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Permanent posterior teeth mandibular first, second and third molars
- 1. Permanent Posterior Teeth MANDIBULAR FIRST, SECOND AND THIRD MOLARS
- 2. General Information Six mandibular molars Three in each quadrant Named for position in the arch, e.g. first, second and third molar Mandibular first molar is first permanent tooth to erupt Its positioning in the arch is important for the appropriate alignment of other permanent teeth Considered the “keystone” of the dental arch Roots are bifurcated
- 4. Mandibular First Molar Characteristics Universal Number: R-#30 L-#19 Eruption Date: 6-7 years First Evidence of Calcification: birth Crown Completion: 2 ½ - 3 years Root Completion: 9-10 years
- 5. Mandibular First Molar Characteristics Function: mastication and comminution Length of Crown: 7.5mm Length of Root: 14mm Antagonists: Maxillary second premolar and first molar
- 6. Mandibular First Molar Identifying Features Five cusps: mesiobuccal, distobuccal, distal, mesiolingual, distolingual Mesial and distal roots Three pulp canals Two in mesial root, one in distal root Largest mandibular tooth First permanent tooth to erupt
- 7. Mandibular First Molar Characteristics
- 8. Mandibular First Molar Buccal Surface View Three flat buccal cusps in size order Mesiobuccal, distobuccal, and distal Divided by grooves Concave mesial side with the contact area in the occlusal third Straight distal side with a more occlusal contact area than the mesial Mesial root curves mesially for half length, then distally Distal root is less curved, with axis in distal direction Root bifurcates about 3 mm below cervical line Has deep developmental depression
- 9. Mandibular First Molar Lingual Surface view Two pointed lingual cusps Mesiolingual and distolingual Visible distal cusp divided by a lingual groove Deep developmental depression at root bifurcation
- 10. Mesial Surface Two visible cusps Mesiobuccal and mesiolingual Mesial marginal ridge about 1mm below cusp tips Cervical line curves occlusally about 1mm Concave area at cervical line that continues onto root Only mesial root is visible Mesial root usually has two pulp canals Broad and straight root, tapering in apical third Broad concavity or depression on root
- 11. Distal Surface Tooth converges toward distal so that some of buccal surface is visible Crown is shorter on distal so all cusps seen Cervical line is relatively straight Shallow depression often evident on root
- 12. Occlusal Surface Wider by 1mm from distal to mesial than from buccal to lingual Five functioning cusps in order of size Mesiolingual, mesiobuccal, distolingual, distobuccal, and distal Central, mesiobuccal, distobuccal, and lingual (Y- shape) grooves Central (circular), mesial, and distal triangular are the major fossae Pits located central, mesial and distal
- 13. Mandibular Second Molar 18, 31
- 14. Mandibular Second Molar Universal Number: R-#31 L-#18 Eruption Date: 11-13 years First Evidence of Calcification: 2½-3 years Crown Completion: 7 – 8 years Root Completion: 14 - 15 years
- 15. Mandibular Second Molar Function: mastication and comminution Length of Crown: 7mm Length of Root: 13mm Antagonists: maxillary first and second molars
- 16. Mandibular Second Molar Identifying Features Four cusps: mesiobuccal, distobuccal, mesiolingual, distolingual Two roots: mesial and distal Two pulp canals: one in each root
- 18. Mandibular Second Molar Variations from First Molar The mandibular second molar varies from the first molar It’s smaller There are only 4 cusps The buccal groove divides the 2 buccal cusps The lingual groove divides the two lingual cusps The mesial side is wider; only one pulp canal The occlusal has more supplementary grooves
- 19. Mandibular First and Second Molars Mandibular first molar has five cusps (3 buccal, 2 lingual) Mandibular second molars have four cusps (2 buccal, 2 lingual) Mandibular Molars have two roots, one mesial and one distal Maxillary molars have three roots, two buccal one lingual All teeth have one pulp canal in each root, but the mandibular first molar is often an exception There are three pulp canals in the two roots: the mesial root has two pulp canals, and the distal root has one The mandibular second molar has only on pulp canal in each root
- 20. Mandibular Third Molar 17, 32
- 21. General Information Both maxillary and mandibular third molars show considerable developmental variation No standard structural description Most likely tooth to have anomalies Often crown displacement and fused/malformed roots
- 22. Mandibular Third Molar Universal Number: 17, 32 Eruption Date: 17-21 years old First Evidence of Calcification: 8-10 years old Crown Completion: 12-16 years old Root Completion: 18-25 years old
- 23. Mandibular Third Molar Function: mastication and comminution Length of Crown: 7mm Length of Root:11mm Antagonists: Maxillary second and third molar
- 24. Mandibular Third Molar Identifying Features Often the crown is atypical Fused roots (two roots) May resemble first or second molar
- 25. Mandibular Third Molar Clinical Considerations Often crowns do not conform to normal size Often have fused roots When well-developed, will look like first or second molar Frequently, the maxillary third molar is heart-shaped, where the mandibular third molar is often atypical.