Permanent Mandibular Molars LECTURE 9 PDF

Permanent Mandibular Molars LECTURE 9 Dr YASAR MANSOUR AMSU Mandibular permanent molars Upper & lower molars show progressive reduction in size posteriorly (similar to maxillary molars) 2 roots; M & D 4 major cusps and 1 lesser-sized 5th cusp in 1st molars Crowns bro...

Permanent Mandibular Molars LECTURE 9 Dr YASAR MANSOUR AMSU Mandibular permanent molars Upper & lower molars show progressive reduction in size posteriorly (similar to maxillary molars) 2 roots; M & D 4 major cusps and 1 lesser-sized 5th cusp in 1st molars Crowns broader MD than BL Broadest MD dimension of all teeth The 2 L cusps are of equal size MB & DB cusps are approximately of equal size  Mandibular permanent 1st molar Buccal aspect The lower first permanent molar has the widest mesiodistal diameter of all of the molar teeth. Three cusps separated by developmental grooves. mesiobuccal cusp, mesiobuccal developmental groove, distobuccal cusp, distobuccal developmental groove, and the distal cusp. The mesiobuccal cusp is usually the widest of the these cusps. The distal cusp is smaller than any of M the buccal cusps and it contributes little to the D buccal surface. Located in distobuccal corner) MB and DB cusps are of equal height The two roots of this tooth are clearly seen. The distal root is usually less curved than the mesial root. BUCCAL SURFACE MESIAL OUTLINE Cervical 1/3 is straight or concave Occlusal 2/3s are convex DISTAL OUTLINE is entirely convex Cervical Line is similar to that of upper 1st molar Buccal surface Buccal cervical ridge in Cervical 1/3 Mesio-buccal groove ends halfway Disto-buccal groove is longer. Buccal surface 2 roots Widely separated Share a common trunk that has a shallow vertical depression Apical half of Mesial root is distally inclined Distal root projects distally without curvature 5 CUSPS ARE SEEN From Buccal VIEW Buccal View: Mesial contact area: Junction of middle and occlusal thirds Distal contact areas: occlusal to the junction of middle and incisal thirds  Mandibular permanent 1st molar Lingual aspect 3 cusps are seen the mesiolingual, the distolingual, and the distal cusp which is somewhat lower in profile. Mesiolingual cusp is usually the widest of the three. A short lingual developmental groove separates the two lingual cusps Cusps are Higher and more conical than B cusps Narrower Mesio-distally than B profile Mesial and distal outlines Generally convex except in the straight or concave Cervical1/3 Convergent cervically surface Cervical 1/3 is flat or concave Occlusal 2/3s are convex Lingual Aspect Roots Vertical shallow depression on the midline of the root trunk Proximal surfaces of roots are visible Mesial aspect Distinctive cervical ridge. The mesial surface may be flat or concave in its cervical third. It is highly convex in its middle and occlusal thirds. The occlusal profile is marked by the mesiobuccal cusp, mesiolingual cusp, and the mesial marginal ridge that connects them. The mesial root is the broadest buccolingually of any of the lower molar roots. MESIALL ASPECT ML cusp is slightly higher than MB Marginal Ridge is higher Mesial marginal groove From buccal cervical ridge, B outline curves sharply lingually L profile is convex Lingual HOC between middle & occlusal 1/3s Mesial surface is flat or concave in the Cervical 1/3 & convex in the occlusal 2/3s Roots Broad BL Blunt apex Proximal root concavity Distal aspect  The distal surface of the crown is narrower buccolingually than the mesial surface.  FIVE cusps are seen from the distal aspect: DB groove D MR is shorter than M & has a distal marginal groove  1/2 of B surface is visible  CL is straight  Narrower BL than M surface  Root  Broad BL, but narrower than M root  Blunt apex  may have shallow depression  B Mandibular First molar 5 developed functional cusps (MB/ ML/ DL/ DB) and the distal cusp The 2 lingual cusps are almost of equal size D M With the size differences above the tooth has a lingual inclination L  MANDIBULAR FIRST MOLARS Mesial and distal Occlusal View: B triangular fossae (minor fossae) MESIAL MARGINAL RIDGE M triangular fossa is longer & more M pit prominent than MB & ML the DISTAL supplementary MARGINAL RIDGE M grooves D D triangular fossa Each cusp has a Distal pit triangular ridge DB & DL supplementary grooves L  Occlusal View: B One Major Fossa: Central fossa Mesio-buccal groove Disto-buccal groove Central groove Lingual groove M Central Pit D The groove pattern is often described as Y-shaped L  Occlusal table  Fossae  Central fossa 2 M & D triangular fossae  Grooves  Central  MB & L terminate in the central pit  DB (y-shape with MB & L  Pits  M, D & central  Permanent Mandibular 2nd molar Buccal aspect Second molar crown is shorter both mesiodistally and Occluso-cervical than 1st molar Two well-developed buccal cusps form the occlusal outline. M D There is no distal cusp as on the first molar. A buccal developmental groove passes midway down the buccal surface and terminates in buccal pit LINGUAL cusps are more prominent (see 4 cusps) Roots are closer together and distally inclined Lingual aspect The crown is shorter than that of the first molar. The occlusal outline is formed by the mesiolingual and distolingual cusps. M & D profiles are less convergent cervically Mesial aspect The mesial profile resembles that of the first molar. Root is narrower BL with sharp apex Distal aspect there is no distal fifth cusp. Less of B surface is visible D root is much narrower BL with a pointed apex There are four well developed cusps with developmental grooves that meet at a right angle to form the distinctive "+” pattern characteristic of this tooth. Crown is rectangular B profile = L in length B M profile = D in length M cusps are wider MD than D cusps More numerous supplemental grooves Straight marginal ridges Mandibular third molars B Mandibular (and maxillary) third molars show more developmental variation than any other permanent tooth. They are also frequently congenitally missing. mandibular third molars vary considerably in size shape and position M D Some third molars resemble the adjacent second molar; some resemble the first mandibular molar with five cusps. L  Mandibular 3rd molar Buccal aspect The crown is often short and has a rounded outline. Highly variable Roots are short, fused & Distally inclined  Lingual aspect the crown is short and highly bulbous. Rounded cusps  Mesial  Mesially and distally, this tooth resembles the first and second molars. But shorter than either of the other molars. Technically, only the mesial surface is a 'proximal' surface. B & L profiles are highly convex  Distance between apices of Mesial cusps is shorter Distal Aspect Almost entire B surface is visible D root is the narrowest BL & shortest of all mandibular molars  OCCLUSAL ASPECT Four or five or cusp version of tooth are present. This surface can be a good copy of the first or second molar, or poorly developed with many accessory grooves. the occlusal surface is CONSTRICTED. with many grooves that are often numerous and short Irregular groove pattern Mesial half is wider bucco-lingually than the distal half. THANK YOU