Lecture 14 dental anatomy.pdf

Lecture 13 Lecture(14) MANDIBULAR SECOND MOLAR Principal identifying features 1- Rounded square occlusal outline. 2- Four cusps, 2 buccal, and 2 lingual. 3- Not as than 6, and close to...

Lecture 13 Lecture(14) MANDIBULAR SECOND MOLAR Principal identifying features 1- Rounded square occlusal outline. 2- Four cusps, 2 buccal, and 2 lingual. 3- Not as than 6, and close together. wide Mesio distally as 6. 4- Buccal aspect has one groove. 5- Many suppl. gr. on the occlusal. surface 6- Two roots which are less broad Buccal aspect 1- The crown is shorter and narrower Mesio-distally than 6. 2- There is one dev. groove dividing the Mesio-buccal and disto-buccal cusps which are equal in size. 3- Two roots (mesial and distal) are less broad and closer together.  Lecture 13 Lingual aspect:- Only the lingual cusp is in view because the tips of the lingual cusps are higher than the buccal cusps. Mesial aspect:- 1- The cervical ridge buccally is less pronounced, and the occlusal surface is constricted bucco-lingually. 2- The cervical line shows no curvature. 3- The 2 roots may be seen from this aspect.  Lecture 13 Distal aspect 1- Absence of distal cusp and disto-buccal groove. 2- Most of the occlusal surface can be seen from this aspect. Occlusal aspect 1- It is roughly rectangular. 2- The central groove is in the center, with the lingual and buccal dev. grooves meeting with the central groove at right angle. 3- Four cusps, 2 buccal (Mesio-buccal, and disto-buccal) and 2 lingual (Mesio-lingual and disto-lingual). 4- Many supplemental grooves radiating from the developmental grooves.  Lecture 13 Mandibular third molar: Principal identifying features 1- The crown is similar to 7 but smaller, and more rounded. 2- Two roots, short, underdeveloped, and often fused. 3- Four cusps (but may be more). 4- Lingually inclined buccal surface. 5- A great number of supplemental grooves. DIFFERENCES BETWEEN UPPER AND LOWER MOLARS subject maxillary mandibular 1 Shape of occlusal aspect Rhomboidal Rectangular 2 Crown width Wider Bucco- Wider mesio- lingually distally than mesio- than bucco- distally lingually 3 Number of roots 3 2 4 Presence of oblique ridge yes no 5 Functional cusps 4 5 6 Shape of cusps (mesial Buccal cusp is Buccal cusp is aspect) sharp rounded Lingual cusp Lingual cusp is rounded is sharp 7 Buccal cusp is rounded no yes Lingual cusp is sharp 8 Developmental groove 6 4 9 Fossa 4 3