Dental Anatomy: Permanent mandibular 2nd molar

Permanent mandibular 2nd molar
It supplements the 1st molar in function, have nearly same general morphology, but differ in the following:
?It is smaller than 1st molar by fraction of millimeter in all dimension, but it is not uncommon to find 2nd molar larger than 1st molar.
?Although 2nd molar has two well developed roots (broad buccolingually), but they are not as broad as those of the first molar, nor are they as widely separated.
?Buccally, only one developmental groove present, buccal groove.
It has only four well developed cusps of nearly equal size, there is neither fifth cusp or distal cusp. DB developmental groove absent.
?Crown and root converge lingually to lesser degree than the 1st molar.
?Cervical ridge buccally is less pronounced than the 1st molar.
?B & L developmental grooves meet the central developmental groove at right angles at the CP, these grooves form a cross (dividing occlusal surface into 4 nearly equal parts).
Permanent mandibular 3rd molar
?The mandibular third molar varies considerably in different individuals and presents many anomalies both in form and in position.
?It supplements the 2nd molar in function, but it is seldom as well developed as the 2nd molar.