Implant occlusion
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Dental implants require different biomechanical considerations from natural teeth. Also, with one of the criteria for long-term implant success being “occlusion,” it becomes imperative for the clinician to be well versed with the different concepts when rehabilitating with an implant prosthesis.
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Implant occlusion
- 2. OCCLUSION IN IMPLANT By: Dr GARIMA SINGH JR-2
- 3. CONTENTS • Introduction • Significance and goals • Implant protected occlusion • Principals of occlusions • Clinical considerations
- 4. INTRODUCTION MISCH ; 2nd edition Dental implants require different biomechanical considerations from natural teeth. Also, with one of the criteria for long-term implant success being “occlusion,” it becomes imperative for the clinician to be well versed with the different concepts when rehabilitating with an implant prosthesis.
- 5. SIGNIFICANCE OF IMPLANT OCCLUSION • Occlusal overload is one of the main causes of peri-implant bone loss and implant prosthesis failure because it can cause crestal bone loss, thus increasing the anaerobic sulcus depth and peri-implant disease states. MISCH ; 2nd edition LOAD
- 6. OVERLOADING FACTORS Overextended cantilever >15mm in the mandible(Shackleton et al. 1994) >10–12mm in the maxilla(Rangert et al. 1989; Taylor 1991) Parafunctional habits/Heavy bite force Excessive premature contacts >100 mm in human(Falk et al. 1990) Large occlusal table Steep cusp inclination Poor bone density/quality Inadequate number of implants Kim Y, Oh TJ, Misch CE, Wang HL. Occlusal considerations in implant therapy: clinical guidelines with biomechanical rationale. Clinical oral implants research. 2005 Feb;16(1):26-35.
- 7. GOALS OF IMPLANT OCLUSION Direct forces along long axis of implant. Minimize lateral forces on implant Distribute force over as many teeth and implants as possible. Place lateral forces as far anterior as possible MISCH ; 2nd edition
- 9. TOOTH IMPLANT 1. CONNECTION PDL Fibres Osseointegration 2.PROPRIOCEPTION Periodontal mechanoreceptors Osseoperception 3. TACTILE SENSITIVITY High Low 4. MOVEMENT a)APICAL b)LATERAL 25-100µm 56-108µm 3-5µm 10-50µm 6.MOVEMENT PATTERN Primary-immediate Secondary-gradual Gradual 7.FULCRUM TO LATERAL FORCE Apical third of root Crestal bone 9 MISCH ; 2nd edition
- 10. Evaluated occlusal awareness by perception of an interference and reported – when teeth oppose each other , interference is perceived at approximately 20µm. An implant opposing a natural tooth - 48µm Opposing implant - 64µm Tooth opposes implant overdenture - 108µm Because of decreased occlusal awareness of dental implants , adaptive responses like closure in a position other than centric occlusion is not perceived. Jacobs R, comparative evaluation of oral tactile function. Clin oral implant res 1991;2:75-80
- 11. R. Jacobs and D. van Steenberghe, Comparative evaluation of oral tactile function by means of teeth or implant supported prostheses, Clin. Oral Impl. Res. 2 (1991), 75–80. Average 100 micron less than 50 micron for implants BONE ACTUALLY GOES ON THE IMPLANTSURFACE Periodontal ligament
- 12. FORCE • A force applied to a dental implant is rarely directed absolutely longitudinally along a single axis. • A single occlusal contact most commonly result in a three-dimensional occlusal force. VECTOR RESOLUTION 12MISCH ; 2nd edition
- 13. DOMINANT CLINICAL AXES IN IMPLANT DENTISTRY MISCH ; 2nd edition
