Maxillary and Mandibular 2nd and 3rd Molars PDF

Maxillary and Mandibular Second and Third Molars Dr. Nina Fatimah Borbon Maxillary Second Molar Supplements the first molar in function Roots are as long as, if not somewhat longer than those of the first molar Distobuccal cusp is not as large or as well developed; smaller No...

Maxillary and Mandibular Second and Third Molars Dr. Nina Fatimah Borbon Maxillary Second Molar Supplements the first molar in function Roots are as long as, if not somewhat longer than those of the first molar Distobuccal cusp is not as large or as well developed; smaller No fifth cusp is evident. Crown is 0.5 mm or so shorter cervico-occlusally than that of the first molar Measurement of the crown buccalingually is about the same. Maxillary Second Molar Two types: RHOMBOIDAL TYPE - occlusal form that resembles that of the first molar HEART-SHAPED TYPE - resembles a typical third molar form with distolingual cusp poorly developed and makes the development of the other three cusps predominate (encircled in red) Maxillary Second Molar  CROWN - little shorter cervicoocclusally and narrower mesiodistally than max 1st molar.  DISTOBUCCAL CUSP - smaller and allows part of the distal marginal ridge and part of distolingual cusp to be seen.  BUCCAL ROOTS - about same length, nearly parallel and inclined distally more than those of the maxillary first molar, to that the end of disbuccal root is slightly distal to the distal extremity of the crown.  Apex of mesiobuccal root is on a line with buccal groove of crown instead of the tip of mesiobuccal cusp, as found on the first molar Maxillary Second Molar Ways in which the second molar differs from the first molar: smaller distolingual cusp distobuccal cusp seen through the sulcus between mesiolingual and distolingual cusps no fifth cusp is evident. apex of lingual root is on a line with the distolingual cusp tip instead of the lingual groove, as found on the first molar Maxillary Second Molar buccolingual dimension of second molar is about the same as that of first molar, but the crown length is less. roots do not spread as far buccolingually but are within the confines of the buccolingual crown outline. Maxillary Second Molar distobuccal cusp is smaller in max 2nd molar than in 1st molar, more of mesiobuccal cusp may be seen from this angle. mesiolingual cusp cannot be seen. apex of the lingual root is in line with distolingual cusp. Maxillary Second Molar  Has two types: 1. resembles first molar – extreme rhomboidal outline occlusally 2. resembles 3rd molar- DL cusp poorly developed, heart- shaped occlusally  No fifth cusp  Presents many supplementary grooves and accidental groove than first molar  More constricted mesiodistally Maxillary Third Molar Resembles & supplements max 2nd molar in function Smaller crown, shorter root Heart-shaped occlusal surface Show more variation in development Age of eruption: 17-21 years Maxillary Third Molar BUCCAL ASPECT CROWN – shorter cervicoocclusally & narrower mesiodistally than 2nd molar ROOT – fused & ends in a taper at apex, functioning as one large root, shorter cervicoapically; distinct slant to distal LINGUAL ASPECT CROWN – only one large lingual cusp, no lingual groove Maxillary Third Molar MESIAL ASPECT Taper to the fused roots and bifurcation in region of apical third Poorly developed with irregular outline DISTAL ASPECT Most of buccal crown surface is seen than in 2nd molar because of more acute angulation of occlusal surface in relation to long axis of root Maxillary Third Molar OCCLUSAL ASPECT Heart-shaped outline: 3 functioning cusp: 2 buccal, 1 lingual Rhomboidal outline: 4 cusps Lingual cusp – large & well developed; little or no DL cusp Many supplemental grooves Mandibular Second Molar supplements first molar in function. CROWN: 4 well-developed cusps: 2 buccal and 2 lingual Neither a distal nor a fifth cusp is evident; distobuccal cusp is larger than found in 1st molar ROOTS: 2 well-developed & widely separated: 1 mesial and 1 distal broad buccolingually but not as those of first molar Mandibular Second Molar  Crown: shorter cervicobuccally, narrower mesiodistally than first molar.  Buccal developmental groove - divide mesiobuccal and distobuccal cusps which are equal in size  Two roots (mesial and distal) - less broad and closer together; shorter than those of first molar; inclined distally; axes forming more of an acute angle with occlusal plane than is found on first molar  Cervical line buccally points sharply toward root bifurcation Mandibular Second Molar  tips of lingual cusps - higher than buccal cusps  Differences between 2nd molar and 1st molar: Crown and root converge lingually but to a slight degree; little of the mesial or distal surfaces may be seen on the aspect Mesiodistal calibration at the cervix lingually is always greater than of the first molar. Curvatures mesially and distally on the crown are more noticeable; prove to be as a slightly lower level than those of the first molar Mandibular Second Molar  tips of lingual cusps - higher than buccal cusps  Differences between 2nd molar and 1st molar: Crown and root converge lingually but to a slight degree; little of the mesial or distal surfaces may be seen on the aspect Mesiodistal calibration at the cervix lingually is always greater than of the first molar. Curvatures mesially and distally on the crown are more noticeable; prove to be as a slightly lower level than those of the first molar Mandibular Second Molar  Cervical ridge buccally is less pronounced, and the occlusal surface is constricted buccolingually.  Cervical line shows no curvature.  Two roots may be seen in mesial aspect  Root - pointed apically  Absence of distal cusp and distobuccal groove  Most of occlusal surface can be seen from distal aspect  Contact area is centered on the distal surface buccolingually and is placed equidistant from the cervical line and marginal ridge. Mandibular Second Molar  Roughly rectangular  Central groove - in the center, with lingual and buccal developmental grooves meeting with central groove at right angle.  Four cusps: 2 buccal (mesiobuccal and distobuccal) and 2 lingual (mesiolingual and distolingual)  Buccal and lingual grooves meet the central developmental groove at right angles at the central pit.  Exhibit more curvature of outline of crown distally than mesially, showing semi-circular outline to the disto-occlusal surface compared with a square outline mesially.  Cusp ridge of distobuccal cusp lies buccal to cusp ridge of the mesiobuccal cusp. Mandibular Third Molar Presents many anomaly both in form and position Supplements 2nd molar in function although tooth is seldom well developed 5 or more cusps Mandibular Third Molar BUCCAL ASPECT Vary in outline CROWN – wider at contact areas mesiodistally than at cervix; short & rounded buccal cusps 2 ROOTS – mesial & distal; shorter with poor development; may be fused for all or part of their length LINGUAL ASPECT Same as 2nd molar except in size & root development Mandibular Third Molar MESIAL ASPECT Resembles 2nd molar except in dimensions Roots are shorter with mesial root tapering more from cervix to apex & more pointed DISTAL ASPECT More spheroidal above cervical line Distal root appear small in length & buccolingual measurement Mandibular Third Molar OCCLUSAL ASPECT More rounded outline & smaller buccolingual measurement distally