Caroliene Meijndert

91 Alvoalar ridge preservation in defect sockets in the maxillary aesthetic zone stability at implant placement of all implants, marginal bone loss was minor, peri- implant soft-tissues were stable and patients and professionals were satisfied with the aesthetic results. To the best of our knowledge, only the Caiazzo et al. (2019) pilot study has published information on the Straumann BLT implant in the aesthetic region. However, they only reported the changes in buccal bone thickness and had a 6 month follow-up. Two other studies, though, focussed on Straumann BLT implants in the molar regions. Levine et al. (2019) noted a survival rate of 98.3% and a marginal bone level change of -0.3±0.46 mm after one year, which is slightly higher than that described by us (-0.07±0.12 mm). However, baseline measurements were made immediately after implant placement, in contrast to our baseline measurement, which was 4 months after implant placement. Pariente et al. (2020) described that most bone loss occurs in the 3 months after implant surgery. Here, the mean bone loss during the first year after implant placement was 0.35±0.23 mm, of which 0.28±0.19mm in the first 3 months. This could explain the difference in results between our and the above mentioned studies. The implant stability quotient was measured in neither the study of Levine et al. (2019), nor the study of Pariente et al. (2020). Moroi et al. (2020) studied implant stability of tapered implants versus cylindrical implants, but these implants were from a different brand and mostly placed in the posterior region. They found a mean ISQ value of 60.2±12.41 at implant placement and 66.6±9.00 at definitive crown placement for the tapered implants. These values were higher than for the cylindrical implants, being 54.7±7.92 and 64.0±5.78 ISQ at respectively implant placement and definitive crown placement. The rationale to use tapered implants is the claimed less risk of bone fenestrations in anatomical undercuts at the apical part of tapered implants, as often is present with the maxillary alveolar processes. And also, in the literature is it is claimed that a tapered implant design has the possible benefit of improved primary stability compared to parallel-walled implants. However, the question was if this is also true in relatively soft bone as is the case in alveolar ridge preservation sites, because initial implant stability measurements in the maxillary aesthetic region were not performed. This is the reason why implant stability has been added as outcome measure in the present study. In the present study the mean ISQ values were high, being respectively 68.9±8.74 and 80.2±2.73, indicating good implant stability at both evaluation time points for this new implant design in the maxillary aesthetic region in sites in which alveolar ridge preservation has been performed. In the literature waiting times to place implants after alveolar ridge preservation differ from 3-6 months (Avila-Ortiz et al., 2019). A long waiting time gives the risk of 5