Loading of implants/ General orthodontics


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Loading of implants/ General orthodontics

  1. 1. WWW.INDIANDENTALACADEMY.COM INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com
  2. 2. • Introduction • Terminologies • Rationale for implant immediate loading • Histologic evaluation – Short term • Long term • Indication for immediate loading • Contraindications for immediate loading • Immediate occlusal loading- Factors that reduce risk WWW.INDIANDENTALACADEMY.COM
  3. 3. • Loading protocols for completely edentulous arches • Loading protocols for posterior maxillary and mandibular arches • Loading protocols for esthetic zone • Progressive loading • Advantages • Disadvantages • Conclusion • References WWW.INDIANDENTALACADEMY.COM
  4. 4. • Patients levels of knowledge and expectations for treatment with dental implants have increased tremendously • Historically, two-stage surgical protocol was proposed. • The introduction of new implant surfaces has made it possible to modify loading protocols WWW.INDIANDENTALACADEMY.COM
  5. 5. TERMINOLOGY Loading of implants Conventional loading Immediate loading Early loading Delayed loading Immediate restoration Int J Oral Maxillofac Implant 2004; 19 WWW.INDIANDENTALACADEMY.COM
  6. 6. Immediate occlusal loading Early occlusal loading Delayed occlusal loading Progressive loading Non functional immediate restoration Non functional early restoration Carl Misch 3 rd edition WWW.INDIANDENTALACADEMY.COM
  7. 7. Lamellar bone Woven bone WWW.INDIANDENTALACADEMY.COM
  8. 8. • Bone interface is stronger on the day of implant placement • As a result of surgical trauma lamellar bone becomes woven bone of repair • Weakest bone- implant interface at 3- 6weeks • Buchs et al (2001) – immediately loaded implant failure occurred between 3- 5 weeks • Decrease surgical trauma and bone remodeling process. WWW.INDIANDENTALACADEMY.COM
  9. 9. • Causes of trauma • Thermal injury • Microfracture of bone • Amount of heat generated • Drill design • Speed • Drill sharpness WWW.INDIANDENTALACADEMY.COM
  10. 10. • Irrigation • Amount of bone prepared • Variation of cortical thickness • Bone cell death at 40˚ C ( Eriksson and Albrektsson,1983) WWW.INDIANDENTALACADEMY.COM
  11. 11. • Self tapping implant – greater bone remodeling • Insertion torque within 45 N-cm • Rationale of immediate loading is not only to reduce the risk of fibrous tissue formation but also to minimize woven bone formation and promote lamellar bone. WWW.INDIANDENTALACADEMY.COM
  12. 12. • The initial histologic evaluation of bone implant interface have reported favorable bone quality around implant • Romanos et al, 2001l demonstrated no statistically significant difference between immediate and delayed loaded implants. • Suzuki et al, 2008 demonstrated higher bone implant interface in immediately loaded implant than in delayed loaded implant. WWW.INDIANDENTALACADEMY.COM
  13. 13. • No statistically significant difference were detected in bone implant interface after 8 months • Less marrow spaces and more compact bone • Studies also have demonstrated greater bone contact in immediately loaded implants after 9 months. WWW.INDIANDENTALACADEMY.COM
  14. 14. • Patients can not tolerate removable prosthesis • Uncomfortable wearing dentures • Do not wish to wait for 3 or more months WWW.INDIANDENTALACADEMY.COM
  15. 15. • The suggested contraindications, in general, for consideration of an immediate loading protocol include the following: • Severe metabolic disease • Inadequate bone volume for correct implant placement • Very poor bone density (D4) • Severe parafunction (eg, bruxing, clenching, tongue thrust) • Noncompliant patient types (eg, diet limitations, gum chewing) • Smokers WWW.INDIANDENTALACADEMY.COM
  16. 16. • Bone microstrain • Surgical technique • Initial implant stability • Quality and quantity of bone • Occlusion WWW.INDIANDENTALACADEMY.COM
  17. 17. • Bone Microstrain • Microstrain level 100times less than ultimate strength of bone may trigger cellular response. • Frost developed a microstrain language for bone based on biological response at different microstrain level. WWW.INDIANDENTALACADEMY.COM
  18. 18. • Titanium has higher modulus of elasticity than bone • Microstrain difference between bone and titanium in frost microstrain zone at 50 units is disuse atrophy • When difference is 50 to 2500 units – ideal loading zone • 2500- 4000 units the zone is mild overload • More than 4000 units it is pathologic overloadWWW.INDIANDENTALACADEMY.COM
