Topic 9.1: Dental Anatomy

How does the Maxillary Central Incisor develope?

1. The initial calcification occurs at 3-4 months

2. The crown is completed at 4-5 years of age

3. The crown errupts in the age of 7-8

4. The root is completed with 10 years of age.

How is the facial anatomy of the Maxillary central incisor?

Flat facial surface

The incisal edge is relatively straight.

The distoincisal angle is curved while the mesioincisal edge is flat.

The root is very big and makes up 2/3 of the tooth.

The crown length (10.5mm) is greater than crown width (8.5mm).

How is the root shaped and how many root canals does the maxillary central incisor have?

Outline of the root is cone shaped and located slightly distal to center line of tooth.

It has one root canal

How is the palatal anatomy of the maxillary central incisor?

• Cervical outline on palatal is more concave than on facial.

• The cingulum occupies the cervical half of the crown. It has distal and mesial marignal ridges

• The Lingual fossa in incisal ½ of crown surface

• Mesial and distal marginal ridges

How is the palatal anatomy of the maxillary central incisor?

• Cervical outline on palatal is more concave than on facial.

• The cingulum occupies the cervical half of the crown. It has distal and mesial marignal ridges

• The Lingual fossa in incisal ½ of crown surface

• Mesial and distal marginal ridges

How is the incisal anatomy of the maxillary central incisor?

• Mesiodistal width is greater than the faciolingual diameter.

• Incisal ridge is perpendicular to mesiodistalbisecting plane.

• Crest of cingulum is slightly distal to the bisecting plane of crown

• Incisal ridge is straight

How does the Maxillary lateral incisor develope?

1. The initial calcification occurs at 1 year of Age.

2. The crown is completed after 4-5 years of age.

3. The crown erupts at 8-9 years of age.

4. The root is completed after 11 years of age.

How is the Facial Anatomy of the Maxillary Lateral Incisor?

Crown outline is trapezoidal

Convex in all directions

Incisal edge more rounded than central

Cervical line is elliptical

What are the differences of the Facial of the Lateral to the Central Maxillary incisor?

• Both mesio- and distoincisal angles of the crown are rounded, but the distoincisal angle is more.

• The cementoenamel junction is more rounded then the one of the central incisor.

• The incisal edge is relatively more rounded and not straight.

• It is smaller and narrower than the central incisor.

• Has more distinct lingual anatomy

How is the lingual anatomy of the lateral maxillary incisor?

• Cingulum limited to cervical third of crown

• Mesial and distal marginal ridges form a V

• The lingual fossa is relatively deep and has a triangular shape.

• It has a Lingogingival groove at distal side of cingulum that may even extend across the cementoenamel junction onto the root (only in lateral)

How is the root of the Lateral maxillary incisor?

• Root is conical and straight.

• The root length is generally same or can be longer as the central.

How is the mesial and distal anatomy of the Maxillary lateral incisor?

Facial crown outline is convex and lingual is slightly concave.

Incisal ridge in line with mid point of faciolingual diameter.

Apex of root is facial to faciolingual long axis bisector.

Incisal Anatomy of Maxillary lateral incisor

Crown is wider mesiodistally by only 1mm and crown converges sharply toward the lingual surface. Incisal edge is converged.

How does the Maxillary Canine develop?

1. The initial calcification occurs with 4-5 months

2. The completion of the crown occurs from 6-7 years

3. The crown errupts in the ages of 11-12

4. The root is completed in the age of 13-15

How is the Facial Anatomy of the Maxillary Canine?

• Has a asymmetrical anatomy in which the distal portion is bigger and has a bigger ridge

• Mesial cuspal ridge shorter than distal cuspal ridge

• Pentagonal crown shape

• Canines have a cusp

• Is the widest of all anterior teeth (8mm)

How is the Palatal/Lingual anatomy of the maxillary canine?

• Cingulum is smooth and well developed and occupies the cervical third of lingual surface

• It has 2 lingual fossas: mesiolingual and distolingual and 1 lingual ridge that separates both fossas and connects the cusp tip and the cingulum

• The crest of the lingual ridge curves slightly to mesial on mesiodistal long axis bisector which makes the distolingual fossa larger than the mesiolingual.

How is the mesio/distal anatomy of the maxillary canine?

• Triangular outline and smoothly convex

• Cusp tip is never linugal and usually slightly facial to faciolingual axis bisector

• convex cingulum and crest of lingual ridge slightly concave

How is the incisal anatomy of the maxillary canine?

• Distal side is longer and mesial is shorter and rounder

• Longer faciolingually than mesiodistally

How is the chronology of the first maxillary premolar?

• The initial calcification occurs after 18-21 months of age

• The completion of the crown takes place after 5-6 years of age

• The crown erupts after 10-11 years

• The root is completed after 12-13 years

How is the facial anatomy of the first maxillary premolar?

• Cusp tip is relatively pointed and slightly distal on mesiodistal long axis bisector

• Mesial cuspal ridge of facial cusp longer than distal

• Facial ridge running along axially from facial cusp

How is the lingual anatomy of the first maxillary premolar?

