Comparative in vitro evaluation of the mechanical behavior of implant–abutment connections for zirconia and titanium implants

Dental implants have significantly improved the rehabilitation of edentulous spaces. With the growing demand for metal-free treatments, zirconia has emerged as an alternative to titanium. While titanium implant connections are well documented, limited evidence exists regarding the mechanical behavior and prosthetic screw loosening of zirconia implants. The Neodent Zi® implant with the ZiLock® ceramic connection remains poorly investigated, particularly in comparison with conventional titanium systems. This study aimed to compare the removal torque values between prosthetic screws in titanium morse taper connection and zirconia ZiLock® connection implants. Twenty implants were divided into two groups: 10 Morse taper connection titanium implants (Neodent® Alvim®) and 10 ZiLock® connection zirconia implants (Neodent® Zi®). Both groups underwent initial torquing, mechanical cycling following ISO 14801 standards, and subsequent removal torque value measurement. Structural analysis of the implants was conducted using a stereomicroscope. Data was presented using descriptive statistics including means, standard deviations (SD), and frequencies. The Shapiro-Wilk test was performed to assess data normality and the Student’s t-test was applied to evaluate differences between groups. Categorical data were subjected to Fisher’s exact test. Statistical significance was established as p < 0.05. The titanium group showed higher mean removal torque values (38.27 Ncm) compared to the zirconia group (25.65 Ncm), with statistically significant differences (p < 0.001). The zirconia group exhibited fractures in two abutments. Zirconia implants with the ZiLock® connection displayed lower removal torque values than titanium implants but within acceptable clinical limits.