Biomechanical behavior of three different types of internal tapered connections after cyclic and static loading tests: experimental in vitro

Background In the long-term success of a dental implant, the reliability and stability of the implant-abutment interface are important. Studies of maximum force of dental implants with different loading values have been used. This study aims to evaluate the influence of the oblique cyclic loading on the maximum force supported in one-piece and two-piece abutments installed on internal tapered implants. Findings Sixty implants and sixty prosthetic abutments were divided into six groups (n= 10): G1 and G2 (two-piece abutments with 16 degrees), G3 and G4 (two-piece abutments with 11.5 degrees), and G5 and G6 (one-piece abutments with 11.5 degrees). A 2-Hz cyclic loading was applied to specimens of G2, G4, and G6, with a number of cycles of 2,400,000. All specimens were inclined by 30 degrees from the vertical axis, and a vertical loading was applied over the tapered connections (ISO 14801). Then, the maximum force was tested by applying a static compression load on the specimens of the 6 groups tested (30 degrees) at a rate of 0.5 mm/s. Statistical analysis was performed using the Shapiro-Wilk (p> 0.05) and Levene (p= 0.789) tests to determine if the data presented homoscedasticity and the Tukey test for multiple comparisons. Tukey test showed that the maximum force supported by G1 and G2 was not affected by the cyclic load, while in G3 and G4 it decreased significantly when subjected to the cyclic load. The G5 and G6 had a significant increase in maximum force supported when subjected to cyclic load. Conclusions Cyclic loading influenced the maximum force supported of G4 and G6 but did not influence G2.