Maxillary Molars

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Maxillary Molars

  1. 1. Generals of MolarsGenerals of Molars and Maxillary Molarsand Maxillary Molars Howard Chi, D.M.D.Howard Chi, D.M.D.
  2. 2. Learning ObjectivesLearning Objectives • Generals of MolarsGenerals of Molars • Anatomy of Maxillary MolarsAnatomy of Maxillary Molars
  3. 3. Generals of MolarsGenerals of Molars
  4. 4. General DescriptionGeneral Description Of MolarsOf Molars • There are 12 permanent molarsThere are 12 permanent molars • First, second and third on each side, bothFirst, second and third on each side, both on the upper and lower archon the upper and lower arch • Under universal numbering system they areUnder universal numbering system they are 1,2,3,14,15,16,17,18,19,30,31,321,2,3,14,15,16,17,18,19,30,31,32
  5. 5. General DescriptionGeneral Description Of MolarsOf Molars • The first molars are centered in the archThe first molars are centered in the arch anteroposteriorlyanteroposteriorly • This is one reason their loss is soThis is one reason their loss is so devastating to arch continuitydevastating to arch continuity • They are the largest and strongest teeth inThey are the largest and strongest teeth in the archthe arch
  6. 6. General Description Of MolarsGeneral Description Of Molars • Frequently, one or more of the third molarsFrequently, one or more of the third molars are congenitally missingare congenitally missing • This occurs in nearly 20% of the populationThis occurs in nearly 20% of the population Can be congenitally missing
  7. 7. General DescriptionGeneral Description Of MolarsOf Molars • The combined mesiodistal width of the threeThe combined mesiodistal width of the three mandibular molars on one side make upmandibular molars on one side make up 51% of the mesiodistal dimension of their51% of the mesiodistal dimension of their quadrantquadrant • The maxillary molars constitute 44% ofThe maxillary molars constitute 44% of their quadrants mesiodistal dimensiontheir quadrants mesiodistal dimension 51% 44%
  8. 8. FunctionFunction Of MolarsOf Molars • Play a major role in the mastication of foodPlay a major role in the mastication of food (chewing and grinding)(chewing and grinding) • Lost of first molar can result in more thanLost of first molar can result in more than 80mm of chewing surface gone80mm of chewing surface gone
  9. 9. Function OfFunction Of MolarsMolars • Important in maintaining vertical dimension ofImportant in maintaining vertical dimension of the facethe face • Important in maintaining continuity within dentalImportant in maintaining continuity within dental arches, thus keeping other teeth in alignmentarches, thus keeping other teeth in alignment • Function in esthetics by keeping the cheeks fullFunction in esthetics by keeping the cheeks full and keeping chin proper distance from the noseand keeping chin proper distance from the nose
  10. 10. Class TraitsClass Traits Of MolarsOf Molars • Crown Size And ShapeCrown Size And Shape – Have occlusal surfaces with three to five cusps – Have broader occlusal surfaces than other teeth
  11. 11. Class TraitsClass Traits Of MolarsOf Molars • Crown Size And ShapeCrown Size And Shape – Crowns of molars are wider mesiodistally than long occlusocervically – Are shorter occlusocervically than other teeth
  12. 12. Class TraitsClass Traits Of MolarsOf Molars • Taper From Buccal To LingualTaper From Buccal To Lingual – Molar crowns taper to the lingual (i.e. crown is narrower on the lingual surface than the buccal surface) – Exception may be maxillary first molars with large distolingual cusps (may taper toward the buccal)
  13. 13. Class TraitsClass Traits Of MolarsOf Molars • Taper To The DistalTaper To The Distal – From an occlusal view all molar crowns taper distally M D
  14. 14. Class TraitsClass Traits Of MolarsOf Molars • Contact AreasContact Areas – Mesial: At or near the junction of the occlusal and middle thirds – Distal: Middle third
