Comparison of the Compressive Strength of 3 Different Implant Design Systems
The aims of this study were twofold: to compare the static compressive strength at the implant-abutment interface of 3 design systems and to describe the implant abutment connection failure mode. A stainless steel holding device was designed to align the implants at 30° with respect to the y-axis. Sixty-nine specimens were used, 23 for each system. A computer-controlled universal testing machine (MTS 810) applied static compression loading by a unidirectional vertical piston until failure. Specimens were evaluated macroscopically for longitudinal displacement, abutment looseness, and screw and implant fracture. Data were analyzed by analysis of variance (ANOVA). The mean compressive strength for the Unipost system was 392.5 psi (SD ± 40.9), for the Spline system 342.8 psi (SD ± 25.8), and for the Screw-Vent system 269.1 psi (SD ± 30.7). The Unipost implant-abutment connection demonstrated a statistically significant superior mechanical stability (P ≤ .009) compared with the Spline implant system. The Spline implant system showed a statistically significant higher compressive strength than the Screw-Vent implant system (P ≤ .009). Regarding failure mode, the Unipost system consistently broke at the same site, while the other systems failed at different points of the connection. The Unipost system demonstrated excellent fracture resistance to compressive forces; this resistance may be attributed primarily to the diameter of the abutment screw and the 2.5-mm counter bore, representing the same and a unique piece of the implant. The Unipost implant system demonstrated a statistically significant superior compressive strength value compared with the Spline and Screw-Vent systems, at a 30° angulation.Abstract

(a) Screw-Vent system sleeves. (b) Spline system sleeves. (c) Unipost system sleeves. (d) Implant sleeves 2 mm below the bone line.

Test block with 30° angulation of implant.

and 4. Figure 3. (a–c) Implant failure. Figure 4. Box plots of compression load (in psi) at implant failure for 3 implant systems.

Contributor Notes
Jose E. Pedroza, DMD, MS, is an assistant professor, School of Dentistry, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico (jpedroza@rcm.upr.edu). Please address correspondence to Dr Pedroza
Ysidora Torrealba, DDS, MSD, is in the graduate program of Prosthodontics, School of Dentistry, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico.
Augusto Elias, DMD, MSD, is a professor and assistant dean of research, School of Dentistry Research Center, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico.
Walter Psoter, DDS, PhD, is an associate professor at the University of Puerto Rico Medical Sciences Campus, School of Dentistry Research Center, San Juan, Puerto Rico and an assistant professor at the New York University College of Dentistry, Department of Epidemiology and Health Promotion.