  19. 19. • Microstrain can be reduced by increasing the functional surface area of bone implant interface. • Increased surface area • Implant number • Implant size • Implant design • Implant body surface condition WWW.INDIANDENTALACADEMY.COM
  20. 20. • Factors affecting force to prosthesis • Patient condition • Implant position • Direction of occlusal loading. WWW.INDIANDENTALACADEMY.COM
  21. 21. • Immediate loading reports with lowest survival rate corresponds to fewer implants loaded • Increases retention • Decreases number of pontics • Reduces fracture of transitional prosthesis • More implants used for maxilla than mandible WWW.INDIANDENTALACADEMY.COM
  22. 22. • 3mm increase in length improves surface area by 20% • No benefit at crestal bone interface • Improves initial stability • Length is more relevant for immediate loading • 1mm increase in width increases surface area by 30 % • Wider implant provide greater area of bone contact at crest of ridge • Bone augmentation done when required WWW.INDIANDENTALACADEMY.COM
  23. 23. • Implant body design should be more specific for immediate loading. • The following would be the design principles, one would want to achieve through an implant design a) Gain initial stability b) Incorporate design factors, that would diminish the effect of shear forces c) Design features that may stimulate bone formation and facilitate bone healing. WWW.INDIANDENTALACADEMY.COM
  24. 24. • A tapered design presents some disadvantage for immediate load application. • The implant doesn’t engage the bone physically until the implant is seated completely into the bone site. • Tapered implant has less overall surface area than parallel wall threaded implant. • May have less thread depth near the apical portion of implant. • Less likely to engage lateral cortical plate in apical half of implant. Tapered implants Parallel wall implantsWWW.INDIANDENTALACADEMY.COM
  25. 25. V shaped Square thread Buttress thread WWW.INDIANDENTALACADEMY.COM
  26. 26. • Thread depth, • Thread thickness, • Thread face angle, and • Thread pitch WWW.INDIANDENTALACADEMY.COM
  27. 27. • Threads have been incorporated into implants to improve initial stability • Strain is more concentrated in the area where bone contacts the crest of the thread and the strain decreased from the crest to the root of the thread. WWW.INDIANDENTALACADEMY.COM
  28. 28. • Square thread design with a flank angle of 3 degree decreases the shear force and increases the compressive load. • V thread design show 10 times greater stress • The surface area of threaded implant can be increased by • Greater no of threads • Lesser distance between the threads • Increased thread depth WWW.INDIANDENTALACADEMY.COM
  29. 29. • It may affect the • Rate of bone contact, • Lamellar bone formation and • Percentage of bone contact. • It may be that although surface texturing of implants do not directly contribute to initial implant stability it may reduce the risk of stability loss and consequently facilitating wound healing. WWW.INDIANDENTALACADEMY.COM
  30. 30. • Patient factor • Increased occlusal load increases risk of failure in immediate loaded implant. • Parafunction habits • Occlusal load direction • Axial load maintains more lamellar bone and has lower remodeling rate compared to offset load • Eliminate posterior cantilever in immediate loaded implants WWW.INDIANDENTALACADEMY.COM
  31. 31. • Implant position • More important factors for completely edentulous arches • Splinted arch position • Mandible divided into three section • Maxilla divided into five section • Occlusal contact • Only anterior contact in transitional prosthesis • Diet • Soft WWW.INDIANDENTALACADEMY.COM
  32. 32. • Modulus of elasticity related to bone quality • BIC is less for less dense bone • Remodeling rate is less for cortical bone than cancellous bone • Immediate loading of implants at bone augmented area is at higher risk WWW.INDIANDENTALACADEMY.COM
  33. 33. • To accurately asses the impact of loading protocols • Maxillary and mandibular protocol • Fixed or removable rehabilitation • Implants placed in healed sites or sockets not yet healed • Machined or rough surface implants WWW.INDIANDENTALACADEMY.COM
  34. 34. • Immediately loaded mandibular overdenture is at least risk of occlusal overload • Success rate of 88 to 97 % • Guidelines for overdenture • Completely edentulous mandibular arch • Opposing maxillary denture WWW.INDIANDENTALACADEMY.COM
  35. 35. • Abundant to moderate bone height and width • At least 12mm prosthetic space • At least 4 implants • Screw type implants • Minimum cantilever • Sleep without overdenture • Parafunctional habits- contraindication WWW.INDIANDENTALACADEMY.COM
