title: Evaluation of torque maintenance of abutment and cylinder screws with Morse taper implants.
abstract: The screw loosening of implant-supported prostheses is a common mechanical failure and is related to several factors as insertion torque and preload. The aim of this study was to evaluate the torque maintenance of retention screws of tapered abutments and cylinders of Morse taper implants submitted to retightening and detorque measurements. Two groups were obtained (n = 12): group I-tapered abutment connected to the implant with titanium retention screw and group II-cylinder with metallic base connected to tapered abutment with titanium retention screw. The detorque values were measured by an analogic torque gauge after 3 minutes of torque insertion. The detorque was measured 10 times for each retention screw of groups I and II, totalizing 120 detorque measurements in each group. Data were submitted to ANOVA and Fisher exact test (P < 0.05). Both groups presented reduced detorque value (P < 0.05) in comparison to the insertion torque in all measurement periods. There was a statistically significant difference (P < 0.05) between the detorque values of the first measurement and the other measurement periods for the abutment screw. However, there was no statistically significant difference (P > 0.05) for the detorque values of all measurement periods for the cylinder screw. In conclusion, the abutment and cylinder screws exhibited torque loss after insertion, which indicates the need for retightening during function of the implant-supported prostheses.
authors.affiliation: Department of Dental Materials and Prosthodontics, Araçatuba Dental School, Universidade Estadual Paulista (UNESP), Araçatuba, São Paulo, Brazil.
authors.forename: Mayara Barbosa
authors.initials: MB
authors.lastname: Ferreira
authors.forename: Juliana Aparecida
authors.initials: JA
authors.lastname: Delben
authors.forename: Valentim Adelino Ricardo
authors.initials: VA
authors.lastname: Barão
authors.forename: Leonardo Perez
authors.initials: LP
authors.lastname: Faverani
authors.forename: Paulo Henrique
authors.initials: PH
authors.lastname: Dos Santos
authors.forename: Wirley Gonçalves
authors.initials: WG
authors.lastname: Assunção
mesh_terms: D001863:Bone Screws; D000044:Dental Abutments; D015921:Dental Implants; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D008422:Materials Testing; D013997:Time Factors; D014025:Titanium; D019415:Torque
chemical_list: D015921:Dental Implants; D014025:Titanium