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John Beumer III DDS, MS Robert F. Faulkner, DDS Kumar C. Shah DDS, MS Division of Advanced Prosthodontics, UCLA Restora(on of posterior quadrants Pa(ent selec(on, and treatment planning This program of instruc(on is protected by copyright ©. No por(on of this program of instruc(on may be reproduced, recorded or transferred by any means electronic, digital, photographic, mechanical etc., or by any informa(on storage or retrieval system, without prior permission.

Restoration of posterior quadrants

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  1. 1. John Beumer III DDS, MS Robert F. Faulkner, DDS Kumar C. Shah DDS, MS Division of Advanced Prosthodontics, UCLA Restora(onofposteriorquadrants Pa(entselec(on,andtreatmentplanning Thisprogramofinstruc(onisprotectedbycopyright.Nopor(onofthis programofinstruc(onmaybereproduced,recordedortransferredbyanymeans electronic,digital,photographic,mechanicaletc.,orbyanyinforma(onstorageor retrievalsystem,withoutpriorpermission.
  2. 2. Table of Contents Treatment options RPDs Fixed dental prostheses Endodontic therapy Implant biomechanics Number of implants per unit Staggered vs. linear configurations Length, implant diameter Cantilevers Occlusal factors Parafunctional activity Strategies to avoid biomechanical related problems Anatomic limitations and the role of preprosthetic surgery Grafting Distraction osteogenesis Socket augmentation and ridge preservation Placement of implants into fresh extraction sites
  3. 3. Implants vs RPDs vCost vMas(ca(oneciency(Kapuretal,1987, 1989.1991a,1991b,1997) Implants may not always be the best choice for the patient
  4. 4. RPDs and Implants Position and lengths Implant site most favored 1st molar position Lengths vary but in recent times some clinicians have reported successful outcomes when using implants as short as 6 mm in length (Gates et al, 2012). InextensionbaseRPDs(KennedyClassIandII)to supplementthesupport,stabilityandreten(onprovided bytheexis(ngden((on.
  5. 5. RPDs and Implants Unanticipated implant failures Poor quality bone Unfavorable biomechanics
  6. 6. Endodontics vs Implants vHigh level of predictability vExtraction of the tooth and replacement with an implant is based on volume and integrity of tooth structure remaining vCost advantages to endo plus restoration vEsthetics Retention of bone and soft tissue
  7. 7. Conventional fixed vs implants o Predictablewhenabutmentsingood condi(on(Pieturssonetal,2007; Walton,2009) o Costeec(ve o Implantspreferredwhenabutments arevirginornearvirgin 15 year follow-up
  8. 8. Things can go wrong with implants Biomechanics Partially Edentulous Patients ! Because of the curve of Spee and the distal angulation of the implants, the occlusal loads (arrow) are nonaxial. ! Note the bone loss around the implants. Linear configurations in the posterior region, such as in this patient, are particularly vulnerable to the effects of nonaxial loading, particularly brachycephalic individuals. Nonaxial loads and implant overload in posterior quadrants Semi-precision attachments usion of the natural tooth abutment ears after delivery the patient noticed the premolar o intrude. Exam revealed that the screw retaining the ad become loose, hence the rotation of this crown. Bruxism - Case Report This is a five year followup x-ray of a patient with an implant supported fixed partial denture. Closer exam revealed both implants to be fractured . The patient was a heavy bruxer. Six months later he presented with significant bone loss around both implants. Bruxism - Case Report This is a five year followup x-ray of a patient with an implant supported fixed partial denture. The patient was a heavy bruxer. Six months later he presented with significant bone loss around both implants. Implant overload Bone loss Implant fractures Peri-implantitis Impaction of cement Implant loss
  9. 9. How can we avoid these complications? Biomechanics Partially Edentulous Patients ! Because of the curve of Spee and the distal angulation of the implants, the occlusal loads (arrow) are nonaxial. ! Note the bone loss around the implants. Linear configurations in the posterior region, such as in this patient, are particularly vulnerable to the effects of nonaxial loading, particularly brachycephalic individuals. Nonaxial loads and implant overload in posterior quadrants Semi-precision attachments usion of the natural tooth abutment ears after delivery the patient noticed the premolar o intrude. Exam revealed that the screw retaining the ad become loose, hence the rotation of this crown. Bruxism - Case Report This is a five year followup x-ray of a patient with an implant supported fixed partial denture. Closer exam revealed both implants to be fractured . The patient was a heavy bruxer. Six months later he presented with significant bone loss around both implants. Bruxism - Case Report This is a five year followup x-ray of a patient with an implant supported fixed partial denture. The patient was a heavy bruxer. Six months later he presented with significant bone loss around both implants. Implant overload Bone loss Implant fractures Peri-implantitis Impaction of cement Implant loss
  10. 10. Implant Biomechanics and Treatment Planning Why should we be concerned with implant biomechanics when we develop a plan of treatment? Because if we are not, we risk implant overload and prosthesis failures such as fracture and screw loosening. Implant overload can lead to bone loss around implants and eventually implant failure.
