Reliability of the Implant Stability Measurement Performed at the Abutment Level. A Retrospective Clinical Trial and an In Vitro Research

Purpose: To verify whether measuring the implant stability quotient (ISQ) at the abutment level is identical to the value obtained at the implant level. Materials and Methods: A retrospective clinical study and in vitro study were performed. For each study, the ISQ measured at the implant level defined the control groups. The values obtained after the abutment seating comprised the test groups, which were divided into three test subgroups corresponding to three different multiunit abutments: (1)straight multiunit abutments (MUAS) and (2)17-degree angled multiunit abutments (MUA17), both with a 2.5-mm collar, and (3)30-degree angled multiunit abutments (MUA30) with a 3.5-mm collar. Data was compared by the Wilcoxon signed-rank test and Kruskal-Wallis test. Results: The control group (59 implants; 79.14 [SD = 3.39]) showed significantly higher measurements than the test group (73.22 [SD = 8.54]). In addition, the subgroup measurements from MUA17 (16 abutments; 66.38 [SD=1.20]) and MUA30 (16 abutments; 69.19 [SD = 0.96]) were lower than the control group. No differences were found in the MUAS (27 abutments; 79.67 [SD = 1.48]) subgroup when compared with the control group (correlation of 0.68). Regarding the in vitro analysis, the control group measurements (36 implants; 68.02 [SD = 1.81]) were significantly higher than the test group (62.57 [SD = 2.87]). The control group measurements were also higher than each test subgroup (12 abutments each): MUAS (65.44 [SD = 0.73]), MUA17 (60 [SD = 0.43]), and MUA30 (62.29 [SD= 0.35]). Conclusions:Based on the results of this study, determining the ISQ at the abutment level results in lower ISQ values than the implant level; note that these measurements may not accurately reflect the actual implant stability. Future research is needed to explore whether and under what circumstances a correlation exists between the ISQ measured at the implant level and abutment level.