- 14. The manner in which forces are applied to implant restorations dictates the likelihood of system failure. If a force is applied some distance away from an implant or prosthesis, bending or torsional failure may result from moment loads. MOMENT LOAD MISCH ; 2nd edition
- 15. The moment of a force about a point tends to produce rotation or bending about that point. This imposed moment load is also referred to as a torque or torsional load MISCH ; 2nd edition
- 16. 100 N Moment Loads = force magnitude X moment arm (perpendicular distance from the point of interest to the line of action of the force) 16MISCH ; 2nd edition
- 17. 17MISCH ; 2nd edition
- 18. • Three clinical moment arms exist in implant dentistry : 18 A) OCCLUSAL HEIGHT B) CANTILEVER LENGTH C) OCCLUSAL WIDTH MISCH ; 2nd edition
- 19. 19MISCH ; 2nd edition
- 20. 20 OCCLUSAL HEIGHT MISCH ; 2nd edition
- 21. 21 MISCH ; 2nd edition
- 22. 22MISCH ; 2nd edition
- 23. Moment load resulting in crestal bone loss Bone loss further increases the occlusal height Increased occlusal height increases moment arm Increased mesiodistal and faciolingual rotations MISCH ; 2nd edition
- 24. MISCH ; 2nd edition
- 25. IMPLANT PROTECTED OCCLUSION By Dr Carl Misch and Dr . MW Bidez Medially positioned lingualized occlusion 14 considerations for following IPO scheme. MISCH ; 2nd edition
- 26. Occlusal considerations No premature occlusal contacts or interferences and Parafunction Occlusal table width Influence of surface area Mutually protected articulation Implant body 0rientation Crown cusp angulation Cantilevers MISCH ; 2nd edition
- 27. Crown height Parafunt -ional activity Occlusal contact positions Implant crown contour Design of prosthesis Occlusal materials Time of loading 27 MISCH ; 2nd edition
- 28. PREMATURE OCCLUSAL CONTACT Occlusal contacts that displaces a tooth, diverts the mandible from its intended movement or displaces a removable denture from its basal seat (GPT 9) The surface area of a premature contact is small , the magnitude of stress in the bone increases proportionately MISCH ; 2nd edition
- 29. 100N 12 DEGRESS AXIAL FORCE 100N X COS 12 = 97.81 N LATERAL FORCES 100N X SIN 12 = 20.79N TOTAL FORCE 118.60N A 12 DEGREE ANGLED FORCE INCREASES THE FORCE TO THE IMPLANT SYSTEM BY 18.6%
- 30. Implant prosthesis should barely make contact and surrounding arch should have initial contact. occlusal contacts axial and of similar intensity on implant crown and adjacent teeth under heavy force. Regular evaluation of occlusal contacts to prevent stress related complications MISCH ; 2nd edition
- 31. SURFACE AREA Adequate surface area sustain load transmitted to the prosthesis Wider implants Increase the number of implant Splinting of implants MISCH ; 2nd edition
- 32. 32 LIMIT SHEAR STRESSES ON BONE ESPECIALLY IN REGIONS OF DECREASED BONE DENSITY USE OF WIDER IMPLANTS INCREASE THE AMOUNT OF THE IMPLANT-BONE INTERFACE PLACED UNDER COMPRESSIVE LOADS MISCH ; 2nd edition
- 33. Implant restorations splinting lead to the better distribution of stress causing lower stress in implant body and bone in comparison with non splinted restorations, especially when the load is applied on the off center of the implant body. Angulations of the implant can reduce cantilever forces when the applied load is in the same direction of implant angulation.
- 34. OCCLUSAL TABLE WIDTH The width of occlusal table is directly related to width of implant body. Offset load Increased risk of porcelain fracture MISCH ; 2nd edition
- 35. 35MISCH ; 2nd edition Wide occlusal tables increase the moment arm for any offset occlusal loads Faciolingual tipping (rotation) can be significantly reduced by narrowing the occlusal tables and/or adjusting the occlusion to provide more centric contact.