  11. 11. Boneisadynamicstructure.Excessiveloadsleadto aresorp(veremodelingresponse Hoshaw et al (1994) observed a resorptive remodeling of the bone around implants subjected to excessive axial loads (300N). Bone loss was observed at the crest around the neck of the implant and in the zone of bone adjacent to the body of the implant Brunski et al, 2000 Recent studies by Myata et al (1998, 2000, 2008) and Nagasawa et al, (2013) have reconfirmed Hoshaw and Brunskis original hypothesis Is it possible to overload the bone anchoring an osseointegrated implant?
  12. 12. Implant Overload - Basic Mechanism vExcessiveocclusalloads,oangleloads, bendingmoments vResul(ngmicrodamage(fractures,cracks, anddelamina(ons) vResorp(onremodelingresponseofboneis provoked vIncreasedporosityofboneintheinterface zonesecondarytoremodeling vViciouscycleofcon(nuedloading,more micro-damage,moreporosityun(lfailure
  13. 13. Implant overload l ImplantalignmentmustconsiderthecurveofSpeeandthe curveofWilson l Inbothsitua(onstheimplantswillbeexposedtobending momentsandpredisposetoimplantoverload. Occlusal force
  14. 14. Implantoverload In posterior quadrants when implants are aligned in a linear fashion they should be aligned consistent with the curve of Spee and the curve of Wilson Curve of Wilson
  15. 15. Implant Biomechanics Whatistheloadbearingcapacityofosseointegrated implantsupportedrestora(ons? Istheloadcarryingcapacityofimplantprostheses inuencedbythequalityofthebonesites? Whatfactorscontrolthemagnitudeoftheloadsthat aredeliveredthroughtheimplantintothesurrounding bone? Whatloadsshouldimplantbornerestora(onsbe designedtoresist?
  16. 16. Karnak The Great Wall PontdeGard You must over engineer your implant restorations, particularly when restoring posterior quadrants with linear configurations in order achieve predictable long term results. Implant Biomechanics
  17. 17. ImplantBiomechanics LOAD BEARING CAPACITY 1.Qualityofbonesite 2.Qualityofbone implantinterface 3.Implantmicrosurfaces Machinedvs microroughvs nano-enhanced surfaces 4. Implant Number and Arrangement Linear vs Curvilinear Length and diameter Angulation ANTICIPATED LOAD (Affected by) Occlusal factors Cusp angles Width of occlusal table Guidance type Anterior guidance Group function Cantilever forces Connection to natural dentition Size of occlusal table Cantilevered prostheses Parafunctional habits (bruxism) Brachycephalics
  18. 18. Loadbearingcapacity Implantnumberandarrangement Boththenumberandarrangementof implantsaecttheloadcarrying capacityofanypar(cularimplant supportedrestora(on. Curvilineararrangementswithstand moreloadthanlineararrangements
  19. 19. Loadbearingcapacity LinearvsCurvilinear o Curvilineararrangementshavethegreatestload bearingcapacity. o Crossarchstabiliza(on
  20. 20. Loadbearingcapacity LinearvsCurvilinear vCurvilineararrangementssuchasseeninthispa(entare verypredictable vThisPFMxedprosthesisis12yearspostinser(on. Occlusion: Group function 12 year follow-up12 year follow-up
  21. 21. Loadbearingcapacity LinearvsCurvilinear Linear configurations restoring the cuspid region, such as the patient on the right, are unpredictable, whereas curvilinear implant arrangements such as shown on the left are very predictable. Predictable Not predictable
  22. 22. Maxilla vs Mandible Bone quality vThesizeandshapeofthetrabeculae isdierentinthemandibleas comparedtothemandible. vThismaybeoneofthereasonswhy theloadcarryingcapacityofimplant supportedprosthesesrestoring posteriorquadrantsinthemandible appearstobesuperiortothoseinthe maxilla. CourtesyDr.C.Stanford
  23. 23. Number of Implants per Unit Posterior Maxilla Whenrestoringposteriorquadrantswithimplantsweareforcedtouse lineararrangementsbyanatomicnecessity.Thereforeinmostinstances: *The third implant dramatically improves the biomechanics of the restoration Oneimplantfor eachdentalunit. Atleastthreewhere possibleinextension areas. One dental unit = premolar
  24. 24. Number of Implants per Unit Posterior Maxilla The distal implants failed 30 months after loading in both these patients because of implant overload.
