Treatment planning of implants in posterior quadrants.pptx

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1. GOOD MORNING

2. Treatment Planning Of Implants In Posterior Quadrants Presented by R. PRIYA DARSHINI DEPARTMENT OF PROSTHODONTICS

3. CONTENTS Introductions Treatment considerations Available space Available bone Implant number and position Occlusal considerations Type of prosthesis Conclusion References

4. INTRODUCTION Treatment planning may be facilitated by determining the desired end result which fulfills the functional and aesthetic needs of the patient.

5. Planning begins with an assessment of the aesthetic and functional requirements , intra oral examination , diagnostic set-ups , radiographic examination , construction of provisional restorations surgical guides . Peter Floyd , treatment planning for implant restorations. BDJ 1999;187; 6 ; 297-305

6. An implant foundation should be designed to support the load and resist stresses while the restoration is in place. Treatment plan established relative to the number and position of missing teeth. The treatment plan is then modified dependent on the force factors. Force factors- Parafunctional habits ( bruxism , clenching, tongue thrust) Crown height and space Masticatory dynamics Arch position Nature of opposing arch Carl E. Misch ; Dental implant prosthetics ; 2005

7. TREATMENT PLANNING CONSIDERATIONS Available space Available bone Implant number and position Occlusal considerations Type of prosthesis

8. AVAILABLE SPACE Mesiodistal Buccolingual Occlusogingival

9. Mesiodistal Mesiodistal space is evaluated in two dimensions. Adequate prosthetic space must exist to provide the patient with a restoration that mimics natural tooth contours. If inadequate prosthetic space exists, it must be created through enameloplasty of adjacent teeth or orthodontic repositioning Jivraj , treatment planning of implants in posterior quadrants. BDJ 2006; 201;13-23

10. Following guidelines should be used when selecting implant size and evaluating mesiodistal space for implant placement The implant should be at least 1.5 mm away from the adjacent teeth The implant should be at least 3 mm away from an adjacent implant A wider diameter implant should be selected for molar teeth. Carl E. Misch ; Dental implant prosthetics ; 2005

11. Spacing is required to provide the following: To allow for 1.5 mm of crestal bone interproximally , this in turn will allow for proper development of a healthy papilla. To develop proper contacts and the contours in the restoration. T o allow for an adequate widt h of soft tissu e between implants and adjacent teeth. For the prosthetic components not to impact on each other. For the effective cleaning of the prosthesis by the patient. To develop harmonious occlusion. To allow for at least 1 mm space from the implant to the adjacent root.

12. Bucco lingual The width of the available bone is measured between the facial and the lingual plates at the crest of the potential implant site. At least 6 mm of bone buccolingually is required for placement of a 4 mm diameter implant and 7 mm for a wider diameter 5 mm implant. Carl E. Misch ; contemporary implant dentistry ; 3 rd edition

13. The minimum available bone width should be such that >1 mm of bone should be present on either side of the implant faciolingually to keep the soft tissue levels stable [Figure 4]. This is critical on the facial side since any bone resorption and ensuing change in the position of the gingival margin will be nonesthetic . [21] Considering the above guideline, in an ideal situation the implant diameter chosen should be at least 3 mm less than the available mesiodistal dimension of the bone and 3 mm narrower than the buccolingual dimension of bone.

14. The implants should be placed so that the projection of the fixture is contained within the anticipated crown form. The screw access should be positioned towards the centre of the occlusal surface. Posterior mandibular fixtures should be placed so that the exit angle of the screw access should point towards the inner incline of the palatal cusp. Posterior maxillary implants should be placed so that the exit angle of the screw access points towards the inner incline of the buccal cusp Jivraj , treatment planning of implants in posterior quadrants. BDJ 2006; 201;13-23

15. Occluso gingival Adequate space for restoration

16. ADEQUATE SPACE FOR RESTORATION Sufficient space must exist to fabricate restorations which are harmonious aesthetically with the adjacent teeth Replacing premolar and molar teeth requires 10 mm of space between the residual ridge and the opposing occlusion. 7 mm would be considered the bare minimum

