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Permanent posterior teeth maxillary first, second and third molars
- 1. Permanent Posterior Teeth MAXILLARY FIRST, SECOND AND THIRD MOLARS
- 2. General Information There are six maxillary molars, three in each quadrant Like premolars, they are named for their position in the arch from anterior to posterior Permanent molars erupt posterior to the primary second molars and do not replace deciduous teeth Nonsuccedaneous The first molar is the first permanent tooth to erupt The mandibular first molar precedes the maxillary first molar by a few months Both usually erupt before permanent central incisors
- 3. General Information With the exception of the third molars, all maxillary molars have at least four cusps. The maxillary first molar usually has a fifth, nonfunctioning cusp, or tubercle, that is positioned on another cusp The fifth cusp is known as the cusp of Carabelli The number of lobes from which a molar develops is the same as the number of cusps Maxillary molars have trifurcated (divided into three) roots Mesiobuccal, distobuccal and lingual Each root has one pulp canal
- 4. General Information Molars are structured so that they are narrower (that is, they converge) toward the posterior portion of the mouth. Thus, the distal of the tooth is narrower than the mesial. Because they have multicups, molars perform major tasks of mastication and comminution by grinding a pulverizing food.
- 6. Maxillary First Molars Universal Number: 3, 14 Eruption Date: 7 years old First Evidence of Calcification: birth Crown Completion:2.5-3 years old Root Completion: 9-10 years old
- 7. Maxillary First Molars Function: mastication and comminution of food Length of Crown: 7.5mm Length of Root: 12mm buccal, 13mm lingual Antagonists: mandibular first and second molars
- 8. Maxillary First Molars Identifying Features Five cusps: Mesiobuccal, distobuccal, mesiolingual, distolingual, cusp of Carabelli Three roots: Mesiobuccal, distobuccal, lingual Three pulp canals, one in each root The Mesiobuccal root may have two pulp canals Cusp of Carabelli, or fifth cusp, located on mesiolingual cusp, is a nonfunctioning cusp Largest and strongest of the maxillary teeth
- 9. Maxillary First Molars Buccal Surface of the crown There are two buccal cusps: Mesiobuccal and distobuccal Two longer lingual cusp tips are visible The buccal groove divides the two buccal cusps; it extends one-half the crown length and terminates in a shallow depression The mesial outline is straight The mesial contact is two-thirds the distance from the cervical line The distal side is convex The distal contact area is in the middle of the surface
- 10. Maxillary First Molars Buccal Surface of the Root There are two buccal roots: Mesiobuccal and distobuccal The Mesiobuccal root extends in a mesial direction for half of its length and then curves distally The distobuccal root is straight for half of its length, then curves mesially The root trunk is about 4mm long before bifurcating A shallow depression extends from the cervical line and terminates in a deep groove at the bifurcation. The lingual root extends between and above the buccal roots
- 11. Maxillary First Molars Lingual Surface Crown: Three visible cusps: mesiolingual, distolingual, and cusp of Carbelli Mesiolingual cusp about three-fifths the width of the crown A cusp of Carabelli positioned on the mesiolingual cusp A fifth cusp groove on mesiolingual cusp if fifth cusp is not present A lingual groove dividing the two lingual cusps Root: A broad, tapered lingual root, the longest of the three roots, with a furrow or depression A visible outline of both buccal roots
- 12. Maxillary First Molars Mesial Surface Crown: Visible cusps: Mesiobuccal, mesiolingual, a cusp of Carabelli A depression on the crown from the contact area to the root trunk A mesial marginal ridge about one-fifth the distance from the cusp tips Root: Two visible roots: a broad, flat mesiobuccal root and a tapered lingual root A depression on the lingual root
- 13. Maxillary First Molars Distal Surface Crown: Visible buccal and occlusal surfaces An almost straight cervical line Root: All three roots visible (only the border of the Mesiobuccal root can be seen) A depression from the cervical line to the distobuccal root No concavity in the root bifurcation
- 14. Maxillary First Molars Occlusal Surface Dimensions that are wider from the buccal to the lingual than from the mesial to the distal Four functioning cusps and a small fifth cusp (in order of size): mesiolingual, Mesiobuccal, distobuccal, distolingual, and cusp of Carbelli Grooves: buccal, central, transverse groove of the oblique ridge, and distal oblique, the lingual and fifth cusp groove are visible from this view Fossae: central, distal linear, mesial triangular, distal triangular
- 15. Maxillary Second Molar 2, 15
- 16. Maxillary Second Molar Universal Number: 2,15 Eruption Date: 12-13 years old First Evidence of Calcification: 2.5-3 years old Crown Completion:7-8 years old Root Completion: 14-16 years old
- 17. Maxillary Second Molar Function: mastication and comminution Length of Crown: 7mm Length of Root: 11mm buccal, 12mm lingual Antagonists: mandibular second and third molars
- 18. Maxillary Second Molar Identifying Features Four cusps: Mesiobuccal, distobuccal, mesiolingual, distolingual Three roots: Mesiobuccal, distobuccal, lingual Three pulp canals: one in each root
- 19. Maxillary Second Molar Maxillary second molar is similar to the maxillary first molar in size, shape and function, but has the following differences: Both the crown and root are slightly smaller The second molar only has four cusps (no cusp of Carabelli) The roots are not as divergent. They are closer together The occlusal surface has more supplementary grooves There is no transverse groove of the oblique ridge
- 20. Maxillary Second Molar Buccal Surface
- 21. Maxillary Second Molar Lingual Surface
- 22. Maxillary Second Molar Mesial Surface
- 23. Maxillary Second Molar Occlusal Surface Grooves: Buccal, lingual, distal oblique, and central groove Fossae: central, distal linear, distal triangular, and mesial triangular Cusps, in order of size: mesiolingual, Mesiobuccal, distobuccal, and distolingual
- 26. Maxillary Third Molar 1, 16
- 27. Maxillary Third Molar Universal Number: 1, 16 Eruption Date: 17-21 years old First Evidence of Calcification: 7-9 years old Crown Completion: 12-16 years old Root Completion: 18-25 years old
- 28. Maxillary Third Molar Function: mastication and comminution Length of Crown: 6.5mm Length of Root:11mm Antagonists: Mandibular third molar
- 29. Maxillary Third Molar Identifying Features Often the crown is heart shaped Fused roots (three roots) May resemble first or second molar
- 30. Maxillary Third Molar Clinical Considerations Because of developmental variations, there is no standard description for the maxillary third molars When well-formed, they will be smaller than, but similar to, the first molars in number of cusps and roots. Usually, however, the roots are fused and the crowns will have numerous supplemental (small, indistinct) grooves.