Principles of tooth preparation/ orthodontic continuing education


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Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.

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Principles of tooth preparation/ orthodontic continuing education

  1. 1. INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. Fixed PartialFixed Partial DenturesDentures
  3. 3. CLASSIFICATION OFCLASSIFICATION OF CROWNSCROWNS 1.1.according to materialsaccording to materials  Complete cast crown (full metal)Complete cast crown (full metal)  Metal ceramic crownMetal ceramic crown  all ceramic crown (metal free ceramic)all ceramic crown (metal free ceramic) 2.according to surfaces covered2.according to surfaces covered  Full veneer crownFull veneer crown  Partial veneer crownPartial veneer crown
  4. 4.
  5. 5. Inlay vsInlay vs CrownCrown
  6. 6. •An inlayAn inlay depends ondepends on internalinternal retention toretention to hold it withinhold it within thethe preparationpreparation
  7. 7. • A crown dependsA crown depends on externalon external retention toretention to resist removalresist removal • ExternalExternal retention isretention is provided byprovided by approximation ofapproximation of the restoration tothe restoration to the opposingthe opposing external axialexternal axial walls of thewalls of the preparationpreparation
  8. 8.
  9. 9. Biomechanical principlesBiomechanical principles ofof Tooth preparationTooth preparation 1.1. Preservation of tooth structurePreservation of tooth structure 2.2. Retention and resistance formRetention and resistance form 3.3. Structural durability of theStructural durability of the restorationrestoration 4.4. Marginal integrityMarginal integrity 5.5. Preservation of the periodontiumPreservation of the
  10. 10. Preservation of tooth structurePreservation of tooth structure  Do not remove excess of toothDo not remove excess of tooth structure ,structure , do not over taperdo not over taper  Tooth becomes weakTooth becomes weak  Pulp health gets jeopardisedPulp health gets jeopardised  Reduction must be adequate , lessReduction must be adequate , less reduction will lead toreduction will lead to overcontouredovercontoured restorationrestoration
  11. 11. Two plane reduction forTwo plane reduction for central incisorscentral incisors
  12. 12. Two planeTwo plane reductionreduction on buccalon buccal aspect ofaspect of mandibulamandibula r molarr
  13. 13.
  14. 14. •
  15. 15. • Retention isRetention is enhanced byenhanced by restricting the pathsrestricting the paths of insertionof insertion • A—multiple paths ofA—multiple paths of insertion andinsertion and removal , decreasedremoval , decreased retentionretention • B---additon of parallelB---additon of parallel sided grooves limitssided grooves limits path of insertion topath of insertion to one direction ,one direction , increases retentionincreases
  16. 16. • To produce anTo produce an optimal 6 degreeoptimal 6 degree taper, each opposingtaper, each opposing axial wall should haveaxial wall should have an inclination of 3an inclination of 3 degrees to the pathdegrees to the path of insertionof insertion
  17. 17.
  18. 18. a functional cuspa functional cusp bevel , in abevel , in a plane parallel toplane parallel to the opposingthe opposing cusp , givescusp , gives adequate bulkadequate bulk to the crownto the crown withoutwithout sacrificing thesacrificing the tooth structuretooth structure
  19. 19. if functional cuspif functional cusp bevel is omitted ,bevel is omitted , crown will becrown will be too thin in thistoo thin in this stress bearingstress bearing areaarea
  20. 20.  if crown thicknessif crown thickness is achieved byis achieved by overtapering theovertapering the axial wall ,axial wall , retention isretention is compromised .compromised . • also health of thealso health of the pulp may bepulp may be jeopardisedjeopardised
  21. 21. in absence ofin absence of functional cuspfunctional cusp bevel , the labbevel , the lab (technician)(technician) may overbulkmay overbulk the crown .the crown . this may leadthis may lead to occlusalto
  22. 22. A. ---- adequate axial reductionA. ---- adequate axial reduction B. ---- inadequate axial reduction results inB. ---- inadequate axial reduction results in crown with thin , weak wallscrown with thin , weak walls C. ---- bulky crown results in promoting plaqueC. ---- bulky crown results in promoting plaque accumulation , jeopardising the health ofaccumulation , jeopardising the health of periodontiumperiodontium (( nietherniether flatflat nornor fatfat ))
  23. 23.