- 36. MUTUALLY PROTECTED OCCLUSION An occlusal scheme in which the posterior teeth prevent excessive contact of the anterior teeth in maximum intercuspation and the anterior teeth disengage the posterior-teeth in all mandibular excursive movements (GPT 9)
- 37. oAnterior guidance of implant prosthesis with anterior implant should be shallow. oForces are distributed to segments of jaws with an overall decrease in force magnitude. MISCH ; 2nd edition
- 38. IMPLANT BODY ORIENTATION Implants are designed for long axis load. Anisotropy is a character of bone where mechanical properties depend on the direction in which bone is loaded. Separation of the load to compressive, tension and shear stresses. MISCH ; 2nd edition
- 39. Cortical bone most withstand compressive forces. Tensile forces: 30% Shear forces : 65% MISCH ; 2nd edition
- 40. Strength of cortical load decreases with increasing angle of applied load MISCH ; 2nd edition
- 41. Whenever lateral/angled cannot be eliminated: increasing diameter of angled abutments selecting implant design with greater surface area additional implant next to most angled implants splinting of implants MISCH ; 2nd edition
- 42. CROWN CUSP ANGLE Angle force influenced by cusp inclination Central groove width increased 2-3mm in posterior implant. Opposing cusp recontoured MISCH ; 2nd edition
- 43. CANTILEVERS A cantilever considered a Class 1 lever Force and length of cantilever are directly proportional to force on implant. MISCH ; 2nd edition
- 44. 44 Force twice as great will be applied to the farthest abutment from the cantilever. The force on the cantilever is a compressive force, whereas the force to the distal abutment is a tensile force. The load on the abutment closest to the cantilever (which acts as a fulcrum) is the sum of the other two components and is compressive. MISCH ; 2nd edition
- 45. 45 MISCH ; 2nd edition
- 46. 46 INCREASE IN IMPLANT NUMBER REDUCES BENDING LOADS AND SHEAR STRESSES REDUCES CANTILEVER LENGTHS For a system with 4-6 implants, Maxillary anteriors : 10mm Maxillary posteriors : 15mm Mandibular posteriors : 20mm MISCH ; 2nd edition
- 47. CROWN HEIGHT Crown height acts as vertical cantilever MISCH ; 2nd edition
- 48. Occlusal Contact Position No buccal cusp contact or marginal ridge contact Primary occlusal contact within diameter of implant within central fossa. Secondary occlusal contact within 1mm of periphery of implants MISCH ; 2nd edition
- 49. IMPLANT CROWN CONTOUR Due to ridge resorption, the direction of the remaining ridge shifts lingually and implant body is most often not under buccal cusp tip position of natural teeth. MISCH ; 2nd edition
- 51. Primary occlusal contacts should be the central fossa Maxillary implant opposing mandibular natural teeth, the mandibular buccal cusp acts as the primary tooth contact. Division A Bone MISCH ; 2nd edition
- 52. maxillary natural tooth and mandibular implant in division A bone , maxillary lingual cusp primary contact MISCH ; 2nd edition
- 53. Maxillary implant supported prosthesis vs mandibular implant supported prosthesis in divison A bone, mandibular buccal cusp maintains primary occlusal contacts. MISCH ; 2nd edition
- 54. Division B Bone Implant position is lingual to natural tooth Submandibular fossa Angulated abutments Crossbite MISCH ; 2nd edition
- 55. Mandibular implants positioned under the lingual cusp when compared with the original natural tooth position. Mandibular reduced buccal contours to avoid offset occlusal contacts. The primary contact of occlusion on an opposing natural posterior maxillary tooth is the lingual cusp MISCH ; 2nd edition
- 56. DIVISION C AND D BONE Bone augmentation performed Division B MISCH ; 2nd edition
- 57. DESIGN TO THE WEAKEST ARCH Identifying the weakest link in the overall restoration Establishing occlusal scheme to protect that component of the structure I MISCH ; 2nd edition
- 58. Most common implant treatment is maxillary denture opposing a mandibular implant supported restoration. Weakest area, premaxilla. Elimination of anterior contact MISCH ; 2nd edition
- 59. If the implants for both arches cannot be loaded in an axial position ,bone density , implant surface area and the prosthesis type determine the area to be protected MISCH ; 2nd edition
- 60. The material selected affect the transmission of forces and the maintenance of occlusal contacts. Occlusal material fracture is the most common complications for restorations on natural teeth or implants. The three most common groups of occlusal materials are porcelain, acrylic and metal. OCCLUSAL MATERIALS MISCH ; 2nd edition
- 62. A stiff prosthesis is preferable over a flexible one in the superstructure which is supported by osseointegrated implants and will distribute loads more effectively to the supporting abutments. SKALAL MISCH ; 2nd edition
- 63. TIMING OF OCCLUSAL CONTACTS The initial difference in vertical movement of teeth and implants in the same arch – 28µm. Initial occlusal contacts should account for this difference or implants will sustain greater loads MISCH ; 2nd edition
- 64. Thin articulating paper used for the initial implant occlusal adjustment in centric relation occlusion under a LIGHT TAPPING FORCE. Initial contact : axial contact on implants , adjacent teeth exihibit greater contacts. Heavy bite forces: equal forces on implant and adjacent teeth MISCH ; 2nd edition
- 65. BASIC PRINCIPLES OF IMPLANT OCCLUSION Bilateral stability in centric occlusion No interferences between centric position and retruded position Wide freedom in centric occlusion Anterior guidance Smooth lateral excursive movements without working/ non-working interferences. Kim Y, Oh TJ, Misch CE, Wang HL. Occlusal considerations in implant therapy: clinical guidelines with biomechanical rationale. Clinical oral implants research. 2005 Feb;16(1):26-35.
