Hygiene Atlas

Atlas · Plate II · Dental Anatomy and Tooth Morphology · 07

Molars

Maxillary first molars have four main cusps, often a cusp of Carabelli, an oblique ridge and three roots, with the palatal root longest and furcations opening buccally, mesially and distally. Mandibular first molars have five cusps and two widely separated roots, mesial and distal, and their short root trunk means the buccal and lingual furcations are exposed early as attachment is lost.

High-yield facts · 9

  1. Maxillary first molar: 4 major cusps plus the cusp of Carabelli on the mesiolingual cusp; mesiolingual is the largest cusp.T6
  2. Maxillary first molar: three roots; palatal is longest; furcations open buccally, mesially and distally.T6
  3. The oblique ridge (mesiolingual to distobuccal cusp) is found only on maxillary molars.T6
  4. Maxillary second molar: smaller, often lacks Carabelli; distolingual cusp is smaller or absent.T6
  5. Mandibular first molar: 5 cusps (MB, DB, D, ML, DL); the mesiobuccal is the largest; the distal is smallest.T6
  6. Mandibular first molar: two roots (mesial and distal); the mesial root is broader and curved with concavities.T6
  7. Mandibular second molar: 4 cusps with a cross (+) groove pattern; roots closer together.T6
  8. Root trunk length decides how soon a furcation is exposed: mandibular first molar trunk is about 3-4 mm; maxillary first molar mesial furcation is about 3.5 mm from the CEJ.T3
  9. Enamel projections (pearls) near a furcation trap plaque and predispose to furcation involvement.T3

Facts are written in our own words; each tag links to its source. Values marked "sources vary" differ between references, so check the one your program uses.