Dental Health Science 1

Permanent DentitionPermanent Molars

Prepared By: Dr. Eman Adnan

College of Dentistry University Of Sharjah

Mandibular Molars

Mandibular molars• The mandibular molars are larger than any

other mandibular teeth. • They are three in number on each side of the mandible ,the first, second, and third mandibular molars. • The first molar lies posterior to the second premolar, followed by the second and third molars. • They perform the major portion of the work of the lower jaw in mastication.

•• Each mandibular molar has two roots, one mesial and one distal. The third and some second molars may show a fusion of these roots.

Mandibular molars

1. Decrease in size, crowns & roots

2. Roots less divergent

3. More distal inclination

4.Cusp number5 cusps 4 cusps

4/5 cusps

Mandibular First Molar•

Measurements: Average length 21.5 mm• Crown length (CL) 7.5mm,• Root length 14 mm• Mesiodistal (MD) diameter 11mm • Buccal Aspect:

the mandibular first molar is the largest tooth in the mandibular arch.

• It has five well-developed cusps: two buccal, two lingual, and a distal cusp.

• It has two well-developed roots, one mesial and one distal. These roots are widely separated at the apices.

MD

Buccal Aspect:

• All five cusps can be seen; the tips of the lingual cusps can be seen because they are higher than the others.

• Two developmental grooves appear on the crown portion; the mesiobuccal developmental groove and the distobuccal developmental groove.

• The mesiobuccal, distobuccal, and distal cusps are relatively flat.

• The cervical line is commonly regular in outline.

MD

Mandibular First Molar• Lingual Aspect:

•Three cusps may be seen: two lingual cusps and the distal cusp. The lingual cusps are high enough to hide the buccal cusp. The lingual developmental groove is between the lingual cusps, extending on the lingual surface.

• The mesial outline of the crown is convex. The crest of contour is higher mesially than distally.

• The distal outline of the crown is straight.

• The cervical line lingually is irregular. The root bifurcation lingually starts at 4mm below the cervical line.

MD

Mesial Aspect:

• . Two cusps and the mesial root only are to be seen: the mesiobuccal and mesiolingual cusps and the mesial root.

• the entire crown has a lingual tilt in relation to the root axis.

• The buccal outline of the crown is convex; this curvature outlines the buccal cervical ridge. The cervical line may assume a straight line.

• The surface of the crown is convex.• The mesial root curve lingually.

B

Ling

Distal Aspect:

• We see more of the tooth than in the mesial aspect because there is a distal convergence of the tooth.

• The distal cusp is in the foreground of the crown portion.

• The distal contact area is placed just below the distal cusp.

• The distal marginal ridge is short.The surface is convex.

• The cervical line is straight.

B

Ling

Mandibular First Molar• Occlusal Aspect:

outline is hexagonal. • The MD measurement is greater than BL.

The mesiobuccal cusp is larger than either of the two lingual cusps, which are almost equal to each other in size; the distobuccal cusp is smaller than any one of the other three mentioned, and the distal cusp is the smallest. The land marks to be identified on this surface are: (a) Central fossa. (b) Mesial and distal triangular fossae. (c) Central developmental groove. (d) Mesiobuccal and distobuccal

• developmental grooves. • (e) Lingual Developmental groove.

(f) Central pit• (g) Mesial and distal marginal ridges.

occlusal

B

DM

Ling

M DB

Ling

Mandibular Second Molar

• Measurements: • Average length 20 mm• Crown length (CL) 7mm, Root length 13mm• Mesiodistal (MD) diameter10.5mm• Buccal Aspect:

The crown is shorter and narrower than the first molar. There is one developmental groove, the buccal developmental groove, between the mesiobuccal and distobuccal cusps. The roots are inclined distally.

MD

Mandibular Second Molar

• Lingual Aspect: The crown and root converge lingually. The mesiodistal at the cervix is always greater than that of the first molar. The contact areas are more noticeable from the lingual aspect; at a lower level, especially in the distal, than those of the first molar.

MD

Mandibular Second Molar• Mesial Aspect: • Except for the differences in

measurement, there are little differences from the first molar. The cervical ridge buccally is less pronounced. Distal Aspect:

• It is similar to the first molar except for the absence of the distal cusp and a distobuccal groove.

• The contact area is centered on the distal surface.

B

B

Ling

Ling

Mandibular Second Molar

• Occlusal Aspect: There is considerable difference from the first molar. The small distal cusp of the first molar is not present, as well as an absence of the distobuccal developmental groove.

occlusal

M D

B

Ling

Mandibular Third Molar• Measurements: Average length 18 mm• Crown length (CL)7mm, Root length11

mm• Mesiodistal (MD) diameter10 mm• Buccal Aspect: • vary in outline

buccal cusps are short and rounded.shows two roots, mesial and distal, shorter than the roots of the first and second molars, and their distal inclination is greater.

• The roots may be separated or fused. Lingual Aspect: The third molar, when well developed, corresponds closely to the form of the second molar except for size and root development.

M

M

D

D

Mandibular Third Molar

• Mesial Aspect &Distal Aspect: This tooth resembles the mandibular second molar except in dimension.

• Occlusal Aspect: similar to second mandibular molar; with a more rounded outline and a smaller buccolingual measurement.

M D

B

Ling

Ling

B