- 68. Bilateral balanced occlusion with opposing complete denture Group function occlusion or mutually protected occlusion with shallow anterior guidance when opposing natural dentition No working and balancing contact on cantilever Infraocclusion in cantilever segment Freedom in centric (1–1.5mm)
- 69. OVERDENTURES
- 70. Bilateral balanced occlusion using lingulized occlusion on normal ridge. Monoplane occlusion on a severely resorbed ridge
- 72. Anterior guidance with natural dentition Group function occlusion with compromised canines Centered contacts, narrow occlusal tables, flat cusps, minimized cantilever Cross bite posterior occlusion when necessary Natural tooth connection with rigid attachment when compromised support
- 74. Anterior or lateral guidance with natural dentition Light contact at heavy bite and no contact at light bite Centered contacts (1–1.5mm flat area) No offset contacts Increased proximal contact
- 75. CONCLUSION The objectives of implant protected occlusion are minimizing overload on the bone–implant interface and implant prosthesis to maintain implant load within the physiological limits of individualized occlusion, and, finally, to provide long-term stability of implants and implant prostheses
- 76. REFERENCES 1. Carl.E.Misch : Implant Dentistry, 2nd ed.,pp 609-629,1999 2. Hobo, Ichida, Garcia: Osseointegration and Occlusal Rehabilitation,1st ed. pp.239-47,1988 3. Shantanu Jambhekar - Occlusion And Occlusal Considerations; IJDA, 2(1), 2010 4. Dhanasekar B-OCCLUSION IN IMPLANT DENTISTRY-ISSUES AND CONSIDERATIONS; JOHCD May 2012;6(2) 5. MD Gross-Occlusion in implant dentistry. A review of the literature of prosthetic determinants and current concepts; Australian Dental Journal 2008; 53:(1 Suppl): S60–S68 6. AKPINAR-A natural tooth’s stress distribution in occlusion with a dental implant; Journal of Oral Rehabilitation 2000 27; 538–545 76
- 77. 7. Rosse Mary Falco Influence of Cusp Inclination on Stress Distribution in Implant-Supported Prostheses. A Three-Dimensional Finite Element Analysis :J of prosth19 (2010) 381–386. 8. Lakshya Kumar -Osseoperception in Implants Supported Prosthesis - A Review ‘: Online J. Med. Med. Sci. Res. 9. Judy Chia - Occlusion for implant-supported fixed dental prostheses in partially edentulous patients: a literature review and current concepts:J Periodontal Implant Sci 2013;43:51-57 10. Carl E. Misch ,Hom-Lay - Occlusal considerations in implant therapy: clinical guidelines with biomechanical rationale: Clin. Oral Impl. Res. 16, 2005; 26–35 77
- 78. THANK YOU
Editor's Notes
- Y IS implant OCCLUSION SO IMPORTANT
- SO SHORTER CANTILEVER LENGTH IS MORE FAVOURABLE . THIS I SHALL BE EXPLAINING IN DETAIL IN LATER PART OF MY SEMINAR. th.ese all ARE probable cause of implant loss and marginal bone loss after loading.
- So our main goal of implant occlusion are;
- Almost all concepts of occlusion are based on those developed with natural dentition. The probable reason for this practise is the similarity (during mandibular movement) in the velocity , the pattern of movement and the operating muscles that are used by patients with implants and those with natural dentitions.
- However, there are a few innate differences between natural teeth and implants, Natural teeth are associated with high occlusal awareness (proprioception) of about 20 μm. However Occlusal proprioception is low in implants The lack of proprioception and the absence of periodontal shock absorption are often associated with increased impact force with an implant-supported prosthesis than with a tooth-supported prosthesis. The presence of periodontal ligament as a shock absorber in a natural tooth brings about an apical intrusion by about 28 μm and lateral movement by around 50-108 μm. In the case of a similar load acting on an implant, no initial movement is seen and the delayed apical movement observed is around 10-50 μm. The same can be attributed to the viscoelastic properties of bone
- Another disadvantage of not having pdl is poor perception of interference as compared to tooth. Which means there is a decresed occlusal awareness with implants and meaning as a result of premature occlusal contact on teeth , mandible may close in a different position to avoid premature contact and result in an occlusion different from centric occlusion.