  15. 15. Arch Traits Of MolarsArch Traits Of Molars Crown Shape From OcclusalCrown Shape From Occlusal Maxillary – square /parallelogram – B-L>M-D Mandibular – rectangular/pentagonal – M-D>B-L
  16. 16. Arch Traits Of MolarsArch Traits Of Molars Number and RelativeNumber and Relative Size of CuspsSize of Cusps Maxillary: 4-5 CuspsMaxillary: 4-5 Cusps – Crown centered over roots – ML cusp: Largest and longest; connects to DB cusp by the Oblique Ridge – ML>MB> DB>DL DL ML DB MB
  17. 17. Arch Traits Of MolarsArch Traits Of Molars MaxillaryMaxillary Cusp of Carabelli:Cusp of Carabelli: • If present, is the fifth andIf present, is the fifth and smallest cuspsmallest cusp • Usually on lingual of MLUsually on lingual of ML cusp of maxillarycusp of maxillary first molarsfirst molars
  18. 18. Arch Traits Of MolarsArch Traits Of Molars Number and Relative Size of CupsNumber and Relative Size of Cups • Mandibular: 4-5 CuspsMandibular: 4-5 Cusps – ML and DL cusps are nearly equal in size (in contrast to maxillary molars) – Distal Cusp is minor fifth cusp, found on the first and sometimes third molars
  19. 19. Arch Traits Of MolarsArch Traits Of Molars • Mandibular TiltMandibular Tilt – All mandibular teeth, including molars, tilt lingually when viewed from mesial or distal (this is not apparent on maxillary molars) – Crowns tilt distally relative to the long axis of the root B L
  20. 20. Arch TraitsArch Traits Of MolarsOf Molars • Maxillary RootsMaxillary Roots – MB, DB, and Palatal roots – Roots are nearly twice as long as the crown – Relative length: Palatal>MB>DB MBDB Palatal
  21. 21. Arch Traits Of MolarsArch Traits Of Molars • Maxillary RootsMaxillary Roots – Roots converge into a broad cervical root base called the Root Trunk
  22. 22. Arch TraitsArch Traits Of MolarsOf Molars • Mandibular RootsMandibular Roots – Two Roots (Mesial and Distal) – Mesial root is usually slightly longer than distal root – Mandibular root trunks are shorter than maxillary root trunks, especially on first molars Root Trunk
  23. 23. Anatomy ofAnatomy of Maxillary MolarsMaxillary Molars
  24. 24. Type Traits ofType Traits of Maxillary 1stMaxillary 1st and 2nd Molarsand 2nd Molars • Relative SizeRelative Size – Second molar is smaller than the first molar in the same mouth, especially M-D – 1st Molar is broader than the 2nd Molar – 2nd Molar crown is often tipped distally on the root trunk
  25. 25. Type Traits ofType Traits of Maxillary 1stMaxillary 1st and 2nd Molarsand 2nd Molars • Buccal GrooveBuccal Groove – Lies between buccal cusps and extends on the buccal surface to the middle third of the crown – Pit is sometimes present at the end of the groove that can be the site of caries
  26. 26. Type Traits ofType Traits of Maxillary 1stMaxillary 1st and 2nd Molarsand 2nd Molars • Proximal ContactsProximal Contacts Same as for all molars: – Mesial: Junction of occlusal and middle thirds – Distal: Middle third Mesial
  27. 27. Type Traits ofType Traits of Maxillary 1stMaxillary 1st and 2nd Molarsand 2nd Molars • Outline ShapeOutline Shape – The crown appears to tilt distally at the cervix – This, coupled with a short distobuccal cusp makes the crown appear shorter on the distal than the mesial
  28. 28. Type Traits ofType Traits of Maxillary 1stMaxillary 1st and 2nd Molarsand 2nd Molars • RootsRoots – Are attached to a root trunk (longer in second molars) at the cervical line – Apical to the root trunk there is a split into three roots – Furcation usually located at the junction of the cervical and middle thirds of the roots
  29. 29. Type Traits ofType Traits of Maxillary 1stMaxillary 1st and 2nd Molarsand 2nd Molars • RootsRoots – Three roots splitting of the root trunk is called a trifurcation