  25. 25. Number of Implants per Unit Posterior Maxilla o The distal implant failed 30 months after loading in both these patients because of implant overload. o The patient was a bruxer
  26. 26. Number of Implants per Unit Posterior Maxilla These implants failed 66 months after loading because of implant overload. Group function was used to restore this patient. Result: Application of excessive lateral forces Implant failure Another problem: Cusp angles too steep and the occlusion was tripodized
  27. 27. Number of Implants per Unit Posterior Maxilla Space allowed only two implants to be placed in this patient. However, note anterior guidance. Design the occlusion to minimize the delivery of nonaxial forces
  28. 28. Number of Implants per Unit Posterior Maxilla Only two implants were placed. Note anterior guidance
  29. 29. Bone Augmentation Horizontal Deficiencies Predictable Lessocclusalforce Fixa(onofthegraeiseasyto accomplish Thebloodsupplytothegraeis usuallyquitegood
  30. 30. Bone Augmentation Vertical Defects Lesspredictable Problems: Tensiononthewoundsecondaryto closureof(ssueaps Poorbloodsupply Dicultyinachievingxa(on Result: Relapse(resorp(on)rateis75%
  31. 31. Sinus Augmentation Advantagesoveronlaygra7s Resorp(onprobablylessthan25% Challenge Elevatethesinusmembranewithoutperfora(on Sinus membrane Bone graft Bone of the residual allveolar ridge
  32. 32. SinusAugmenta(on Implants can be placed simultaneous when there is 4-5 mm over the sinus and primary immobilization of the implants can be achieved Otherwise implant placement delayed for 6-9 months
  33. 33. Sinus augmentation Predictable(Jensenetal, 1997;AghalooandMoy, 2007) Sourcesofgraematerial includechin,ramus,andiliac crestsome(mesmixedwith bonesubs(tutes. Complica(ons Lossofgraematerial Blockageoftheos(um Incompleteeleva(onofthe sinuspreventnormalsinus drainage
  34. 34. PRE-OP 4M POST-OP 2M POST-OP
  35. 35. Sinus augmention This patient was restored following a sinus lift and graft. Autogenous chin bone was used. She is 10 years post treatment and doing well. Note: Best results achieved when there is 4-5 mm of normal bone over the sinus before the procedure
  36. 36. Sinus augmentation Thispa(entwasrestoredfollowinga bilateralsinuslieandgrae. Freezedriedbonewasusedtograethelee maxillarysinus. Theimplantsplacedinthisgraefailed18 monthsfollowingdeliveryoftheimplant supportedxedpar(al denture.