- Normal tooth can absorb a force upto 100 micron as compared to less than 50 microns for implants becoz of the absence of pdl Therefore implants are more “rigid” than teeth and consequently are more prone to failure .. have mechanoreceptors to tune occlusal forces via the central nervous system . Feedback leads to a reduction of the occlusal forces (i.e., ending the chewing action),which prevents tooth failure. Such a safety mechanism is lacking with implants and occlusal forces can accumulate to the point of failure
- NOW the force or load applied on the dental implant can be studied according to the direction of force. It may be directed absolutely along single axis of implant which is very rare. Or the force could be angulated which is the case with occulusal contact where it results into three dimensional occlusal force or vector resolution
- The force can be applied along three axises that is Mesiodistal ,,, apicocoronal ,,,linguofacial A total of six moments develop about the three clinical coordinate axis
- From here to here is the moment arm and here is the force applied. Moment equals force into moment arm so the prosthesis has the tendency to rotate in this direction.
- MOMENT LOADS TEND TO INDUCE ROTATIONS IN THREE PLANES . CLOCKWISE AND COUNTERCLOCKWISE ROTATIONS IN THESE PLANES RESULT IN SIX MOMENTS Such moment loads induce microrotations and stress concentrations at the crest of the alveolar ridge of the implant-to-tissue interface, which leads to crestal bone loss.
- Occlusal height serves as moment arm for force components directed along faciolingual axis .
- and along mesiodistal axis.
- Moment of a force along the vertical axis is not affected by the occlusal height because there is no effective moment arm.
- These are THE CONSEQUENSES OF OVERLOAD ON IMPLANT WHICH ULTIMATELY LEADS TO IMPLANT FAILURE. SO THAT’S Y , EVEN AFTER A PROPER DIAGNOSIS, TREATMENT PLANNING AND SURGERY, THE PROSTHETIC CONSIDERATION /OCCLUSAL CONSIDERATION IS IMPORTANT.
- THE DIFFERENCES BETWEEN NATURAL TEETH AND IMPLANTS LEAD TO ESTABLISHMENT OF IMPLANT PROTECTED OCCLUSIONN As it stems from the change in relation of edentulous maxillary ridge to mandibular ridge due to resorption in a medial direction.
- Mandible always searches for path having no interferences so premature contacts diverts the mandible from its normal path. As we know that pressure or stress = force by area so as the surface area of premature contact is small, so stress increases proportionately. Premature contact occurs on cuspal inclines so these stress divide into a horizontal component and increasing compressive and tensile stress.
- Premature contact occurs on cuspal inclines so these stress divide into a horizontal component and increases compressive and tensile stress. So A 12 DEGREE ANGLED FORCE INCREASES THE FORCE TO THE IMPLANT SYSTEM BY 18.6%
- to correct premature contacts. Using articulating paper. First we will go with initial light contact where the implant prosthesis barely makes contact then we go for heavy occlusal forces in which both the implant and crown share similar intensity because Natural tooth exhibits greater vertical movement than implants. Heavy occlusal loads position the natural teeth closer to depressed position of implant, permitting equal sharing of loads between implants and natural teeth.
- As we know Stress= force/area, when we increase the area the stress is decreased. So adequate surface area sustain load transmitted to the prosthesis How can we increase the surface area ?? By placing wider implants, increasing the number of implants. as we increase the number of implants the stress is distributed and less force is trasmited to the transosteal region as seen in this picture. Splinting the implants further add to the retention and resistance by reducing the horizontal force transmitted to the bone and prevention of screw loosening in abutment.
- A restoration mimicking the occlusal anatomy of natural teeth often results in offset load, increased stress and Increased risk of porcelain fracture. So in nonesthetic region width of occlusal table must be reduced in comparison to natural tooth.
- Next is mutually protected occlusion
- Because steeper anterior guidance result in greater are forces on anterior implants. Rationale of mutually protected occlusion is that the forces are distributed to segments of jaws with an overall decrease in force magnitude. In cases where we have to increase the anterior guidance to disclude the posteriors then we use two or more implants splinted together.