17. Available bone Available bone is that portion of a partially or totally edentulous alveolar ridge that can be used to insert an endosteal implant, or basal bone that can be used to support a subperiosteal implant. (Charles M. Weiss) Bone is measured in width, height length, angulation and crown height/implant body ratio. Carl E. Misch ; contemporary implant dentistry ; 3 rd edition

18. Classification Of Available Bone Division A (abundant bone) Division B (barely sufficient bone) Division C (compromised bone) Division D (deficient bone)

19. BONE DENSITY CLASSIFICATION Lekholm and Zarb (1985) Quality 1 : composed of homogeneous compact bone Quality 2 : thick layer of compact bone surrounding a core of dense trabecular bone Quality 3 : thin layer of cortical bone surrounding dense trabecular bone of favorable strength Quality 4 : thin layer of cortical bone surrounding a core of low density trabecular bone

20. BONE DENSITY CLASSIFICATION According to Misch D1 – dense cortical D2 –thick dense to porous cortical bone and coarse trabecular bone within D3 – porous cortical (thin) and fine trabecular bone within D4 – fine trabecular

21. Posterior maxillary bone loses volume faster than any other region. Not only the periodontal diseases cause initial bone loss before the loss of teeth, but the crestal bone loss is substanstial after tooth extraction. In addition , the maxillary sinus after tooth loss expands towards the crest of the edentulous ridge. As a result posterior maxilla is greatly reduced as a result of dual resorption from crest of ridge and pneumatisation of maxillary sinus after tooth loss . As a consequence, the posterior maxilla is more often indicated for bone augmentation compared with any intra oral location.

22. Review of literatue for treatment of posterior maxilla : Approaches for placement of implant Avoid sinus and place implants anteriorly , posteriorly or medially. Place implants and perforate the sinus floor. Use subperiosteal implants Perform horizontal osteotomy , interpositional bone grafting and then endosteal implants. Elevate sinuses during implant placement Perform lateral wall approach, sinus graft and simultaneous or delayed implant placement.

23. 1970 – Tantum – autogenous rib onlay bone Onlay grafts below alveolar crest decreases the posterior intradental height, yet there was only little bone for endosteal implants. 1974 – Tantum – modified Caldwell-Luc Crestal ridge of maxilla was infractured and used to elevate the maxillary sinus membrane. Autogenous bone was added in the area previously occupied by inferior third of the sinus, and the endosteal implants were inserted in this grafted bone after 6 months.

24. 1980 –application of sub- antral augmentation technique with a lateral maxillary approach with use of synthetic bone. 1980 – Boyne and James – autogenous bone for subantral grafts. 1981 – Tantum –submerged titanium implants Advantages of submerged healing, and use of ti instead of aluminium oxide as biomaterial, improved biomechanics and improved surgical technique made this implant modality more predictable.

25. 1984 – Misch – treatment approach based on the amount of bone below the antrum and further expanded to include the available bone width related to surgical approach and implant design

26. Opposing landmarks are more limiting in posterior regions. As a result, in areas where greater forces are generated and the natural dentition has wider teeth and even two or three teeth, narrower and shorter implants are often used. In a study by Rustia (1995) on 431 patients revealed that placement of implants atleast 6mm in length was possible in only 38% (maxilla) and 50%(mandible) in posterior region

27. General guideline- 2mm of surgical error is maintained between the implant and any adjacent landmark. This margin of error is critical when the opposing landmark is a mandibular inferior alveolar nerve or a maxillary sinus

28. Implant number and position Stress to implant system – reduced by increasing the area over which the force is applied. Effective method to increase the surface area of implant support is by increasing the number of implants used for support. Bidez and Misch – force distributed over 3 abutments resulted in less localised stress to crestal bone than 2 abutments.

29. When 3 posterior teeth are missing, two or three implants may be required. The number of implants is dependent on bone quantity and quality. Often in the maxilla where less dense bone is found, surgeons favour placing three implants — one for each tooth.

30. Bone volume is inadequate - decision regarding bone augmentation procedure or approach of cantilevering . When cantilevering, the occlusal surface of the cantilever should be minimised and occlusal contact should be controlled so that the majority of the load is distributed along the long axis of the implants Rangert B , Bending overload and implant fracture. A retrospective clinical analysis . Int J Oral Maxillofac Implants 1995; 10: 326-334.