  37. 37. CrestalAugmenta(on Augmenta(onofver(caldefectsinposteriormandibular quadrantswithfreeautogenousbonegraeshasbeen unpredictable.Followingsurgerytherelapserateisabout75%and furtherbonelossisalsoseenaeerloading.Why? a) Tensiononthewounduponclosure b) Poorbloodsupply c) Dicultyisachievingproperxa(onofthegrae
  38. 38. Pterygoid implants As an alternative to sinus augmentation Success rates in excess of 90% Courtesy Dr. A. Pozzi
  39. 39. *Removable Partial Dentures* Removable partial dentures properly designed and fabricated provide the patient with masticatory function equivalent to that obtained with an implant supported fixed partial dentures (Kapur, et al, 1992) and this service should be offered to the patient before grafting is considered.
  40. 40. Number of Implants per Unit Posterior Mandible Two is sufficient for most patients Why? vThe trabecular bone is more dense vCortical layer is thicker
  41. 41. Number of Implants per Unit Posterior Mandible vThere is bone over the nerve for only short implants vBone quality is poor vWhen restoring four dental units Three are recommended when:
  42. 42. Number of Implants per Unit Posterior Mandible Three implants were used to restore four units in this patient
  43. 43. Posterior Mandible Limiting Factors vInferior alveolar nerve(arrow) vInsufficient bone over the nerve to permit placement of a 10 mm or longer implant vUni-cortical anchorage (arrow)
  44. 44. Many patients such as this one, present with moderate to severe resorption precluding placement of implants unless the inferior alveolar nerve displaced. Posterior Mandible Limiting Factors
  45. 45. Displacement of the Inferior Alveolar Nerve Thisprocedureenablesplacementofimplantsofsucientlengthwithbicor(calanchorage. Althoughtheriskofnerveinjuryisrela(velysmallthemorbidi(esassociatedwithinjury maybesevere. Therefore,theseissuesmustbethoroughlydiscussedwiththepa(entbeforeproceeding withtheprocedure.
  46. 46. Crestal Augmentation Augmenta(onofver(caldefectsinposteriormandibularquadrantswithfree autogenousbonegraes(A)hasbeenunpredictable.Followingsurgerytherelapserate isabout75%andfurtherbonelossisalsoseenaeerloading(B).Why? a)Tensiononthewounduponclosure b)Poorbloodsupply c)Dicultyisachievingproperxa(onofthegrae BA Presently,distrac(onosteogenesisistheonlyreasonably predictablemethodforenhancingthissitever(cally.
  47. 47. Mandibular Onlay Grafting Patients = 13 Total grafts = 21 Follow-up: 3 mos 72 mos Avg. = 26 mos Avg. height gained with block graft = 4.21 mm Avg. height of graft remaining on f/u = 1.05 mm Overall, 75% of initial graft height was lost Complication(s) 6 of 21 sites demonstrated wound dehiscence 28.6% complication rate
  48. 48. Distraction Osteogenesis 4-5 mm of bone required over the nerve Distract 1mm per day Relapse rate is 25 % Wait 6 months for consolidation before implant placement
  49. 49. Horizontal vs vertical augmentation Predictable
  50. 50. Use of Short Wide Diameter Implants in the Posterior Mandible This practice has not been predictable. The short implants are particularly prone to occlusal overload and bone loss. This is a 2 and 7 year follow-up x-ray of two 6 mm diameter implants.
  51. 51. UseofShortWideDiameter ImplantsinthePosteriorMandible The implants failed 15 years after insertion.
  52. 52. If implants of adequate length cannot be used, consider removable partial dentures Mastication efficiency of distal extension RPDs is equivalent to implant supported fixed partial dentures.
  53. 53. When in doubt add the 3rd implant in posterior quadrant cases. Minimize the length and width of the occlusal table Linearcongura(ons Over engineer your cases
  54. 54. Over-engineer your linear quadrant cases vWhen in doubt re: the quality of the implant site bone, history of parafunction etc., add the third implant
  55. 55. Over-engineer your linear quadrant cases vMinimize the width of the occlusal surfaces. They should be no wider than a premolar Note: The buccal-lingual dimension is excessive However,thereisaawinthedesignofthiscase. Whatisit?
