Lecture 6 DENTAL ANATOMY Dr.SattarHmadat
Permanent Maxillary Second Molar
Principal identifying features:
No fifth cusp “cusp of Carabelli” is evident.
2- Roots are less divergent and may be coalescent (joined together), and the roots of this tooth are as long as.longer than, those of the first molar
3- Both distal cusps (distobuccal and distolingual cusps) are less developed.
4-The crown is smaller in overall dimensions than the maxillary first molar.
1- The crown is a little shorter cervico-occlusally (about 0.5mm) and narrower mesio-distally than the maxillary first molar.
2-The distobuccal cusp is smaller and allows part of the distal marginal ridge and part of the distolingual cusp to be seen
3- The buccal roots are about the same length. They are more nearly parallel and are inclined distally more than those of maxillary first molar. So, the end of the distobuccal root is slightly distal to the distal extremity of the crown and the apex of mesiobuccal root is on a line with the buccal groove of the crown instead of the tip of the mesiobuccal cusp as in the maxillary first molar.
4-The palatal root is the longest root (1mm longer than the buccal roots).
1- The distolingual cusp is smaller than that in the maxillary first molar.
2-Part of the distobuccal cusp may be seen mesial to the distolingual cusp (through the sulcus between the mesiolingual and distolingual cusps).
3-No fifth cusp is evident.
4-The apex of the lingual root (palatal root) is in line with the distolingual cusp tip instead of the lingual groove as was found in the maxillary first molars.
1-The buccolingul dimension is the same as that of the maxillary first molar, but the crown length is less.
2-The roots are less divergent buccolingually than those of the maxillary first molar, being within the confines of the crown.
Because the distobuccal cusp is smaller than in the maxillary first molar(i.e. more smaller in comparison to the mesiobuccal cusp), more of the mesiobuccal cusp may be seen from this aspect.
1-The rhomboidal shape of the occlusal aspect is more visible. In comparison with the maxillary first molar, the acute angles of the rhomboid are less and the obtuse angles are more.
2-The buccolingual diameter is the same as in maxillary first molar, but the mesiodistal diameter is approximately 1mm less.
3-The distal cusps (distobuccal and distolingual cusps) are smaller and less developed than those in the maxillary first molar.
4 -No fifth cusp.
5-It is not uncommon to find more supplemental grooves as well as pits on the occlusal surface than are usually found on the maxillary first molar.
Maxillary Third Molar
The third molar supplements the second molar in function, and its fundamental design is similar. all third molars, mandibular and maxillary show more variation in development than any of the other teeth in the mouth.
Principal identifying features:
1-It is the smallest maxillary molar tooth.
2-Triangular occlusal outline, the distolingual cusp is very small and poorly
developed and it may be absent.
3-The roots are shorter, convergent, often fused, and usually are three in number.
4-The mesiolingual cusp is the largest cusp.
5-It may have many variations:
Heart shaped type with three cusps (most common type).
Rhomboidal shaped type with four cusps.
One cusp type occlusally (peg shaped).
Buccal Aspect Lingual Aspect
Mesial Aspect Distal aspect