MANDIBULAR MOLARS

General Features The three mandibular molars resemble each other in morphology two well-developed roots ; Mesial and Distal In mandibular molars, the mesiodistal dimension of the crown is larger than the buccolingual dimension by about 1 mm. It can be remembered that the maxillary molars are wider buccolingually than they are mesiodistally. M1M2 M3

Permenant Mandibular 1 st Molar

Permenant Mandibular first Molar General features Development Average measurments Crown Occlusal Buccal Lingual Mesial Distal Root

Mandibular 1 st molar General features largest and strongest tooth in the mandibular arch It has five cusps: Two buccal, two lingual and a distal cusp Two roots—mesial and distal.

Development “6 Year Molars” 1 st Non-Succedaneous Tooth That Erupts Formed from 5 Developmental Lobes First Evidence of Calcification at Birth Enamel Completed2.5 Yrs Eruption6-7 Yrs Root Completed9-10 Yrs

The crown has 5 Aspects 1- Occlusal 2- Buccal 3-Lingual 4-Mesial 5- Distal

Occlusal Aspect Outline/Geometric shape: hexagonal with unequal sides. Boundaries of Occlusal Surface : the cusp ridges of all the five cusps and the marginal ridges. Relative Dimensions : The MD measurment is greater than the BL The crown is bulkier mesially than distally Lingual Convergence :the mesial and distal surfaces converge lingually making the lingual surface narrower

Occlusal Aspect Elevations : Cusps and ridges Depressions : Grooves and pits Fossae

CUSPS Mesiobuccal Mesiolingual Distolingual Distobuccal Distal

Ridges Cusp Ridges Triangular ridges Marginal ridges The distal marginal ridge is shorter and at a lower level than the well-developed mesial marginal ridge.

Grooves four developmental grooves The central developmental groove The MB developmental groove joins the central developmental groove mesial to the central pit and runs buccally separating the MB and DB cusps and ends on the buccal surface in the buccal pit. The DB developmental groove from central Groove, runs distobuccally between the DB and distal cusps to end on the buccal surface The lingual developmental groove from the central pit and extends onto the lingual surface separating the two lingual cusps supplemental grooves

Fossae One major fossa The central fossa is a circular large depression in the center of the occlusal surface. Two minor fossae mesial and distal triangular fossae. The mesial triangular fossa has the mesial marginal ridge as base, the mesial pit as apex The distal triangular fossa is smaller than the Mesial triangular fossa. It has the distal marginal ridge as the base, distal pit as the apex

PITS The central pit is at the center of the central fossa. The mesial and distal pits are in the mesial and distal triangular fossae respectively

Buccal Aspect Geometric shape: Trapezoidal Cusps: All the five cusps are visible from buccal aspect The lingual cusps are seen in the background as they are at higher level than the buccal cusps The MB cusp is wider than the DB cusp, which is sharper Buccal cusps are flattened Buccal surface is convex in the cervical third forming the Buccal Cervical Ridge

Buccal Aspect The two buccal cusps are separated by the mesiobuccal developmental groove which runs on buccal surface to end in the buccal pit The Distobuccal and distal cusps are separated by the distobuccal developmental groove Mesial outline: convex with height of contour at junc of occ and middle thirds Distal outline: covex-height of contour at middle third Cervical outlne: curved apically

Lingual Aspect Geometric shape: Trapezoidal Cusps: Only lingual cusps can be seen and small part of the distal Lingual cusps are higher and more conical Lingual cusps are separated by the lingual deleopmental grooves Lingual surface is narrower than buccal (crown tapered lingually)

Mesial Aspect Geometric shape : Rhomboidal Crown has a Lingual Tilt in Relation to the Root Axis The buccal outline more b convex in the cervical third-The height of contour is in the cervical third of the crown. Lingual Outline evenly convex from cervix to the ML cusp tip-The height of contour is at the middle third. Cervical Outline The cervical line may be straight or slightly curved occlusally Buccolingual measurment is greater than distal Mesial Contact area: junction of occ and middle thirds

Distal Aspect Distal surface is shorter and narrower Distal marginal ridge shorter than mesial Most of B surface and some of L can be seen DB Groove extends Halfway Down the D Surface distal contact area is on the distal contour of the distal cusp more broad and buccally and at a higher level than mesial contact.

Roots 2 well developed roots Mesial and Distal Size: Twice as long as the crown both same length Form: Bifurcation near to cervical line(3-4 mm) Mesial root has a straight vertical axis Distal root slants distally Mesial root has a deep concavity

Permenant Mandibular 2 nd Molar

General features Development Average measurments Crown Occlusal Buccal Lingual Mesial Distal Root

Development 4 Developmental Lobes Important Times: 1 st Calcification2.5-3 Yrs Enamel Completed7-8 Yrs Eruption11-13 Yrs Root Completed14-15 Yrs

Occlusal Aspect Geometric Shape The occlusal aspect of the 2nd molar is rectangular Dimensions: Buccally as wide as lingually MD greater than BL All the four angles are nearly equal, and form right angles.

Occlusal Aspect 4 cusps The central developmental groove buccal and lingual grooves meet the central groove at right angles at the central pit The groove pattern forms a typical plus mark ‘+’ or a cross in the center dividing the occlusal portion into four nearly equal parts There is no distobuccal groove.

Occlusal View (cont) Supplemental Grooves Radiate From the Developmental Grooves Making the Cusp Slopes Not as Smooth NO lingual convergence

Buccal Aspect Geometric shape: Trapezoidal The MB and DB cusps are equal in width and separated by buccal developmental groove. The buccal cervical ridge may not be as pronounced as in the mandibular 1st molar.

Lingual Aspect The lingual surface is nearly as wide as the buccal surface The mesiolingual and distolingual cusps are of equal width and are sharper than the buccal cusps The lingual developmental groove separating the two lingual cusps runs onto the lingual surface.

Mesial Aspect Only mesiobuccal and mesiolingual cusps are seen from the mesial aspect The crown shows a lingual inclination on the root base Mesial contact area: It is at the center of the Mesial surface both cervico-occlusally and buccolingually.

Distal Aspect no distal cusp The distal contact area: It is at the center of the distal surface both cervico-occlusally and buccolingually.

Roots closely spaced nearly parallel to each other. Both the roots have their axes distally inclined 2 nd molar !st molar

Permenant 3 rd Molars

Mandibular permenant 3 rd molars considerable variation in their size, form and position. occlusal anatomy is highly variable; *four cusps like mandibular 2nd molar five cusps like mandibular 1st molar *more than five cusps appearing like small tubercles tend to be oversized rather than undersized.

Occlusal View Most Often Similar to 2 nd Molar More Rounded Outline Occlusal Table is Ovoid in Outline Highly Constricted MD and BL 4 Cusps – Irregular in Form Pit and Grooves Very Irregular

Buccal View Highly Variable Short Length; Highly Bulbous

Lingual View Short Roots : Close Together or Fused

Occlusion, Roots, Pulp Spaces Highly Variable Eruption Angulation may be a concern Distal Root is Smallest of Mandibular Molars Third Root