Preload evaluation of different screws in external hexagon joint.
OBJECTIVE
This study compared the maintenance of tightening torque in different retention screw types of implant-supported crowns.


METHODS
Twelve metallic crowns in UCLA abutments cast with cobalt-chromium alloy were attached to external hexagon osseointegrated implants with different retention screws: group A: titanium alloy retention screw; group B: gold alloy retention screw with gold coating; group C: titanium alloy retention screw with diamond-like carbon film coating; and group D: titanium alloy retention screw with aluminum titanium nitride coating. Three detorque measurements were obtained after torque insertion in each replica. Data were evaluated by analysis of variance (ANOVA), Tukey's test (P < 0.05), and t test (P < 0.05).


RESULTS
Detorque value reduced in all groups (P < 0.05). Group A retained the highest percentage of torque in comparison with the other groups (P < 0.05). Groups B and D retained the lowest percentage of torque without statistically significant difference between them (P > 0.05).


CONCLUSIONS
All screw types exhibited reduction in the detorque value. The titanium screw maintained the highest percentage of torque whereas the gold-coated screw and the titanium screw with aluminum titanium nitride coating retained the lowest percentage.
Department of Dental Materials and Prosthodontics, Araçatuba Dental School, Universidade Estadual Paulista (UNESP), Araçatuba, São Paulo, Brazil. wirley@foa.unesp.br
Wirley Gonçalves
WG
Assunção
Juliana Aparecida
JA
Delben
Lucas Fernando
LF
Tabata
Valentim Adelino Ricardo
VA
Barão
Erica Alves
EA
Gomes
Idelmo Rangel
IR
Garcia
D000704:Analysis of Variance; D020099:Coated Materials, Biocompatible; D003442:Crowns; D015921:Dental Implants; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention / Q000295:instrumentation*; D019094:Dental Prosthesis, Implant-Supported; D003799:Dental Stress Analysis; D006047:Gold Alloys; D014025:Titanium; D019415:Torque
D020099:Coated Materials, Biocompatible; D015921:Dental Implants; D006047:Gold Alloys; C041500:titanium nitride; D014025:Titanium