Influence of reverse torque values in abutments with or without internal hexagon indexes.
BACKGROUND
The mechanical stability of the implant-abutment connection is of fundamental importance for successful implant-supported restorations. Therefore, understanding removal torque values is essential.


OBJECTIVE
The purpose of this study was to evaluate the reverse torque values of indexed and nonindexed abutments of the Morse Taper system.


METHODS
Twelve Morse taper implants with their respective abutments were divided into 2 groups (n=6): group NI, nonindexed abutments; and group IN, indexed abutments. Each abutment received a sequence of 2 consecutive torques for insertion (15 Ncm) at an interval of 10 minutes, and 1 reverse torque, all measured with a digital torque wrench. The Student t test with a 5% significance level was used to evaluate the data.


RESULTS
Statistical analysis showed no significant difference in reverse torque values between nonindexed and indexed abutments (P=.57). When comparing insertion torque and reverse torque values between the groups, group NI presented a mean torque loosening percentage of 8% (P=.013), whereas group IN presented a loosening of 15.33% (P<.001).


CONCLUSIONS
The use of indexed abutments for the Morse taper system presented similar biomechanical stability when compared with nonindexed abutments, both with a significant reduction in reverse torque values.
Doctoral student, Faculty of Dentistry, Federal University of Rio Grande do Sul - Porto Alegre, Rio Grande do Sul, Brazil.
Daiane
D
Cerutti-Kopplin
Lecturer, Department of Prosthodontics, Dental School, University of Southern Santa Catarina, Santa Catarina, Brazil.
Dimas João
DJ
Rodrigues Neto
Professor, Department of Prosthodontics, Bauru Dental School, University of Sao Paulo, Sao Paulo, Brazil.
Accácio
A
Lins do Valle
Associated Clinical Professor and Research Coordinator, Department of Prosthodontics, Dental School, University of Southern Santa Catarina, Santa Catarina, Brazil. Electronic address: jeffripe@rocketmail.com.
Jefferson Ricardo
JR
Pereira
D001696:Biomechanical Phenomena; D000044:Dental Abutments; D003722:Dental Alloys / Q000737:chemistry; D059605:Dental Implant-Abutment Design; D017268:Dental Prosthesis Retention; D017276:Friction; D006801:Humans; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013997:Time Factors; D019415:Torque
D003722:Dental Alloys; D013193:Stainless Steel