Clinical and experimental studies of bone substitutes and dental implants in compromised bone sites

Abstract: Background: With an ageing population, an increase of more challenging implant treatments is expected. In this thesis, we evaluate the outcome of two faster implant protocols, in patients with compromised alveolar bone. We examine the bone integrating abilities of two new synthetic bone substitute materials and in another paper, we discuss the effects of nonsteroidal anti-inflammatory drugs (NSAID) on bone healing.Aim: In paper I we investigate implant survival and effect of reduced implant-tooth distance. In paper II we evaluate the long-term implant survival and function of immediately loaded implants. In paper III & IV, we analyse if added NSAID reduce postoperative pain and if it has a reduced effect on new bone formation in a rabbit sinus lift model. We also investigate if a ceramic compound (CPC, granules) and hydrogel (HABP.CaP) result in a similar or larger bone amount, in comparison with bovine bone mineral. In Paper V we assess new bone formation adjacent to a hollow CPC implant.Material & Methods: Paper I present a clinical and radiological follow-up, performed on subjects that previously received 3.0-3.3 mm diameter implants in the aesthetic area. In paper II, clinical and radiographic examinations were performed on subjects that had received six implants each with immediate loading in the maxilla 8-11-year ago. For paper III-IV, pain was assessed by clinical examination and scoring of facial expressions from photos. Histomorphometry and histology evaluations were performed. In paper V, a critical radius defect was created and either replaced by particulate autologous bone (AB) or a CPC implant. Qualitative and quantitative radiographic and histology evaluations were performed. Results: In paper I, an implant survival of 97.2% up to 124 months was shown with a tooth-implant distance in many cases of  <1.5 mm. Discoloration and recession of the buccal gingiva was the most frequent patient concern. In paper II a cumulative implant survival rate was 81.9 % at the final follow-up. In paper III and IV it was shown that NSAID had no effect on pain relief or bone formation. No difference was shown between CPC and control, but both showed larger bone amount and BIC than HABP.CaP. In paper V new bone was seen in sites throughout the entire CPC implant.Conclusion: Satisfactory long-term dental implant results can be obtained without bone augmentation in most patients with atrophic alveolar bone, but there is still a minority in this group that may benefit of bone enhancement prior to implant treatment. To avoid the negative effects of autologous bone grafting, synthetic materials as the presented CPC, have shown promising results as a solution or alternative to existing bone substitutes in animal models.