  30. 30. Maxillary FirstMaxillary First Molar RootsMolar Roots • Much variation in the shapes of rootsMuch variation in the shapes of roots • The MB and DB roots are often bent in suchThe MB and DB roots are often bent in such a way as to resemble the handles of a paira way as to resemble the handles of a pair of pliersof pliers • This is a contrast to second molars whichThis is a contrast to second molars which have MB and DB roots closer and morehave MB and DB roots closer and more nearly parallelnearly parallel 1st 2nd
  31. 31. Maxillary FirstMaxillary First Molar RootsMolar Roots • The MB and DB roots often curve distallyThe MB and DB roots often curve distally • The apical third of the MB rootThe apical third of the MB root maymay curvecurve distally enough to put its apex distal to thedistally enough to put its apex distal to the buccal groovebuccal groove
  32. 32. Maxillary SecondMaxillary Second Molar RootsMolar Roots • MB and DB roots less curved than on firstMB and DB roots less curved than on first molarmolar • More nearly parallel with each otherMore nearly parallel with each other • Both bent toward the distal in the apicalBoth bent toward the distal in the apical thirdthird 2nd
  33. 33. Lingual AspectLingual Aspect Of Maxillary MolarsOf Maxillary Molars • Crown - Relative Size and TaperCrown - Relative Size and Taper – Due to the prominent DL cusp, crown may be as wide or wider on the lingual for the first molar – This is not as likely on the second molar
  34. 34. Lingual AspectLingual Aspect Of MaxillaryOf Maxillary MolarsMolars • The crown of the second molar usuallyThe crown of the second molar usually appears smaller than the first molarappears smaller than the first molar • This is due mainly to the smaller orThis is due mainly to the smaller or nonexistent DL cuspnonexistent DL cusp 1st 2nd
  35. 35. Number And Description OfNumber And Description Of Lingual Cusps - First MolarLingual Cusps - First Molar • Two well defined cusps, ML and DLTwo well defined cusps, ML and DL • ML is usually the highest and largest of allML is usually the highest and largest of all cusps on any maxillary molarcusps on any maxillary molar • Often a fifth cusp, the cuspOften a fifth cusp, the cusp of Carabelli, which variesof Carabelli, which varies greatly in size and developmentgreatly in size and development 1st
  36. 36. Number AndNumber And Description Of LingualDescription Of Lingual Cusps - Second MolarCusps - Second Molar • There are two types of maxillary secondThere are two types of maxillary second molars based on number of cusps, 4 or 3molars based on number of cusps, 4 or 3 • On the four-cusp second molar there is aOn the four-cusp second molar there is a ML and DL cuspML and DL cusp • On the three-cusp second molar the DLOn the three-cusp second molar the DL cusp is missingcusp is missing
  37. 37. Roots Of First MolarsRoots Of First Molars From The LingualFrom The Lingual • On first molars the palatal root is the thirdOn first molars the palatal root is the third longest of any maxillary tooth (after caninelongest of any maxillary tooth (after canine and second premolar)and second premolar) • Tapers apically to a blunt or rounded apexTapers apically to a blunt or rounded apex • There is usually a depression on the lingualThere is usually a depression on the lingual aspect of the palatal rootaspect of the palatal root Depression
  38. 38. Roots Of Second MolarsRoots Of Second Molars From The LingualFrom The Lingual • The lingual (palatal) root is as long as theThe lingual (palatal) root is as long as the lingual root of the first molarlingual root of the first molar • The buccal roots bend towards the distalThe buccal roots bend towards the distal and are more paralleland are more parallel Note Distal Bend
  39. 39. Proximal AspectProximal Aspect Of First MolarsOf First Molars • CuspsCusps – From the mesial, the crown appears broad faciolingually – Two or three cusps can be seen from the mesial (MB, ML, and Cusp of Carabelli) – Distal cusps are shorter and generally not seen from the mesial 1 2 3