  56. 56. Staggered vs linear configuration in posterior quadrants This has been studied using a photoelastic model by Itoh, et al, 2003 Staggered implant configuration 1.5 mm 1.5 mm 1.5 mm Straight line implant configuration
  57. 57. Staggered vs linear configuration Staggered implant configuration 1.5 mm 1.5 mm 1.5 mm Straight line implant configuration Itoh and Caputo, et al 2003 Isitbiomechanicallymorefavorable? vYes,par(cularlywithspecic chewingcycles.Nonlinear arrangementsresistlateralforces moreeec(vely vIstheimprovementclinically signicant?Thisisunknown
  58. 58. Staggered vs linear configuration Staggered implant configuration 1.5 mm 1.5 mm 1.5 mm Straight line implant configuration Probably not. In the posterior quadrants you cant get enough stagger to make much of a difference biomechanically. Itoh and Caputo, et al 2003 Isitfeasibleintheposteriorquadrants?
  59. 59. Implants in Compromised Sites Posterior maxilla Posterior mandible over the inferior alveolar nerve in partially edentulous patients Craniofacial application Theore(callyperhaps. Howeverweneedwell designedclinicaloutcome studiestodetermine predictability Canweuseshorterimplants?
  60. 60. Length and diameter of Implants vShort implants, such as this 7 mm screw shaped implant, demonstrate unfavorable stress distribution patterns as seen in this study performed with finite element analysis. Longer implants distribute stresses more favorably. vGiven the bone anchorage achieved with modern surfaces, failures are most likely to occur in the trabecular bone vFailure rates approach 25% for machine surface implants 7 mm in length (Wyatt and Zarb, 1998; Winklet et al, 2000) Avoid the use of implants less than 10 mm in length and 4mm in diameter when restoring posterior quadrants. Cho et al, 1993
  61. 61. Two year followup data from Moy and Sze,93 Note the high failure rates with the 7 mm and 10 mm implants in the posterior maxilla. LengthanddiameterofImplants
  62. 62. Implant length vs diameter Using a photoelastic model, Caputo et al, 2002 attempted to determine whether increasing the diameter of the implant or increasing the length of the implant had a significant impact on stress distribution. They concluded that: Does increasing the diameter compensate for the lack of sufficient length?
  63. 63. Implant length vs diameter Lingual load Axial load Buccal load Most equitable load transfer with axially directed loads. Under comparable loading conditions, the stresses transferred by the wide diameter implant were only slightly lower than the same length narrow implant. For implants tested, increased length was more important than diameter in stress reduction. Caputoetal,2002
  64. 64. Implant length vs width Failure rates of short wide diameter implants approaches 20%. 2 years 8 years Cho,InHoetal, 1992 14 years
  65. 65. Implantlengthvswidth l Over-prepara(onand/oroverhea(ngoftheosteotomysite.This mayprecipitateearlylossofbone,par(cularlyaroundtheneckof theimplant. l Implantoverload. l Insucienttrabecularboneencasingtheimplantonitsbuccal andlingualaspectleadingtoprogressiveboneloss.
  66. 66. Ideal Implant Diameter 4-5 mm in diameter Less than 4 mm the rate of implant fracture is unacceptably high Implants 3.75 mm in diameter have a 5-7% fracture rate More than 5 mm the higher the failure rate. Implants 6 mm in diameter have a 20% failure rate Implants 4-5 mm in diameter have a less than 5% failure rate
  67. 67. Implant Angulation Posterior vs Anterior v Implants in the posterior quadrants should be placed so that occlusal loads can be directed axially in the posterior quadrants. v In the anterior region, anatomic necessity precludes implant placement perpendicular to the occlusal plane. v However, the forces used to incise the bolus are only about of those used posteriorly to masticate the bolus. For this and other reasons implant overload is rarely seen in the anterior regions.
