The mandibular third molars are extremely variable in size and shape of both crown and root portions.
There are two basic forms:
- Type I resembles the permanent second molar 50%. It has four cusps and the same general occlusal pattern
and contour. Ordinarily the size is the same, but range from very small larger than any other molar.
- Type II resembles the permanent first molar (40%) with five cusps and a similar occlusal pattern and contours. In 10% of cases it has more than five
or less than four cusps.
The roots are extremely variable in size,number and curvature.Single fused roots are common.Most often,root length is less than other mandibular molars regardless of the crown size. The most common root torm reveals two
short curved roots.
Pulp cavity, If it is well developed and is comparable to the second molar in shape the pulp cavity will resemble the second molar.However,if it differs,it follows the general outline of the tooth.