labial lobe

Buccal ridge 

Found on the buccal surfaces of premolars

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Result of the overdevelopment of the middle buccal lobe

Cervical ridge 

Found on the cervical 1/3 of the facial surfaces of all teeth

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Lingual surfaces o

Incisal ridges – found on the incisal 1/3 of lingual surfaces of all incisors

o

Cusp ridges – found on the incisal 1/3 of lingual surfaces of canines and premolars

o

Lingual ridges – found on middle 1/3 of lingual surface of upper and lower canines.

o

Marginal ridges – found on the mesial and distal margins on the lingual surfaces of all anterior teeth

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Occlusal surfaces o

o

Marginal ridges 

Found on the occlusal surfaces of all posterior teeth

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mesial and distal to the triangular fossae

Triangular ridges 

o

Transverse Ridge 

o

Found on the occlusal surfaces of all posterior teeth forming cusps.

Formed from the extension of the triangular ridges of the buccal and lingual cusp

Oblique ridge 

Formed from the extension of the triangular ridges obliquely.

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Usually found on maxillary molars, connecting between ML and DB cusps.

Crown Depressions

Linear Depressions 

Developmental Grooves – linear depression denoting complete union/fusion of primary lobes

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Supplemental grooves – small irregularly placed auxiliary grooves that branches from developmental grooves. They do not represent the complete union/fusion of the lobes. They are found on the occlusal surfaces of 7’s, 8’s and lower 5’s

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Fissures – found on the bottom of developmental grooves result from incomplete union of the primary lobes. It is a fault in enamel. These can not be seen but can feel it.

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Sulcus – broad depression or valley on the occlusal surfaces of posterior teeth

Circumscribed Depressions 

Fossa – small depression or concavity found on both anterior and posterior teeth o

Lingual Fossa – found on the lingual surfaces of anterior teeth

o

Mesial and Distal Triangular Fossa – found on the occlusal surfaces of posterior teeth, mesial and distal to the marginal ridges

o

Central Fossa – found on the occlusal surfaces of molars. They are formed by the converging of ridges, terminating at a central point where there is the junction of grooves

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Pits o

o

True – small pinpoint depression present at the bottom of a fossa 

Central pit – found at the bottom of a central fossa

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Mesial and distal pits – found at the bottom of the mesial and distal triangular pits

Faulty – usually found at the end of the developmental groove and it’s the result of incomplete formation of enamel 

Buccal Pit – located at the end of the buccal developmental grooves or lower molars

Socket – the bony space in the alveolar bone containing the roots of erupted tooth Crypt – bony space in the alveolar bone containing the developing unerupted tooth