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ePaper created 2017-03-17, 12:34:42 | version 1.38.0
| case report The post-extraction immediate implant A new approach for illing residual bone defects Authors: Prof. Dr Mauro Labanca, Dr Ernesto Amosso & Prof. Dr Luigi F. Rodella, Italy Literature Introduction In international literature, a growing number of studies have assessed and quantified alveolar bone resorption following an extraction procedure.1-4 After dental extraction, height and width of the residual bone ridge suffer a reduction that appears to be greater in the first 30 days1 and about 50 per cent of the total resorption in the first 3 months3. The exact causes of this mechanism are controversial and cur- rently under discussion.4-8 In order to limit bone re- sorption after the act of extraction, several tech- niques have been proposed. Different regenerative procedures designed to preserve the alveolar bone crest have been used over the years and analysed in the literature. However, de- spite these procedures reducing buccolingual re- sorption, it has been demonstrated that there is still a loss of bone after healing.9–11 Paolantonio (2001) was the first to argue that post-extraction implant placement could prevent bone resorption.12 Others have dismissed this hypothesis after ample studies on humans4, 13–17 and animals19, 20 that, despite posi- tioning of the fixture, there is still buccolingual re- sorption of the ridge. The principle that determines the peri-implant bone loss has not yet been ade- Fig. 1: Preoperative periapical X-ray image evidenced dental fracture on 14. Fig. 1 16 implants 1 2017 quately clarified, but several factors appear to be im- plicated such as localisation (anterior/posterior), the thickness of the buccal wall, the gap between the im- plant surface and the bone wall, the type of surgical technique used (with/without flap), the presence of interdental osseous peaks and the surface treatment of the implant.19, 22 Moreover, due to a frequent radicular anatomical variability with respect to the profile of the implant, after positioning of a post-extraction fixture there is often a gap between the implant surface and the bone wall (residual bone implant gap, BIG).16 Although the BIG can be reduced by the presence of a blood clot,18 the use of biomaterials as support has been verified and validated by several studies on animals20, 30-32 and humans21, 25-29. As demonstrated in a study by Han et al. (2011), the regeneration of the peri-implant de- fect with biomaterial, associated or not associated with the membrane, increases the percentage of bone to implant contact (BIC).33 During the above-described regenerative proce- dure, usually priority is given to the most coronal por- tion with the objective of limiting bone resorption, maintaining interproximal peaks if present, better managing gingival aesthetics and preventing invagi- nation of soft tissue in the defect. Instead, our proto- col provides for the positioning of biomaterial even before implant placement. This allows greater primary implant stability already during insertion. Also, in consideration of the fact that most of the existing fix- tures are self-tapping, the macrostructure of the im- plant favours progression of the inserted particulate downward by first placing it in those areas of apical defect otherwise not easily accessible in the next phase. It should also be remembered that it is the more vascularised apical portion that originates the regen- erative push that will then progress in the coronal direction, thus increasing the BIC.34