Marginal bone maintenance around implants placed in subcrestal level: a 2 to 9 years retrospective study
NL6QV ePOSTER CLINICAL RESEARCH – PERI-IMPLANT BIOLOGY
Background: The design and the location of the implant-abutment interface (IAI) has been deeply examined to minimize the early marginal bone resorption. It was observed that internal tapered IAI may provide better results in terms of stability, seal performance and better load distribution compared to butt-joint interfaces. Nevertheless, there is limited information on the medium- to long-term marginal bone maintenance around implants placed at subcrestal level.
Aim/Hypothesis: The aim of the present retrospective study was to determine the radiographic marginal bone stability around implants placed at subcrestal level during a follow-up of 2 to 9 years, and to identify the risk factors for bone loss.
Materials and Methods: All selected patients who gave their consent for the study, were recalled for a follow-up visit (t1) between September 2018 and February 2019. The following data were recorded: type of prosthesis, implant diameter and length, implant site, date of the prosthetic delivery, patient condition, including smoking habit (>10 cig/die), presence of type-2 diabetes. During the follow-up visit, an intraoral peri-apical radiograph and a clinical examination were performed. The radiographic images were then analyzed with a software program (Image J, NIH, Montgomery County, Maryland, USA). Marginal Bone Level (MBL) was measured for t0 and t1 as the following: the distance between the implant neck (bevel) and the first bone-to-implant contact. Measurements were taken for the mesial and the distal aspect of each implant. MBL change was calculated as the difference of MBL at the follow-up examination(t1) and MBL at baseline (t0).
Results: According to the inclusion and exclusion criteria 93 patients were included. A total of 410 implants were positioned and the average follow-up period was 2.72 years. At the follow-up examination (t1), peri-implant mucositis was observed for 24 implants (prevalence: 5.9%) while peri-implantitis was observed for 16 implants (prevalence: 3.9%). The highest prevalence (16.7%) was observed at 7 years of follow up (2 implants out of 10). Mean MBL was -1.09 ± 0.65 mm and -1.00 ± 0.37 mm at t0 and t1, respectively. Furthermore, a mean MBL change of -0.09 ± 0.68 mm was calculated. The multiple regression analysis revealed that the combination of the time from prosthetic delivery (follow-up), the initial vertical position of the implant (MBL(t0)), and the presence of type-2 diabetes (Diabetes) provides the highest predictability of MBL change (adjusted R2: 0.213). Follow-up resulted to be the most significant predictor for MBL change (t = 8.165; P < 0.001), followed by the MBL(t0) and diabetes.
Conclusions and Clinical Implications: Implants with internal conical connection and a platform switching of the abutment, placed at a subcrestal position of approximately 1 mm showed stable MBL with a low rate of peri-implant disease in a medium- to long-term follow- up. MBL change seems to be mostly influenced by the combination of time from prosthetic delivery, the initial vertical position of the implant and the presence of type-2 diabetes.
Keywords: dental implant, bone loss, retrospective study, subcrestal bone level