- Whether occlusal load is applied to angled implant body or an angled load is applied to an implant body perpendicular to occlusal plane, the biomechanical risk increases. This is attributed to anisotropic nature of bone, resulting in separation of load to compressive, shear and tensile stresses. Anisotropy refers to character of bone whereby mechanical properties depend on the direction in which bone is loaded. the greater the angle of load, greater is shear component of the load.
- Cortical bone is strongest and most able to withstand compressive forces. Its ability to withstand tensile and shear forces is 30% and 65% less, respectively, than its ability to withstand compressive forces as seem in this bar diagram.
- Strength of cortical load decreases with increasing angle of applied load. According to this table when a force at a 30 degree angle decreases the bone strength limit by 10% under compression and by 25% under tention and same goes for 60 degree angle. So increase in shear stresses causes increased crestal bone losses and impairs successful bone growth.
- Whenever lateral/angled loads cannot be eliminated, a reduction in force magnitude or additional surface area of implant surface is indicated to reduce the risk of bone loss or of implant component fracture. So these measure include…
- force angulation to implant is body influenced by cusp inclination which inturn will increase crestal bone stress. So to decrease effect of these forces, the occlusal contact on implant crown should be on flat surface perpendicular to implant body. Increasing width of central groove to 2-3 mm in posterior crown which are positioned over center of implant abutment. Opposing cusp recontoured to occlude in central fossa over implant body.
- .
- When a force is applied to the cantilever, a force twice as great will be applied to the farthest abutment from the cantilever. That is this one.The force on the cantilever is a compressive force, whereas the force to the distal abutment is a tensile force. that is this one. The load on the abutment closest to the cantilever (which acts as a fulcrum) is the sum of the other two components and is compressive. That is this one.
- LINGUAL FORCE COMPONENT ALSO INDUCE TWISTING MOMENT ABOUT IMPLANT NECK IF APPLIED THROUGH THE CANTILEVER LENGTH
- For a system with 4-6 implants, the following cantilever lengtha are recommended. .
- An increased crown height acts as a vertical cantilever, magnifying stress at implant bone interface. It also leads to angled load with a greater lateral component of force. How it does that I have explained ealier.
- Ideal occlusal contact should be over implant body. This contacts should lead to axial loading of implants. A posterior implant hence is placed under central fossa of implant. A buccal cusp contact or marginal ridge contact is an offset or cantilever load as these are several milimeter away from implant body. Also the marginal ridge contacts are more damaging than buccal contact as mesiodistal dimension of crowns is more than buccolingual dimention. Thus ideally primary occlusal contact should reside within diameter of implant within central fossa. The secondary contact should be within 1mm of periphery of implants to decrease moments load.
- In fact it is under or near central fossa or more lingual under lingual cusp of natural tooth depending on resulting position of remaining ridge due to resorption.
- So what are the types of resorbed ridges. Bone height, length, direction of load, divison a : posterior mandible and anterior maxilla
- Lingual cusp of maxillary crown placed out of occlusal contact to eliminate offset loads. Maxillary buccal cusps maintain esthetics where required and prevent cheek bite.
- Mandibular lingual cusps out of occlusal contacts and width of lingual cusps prevents tongue entrapment between occlusal surfaces. Mandibular buccal cusps reduced in height ( to reduce offset load ) and width ( to prevent cheek entrapement)
- When axial loading of both arches is not possible it is recommended to favour weaker arches that is maxilla. Widened central fossa of maxillary implant to receive primary contact. Maxillary buccal cusp maintain esthetics and prevent cheek bite and lingual cusp is out of contact and reduced width. Lingual cusp of mandibular implant crown placed out of occlusal contact to eliminate offset loads.
- In division b bone, implant position is often lingual to natural tooth. In cases of mandibular posterior implants limitation is imposed by submandibular fossae. In case of excessive medial positioning of the implant, it may be necessary to use angulated abutment and a straight lingual profile. Maxillary posterior implants in division b bone may require restoration in crossbites, primary occlusal contact over implant, maxillary lingual ovejet prevents tongue bite and mandibular buccal overjet prevents cheek bite.
- IN Case of division c and d bone , all attempts must be made to perform a bone augmentation procedure and create a condition as close as possible to division b bone.