  40. 40. Proximal AspectProximal Aspect Of First MolarsOf First Molars • Mesial marginal ridge is moreMesial marginal ridge is more occlusal than distal, thus very little of theocclusal than distal, thus very little of the occlusal table can be seen from mesialocclusal table can be seen from mesial • There is considerable narrowing of theThere is considerable narrowing of the occlusal surface from crest of curvature,occlusal surface from crest of curvature, resulting in a narrow occlusal tableresulting in a narrow occlusal table
  41. 41. Proximal AspectProximal Aspect Of First MolarsOf First Molars • From the distal, four cusps are visible (mayFrom the distal, four cusps are visible (may also see Cusp of Carabelli)also see Cusp of Carabelli) Distal
  42. 42. Proximal AspectProximal Aspect OfOf Second MolarsSecond Molars • From the mesial and distal aspect, looksFrom the mesial and distal aspect, looks much like the first molar, but no cusp ofmuch like the first molar, but no cusp of Carabelli is presentCarabelli is present • DL cusp is absent on more than one third ofDL cusp is absent on more than one third of these teeththese teeth Mesial Distal
  43. 43. Crest OfCrest Of CurvatureCurvature • On the buccal is located in the cervicalOn the buccal is located in the cervical thirdthird • On the lingual (palatal) in the middle thirdOn the lingual (palatal) in the middle third L B
  44. 44. Taper NarrowerTaper Narrower To DistalTo Distal * On both first and second molars, the crown* On both first and second molars, the crown is narrower buccolingually on the distalis narrower buccolingually on the distal than the mesialthan the mesial 2nd Distal 1st Distal
  45. 45. MarginalMarginal RidgesRidges • On both first and second molars the mesialOn both first and second molars the mesial marginal ridge is concave and moremarginal ridge is concave and more occlusally located than the distal marginalocclusally located than the distal marginal ridgeridge • It is also longer buccolingually than theIt is also longer buccolingually than the distal marginal ridgedistal marginal ridge 2nd Mesial 1st Mesial
  46. 46. TuberculesTubercules • If present are usuallyIf present are usually found on the mesialfound on the mesial marginal ridge of firstmarginal ridge of first molars (rarely found onmolars (rarely found on 2nd molars or distal2nd molars or distal marginal ridge of firstmarginal ridge of first molars)molars) 1st Mesial
  47. 47. MarginalMarginal RidgeRidge GroovesGrooves • Marginal ridge grooves are more commonMarginal ridge grooves are more common on the mesial than the distalon the mesial than the distal • More common on first molars than secondMore common on first molars than second molarsmolars 2nd Mesial 1st Mesial
  48. 48. CervicalCervical LineLine • The mesial cervical line has a slightThe mesial cervical line has a slight occlusal curvatureocclusal curvature • There is slightly less curvature on the distalThere is slightly less curvature on the distal than the mesialthan the mesial 1st Distal 1st Mesial
  49. 49. • The mesial contact area is a the junction ofThe mesial contact area is a the junction of the middle and occlusal thirdsthe middle and occlusal thirds • The distal contact area is in the middleThe distal contact area is in the middle thirdthird 1st Distal 1st Mesial ProximalProximal ContactsContacts
  50. 50. Roots Of MaxillaryRoots Of Maxillary Molars FromMolars From The ProximalThe Proximal • From the mesial view the MB root is broadFrom the mesial view the MB root is broad buccolingually and is shorter than thebuccolingually and is shorter than the lingual rootlingual root • The MB root obscures the view of the DBThe MB root obscures the view of the DB rootroot • Apex of the MB root is in line with the MBApex of the MB root is in line with the MB cusp tipcusp tip MB
  51. 51. Roots Of MaxillaryRoots Of Maxillary Molars FromMolars From The ProximalThe Proximal • The lingual root is the longest and oftenThe lingual root is the longest and often banana shapedbanana shaped • On first molars extends well beyond theOn first molars extends well beyond the crown linguallycrown lingually • Usually curved buccolinguallyUsually curved buccolingually L
