Novel CAD–CAM fabrication of a custom-made ball attachment retentive housing: an in-vitro study

Purpose This study aims to evaluate the digitally designed ball attachment housing in its initial retentive force and after 2 years of simulated clinical use and to compare it with the regular nylon ball attachment housing. Materials and methods Twenty implants with their corresponding ball abutments (diameter 4.5 x 4.0 mm) were inserted in resin blocks. They were divided into two groups. In Group I, ten ball abutments each received their corresponding conventional attachment with nylon rings. In Group II, ten ball abutments received the novel CAD-CAM polyetheretherketone ball attachment housing. A universal testing machine was used to measure the retention force. The achieved maximum values of retention force were recorded at the beginning of the study (initial retention) and after 2 years of artificial ageing (2000 cycles of insertion and removal). Results were statistically analyzed using an independent sample T test. Results The PEEK attachment housing showed high retention forces (25.12 [+ or -] 0.99 N) compared to the conventional attachment with a nylon ring (15.76 [+ or -] 0.93 N) in the initial dislodgement test. There was a statistically significant difference in mean retention at the initial retention test and after 2 years of stimulated usage between the two studied groups, p = 0.000. Conclusions Within the limitations of this study, the novel CAD-CAM-PEEK attachment showed high retention characteristics compared to the conventional attachment with nylon rings, initially and after simulated long-term use. Keywords: CAD-CAM-PEEK attachment, Measurement of retention, Custom-made attachment