Chapter 02: Consensus Statements on Ridge Augmentation and Review of the Literature
2
Consensus Statements on Ridge Augmentation and Review of the Literature
Various groups were appointed to deal with different topics at the 4th ITI Consensus Conference in Stuttgart in 2008. Group 4 was assigned to review surgical techniques and biomaterials used in implant dentistry and to evaluate the available evidence supporting their use. Two of four review papers that had been prepared for Group 4 were devoted to materials and methods for ridge augmentation:
Simon Storgård Jensen and Hendrik Terheyden: Bone augmentation procedures in localized defects in the alveolar ridge: Clinical results with different bone grafts and bone-substitute materials. A review (Jensen and Terheyden 2009)
Matteo Chiapasco, Paolo Casentini and Marco Zaniboni: Bone augmentation procedures in implant dentistry (Chiapasco and coworkers 2009).
These review papers formed the basis for discussing and subsequently formulating a series of consensus statements and recommendations for clinical procedures (Chen and coworkers 2009). Section 2.1 summarizes the consensus statements and clinical recommendations pertaining to ridge augmentation procedures. Section 2.2 will then update the reader on the more recent literature that has been added since these consensus statements were published in 2009.
2.1
Consensus Statements and Treatment Guidelines Formulated at the 2008 ITI Consensus Conference
2.1.1Consensus Statements
General statements
Several surgical procedures are available and effective for the augmentation of deficient edentulous ridges to allow implants to be placed. However, most of the studies are retrospective in nature, with small sample sizes and short follow-up periods.
Therefore, direct comparisons between studies should not be made and definitive conclusions cannot be drawn.
There are a variety of defect situations with increasing complexity ranging from fenestrations, to dehiscences, to lateral deficiencies, and to vertical deficiencies including combinations of these.
There are a variety of augmentation materials available with different biologic and mechanical properties ranging from particulate alloplastic materials to intraorally harvested block grafts.
Survival rates of implants placed in regenerated bone after treatment of localized defects in the alveolar ridge are comparable to survival rates of implants placed in native bone.
It was not possible to demonstrate the superiority of one augmentation technique over another based on implant survival rates.
Dehiscence- and fenestration-type defects
Augmentation of dehiscence- and fenestration-type defects is effective in reducing the amount of exposed implant surface. Complete resolution of dehiscence and fenestrationtype defects cannot be predictably accomplished irrespective of the grafting protocol employed.
Increased defect fill was observed when the augmentation procedure included the use of a barrier membrane.
Survival rates of implants placed simultaneously with augmentation of dehiscence or fenestration type defects are high.
Horizontal ridge augmentation
Techniques are available to effectively and predictably increase the width of the alveolar ridge.
Augmentation utilizing autologous bone blocks with or without membranes results in higher gains in ridge width and lower complication rates than the use of particulate materials with or without a membrane.
Survival rates of implants placed in horizontally augmented alveolar ridges are high.
Vertical ridge augmentation
Techniques are available to increase the height of the alveolar ridge. However, their predictability is substantially lower compared to horizontal ridge augmentation procedures.
Augmentation utilizing autologous bone blocks with or without membranes results in higher gains in ridge height than the use of particulate materials with or without a membrane.
The complication rate related to vertical augmentation of the alveolar ridge is substantially higher compared to horizontal ridge augmentation procedures.
Survival rates of implants placed in vertically augmented alveolar ridges are high.
Maxillary sinus floor elevation using the transalveolar approach
Maxillary sinus floor elevation using the transalveolar approach is predictable for augmenting bone in the posterior maxilla.
A variety of grafting materials can be safely and predictably used, alone or in combination. These materials include autografts, allografts, xenografts, and alloplastic materials.
At present, it is not clear whether the introduction of a grafting material improves the prognosis.
Onlay bone grafting of extended resorption of edentulous ridges
Autologous onlay bone grafting procedures are effective and predictable for the correction of severely resorbed edentulous ridges to allow implant placement. An uneventful healing/consolidation of grafts taken from intra- and/or extraoral donor sites occurs in the majority of cases.
Acceptable survival rates of implants placed in maxillae and mandibles reconstructed with autologous onlay bone grafts are reported. The survival rates are slightly lower than those of implants placed in native bone.
Maxillary sinus floor elevation using the lateral approach
Maxillary sinus floor elevation procedures are predictable for augmenting bone in the posterior maxilla.
A variety of grafting materials can be safely and predictably used, alone or in combination. These materials include autografts, allografts, xenografts, and alloplastic materials.
The use of autografts does not influence survival rates of rough surface implants, but may reduce healing times.
The quantity and quality of bone in the residual maxilla influence survival rates of implants independently from the type of grafting procedure.
Survival rates of rough surface implants placed in augmented maxillary sinuses are similar to those of implants inserted in native bone.
Split-ridge/ridge expansion techniques with simultaneous implant placement
Split-ridge and expansion techniques are effective for the correction of moderately resorbed edentulous ridges in selected cases.
Survival rates of implants placed at sites augmented using split-ridge/ridge expansion techniques are similar to those of implants inserted in native bone.
Split-ridge technique with interpositional bone grafts
There is a lack of evidence concerning the split-ridge technique with interpositional bone graft and delayed implant placement.
Vertical distraction osteogenesis
Alveolar distraction osteogenesis can be used to augment vertically deficient alveolar ridges in selected cases.
Alveolar distraction osteogenesis has a high rate of complications. These include change of the distracting vector, incomplete distraction, fracture of the distracting device, and partial relapse of the initial bone gain.
Survival rates of implants placed at sites augmented using distraction osteogenesis are similar to those of implants inserted in native bone.
Le Fort I osteotomy with interpositional autologous bone grafts
Le Fort I osteotomy with interpositional autologous bone graft can be used successfully to treat atrophy of the maxilla including cases associated with severe intermaxillary discrepancy.
2.1.2Treatment Guidelines
Bone augmentation procedures should always follow a prosthetically driven plan to allow ideal three-dimensional implant positioning. The concept of "prosthetically driven bone augmentation" should be taken into consideration whenever possible.
Localized defects
Dehiscence and fenestration-type defects may be successfully managed using a particulate autograft or bone substitute covered with a membrane.
Horizontal ridge augmentations often require the use of an autologous block graft, which may be combined with a membrane and/or a particulate autograft or bone substitute.
Vertical ridge augmentations most often require the use of an autologous block graft, which may be combined with a membrane and/or a particulate autograft, allograft, or xenograft. Despite the use of an autologous block graft, elevated rates of complications, including graft resorption, and a need for additional grafting have to be anticipated. Even localized vertical bone deficiencies may require advanced surgical procedures like distraction osteogenesis, interpositional grafts, or onlay grafts from extraoral donor sites.
The clinician should be aware that the obtainable defect fill decreases and complication rates and need for additional grafting procedures increase with more demanding defect types. The augmentation material should be selected according to the biological and mechanical characteristics needed in the...
