permanent maxillary molars

BASIM ZWAIN LECTURESDENTAL ANATOMY

PERMANENT MAXILLARY MOLARS

Professor Dr. Basim ZwainFaculty of DentistryUniversity of Kufa

[email protected]

PERMANENT MAXILLARY MOLARSThe largest and strongest maxillary teeth.Have 3 roots 2 buccal, and 1 lingual.Unprecedented as they erupt behind deciduous molars.The main functions of molars is grinding the food, and

supporting the muscles of mastication, and vertical dimension.

They decrease in size as they go posteriorly therefore the first molar is the largest, then the second molar and lastly the third molar.

MAXILLARY FIRST MOLARIt is the largest tooth in the maxillary arch.

Principal identifying features1- Rhomboidal occlusal outline.2- The cusp of carabelli (non functional cusp), on the lingual

surface of the mesiolingual cusp.3- There is an oblique ridge between the mesiolingual and

distobuccal cusps.4- Three well separated and well developed roots. The lingual

root is the longest.

MAXILLARY FIRST MOLARBuccal aspect1- The crown is roughly

trapezoidal, and the cervical line shows little convexity, which is directed towards the root.

2- The mesial outline of the crown is straight curving occlusally as it reaches the contact area which is at the junction of the occlusal and middle thirds.

3- The distal outline of the crown is convex, the crest of curvature is at the centre of the middle third.

MAXILLARY FIRST MOLARBuccal aspect4- The mesiobuccal cusp is broader

than the distobuccal cusp, and its mesial and distal slopes meet at an obtuse angle, while the mesial and distal slopes of the distobuccal cusp meet at sharper right angle. We may see the lingual cusps.

5- The buccal developmental groove divides the 2 buccal cusps in equal distance and it terminates apically.

6- The 3 roots are visible and inclined distally. The lingual root is the longest, and the mesiobuccal and distobuccal roots are equal in length.

MAXILLARY FIRST MOLAR

Lingual aspect1- Only lingual cusps can be seen.

The mesiolingual cusp is the largest cusp of in the tooth, and accounts to 3/5 of the mesiodistal width of the tooth, the distolingual cusp accounts to 2/5.

2- The lingual developmental groove starts approx. at the center mesiodistally, and curves sharply distally, then continues on the occlusal surface.


Lingual aspect3- The fifth cusp (cusp of Carabelli) is

1.5 mm cervical to the mesioling. cusp tip. An irregular dev. groove separates the cusp from the mesiolingual cusp.

4- There are 3 roots visible, the lingual root makes most of the aspect.

MAXILLARY FIRST MOLARMesial aspect1- The buccal outline has a crest of

curvature within the cervical third, then it continues with a convex outline until the tip of the cusp.

2- The lingual outline has a crest of curvature within the middle third, and it shows a convex pattern until it reaches cusp of Carabelli which shows another convexity.

3- The mesial marginal ridge is located at a level 1/5 of the height of crown from the tip of the cusps.

4- The cervical line curves occlusally about 1mm.


Mesial aspect5- The intercuspal distance of the 2

mesial cusps is a little more than half the buccolingual dimension of the crown.

6- The mesial contact area is buccal to the buccolingual center of the crown.

7- The lingual and the mesiobuccal roots are seen, and the latter is wider buccolingually.

MAXILLARY FIRST MOLARDistal aspect1- The general outline is similar to that

of the mesial aspect, but the buccolingual measurement is more mesially than distally due to the tilt of the buccal side of the crown.

2- The distal marginal ridge is located more cervically so that we can see part of the occlusal surface.

3- The cervical line’s curvature is zero.4- All the 3 roots are visible. The

distobuccal root is the smallest one.

MAXILLARY FIRST MOLAROcclusal aspect1- The occlusal outline is

rhomboidal, with the mesial and lingual measurements being greater than distal and buccal measurements respectively.

2- Four well developed cusps, mesiolingual (the largest), then mesiobuccal, then distolingual, then distobuccal, then fifth (Carabelli’s) cusp.

MAXILLARY FIRST MOLAROcclusal aspect3- The mesiobuccal, and

distolingual line angles are acute, and mesiolingual, and distobuccal line angles are obtuse.

4- There is an oblique ridge made from the union of the ∆ ridge of the distobuccal cusp and the distal ridge of the mesiolingual cusp. It crosses the occlussal surface obliquely.

MAXILLARY FIRST MOLAROcclusal aspect5- There are 4 fossaea) Major fossae (i) Central fossa is roughly

triangular in shape, mesial to oblique ridge.

(ii) Distal fossa is linear, distal to oblique ridge.

b) Minor fossae (i) Mesial ∆ fossa. It is distal

to mesial marginal ridge.(ii) Distal ∆ fossa. It is mesial

to distal marginal ridge.

MAXILLARY FIRST MOLAROcclusal aspect6- There are 6 developmental

groovesa) Central developmental

groove. From central pit to mesial ∆ fossa.

b) Buccal developmental groove. From central pit buccally between the mesiobuccal and distobuccal cusps.

c) Distal oblique groove. From distal ∆ fossa going obliquely.

MAXILLARY FIRST MOLAROcclusal aspect6- There are 6 developmental

groovesd) Lingual developmental

groove joins distal oblique groove, goes between mesiolingual and distolingual cusps and travels cervically.

e) Transverse groove of the oblique ridge. It crosses the oblique ridge.

f) Fifth cusp groove. Between the fifth cusp and the mesiolingual cusp.

MAXILLARY FIRST MOLAROcclusal aspect7- There are 3 pitsa) Central pit is located in the

deepest part of the central fossa. It is a result of the junction of central and buccal developmental grooves.

b) Mesial pit is located in the deepest part of the mesial ∆ fossa.

c) Distal pit is located in the deepest part of the distal ∆ fossa.

MAXILLARY SECOND MOLAR

Principal identifying features

1- Fifth cusp is less evident.

2- Roots are less divergent, and may

be joined together.

3- Both distal cusps are less

developed.

4- The crown is smaller in overall

dimensions than the 6.


Buccal aspect

1- The crown is shorter and

narrower mesiodistally.

2- The distobuccal cusp is smaller,

so some part of the distal

surface is seen.

3- The roots are closer together.


Lingual aspect

1- The distolingual cusp is smaller.

2- Part of the distobuccal cusp is

seen distal to the distolingual

cusp.

3- No evidence of presence of the

fifth cusp.


Mesial aspect

1- The divergence of the roots is less

than that of the max. first molar.


Distal aspect

1- Because the distobuccal cusp

is smaller than the

mesiobuccal cusp more of the

mesiobuccal cusp is seen.

MAXILLARY SECOND MOLAROcclusal aspect

1- Rhomboidal shape of occlusal

aspect is more visible (acute angles

are less and obtuse angles are

more).

2- Buccolingual diameter is the same as

first molar, but mesiodistal diameter

is 1mm less.

3- The distal cusps are smaller and less

developed.

4- No fifth cusp.

MAXILLARY THIRD MOLAR

Principal identifying features1- Triangular occlusal outline.

Distolingual cusp is often absent.

2- Roots are shorter, convergent, often fused, and usually are 3 in numbers.

3- smallest maxillary molar.4- The mesiolingual cusp is the

largest.

MAXILLARY THIRD MOLAR5- It may have many variations occlusally:

a)Heart shape type with three cusps.

b) Rhomboidal shape type with four cusps.

c) One cusp type (peg shaped).

d) Congenitally missing.

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permanent maxillary molars

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