Discussion
bone loss, peri-implantitis
BONE LOSS
The results from the present randomized clinical trial have shown that both types of implants were associated with stable marginal bone levels and an improvement in the soft tissue contour. Both groups showed minimal bone loss 1 year after loading (0.16 mm in the test group and 0.45 mm in the control group). However, no statistically significant differences were detected when comparing the convergent and the straight implant neck.These results are comparable to those published by Agustín-Panadero et al. 2019 [The convergent transmucosal neck presents a similar philosophy to the platform switching concept. The idea is to give the soft tissue a greater horizontal space and to shift coronally the implant-abutment connection, which at the same time could prevent bone remodeling by providing a better sealing [It should be noted that peri-implantitis developed fast and it was greater in the test group (3 implants in the test and 1 implant in the control). This is in agreement with the study by Derks et al. that showed that the onset of peri-implantitis occurred early [In the present study, we have observed a greater increase in soft tissue contour thickness around the convergent transmucosal neck (1.96 ± 2.69 mm) than in the conventional bone-level implant (0.65 ± 0.42 mm). However, this difference has not been statistically significant. Similar results around the convergent transmucosal neck have been reported in a recent case series, showing that these implants, together with crowns using the B.O.P.T. philosophy, experienced a significant increase in soft tissue thickness, both at the buccal (0.56 ± 0.46 mm) and at the lingual (0.33 ± 0.45 mm) surfaces 10 months after prosthetic loading [Different esthetic parameters have been reported when using implants with a convergent transmucosal neck. In the prospective study published by Patri et al. 2017 [Several studies have shown that the most frequent pattern was the apical migration of the mucosal margin [There is a great heterogeneity in the parameters and methods used to evaluate the esthetics and the volume of the peri-implant soft tissues [