Statement of problem: Dental implants are typically made of titanium. However, with the current systems in the market, it is common for the implant neck to show through the gingival tissues as a black or dark grey line and/or as a grayish discoloration of the periimplant soft tissue.
Purpose: The purpose of this study was to test a new implant design; the ceramic neck implant is a novel implant design for tooth replacement. The key component of this novel design is the ceramic shell that covers the polished collar of the tissue level titanium implant and masks its dark color, which gives an appearance that mimics natural dentition. The main aim was to determine the maximum torque for fracturing the ceramic shell and compare it to clinical implant insertion torque value.
Material and Methods: Thirty type 4 commercially pure titanium endosseous implants of three different diameters (3.3, 4.1, 4.8 mm) were used in this study. Porcelain was applied in 0.5 mm thickness on the polished collar of each implant as determined in a previous article. Axial-torsional universal testing machine was used to twist the implants at X N.cm/s until failure. The data (n=10) were statistically analyzed by ANOVA/Tukey test with a significant level α = .05. The maximum torque for each diameter group was also compared to optimum clinical implant insertion torque value of 35 Ncm (control) using one sample T-test (P<.001).
Results. None of the tested groups had a fractured ceramic shell at all. Instead, the implants carriers have fractured at certain torque levels. Therefore, the fracture of the implants carriers was selected as the maximum (failure) torque value. There was statistical difference for the failure torque (Mean ± SD) between 3.3 mm diameter and the other two diameters (P<.001) (F=15.6) while no statistical difference was found between the 4.1 mm and 4.8 mm diameters (p=.106). A statistically significant difference was found between failure torque of any one of the tested groups and the clinical insertion torque (P<.001).
Conclusions: Ceramic shells did not fracture. Instead, implants carriers have fractured at certain torque levels. These levels were sufficiently higher than the clinical torque values. This means that there are fewer chances that a fracture might happen while inserting the novel ceramic neck implant and/or the abutment.