Maxillary 3rd molar morphology, Slides of Oral Biology

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MAXILLARY 3

rd

MOLAR

MAXILLARY 3

rd

MOLAR

OUTLINEOUTLINE

▰ Chronology

▰ General Features

▰ Buccal aspect

▰ Lingual aspect

▰ Mesial aspect

▰ Distal aspect

▰ Occlusal aspect

▰ Endodontic anatomy

2

GENERAL FEATURESGENERAL FEATURES

▰ (^) Often appears as developmental anomaly. ▰ (^) Vary considerably in size, shape, contour & relative position to the other teeth. ▰ (^) Supplements 2nd^ molar in function & similar in fundamental design. ▰ (^) Crown is smaller & roots are shorter, with inclination towards fusion with the resultant anchorage of one tapered root.

▰ Its heart-shaped when viewed from occlusal aspect.

▰ Mostly, DL cusp is very small & poorly developed or may be absent

entirety.

▰ Triangular occlusal outline.

▰ Distolingual cusp is often absent.

▰ Roots are shorter, convergent, often fused, and usually are 3 in

numbers.

▰ smallest maxillary molar.

▰ The mesiolingual cusp is the largest

LINGUAL ASPECTLINGUAL ASPECT

▰ (^) Only one large lingual cusp is present. ▰ (^) No evident lingual groove. ▰ (^) In many cases, a third molar with the same essential features has a poorly developed DL cusp with a development groove lingually.

MESIAL ASPECTMESIAL ASPECT

▰ Aside from measurments, main feature is the taper to the fused

roots & a bifurcation, usually in apical 3rd^ region.

▰ Root portion is considerably shorter than the crown length.

▰ Crown & root portion tend to be poorly developed with irregular

outlines.

OCCLUSAL ASPECTOCCLUSAL ASPECT

▰ Heart-shaped outline.

▰ Lingual cusp is larger & well developed.

▰ Little or no evident lingual cusp which gives a semi-circular outline to the tooth

from one contact area to another.

▰ Three functional cusps: 2 buccal & 1 lingual.

▰ Many supplemental grooves and accidental grooves are visible unless the tooth is

very much worn

▰ (^) May show 4 distinct cusps. ▰ (^) This type may have strong oblique ridge , a central fossa & a distal fossa , with a lingual developmental groove similar to that of rhomboid shaped 2nd^ molar. ▰ (^) Crown converges more lingually: hence losing rhomboidal shape.

VARIATIONS &

ANOMALIES

VARIATIONS &

ANOMALIES

▰ Shows most divergent crown & root form. ▰ Crown size varies from simple, tiny one cusp from, often devoid of grooves & pits called Peg third molar, to large crown with numerous cusps or trabecles and excessive number of randomly placed pits & grooves. ▰ The number of root branche smay vary from one to as many as seven or eight. Root length, curvature s and deflections at odd angles are common. ▰ Third molars are often^ congenitally missing^ or^ impacted. ▰ Supplementay Teeth:^ rare, are sometimes just found distal 3rd^ molar area & usually impacted.

FUNCTIONS OF

MOLARS

FUNCTIONS OF

MOLARS

 (^) Play a major role in the mastication of food(chewing and grinding)  (^) Lost of first molar can result in more than 80mm of chewing surface gone  (^) Important in maintaining vertical dimension the face  (^) Important in maintaining continuity within dental arches, thus keeping other teeth in alignment  (^) Function in esthetics by keeping the cheeks full and keeping chin proper distance from the nose