Mandibular Permanent Molars Quiz

Mandibular Permanent Molars

• The permanent mandibular molars are the largest teeth in the mandibular arch.
• They function as chewing/grinding tools.
• There are three molars per dental quadrant.
• Size decreases progressively as the tooth is situated more posteriorly.
• The crowns are shorter cervico-occlusally than those of the mandibular anterior teeth.
• Mandibular molars differ from maxillary molars in several ways:
  • Two roots
  • Derived from five cusps
  • Crowns are oblong, wider mesio-distally
  • Fissure pattern is generally cross-shaped
  • Lingual cusps are of more equal size
  • Buccal cusp tips are shifted lingually, showing more buccal view occlusally

Mandibular First Molar

• Calcification evidence: Birth
• Enamel completed: 3 years
• Eruption: 6 years
• Root completed: 9-10 years
• Usually the first permanent teeth to erupt
• Three cusps (mesio-buccal, disto-buccal, distal)
• Distal cusp is smallest, mesio-buccal cusp is widest
• Fissure separates mesio-buccal and disto-buccal cusps (Mesio-buccal developmental groove)
• Mesiobuccal groove originates from the central fossa on the occlusal surface and terminates in a buccal pit

Buccal Aspect

• Three cusps: mesio-buccal, disto-buccal, distal.
• Distal cusp is the smallest, mesio-buccal cusp is the widest.
• A fissure separates the mesio-buccal and disto-buccal cusps. (Mesio-buccal developmental groove)
• The mesio-buccal groove originates from the central fossa, terminating in a buccal pit.
• Mesio-buccal and disto-buccal cusps are approximately equal in length.
• The distal cusp is conical and smaller than other two.
• Separated from disto-buccal cusp by Distobuccal Developmental groove
• The buccal surface is markedly convex, especially at the cervical third.
• Convexity due to characteristic lingual inclination of the buccal cusps.
• Both mesial and distal crown profiles converge towards the cervical third.

Lingual Aspect

• Two lingual cusps: mesiolingual and distolingual
• Mesiolingual cusp is slightly larger.
• Fissure between lingual cusps (lingual developmental groove) originates from the central pit, doesn't extend significantly down the lingual surface.
• Lingual surface is convex in occlusal & middle thirds, flat or concave cervically.
• Part of occlusal & proximal sides visible from lingual view due to lingual occlusal slope & taper.
• Wider on buccal than lingual side.
• Mesial and distal profiles of lingual aspect are convex.
• Crest of contour (contact area) is higher on the mesial than distal side due to the distal slope of the tooth.
• Both contact areas in middle third of tooth.
• Bifurcation of the two roots begins with bifurcation groove on the root trunk, in line with the lingual developmental groove.
• Lingual cervical surface is rather flat compared with the convex buccal cervical surface.
• Cervical line is straight mesiodistally.

Mesial Aspect

• Two cusps visible: mesiolingual and mesiobuccal
• Mesiolingual cusp is higher and more conical.
• Mesial Marginal Ridge (MMR) joining mesiobuccal and mesiolingual cusps is V-shaped.
• MMR is notched at midpoint.
• Mesial surface is flat or concave cervically, convex in middle and occlusal thirds.
• Only one root, the mesial root, is visible.
• Mesial Marginal Groove traverses the MMR.
• Slight buccal bulge in cervical third: Buccocervical Ridge.
• Lingual height of contour is at the center of the middle third of the tooth.
• Cervical line tends to curve occlusally about 1mm in the center of the mesial surface, located higher on lingual side than buccal by almost 1mm.

Distal Aspect

• Distal Marginal Ridge (DMR) joining distal and distolingual cusps is V-shaped.
• Distolingual cusp is the largest of three distal cusps from a distal surface view.
• Cervical third of distal surface is relatively flat.
• Distal surface is more convex than mesial surface due to the distal cusp.
• Distobuccal groove separates distobuccal and distal cusps.
• DMR is not as wide as the MMR, bisected by the Distal Marginal Groove (DMG), located lingual to the center of the tooth.
• Crown tapers and converges distally, greater amount of occlusal table is seen in distal view.
• Distal contact area is on the distal cusp and is centered over the distal root.

Occlusal Aspect

• Crown outline form is pentagonal.
• Crown is broader mesiodistally than buccolingually.
• Occlusal table tapers lingually and distally.
• Mesiodistal Occlusal Fissure (MOF) divides occlusal surface into lingual and buccal parts.
• MOF arises from a deep central fossa.
• Five functional cusps: three on buccal side (mesiobuccal, distobuccal, distal) and two on lingual side (mesiolingual, distolingual)
• Lingual cusps are higher and more pointed than buccal.
• Mesiobuccal cusp is wider than lingual cusps (which are similar in size).
• Buccal cusp tips are lingually displaced, rounded, and lower than lingual cusps.
• Distal cusp is the smallest, slightly displaced buccally.
• All developmental grooves converge at the central pit in the central fossa.
• Central fossa is a concave area bordered by distal slope of mesiobuccal cusp; mesial and distal slopes of distobuccal cusp, distal slope of mesiolingual cusp and mesial slope of the distolingual cusp.
• Two other fossae (Mesial and Distal Triangular Fossae).
• Two buccal grooves and lingual groove form Y-shaped groove pattern.
• In 90% of cases, mesiolingual cusp joins distobuccal cusp across floor of central fossa.
• This pattern is termed Dryopithecus pattern, characteristic of anthropoid apes and their ancestors (Dryopithecines).

Roots and Pulp Morphology

• Two roots (mesial and distal) arising from a common root stalk or trunk.
• Roots are markedly flattened mesiodistally.
• Mesial root usually deeply grooved.
• Both roots curve distally.
• Pulp cavity consists of pulp chamber and three pulp canals generally.
• Mesial root houses two pulp canals (mesiobuccal and mesiolingual); distal root houses a larger pulp canal.
• Pulp horn under each cusp (i.e., five pulp horns).
• Sometimes four root/pulp canals, particularly in the distal root, may be present (distobuccal and distolingual canal).

Mandibular Second Molars

• Calcification evidence: 2-3 years
• Enamel completed: 7-8 years
• Eruption: 11-13 years
• Root completed: 14-15 years
• Crown appears smaller than a mandibular first molar.
• Only two buccal cusps, equal mesiodistal dimensions.
• A fissure connects buccal cusps from occlusal surface, terminating halfway up the surface.
• Buccal surface is a highly convex shape.
• Crown shows less lingual convergence than a mandibular first molar due to the absence of a distal cusp.
• Crown is noticeably shorter than a mandibular first molar

Mandibular Third Molars

• Morphology is variable and unpredictable.
• Smallest of mandibular molars but can be as large as a first molar.
• Crown has four or five cusps, a rounded rectangle or circular shape.
• Mesial cusps are larger than distal cusps.
• Calcification: 8–10 years
• Enamel completed: 12-16 years
• Eruption: 17-21 years
• Root completed: 18-25 years
• Occlusal surface is wrinkled with irregular groove pattern and numerous pits.
• Roots are often shorter and more acutely inclined to the distal side and are frequently fused.

Test your knowledge about mandibular permanent molars, including their functions, anatomy, and characteristics. This quiz covers crucial details such as the completion of enamel and unique patterns associated with these teeth. Perfect for dental students and professionals looking to refine their understanding.