- All treatment planning decisions for ipo should be based on carefull consideration of
- The amount of force distributed to a system can be reduced by stress relieving components that may dramatically reduce the impact loads to implant support. In this cases the weakest area is the premaxilla. So we eliminate the anterior contact.
- 1.MOST ESTHETIC IS PORCELAIN BUT PORCELAINE FRACTURE IS SECOND MOST COMMON CAUSE OF PROSTHETIC FAILURE 2.IMPACT LOAD IS INCREASED FORCE PRIMARILY DUE TO SPEED OF CLOSURE AND DAMPENING EFFECT OF OCCLUSAL forces. IMPACT LOAD IS LOWEST FOR ACRYLIC, INCREASES WITH COMPOSITE AND METAL OCCLUSALS INCREASE EVEN MORE WITH ENAMELAND INCREASE EVEN MORE WITH PORCELAIN. 3.CHEWING EFFICIENCY OF ACRYLIC IS LOWER THAN PORCELAIN OR METAL BUT THERE IS NO DIFFERENCE IN GOLD AND PORCELAIN. 4.ACRYLIC WEARS 7-30 TIMES FASTER WHEN OPPOSING GOLD, RESIN, ENAMEL OR PORCELAIN, GOLD OCCLUSAL SURFACE WEAR LESS WITH ANY OTHER COMBINATION OF MATERIALS.. PORCELAIN OPPOSING PORCELAIN WEAR MORE THAN PORCELAIN OPPOSING GOLD OR METAL.COMPOSITE RESIN IS THREE TIMES STRONGER THAN ACRYLIC. 5.Material fracture is one of the most common factors that leads to refabrication of a prosthesis.Composite resin is 3 times stronger than acrylic. Metal occlusals do not easily fracture, provide good wear porcelain. Porcelaine fracture is most common condition and ideal thickness of porcelain to prevent breakage is approximately 2mm. 6.Metal shrinkage is 10 times less than porcelain or acrylic and therefore permits fabrication of more passive casting. Accuracy of casting is paramount in screw retained prosthesis , occlusal material make a significant difference. 7.Acrylic restorations receive their strength from bulk and so require greater interarch space. Metal occlusals require the least amount of space. So overall metal is an excellent occlusal material with improved properties in accuracy,wear, fracture resistance, abutment retention, and good qualities for impact or static force. and Esthetic is best satisfied with porcelain.
- The implant prosthesis should barely contact, and the adjacent teeth should exhibit greater initial contacts. Only axial occlusal contacts should be present on the implant crown , a heavy bite force depresses the natural teeth, positioning them closer to the depressed implant position and equally sharing the load.
- So ingeneral these are the basic principles that should be taken care to maintain implant occlusion.Stabilize masticatory system,Proper force distribution., Reduce possibilities of premature contact. Wide freedom in centric accomplish more favourable vertical lines of force and thus minimize the premature contact during function. Anterior or canine guidance to potentially decrease the destructive forces in posterior implants. Smooth and even lateral working contacts without cantilever contacts in posterior region preferred to provide proper force distribution.
- The inflraocclusion on cantilever unit was suggested to reduce fatigue and technical failure of prosthesis.
- Anterior guidance in excursions and initial occlusal contacts on natural dentition will reduce lateral force on implants. Group function occlusion utilized when anterior teeth are periodontally compromised. Reduced inclination of cusps, centrally oriented contacts with a 1-1.5mm flat area, a narrowed occlusal table and elimination of cantilvers controls the bend overload in posterior restoration.
- THE OCCLUSION IN SINGLE IMPLANT SHOULD BE DESIGNED TO MINIMIZE OCCLUSAL FORCE ONTO THE IMPLANT AND TO MAXIMIZE FORCE DISTRIBUTION TO ADJACENT NATURAL TEETH. TO DISTRIBUTE OCCLUSAL FORCES ON TEETH AND IMPLANTS. LIKE THE POSTERIOR FIXED PROSTHESIS Reduced inclination of cusps, centrally oriented contacts with a 1-1.5mm flat area, a narrowed occlusal table IS UTILIZED FOR POSTERIOR SINGLE TOOTH IMPLANT RESTORATION. INCREASED PROXIMAL CONTACTS IN THE POSTERIOR REGION MAY PROVIDE ADDITIONAL STABILITY OF RESTORATIONS.