  52. 52. Roots Of MaxillaryRoots Of Maxillary Molars FromMolars From The ProximalThe Proximal • From the distal, the DB root is shorter andFrom the distal, the DB root is shorter and narrower than the MB rootnarrower than the MB root • Can see the outline of both roots from theCan see the outline of both roots from the distaldistal Distal
  53. 53. Roots Of MaxillaryRoots Of Maxillary Molars FromMolars From The ProximalThe Proximal • On second molars roots are much lessOn second molars roots are much less spread apartspread apart • Lingual roots is also straighter, usually notLingual roots is also straighter, usually not extending past confines of the crownextending past confines of the crown 2nd Mesial 1st Mesial
  54. 54. Occlusal AspectOcclusal Aspect OfOf First MolarsFirst Molars • The contour of first molarsThe contour of first molars is not square, but gives thatis not square, but gives that impression when compared to other teethimpression when compared to other teeth • It is roughly a parallelogramIt is roughly a parallelogram
  55. 55. Occlusal AspectOcclusal Aspect OfOf Second MolarsSecond Molars • The second molar is wider buccolinguallyThe second molar is wider buccolingually than mesiodistally and tapers to the lingualthan mesiodistally and tapers to the lingual • Much variation in second molar due to sizeMuch variation in second molar due to size and location of DL cuspand location of DL cusp
  56. 56. Occlusal AspectOcclusal Aspect OfOf Second MolarsSecond Molars • The four-cusp version of the second molarThe four-cusp version of the second molar is less square in appearanceis less square in appearance
  57. 57. Number AndNumber And Size Of CuspsSize Of Cusps • Generally there are four cuspsGenerally there are four cusps • First molar possess a fifth cusp 70% of theFirst molar possess a fifth cusp 70% of the timetime • Second molar may be missing the DL cuspSecond molar may be missing the DL cusp 14 3 2 5 14 3 2
  58. 58. Oblique Ridge UniqueOblique Ridge Unique To Maxillary MolarsTo Maxillary Molars • The oblique ridge connects the DB cuspThe oblique ridge connects the DB cusp with the ML cuspwith the ML cusp • It is present in second molars, but smallerIt is present in second molars, but smaller than the oblique ridge of first molarsthan the oblique ridge of first molars
  59. 59. Fossae OnFossae On Four-CuspFour-Cusp MolarsMolars • There are generally fourThere are generally four fossae on four-cusp molarsfossae on four-cusp molars 1) Central Fossa 2) Mesial Triangular Fossa 3) Distal Triangular Fossa 4) Distal Fossa 1 23 4
  60. 60. Grooves On Four-Cusp MolarsGrooves On Four-Cusp Molars Buccal Groove Central GrooveCentral Groove Transverse Groove Of The Oblique Ridge Lingual Groove Fifth Cusp Groove Distal Oblique Groove
  61. 61. Fossae And GroovesFossae And Grooves OnOn Three-Cusp MolarsThree-Cusp Molars • The distal fossae and both the distal obliqueThe distal fossae and both the distal oblique and lingual grooves are absentand lingual grooves are absent
  62. 62. Maxillary ThirdMaxillary Third MolarsMolars
  63. 63. Maxillary ThirdMaxillary Third MolarsMolars • General description difficultGeneral description difficult due to great variationdue to great variation • Roots and crown shorter than first orRoots and crown shorter than first or second molarsecond molar • Crown often possess more supplementalCrown often possess more supplemental groovesgrooves • May possess three, four or five cuspsMay possess three, four or five cusps
  64. 64. Roots OfRoots Of MaxillaryMaxillary Third MolarsThird Molars • Possess three roots, but more often they arePossess three roots, but more often they are fused for most of their lengthfused for most of their length • Roots are shorter than those of first andRoots are shorter than those of first and second molarsecond molar Mesial Buccal

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