Aim: The aim of this study was to assess the impact of cyclic loading on screws attaching four different abutments to internally connected implants.
Materials and methods: Four groups (seven implants each) of dissimilar abutments: Straumann solid abutment (group I), southern implants solid abutment (group II), implant direct straight abutment (group III), and Blue Sky Bio regular platform abutment (group IV). Abutments were connected to Straumann tissue-level implants. Each implant was rigidly secured in a stainless steel cylindrical jig. A torque controller was used to tighten the abutments at 35 Ncm. A 150 N cyclic load for 1 million cycles was applied to the implant at a 30° angle to the long axis to the implants. Periotest values (PTVs) were measured before and after cyclic loading and a digital torque gauge was used to detect the removal torque values (RTVs) of abutments. The data were analyzed statistically using SPSS statistical software. Kruskal–Wallis tests and one-way analysis of variance (ANOVA) were used to compare RTVs and PTVs after application of equal loads for each group. The Spearman correlation coefficient was applied to compare RTVs and PTVs after loading.
Results: The Straumann solid abutment and the southern implants abutment showed no mechanical failures. Screws fracture was noted in nearly 85% of implant direct abutment, and 55% of the Blue Sky Bio abutments. The final mean PTV of the Blue Sky Bio abutments, the southern implants, and implant direct straight abutment was considerably higher than the final mean PTVs of Straumann solid abutment. The initial mean PTV (–4.36 ± 0.47) was lower than the final mean PTV (4.85 ± 5.58). The Straumann solid abutment RTVs values were considerably higher than that of the other abutments.
Conclusion: Abutments from the different manufacturers have different physical and chemical characteristics so there will be a potential risk of mechanical failure when the interchangeable abutments are used.
Clinical significance: The use of an abutment manufactured by the same implant company is highly recommended for the avoidance of loosening of the abutment screws.
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