  68. 68. vNonaxial loads result in load magnification. Kinni et al (1987), using photoelastic analysis and Cho et al (1993), using finite element analysis, demonstrated that nonaxial loads concentrated potentially clinically significant stresses around the neck and at the tip of the implant. Implant angulation Cho,InHoetal,1992
  69. 69. Curve of Wilson ImplantAngula(on Curve of Wilson Curve of Spee
  70. 70. Implant angulation vImplantalignmentmustconsiderthecurveof SpeeandthecurveofWilson Nonaxialloadsandimplantoverloadinposterior quadrants
  71. 71. ImplantAngula(on CAC-CAMtechnologiespermit: lDevelopmentofvirtualdiagnos(cwax-ups lSurgicaldrillguideswhichpermitcontrolled direc(onaldrillingasopposedtofreehanddrilling
  72. 72. ImplantAngula(on Controlled directional drilling is preferred because it results in few errors in implant angulation and position as opposed to free hand drilling
  73. 73. ImplantAngula(on CAD-CAM can also be used to design and mill custom abutments and prototype restorations
  74. 74. Cantilevers and Linear Configurations in Posterior Quadrants They are particularly detrimental and are therefore contraindicated when using linear configurations to restore posterior quadrants. They cause subject the implants to bending, load magnification and overload the bone around the implant adjacent to the cantilever. MesialanddistalcanClevers
  75. 75. Theyarewelltoleratedwhen implantsupportedrestora(ons areusedtorestorethe edentulousmandible,solong as: Thecan(leveredsec(oniswithina reasonablelimit Theimplantsarearrangedina reasonablearcofcurvature. Rigidframeworkswithcrossarch stabiliza(onareused Cantilever forces Cantilever section
  76. 76. Cantilevers Implant Overload Note the bone loss around the dental implants adjacent to the cantilever. Restorations designed in this fashion, especially in the posterior maxilla, have a poor prognosis.
  77. 77. Limit buccal, lingual and cantilevers The occlusal tables are excessively wide in this case. Buccal and lingual cantilever forces may lead in selected patients to: Prosthesis failures Porcelain fractures Screw fractures Implant overload and bone loss
  78. 78. Occlusal Anatomy and Biomechanics vNarrow occlusal table Goal: Reduce the buccal - lingual cantilever effect
  79. 79. Avoidbuccalandlingualcan(levers The occlusal table must be narrowed to avoid buccal and lingual cantilevers. Molars should be no wider than premolars as shown in these two examples.
  80. 80. Solitary implants restoring single molars Cantilever effect When the food bolus is applied to the marginal ridge (B), the restoration is easily tipped because the crown is supported by such a narrow platform. Result: Cantilever forces lead to screw loosening, implant fracture and overload the bone anchoring the implant. BA
  81. 81. Fracture Implant fractured after 30 months of function Solitary implants restoring single molars Cantilever effect
  82. 82. Single tooth restorations in the molar region Cantilever effect This implant was too short and too narrow to withstand occlusal loads and bone loss caused by the resorptive remodeling response led to its loss. 4 mm diameter implant MesialcanClever
  83. 83. Single Tooth Restorations Distal Extension Defects
  84. 84. Distal Extension Defects
  85. 85. Restoration of single molar sites - Solutions In this patient a wide diameter implant was used to restore the first molar. Eliminatethecan(leverbyusing Widediameter Mul(pleimplants
  86. 86. Restoration of single molar sites Custom abutment Lingual set screw Inthispa(ent,two4mmdiameterimplantwereusedto restoretherstmolar.Thewidthoftheocclusaltablewas limitedtothewidthofthe naturalpremolar, therebyelimina(ngany possiblebuccalor lingualcan(levers.
  87. 87. Restoration of single molar sites Note: Hygiene access for proxy brush Note width of occlusal table
  88. 88. Splinted vs Nonsplinted Pa(entpresentedwithafailedendodon(callytreated#30.This toothwasextractedandthespacerestoredwithanimplant. Severalyearslatertheendodon(ctherapyon#29failedandthistoo wasreplacedwithandimplantrestora(on.
  89. 89. SplintedvsNonsplinted Theseimplantswerenotsplinted Notetheanteriorgroupfunc(on Mandibularbonesitesfavorable Pa(entdidnotdemonstrateevidence ofparafunc(onalac(vity Longimplants
  90. 90. SplintedvsNonsplinted From a theoretical biomechanical perspective splinted designs are more favorable than unsplinted designs, but whether this difference is clinically significant has yet to be determined with properly desinged clinical outcome studies.
