Lecture 8 dental anatomy dr. Sattar Hmadat

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Lecture 8 DENTAL ANATOMY Dr.Sattar Hmadat

Mandibular Second Molar
Principal Identifying Features

1- It is smaller than the first molar in all dimensions.

2- It has four well-developed cusps; two buccal and two lingual of nearly

equal size.

3- There is no distal cusp but the distobuccal cusp is larger than that of

the first molar.

4-It has two roots; one mesial and one distal. They are broad bucco-

lingually, but they are not as broad as those of the first molar, nor are

they as widely separated.

Buccal Aspect

1- The crown is shorter cervico-occlusally and

narrower mesio-distally than that of the first molar.

2-There is only one developmental groove, the buccal

developmental groove, which separates between the

mesiobuccal and distobuccal cusps.

3- Both mesiobuccal and distobuccal cusps are nearly

equal in their mesio-distal measurements.

4-The cervical line in many instances points sharply

to the root bifurcation.

5-The roots are shorter than those of the first molar. They

are usually closer together and are parallel to each other. They are

inclined distally forming an acute angle with the occlusal plane than is

found on the first molar.

Lingual Aspect

1-The crown and the roots converge lingually but to a

slight degree, therefore:

    1. Little of the mesial and distal surfaces may be seen from this aspect.

    2. The mesiodistal dimension cervically is greater than that of the first molar.

2-The contact areas are more noticeable from this

aspect, and they are slightly more cervically

positioned than those of the first molar.

Mesial Aspect

1-The buccal cervical ridge is less pronounced

compared to the first molar.

2-The mesial root has a somewhat pointed apex.

Distal Aspect

From this aspect, this tooth is similar in form to the first molar except for the absence of a distal cusp and The contact area is centered on the distal surface bucco-lingually and is centered between the cervical line and the marginal ridge.

Occlusal Aspect

1- The occlusal surface is rectangular in shape.

2- The small distal cusp is not present and there is no distobuccal groove.

3-The buccal and lingual developmental grooves meet the central developmental groove at right angles at the central pit. These grooves form a cross, dividing the occlusal surface into four parts that are nearly equal.

4- Unlike the first molar, the occlusal surface is not smooth but is roughened

by many supplemental grooves radiating from the developmental grooves.

5- Many teeth show considerable prominence cervically on the mesiobuccal

lobe only.

6- The cusp ridge of the distobuccal cusp lies buccal to the cusp ridge of the

mesiobuccal cusp.

Mandibular Third Molar

Principal Identifying Features

1- This tooth varies considerably in different individuals and present

many anomalies both in form and position.

2- Generally, this tooth is more similar to the second molar regarding the

number of cusps and occlusal form than it does to the first molar. It has

a tendency for a more rounded occlusal outline and a smaller bucco-

lingual dimension distally.

3- The size of the tooth is variable; ranging from large teeth larger than

the second molar with five or more cusps to dwarfed (small) teeth.

4- Usually there are two short roots, one mesial and one distal. These are

usually shorter than the roots of the first or second molars with greater

tendency for distal inclination in relation to the occlusal plane.

Sometimes there are more than two roots or the roots may be fused.

5- The tooth could be congenitally missing.

Buccal Aspect

Lingual Aspect

Occlusal Aspect

Mesial Aspect Distal Aspect

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