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Available bone
- 1.
- 2. CONTENTS INTRODUCTION AVAILABLEBONE BONE HEIGHT BONE WIDTH BONE LENGTH BONE ANGULATION CROWN HEIGHT SPACE DIVISION OF BONE SUMMARY
- 3. Introduction Long termsuccess in implant dentistry requires certain important criteria .There are more than 50 criteria that are required in treatment planning. Once the prosthodontic needs of the patient have been determined,the most important criteria is the available bone.
- 4. AVAILABLE BONE Describesthe external architecture or the quantity of bone present in edentulous area considered for implants
- 5. AVAILABLE BONE 1.5-2mm-Surgicalerror. Root form implants-width Diameter and Mesiodistal length of available bone length of implant Height of bone available
- 6. Implant width S=F/A 0.25mm increase in diameter,5-8% surface area increases. Increase in dia-less stress at crestal bone implant interface. Implant Height Also affects total surface area. 3mm longer implant 20-30% increase in surface area. Initial stability of implant
- 7. It ismeasured in terms of Bone height Bone width Bone length Bone angulation Crown-height space
- 8. Available bone height Radiographic Evaluation- OPG Anterior regions of jaws- greatest height Maximum height-Maxilla and mandible-sites The minimum bone height for a predictable long term endosteal implant survival is 12 mm.
- 9. Skeletal relationships-Class2 and class 3 Posterior jaws –more limiting for implant height Suggested bone height -12mm
- 10. Available bone height Dense bone may accommodate shorter implant but a porous bone may require longer implant. More imp.as affects implant length and crown height. Once the minimum bone height is established width is more important than additional height.
- 11. Available bone width Measured between the facial and lingual plates at the crest . The crest is supported by a wider base. Osteoplasty Exception-ant maxilla
- 12. Available bone width Minimum bone width for a 4mm root form implant is more than 6 mm. Reduced width -narrower diameter implant. Initial width of available bone is related to crestal bone loss,after loading.
- 13. Available bone length The mesiodistal length of bone in an edentulous area is limited by adjacent teeth or implant. Implant - 1.5 mm adjacent tooth and 3mm from adjacent implant -For a bone width of 5mm the minimum length is 8mm.
- 14. Ideal implantwidth for single tooth or multiple implants. Natural tooth being replaced
- 15. Available bone angulation It represents the root trajectory in relation to occlusal plane. Acceptable bone angulation depends on the width of the ridge. For wider ridges bone angulation can be as much as 25 degrees . For narrower ridges acceptable angulation is 20 degrees
- 16. Ideally,angulation is: 1.Perpendicular to occlusal forces. 2.Aligned with forces of occlusion 3.Parallel to long axis of prosthodontic restoration.
- 17. Rarely boneangulation remains ideal. Mandibular Teeth: lingually inclined in posterior region and labial inclination in anterior region. Anterior region in both jaws is usually deficient in bone Posterior mandible –submandibular fossa dictates angulation
- 18. Crown-Height space Verticaldistance from the crest of the ridge to the occlusal plane. Affects appearance , amount of moment of force on the implant and surrounding crestal bone. Considered as a vertical cantilever. Greater the CHS,greater the moment of force,or lever arm. Ideally,CHS should be =,< 15mm.
- 19. LEKHOLM and ZARB(1985) TYPE 1 TYPE2 TYPE3 TYPE4
- 20. Classification of availablebone DIVISION A DIVISION B DIVISION C DIVISION D Misch and Judy in 1985
- 22. DIVISION A BONE Consistsof abundant bone in all directions Dimensions Width>6mm Height>12mm Length>7mm Angulations<25 degrees CHS < or =15mm
- 23. DIVISION A BONE Treatment options Division A root forms or wider implants . All prosthetic options. Limited inter arch space. (High profile O-ring) Osteoplasty .
- 24.
- 25. FP-3 restoration inDiv A bone
- 26.
- 27. DIVISION B BONE Barely sufficient bone. Ridge width is reduced. M-D width of bone is less…so 3mm implants.
- 28. DIVISION B BONE Dimensions Width 2.5mm-6mm B+ :4-6mm B-w:2.5-4mm Height> 12mm Length> 6mm Angulations <20 degrees CHS <15mm
- 29. Treatment options 3Rx:- 1) Modify the narrower div B bone to div A by osteoplasty However after osteoplasty the ridge height should not become <10 mm And place division A root form
- 30. 2) Narrowdiameter division B root form angulation <20 available bone length atleast 12mm to ensure adequate surface area for narrow diameter implants The design of prosthesis also changes with osteoplasty procedures.
- 31. 3) Ridge augmentation In cases where osteoplasty will result in ridge height less than 10mm, ridge augmentation instead should be done.
- 32.
- 33. DIVISION C(COMPROMISED BONE) Deficient in one or more dimensions Resorption first occurs in width .The bone is called C-w Then in height. The bone is called C-h Posterior maxilla VS Anterior maxilla Posterior mandible VS anterior mandible.