31. Choice between using two or three implants is also related to the biomechanics of the prosthesis and how load is distributed. With three implants it is possible to offset the implants and position them for a tripod effect. This has been claimed to give a more optimal bone support than a linear arrangement Rangert B , Bending overload and implant fracture. A retrospective clinical analysis . Int J Oral Maxillofac Implants 1995; 10: 326-334.

32. Cantilevers are force magnifiers and represent risk factor in support, screw loosening, crestal boneloss , fracture and any other factor negatively affected by force. Implant number and position should aim at eliminating cantilevers whenever possible, esp when other force factors are increased.

33. When insufficient osseous volume exists in the posterior maxilla and the patient does not want to undergo a sinus augmentation procedure, consideration must also be given to implant placement in the tuberosity area. This technique provides adequate posterior support and eliminates the potential problems encountered with cantilevers. Bahat O . Osseointegrated implants in the maxillary tuberosity : report on 45 consecutive patients . Int J Oral Maxillofac Implants 1992; 7: 459-467.

34. Ideally the bone angulation is aligned with the forces of occlusion and is parallel to the long axis of the Prosthodontic restoration. The alveolar bone angulation represents the root trajectory in relation to the occlusal plane. The limiting factor of angulation of force between the body and the abutment of an implant is correlated to the width of bone.

35. In edentulous areas with a wide ridge, wider root form implants may be used. Such implants allow modifications up to 30 degrees divergence with the adjacent implant, natural teeth, or axial forces of occlusion. Narrow yet adequate width ridge often requires a narrower design root form implant. This limits the acceptable angulation of bone to 20 degrees

36. Occlusal considerations Consideration of bone density and volume, anticipated loads and planned restorative design are all important to review before number, length and diameter of implants are determined. Masticatory forces developed by a patient restored with implant supported restorations are equivalent to those of a natural dentition. When treatment planning patients for implant supported restorations, a general assessment of the likely load to be placed on the implants should be made. Carr A . Maximum occlusal force levels in patients with osseointegrated oral implant prosthesis and patients with complete dentures. Int J Oral MaxillofacImplants 1987; 2: 101-108.

37. Implants are ankylosed to the surrounding bone without an intervening periodontal ligament. The mean values of axial displacement of teeth in the socket vary between 25-100 microns. The range of motion of osseointegrated implants has been reported to be approximately 3-5 microns

38. Displacement of a tooth begins with an initial phase of periodontal compliance that is non linear and complex, followed by a secondary movement phase occurring with the engagement of the alveolar bone An implant deflects in a linear and elastic pattern and movement of the implant under load is dependent on elastic deformation of the bone. Study by Stern et al - found that implants are more susceptible to occlusal overloading than natural teeth Mericske -Stern R ; Threedimensional force measurements on mandibular implants supporting overdentures . Int J Oral Maxillofac Implants 1992; 7: 185-194.

39. Techniques should be used to minimise excessive loading on implant supported restorations. The occlusion should be evaluated and organised so that there is anterior guidance and disclusion of posterior teeth on lateral excursion. There should be no contact of posterior teeth on both working and non working sides.

40. If the canine is compromised, group function is acceptable. Initial occlusal contact should occur on the natural dentition. The centric contacts are adjusted with light occlusal contact on the implants; the rationale for this is that the opposing natural dentition is often compressed on firm closure.

41. Cuspal inclinations on implant supported restorations should also be shallower; anterior disclusion is also easier to develop when posterior occlusal anatomy is shallow. As stated previously any type of cantilever force should be minimised , which includes anterior, posterior and buccolingual cantilever. When there has been extreme resorption of the maxillary bone, teeth may need to be set in a crossbite relationship to minimise offset loads.

