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

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(2020) 6:41

RESEARCH

International Journal of Implant Dentistry

Open Access

Biomechanical behavior of three different types of internal tapered connections after cyclic and static loading tests: experimental in vitro Marcos Boaventura de Moura1* , Karine Regina Tolesano Loureiro1, Livia Bonjardim Lima1, Christian Felippi2 and Paulo Cézar Simamoto Júnior1

Abstract: Background: In the long-term success of a dental implant, the reliability and stability of the implantabutment 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 (twopiece abutments with 16°), G3 and G4 (two-piece abutments with 11.5°), and G5 and G6 (one-piece abutments with 11.5°). 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° 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°) at a rate of 0.5 mm/s. Statistical analysis was performed using the ShapiroWilk (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. Keywords: Biomechanics, Dental implants, Torque

Introduction Several modifications in implant-abutment design have been made since the 1990s. The screws material and the coefficient of friction between the coupled surfaces were made to reduce the complications of the connection [1]. The mechanical complications of external connections remain a concern in the implant community. To overcome the connection problems, a new concept of internal * Correspondence: [email protected] 1 Department of Occlusion, Fixed Prosthodontics and Dental Materials, School of Dentistry, Federal University of Uberlandia, Av. Pará 1720, Bloco 4LB, sala 39, Uberlandia, MG 38405-902, Brazil Full list of author information is available at the end of the article

connection has been developed [2]. The internal connection has mechanical advantages, such as drastic reduction of screw fractures, distancing the occlusal forces deep into the implant, and protecting the screw from overload [3]. In addition, deep joints in internal connections are more prone to withstand bending forces than the flat joints of ex