- 34. Inform patient aboutbone loss
- 35. Dimensions unfavorable in Width (c-w) :0 to 2.5mm Height(c-h)-<12mm Angulation (c-a)>30 degrees CHS > 15mm
- 36. Uncommon subcategory C-a Avbl bone adequate in height and width Angulation greater than 30 degree
- 38. Treatment options 1)C-w ridge a)Osteoplasty which converts it to C-h ridge type with adequate width b) Bone augmentation can be done
- 39. Treatment options 2)C-hridge can be treated with a) Greater no of endosteal implants of reduced height. b) Ridge augmentationton to upgrade div C to div A c) Subperiosteal –Circumfrential and unilateral. Disk design implants
- 41. DIVISION D (DEFICIENTBONE) Characterized by severe atrophy of alveolar process as well as basal bone Basal bone loss: Flat maxilla Pencil-thin mandible CHS>20mm
- 42. Treatment options Ridgeaugmentation is the treatment of choice. Complete implant supported dentures indicated Fixed restorations X RP-5 not suggested.
- 43. 90 percentof autogenous graft resorbs in 5 years- so not intended for denture support. Chances of dental cripple.
- 44. Subperiosteal implants-themyth. If adequate bone present in mandibular anteriors with D bone in posteriors- Root form implants. Tripodal sub-periosteal implants. Mandibular staple implants Ramus frame implants
- 45. Summary In implant dentistryprosthesis is designed at onset of treatment to satisfy patients needs and desires. Bone is THE most critical criteria in determining the success.
- 46. References Misch 3rdedition Babbush:art and science
Editor's Notes
- #5 Past-only bone Present-advent of graft,modified implant site
- #6 More critical when IAN canal present. No complication when in sinus,inferior cortical border,cribriform plate of natural tooth.
- #7 Implant height-greater bone-implant interface and greater resistance to rotational torque during screw tightening. Min. height of implant-dense bone-short implant 8mm,porous bone-long implant.
- #9 such as the maxillary sinus or the mandibular canal
- #10 Before 1981,Branemark screw type implants provided single implants-3.75 dia..and were used at all locations..Implant height was 9mm,and implant failure rate was significantly highr if smaller lengt implants were used .13%-failure-10mm 18%--------8mm 25%.........7mm
- #13 Edentulous ridge greater than 6mm width-less crestal bone loss.
- #14 Surgical error-compensation+Tooth crestal defect-less than 1.4mm.so if bone loss occurs from a crest module,ot adjacent tooth,it will not spread to adjacent structures.
- #15 Tooth has greater width at Interproximal contact…..narrow at CEJ……Narrower at 2mm below CEJ….should be 1.5 mm from natural tooth.eg maxillary 1st pm----8mm at interprox contact….5 mm at CEJ…4 mm at 2mm below CEJ….So 4 mm implant should be placed 1.5mm from adjacent tooth.
- #16 where narrow diameter implant is used ,greater stresses are produced ,here the
- #18 Width of the bone is a limiting factor.wide bone-25 degrees….narrow -20 degrees.
- #20 Doesnot follow natural resrption phenomenon……..only about residual bone.
- #24 Root form implant 4mm or greater..for molars 5-6 mm
- #26 MOST IDEAL time for implants.
- #28 25 percent decrease in bone width in first yr……40 percent in 1-3 yrs…..and may remain for 15 yrs in anterior mandible. post mand resorbs 4 times as fast as anterior. Post max region has fastest decrease of bone height of any intraoral region.
- #29 As bone resorbs,width of available bone decreases at expense of facial cortical plate,as lingual cortical plate is thick.25%decrease in 1st yr and 40 % dec in width 2nd yr. after Xn .---slight to mild atrophy
- #32 Alloplast,allografts with Guided bone regenerations are performes.Augmentation in height is more difficult than width,except in maxillary posterior regions,where sinus grafts are better suited for height augmentation.
- #33 Grafted ridges----Fixed prosthesis Osteoplasty-------removable prosthesis.
- #34 Moderate to advanced atrophy.
- #35 C-w bone -----c-h bone….D bone. Pts gen want mandiblular denture to be stable,so implants are put up only in mandible……pt should be informed about severe bone loss with time in posterior regions,rendering usage of advanced grafting procedures.
- #38 Restoring div c requires greater skill and training ,instead of div a or B. Root form implants placed in this condition ,may lead to positioning implants within floor of the mouth,and compromise prosthetic reconstruction,speech and comfort.
- #39 Augmentation is tough,as greater amount of bone volume is reqd,and recipient bed is small.
- #40 Sinus grafts for c-h ridge is excellent option---10 mm of vertical bone can be augmented. Several studies indicate that less than 10 mm of implant length---failure rates are increased…after prosthetic delievery. Reason-1.inadequate implant support 2.Mafnification of force from excessive CHS.