• entire tooth converges towards the lingual

• Lingual cusp shorter than the facial cusp

• The lingual cusp tip is slightly mesial to the mesiodistal long axis bisector

• Both lingual cusps of premolars swing to mesial aspect

How is the mesial/distal anatomy of the first maxillary premolar?

• Mesial marginal development groove on mesial surface

• Distal aspect does not have a groove

How is the occlusal anatomy of the maxillary first premolar?

• Has two major cusps: facial and lingual

• the linugal cusp is 1mm shorter

• Faciolingually wider than mesiodistally (2mm)

• Mesial cuspal ridge of facial cups islonger than distal

• cusp tip of facial cusp is positioned distal to mesiodistal bisector

• central groove connects mesial and distal triangular fossae and extends over mesial margina

How is the root of the maxillary first premolar?

• 2 roots: facial and lingual

• At least 2 root canals and if there is a third, it will be in the facial root

• Rarely single root with 2 canals

How is the chronology of the maxillary second premolar?

1. The initial calcification occurs after 24 months

2. Completion of crown 6-7 years of age

3. The tooth erupts after 10-12 years of age

4. The root is completed after 12-14 years

How is the facial anatomy of the maxillary second premolar?

Facial anaromy

• Pentagonal shape

• 2 cusps: facial and lingual with nearly equal size

• Distal cuspal ridge longer than distal

• Facial ridge not as prominent as that of the maxillary 1st premolar

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How is the Root of the maxillary second premolar?

• Root length longer

• Typically has one root with 2 pulp canals

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How is the lingual anatomy of the maxillary second permolar?

• Outline of both cusps visible

• Both cusps are in line

• Lingual cusp little rounder than facial

How is the occlusal anatomy of the maxillary second premolar?

• Cusp tips in line with each other and slighty mesial to the mesiodistal bisector

• Line angles more rounded and balanced look

• mesial and distal irregular triangular fossae near the center

• Several supplemental grooves

• Central groove smaller than of the first premolar

How is the chronology of the maxillary first molar?

1. The initial calcification of the maxillary first molar occurs at birth

2. The crown is completed during the 3-4 years of age

3. The crown erupts in the of 6

4. The root is completed after 9-10 years

How is the facial anatomy of the maxillary first molar?

• The crown has a trapezoidal outline

• Facial groove that extends occlusocervically between the mesiofacial and distofacial cusps to middle of facial surface

• Facial cusps more pointed and taller than lingual

• Mesial cusps taller than distal

How is the root of the maxillary first molar?

• Three roots with 3-4 root canals and root depressions

• Lingual root longest then mesiofacial and then distofacial

• Mesiofacial root has 50% probability of having 2 root canals

How is the lingual anatomy of the maxillary first molar?

• Only lingual cusps visible

• Mesiolingual cusp is the largest and the mesiodistal the widest

• Lingual groove begins at lingual border as an extension of distal oblique groove

• Fifth (carabellis) cusp is located on the lingual aspect of the mesiolingual cusp

• cuspal edges parallel to and about 2mm cervical to the occlusal outline of mesiolingual cusp

How is the mesial anatomy of the maxillary first molar?

• carabellis cusp is visible

• mesiofacial root covers the distofacial root

How is the distal anatomy of the maxillary first molar?

Distofacial root is the smallest

How is the occlusal anatomy of the maxillary first molar?

• 4 well developed cusps and 1 carabellis cusp

• Wider faciolingually than mesiodistally (1mm)

• Crown wider mesially than distally and wider lingually than facially

• Cusp sizes →: ML, MF, DF, DL,CB

• Oblique ridge from ML to DF cusp that is produced by the meeting of the triangular ridge of distofacial cusp and distal cuspal ridge of mesiolingual cusp

• Sometimes there is also a transverse groove of the oblique ridge that crosses it from central to distal fossae

How is the chronology of the maxillary second molar?

• The initial calcification occurs at 3 years of age

• The crown is completed with 7-8 years of age

• The crown erupts in the age of 12 years

• The root is completed after 14-16 years

How is the root of the maxillary second molar?

• 3 roots: L → MF → DF

• 3-4 Root canals

• Less divergent than 1st molar

• Limited depressions

How is the facial anatomy of the maxillary second molar?

• Facial cusps are smaller in height than first molar

• Distofacial cusp shorter than the mesiofaciak cusp

• Facial groove is shorter

• Mesiofacial and distofacial roots visible

How is the lingual anatomy of the maxillary second molar?

• Mesiolingual cusp is more nearly centered and bigger and more developed than the distolingual cusp

• Single lingual root visible

• Very rarely 5th cusp

How is the distal anatomy of the maxillary second molar?

• More of occlusal anatomy visible

• Distofacial smaller than mesiofacial

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How is the occlusal anatomy of the maxillary second molar?

• similar occlusal anatomy to the maxillary 1st molar

• Msdt diameter smaller (1 mm)

• Distal cusps are smaller

• Usually has more secondary grooves.

• Wider faciolingually than mesiodistally.

• no carabellis