  91. 91. Criteria for splinting If the patient shows signs of parafunctional activities. If the quality of bone anchoring the implants is questionable (type IV bone, or if the implants are in grafted sites). Misangled implants ie, implants that are not perpindicular to the plane of occlusion. If relatively short implants have been employed (less than 10 mm in length). If the patient presents with or is to be restored with group function. Linear configurations of implants lack cross arch stabilization and are less able to resist bending moments (nonaxial loads) and implant angulations that are not ideal result in the application of bending moments. All maxillary posterior quadrant cases.
  92. 92. lWhenimplantsof10inlengthorlongerareplaced. lWhenthequalityofboneisgood. lImplantsplacedwithperfectangula(on (perpendiculartotheplaneofocclusion) lAbsenceofparafunc(onalac(vity. Nonsplinteddesignsareusedwhenrestoringposterior quadrantsonlyinthemandibleandunderthefollowing circumstances:
  93. 93. Connecting Implants to Natural Dentition How do you minimize cantilever forces? Semiprecision (nonrigid) vs rigid attachments
  94. 94. Connecting Implants to Natural Dentition Posteriorimplantapachedtoanteriorabutment Rigidapachment Nonrigidapachment Nishimuraetal,1999 Loads applied in the pontic area
  95. 95. Connecting Implants to Natural Dentition Rigidvsnonrigidapachments Nodierenceaslongasthenonrigid(semi-precision) apachmentsremainfullyseated
  96. 96. Semi-precision Attachments Problems vIntrusion of the natural tooth leading to: vCantilever affect vLoad magnification vResorptive remodeling response vBone loss (arrows) Semi-precision attachment
  97. 97. Semi-precision attachments Intrusion of the natural tooth abutment Eleven years after delivery the patient noticed the premolar began to intrude. Exam revealed that the screw retaining the molar had become loose, hence the rotation of this crown.
  98. 98. Rigid Attachments* Intrusion is prevented with rigid attachments Screw retained tube lock attachment *Shared support
  99. 99. Rigid Attachments* Screwretainedtubelockapachment *Shared support
  100. 100. Occlusal Anatomy and Biomechanics Narrow occlusal table Flat cusp angles Lingualize or buccalize
  101. 101. Occlusal Anatomy and Biomechanics vNarrow occlusal table Goal: Reduce the cantilever effect
  102. 102. Parafunctional activity Thisisaveyearfollowupx-rayofa pa(entwithanimplantsupported xedpar(aldenture. Closer exam revealed both implants to be fractured . The patient was a heavy bruxer. Six months later he presented with significant bone loss around both implants.
  103. 103. Parafunctional activity This patient did well with this implant supported fixed partial denture for more than four years (note 4 year follow-up x-ray). However, soon thereafter, the anterior implant fractured, the bridge was removed and a trephine used to remove the implant.
  104. 104. Occlusion Partially edentulous patients when restoring posterior quadrants with implants Anterior guidance Anterior group function Group function Courtesy Dr. M. Hamada
  105. 105. Implants in the Maxillary Cuspid Region Mutually Protected Occlusion (Group Function) Patient in right working position. Note lateral guidance is provided by the premolars and the central incisor. Result: Lateral forces on the implants are minimized. Courtesy Dr. M. Hamada
  106. 106. Anterior (canine) guidance Space allowed only two implants to be placed in this patient. However, note anterior guidance. Design the occlusion to minimize the delivery of nonaxial forces
  107. 107. Mutually Protected Occlusion Only two implants have been placed to restore the corner of the arch in this patient. (b,c) The implants were inclined towards the labial and milled customized abutments were used. Note that the minimal height of the buccal wall of the posterior abutment. As a result retention was designed to be achieved with lingual set screws as opposed to cement.
  108. 108. Mutually Protected Occlusion (d)Thenishedprosthesis. (e)Itisadjustedsothatcontactduringlateral excursionisprovidedbythenaturalden((onandnottheimplants.