  36. 36. • Guidelines for fixed prosthesis • 8 more implants in maxillary arch and 5 or more in mandibular arch • 10mm in length and 4 mm in width • Thread design and rough surface implants • Mandible divided in 3 section • Maxilla divided in 5 section • Only anterior teeth contact • No cantilever in transitional prosthesis • Soft diet WWW.INDIANDENTALACADEMY.COM
  37. 37. • Load the implant on the day of surgeryOption 1 • Make impression at surgery, at suture removal transitional prosthesis delivered. Option 2 WWW.INDIANDENTALACADEMY.COM
  39. 39. • Most reports suggest immediate restoration rather than full occlusal loading • Transitional retsoration mainly for esthetics • No occlusal contact • Non functional immediate teeth concept is suggested. WWW.INDIANDENTALACADEMY.COM
  41. 41. • Advantages of non functional immediate tooth concept • Esthetic restoration replaces missing teeth • Implants splinted together • Emergence profile created • Soft tissue is mature at final prosthesis • Decrease risk of biomechanical overload WWW.INDIANDENTALACADEMY.COM
  42. 42. • Disadvantage of Non functional immediate teeth • Increased overload compared to submerged implants • No evaluation of crestal bone directly • Parafunction from foreign habits may cause trauma • Impression material or acrylic may get entrapped WWW.INDIANDENTALACADEMY.COM
  43. 43. • Single tooth implant considered for immediate restoration when • Natural tooth require extraction • Esthetic zone • The soft tissue drape is in ideal condition • Bony housing around the implant is intact including the facial plate. WWW.INDIANDENTALACADEMY.COM
  44. 44. One piece implant Implant - abutment WWW.INDIANDENTALACADEMY.COM
  46. 46. • Gradual increase in load during prosthetic fabrication stimulates an increase in density • Pierazzini demonstrated development of dense trabeculae around progressively loaded implants in animals. • Implementation of progressive loading is more critical in lesser bone densities as they are several times weaker than the cortical bone. WWW.INDIANDENTALACADEMY.COM
  47. 47. • Time • Two surgical appointment between implant surgery and stage II are separated by 4-8 wks • Prosthetic appointment during which implants are sequentially load are separated by 2- 4 wks • Diet • Controlled to prevent overloading • Soft diet • Normal diet is permitted only after final prosthesis function, occlusion and cementation is evaluated. WWW.INDIANDENTALACADEMY.COM
  48. 48. • Occlusal material • Acrylic – transitional prosthesis • Metal/ porcelain- final prosthesis • Occlusion • Gradually intensified • Prosthetic design • Avoid load on implants during initial healing • Transitional prosthesis- splinting of implants WWW.INDIANDENTALACADEMY.COM
  49. 49. • Implants placed • After 1 – 4 wks, impression made for transitional prosthesis • Transitional prosthesis completely out of occlusion • Impression for final prosthesis • Metal try in • Provisional cementation of final prosthesis • Final evaluation and cementation of prosthesis WWW.INDIANDENTALACADEMY.COM
  50. 50. • A second stage surgery is eliminated. • This saves patient pain and suffering • Removable prosthesis not required • Soft tissue is allowed to mature • Implants are splinted together during healing which is biomechanically superior. WWW.INDIANDENTALACADEMY.COM
  51. 51. • Risk of failure • More number of implants are placed making treatment expensive WWW.INDIANDENTALACADEMY.COM
  52. 52. • The delayed loading protocol is being evaluated for more than 30 years. • However in some patient condition this may cause psychological, social or speech problems. Immediate loading after implant surgery is the alternative of these problems. A benefit/risk ratio should always be weighed prior to doing such a procedure. WWW.INDIANDENTALACADEMY.COM
  53. 53. • Contemporary Implant dentistry – Carl E Misch 2nd and 3 rd edition • International journal of oral maxillofacilal implant , 2004; 19: 109-113 • International journal of oral maxillofacilal implant, 2004; 19: 75- 107 • International journal of oral maxillofacilal implant, 2009; 24: 158-168 • International journal of oral maxillofacilal implant, 2009; 24: 132- 146 WWW.INDIANDENTALACADEMY.COM
  54. 54. • International journal of oral maxillofacilal implant, 2009; 24 169 – 179 • International journal of oral maxillofacilal implant, 2009; 24: 147-157 • Australian dental journal, 2008; 53(suppl): S69-S81. • Stomatologija, Baltic dental and maxillofacial journal,2004; 6: 51-54. WWW.INDIANDENTALACADEMY.COM
  55. 55. For more details please visit www.indiandentalacademy.com WWW.INDIANDENTALACADEMY.COM