Primary Stability and Fracture Resistance of Zirconia and Titanium Implants: A Paired Comparative In Vitro Study

To compare the insertion torque (IT) and removal torque (RT) of Neodent Zi zirconia (Zr) implants (Straumann) and Neodent Alvim titanium (Ti) implants (Straumann) while measuring both the maximum torque (MT) supported by the Zr implant and the MT sustained by the assembler of the implants until fracture.

In this in vitro study, 24 implants with the same microgeometry were split into two groups-12 Zr implants and 12 Ti implants-and compared. Implant bed preparations were completed in bovine ribs following a standardized drilling protocol. Then the IT, RT, MT to fracture, and MT to fracture of the assembler were completed using a calibrated torque meter. Data was presented using descriptive statistics including means, SDs, medians, and quartiles. The Shapiro-Wilk test was used to verify data normality and the Wilcoxon test was used to evaluate differences between groups. Statistical significance was established as P < .05.

Zr implants showed an IT of 89.33 ± 31.18 Ncm and an RT of 84.89 ± 32.92 Ncm. Ti implants showed an IT of 77.58 ± 28.96 Ncm and an RT of 76.75 ± 31.29 Ncm without significant differences (P > .05). In relation to fracture under rotational force, the Zr implants. fractured at 106.17 ± 22.54 Ncm, and the implant assembly fractured at 84.00 ± 13.14 Ncm.

Neodent Zi implants showed stability but a lower fracture torque than the Alvim Ti implants. As the fracture values of the assembler were significantly lower than the fracture values of the Zr implants, it can be stated that, as recommended by the manufacturer, they act as a safety measure during placement.