42. Type of prosthesis Screw retained or cemented Splinted or non- splinted Abutment level vs implant level restoration. Segmented vs non-segmented

43. Screw retained or cemented Many advantages of prosthesis retrievability can be afforded by screw retention. Retrievability facilitates individual implant evaluation, soft tissue inspection and any necessary prosthesis modifications. Additionally, future treatment considerations can be made more easily and less expensively. Porcelain repair, changing the shade of a restoration and creating additional access for oral hygiene become minor issues if the prosthesis can be easily unscrewed

44. Cemented type restorations provides a more aesthetic result, as screw access holes can be avoided. With this practice abutment screws must stay tight because a loose screw cannot be easily accessed. A cemented prosthesis may require sectioning to tighten a loose abutment.

45. The choice for screw retained or cemented restoration - influenced by the tooth that is being replaced. The occlusal surface of a premolar is small and patients may object to occlusal access holes in restorations replacing the first and second premolar. These restorations may be designed to be cement retained.

46. When using cement retained restorations in these teeth, caution must be exercised in the design of the custom abutment. Abutments should be designed to follow the contours of the gingiva , meaning that scalloping of the abutment is required in interproximal regions. Circular margins of the restorations will result in the cement margin being deeper in some locations than others. The margin of the abutment should also be kept as minimally subgingival as aesthetics will allow. Placing a cement margin too deep will cause the practitioner difficulty in removal of excess cement

47. Splinted Or Non-splinted According to Jivraj - When multiple implants are placed in posterior quadrants they should be splinted. Stress distribution can be manipulated by splinting. The retention of the prosthesis is also improved with a greater number of splinted abutments. Splinting also has biomechanical advantages in that it will also reduce the incidence of screw loosening and unretained restorations. Practical advantages include fewer proximal contacts to adjust and delivery of the restoration can be performed more efficiently.

48. Segmented vs non-segmented cemented restorations - the abutments placed should embody the transitional contours required to allow proper contour of the restorations The cement margin should not be placed more than 1 mm sub mucosal to facilitate cement removal. When cement retention is desired there must be sufficient inter occlusal space.

49. When implants are aligned to allow screw retention, unless the soft tissue depth is more than 3 mm, implant supported restorations are almost always restored directly to the implant. Screw retained abutments are only used when the implants are placed deeply or soft tissue depth is excessive; the abutment merely facilitates restorative procedures as there is less soft tissue interference when the restorative interface is raised.

50. when a titanium interface is desired and in these situations abutments can be selected to allow a supra mucosal restorative interface. Disadvantages of this will be that there will be a display of metal on the restoration and there will be less room for transitional contours. At times when screw retained pre angled abutments are required, the implant must be planned to be placed deeper to accommodate the thickness of the abutment

51. According to Celletti (1995) - loading to angled implants is not detrimental to implants – however loading implants at an angle can be problematic to the screw joint between the restoration and the abutment.

52. CONCLUSION Decisions to use implants should be based on prosthetically oriented risk assessment. When replacing long span fixed partial dentures consideration should be given to decreasing the number of pontics and increasing the number of implant abutments. Use of implants allows the clinician to segment the restoration

53. Prosthetically oriented risk assessment involves comprehensive evaluation of potential abutment teeth. Decision has to be made maintain a compromised tooth versus placing an implant.

54. References ` Carl E. Misch ; Contemporary implant dentistry; 2005 Charles M. Weiss; Principles and practice of implant dentistry Misch CE ; dental implant prosthetics; third edition

55. Peter Floyd , treatment planning for implant restorations. BDJ 1999;187; 6 ; 297-305 Cibirka et al. Determining the force absorption quotient for restorative materials used in implant occlusal surfaces. J Prosthet Dent 1992; 67: 361-364. Mericske -Stern R ; Threedimensional force measurements on mandibular implants supporting overdentures . Int J Oral Maxillofac Implants 1992; 7: 185-194. Carr A . Maximum occlusal force levels in patients with osseointegrated oral implant prosthesis and patients with complete dentures. Int J Oral MaxillofacImplants 1987; 2: 101-108. Bahat O . Osseointegrated implants in the maxillary tuberosity : report on 45 consecutive patients . Int J Oral Maxillofac Implants 1992; 7: 459-467. Jivraj , treatment planning of implants in posterior quadrants. BDJ 2006; 201;13-23