  109. 109. Anterior Group function with Centric Only Contact Note: The cusp angles are flat and the occlusal tables are narrow Result: Lateral forces on the implants are minimized
  110. 110. Restoring the Cuspids: Mutually Protected Occlusion (Group Function) Patient in right and left working position. Note lateral guidance is provided by the premolars and the central incisor. Result: Lateral forces on the implants are minimized. Right working Left working
  111. 111. Restoring the corner of the arch : Mutually protected occlusion plus implants Group function was used to distribute lateral loads as widely as possible in order to reduce the risk of implant overload
  112. 112. Materials for the occlusal surfaces o Layered porcelains o Susceptable to fracture o Milled monolithic zirconia o Metal occlusal surfaces
  113. 113. Metal Ceramic Resin Materials for the occlusal surfaces
  114. 114. Strategies to Avoid Implant Complications Place implants perpendicular to the occlusal plane (Note that the occlusal plane is not flat Curve of Wilson, Curve of Spee) Posterior quadrants of partially edentulous patients Placeimplantsintooth posi(ons When in doubt, always add the third implant Avoid use of cantilevers in linear configurations
  115. 115. Strategies to Avoid Implant Complications Restore anterior guidance PosteriorquadrantsofparCallyedentulouspaCents If required to attach to natural dentition, do so with a rigid attachment system Control the occlusal factors (cusp angles, width of the occlusal table) Avoid use of short implants (less than 10 mm
  116. 116. Preservation of bone and soft tissues following extraction lSocketaugmenta(on-treatmentoffreshextrac(on socketswithintactbuccalandlingualbonewalls. lRidgepreserva(on-treatmentoffreshextrac(on socketswithdecientbonewallsinordertomaintain ridgecontours. lRidgeaugmenta(on-augmen(ngedentuloussites thatareinsucientforimplantplacement.
  117. 117. Socket augmentation Socketaugmenta(onisdenedastreatmentoffreshextrac(on socketswithintactbuccalandlingualbonewalls. vMany methods attempted vNo consensus re: its value or the best method CourtesyDr.T.Han
  118. 118. Socketaugmenta(on vWhen successful, following healing implants can be placed in ideal positions with proper angulation vMany methods attempted vNo consensus re: its value or the best method CourtesyDr.T.Han
  119. 119. Ridge preservation Ridgepreserva(onisdenedastreatmentoffresh extrac(on sockets with decient bone walls in ordertomaintainridgecontours. v Many methods attempted v No consensus re: its value or the best method CourtesyDr.D.Krill
  120. 120. Ridge preservation Ridgepreserva(onisdenedastreatmentoffresh extrac(on sockets with decient bone walls in ordertomaintainridgecontours. v Problematic in patient presenting with active infection. CourtesyDr.D.Krill
  121. 121. Ridge augmentation l Ridgeaugmenta(onisdenedasaugmen(ngedentuloussitesthat areinsucientforimplantplacement. Appears to the most predictable CourtesyDr.P.Moy
  122. 122. Loss of vertical and horizontal bone volume following extraction can be significant v3-4 mm of resorption can occur during the first 6 months post- extraction (Atwood et al, 1971 and others) vProbably secondary to expession of specific genes in oral mucosa to promote wound contraction and closure (Sukotjo et al, 2002; Suwanwela et al, 2011) Placement of Implants into Fresh Extraction Sites
  123. 123. PlacementofImplants intoFreshExtrac(onSites Will placement of an implant impact the process of resorption? It appears not. There will still be resorption of the facial plate of bone even in the presence of an implant placed immediately upon exstraction Radiographic finding of root resorption Courtesy Dr. TL Chang
  124. 124. Implants in fresh extraction sites Atrauma(cextrac(onandaplesssurgery lRememberthatthevasculatureofthelabialplateassociated withthePDLhasbeensignicantlycompromisedbythe extrac(on lEvenunderthebestofcircumstancestherewillberesorp(on ofthefacialplateofbone CourtesyDr.T.Han
  125. 125. Mucosal advancement flaps Facilitates hygiene The more keratinized tissue the better because over time the patient slowly loose the attached tissue, particularly on the buccal side of the mandibular molars
  126. 126. vVisitofr.orgforhundredsof addi(onallecturesonComplete Dentures,FixedProsthodon(cs, ImplantDen(stry,Removable Par(alDentures,Esthe(cDen(stry andMaxillofacialProsthe(cs. vThelecturesarefree. vOurobjec(veistocreatethebest andmostcomprehensiveonline programsofinstruc(onin Prosthodon(cs