An In Vitro Load Evaluation of a Conical Implant System with 2 Abutment Designs and 3 Different Retaining-Screw Alloys

Purpose: The aim of this in vitro study was to evaluate the load resistance in a conical implant system by comparing combinations of 2 different abutment head angles and 3 different retaining screw materials. Materials and Methods: The retaining screw materials (titanium alloy, gold alloy, and commercially pure titanium) were tested with abutment-head angles of 20 degrees and 45 degrees. Six groups of 10 specimens each were prepared. An oblique (30-degree) compression test was performed in a Lloyd LRX universal testing machine with the abutment attached to a superstructure with a retaining screw. All specimens were loaded until fracture or permanent deformation occurred. The results were evaluated statistically with Wilcoxon signed rank test for variance distribution (P .05 considered significant). Results: There were statistically significant differences in load resistance between 20-degree and 45-degree abutments. The titanium screws (titanium alloy and commercially pure) in the 45-degree abutment group had almost equal mean values, while the gold alloy had a significantly lower value. In the 20-degree abutment group, significantly higher values were found with commercially pure titanium compared to titanium alloy and gold alloy, but the difference between the values for the gold and titanium alloys was not significant. Discussion: The angulation of the abutment head played the most significant role in determining the amount of load withstood, but the material used for the screw was also relevant. Conclusion: A 45-degree abutment can be combined with a retaining screw of any of these materials to create a functional implant system. The test also substantiated that, irrespective of the retaining-screw material, a 20-degree abutment could resist loading forces of at least 900 N. Keywords: dental implant failures, dental implants, implant abutments, implant loading