Influence of prosthetic screw material on joint stability in passive and non-passive implant-supported dentures.
OBJECTIVE
This study evaluated the influence of prosthetic screw material on joint stability in implantsupported dentures at two levels of fit.


METHODS
Ten mandibular implant-supported dentures were fabricated. Twenty cast models were fabricated using these dentures. Four groups (n=10) were tested, according to the vertical fit of the dentures [passive and non-passive] and prosthetic screw materials [titanium (Ti) or gold (Au) alloy]. The one-screw test was performed to quantify the vertical misfits using an optic microscope. The loosening torque for the prosthetic screws was measured 24 hours after the tightening torque (10 Ncm) using a digital torque meter. Data were analyzed by two-way ANOVA and Tukey's test (alpha=0.05).


RESULTS
Overall, dentures with passive fit and Ti screws resulted in significantly higher loosening torque of the prosthetic screws (p<0.05). No significant interaction was found between fit level and screw material (p=0.199). The prosthetic screw material and fit of implant-supported dentures have an influence on screw joint stability. Ti screws presented higher joint stability than Au screws and minimum of misfit should be found clinically to improve the mechanical behavior of the screw joint.
Department of Prosthodontics and Periodontics, Dental School of Piracicaba, State University of Campinas, 901 Avenue Limeira, Piracicaba, SP 13414-903, Brazil.
Aloísio Oro
AO
Spazzin
Guilherme Elias Pessanha
GE
Henriques
Mauro Antônio
MA
de Arruda Nóbilo
Rafael Leonardo Xediek
RL
Consani
Lourenço
L
Correr-Sobrinho
Marcelo Ferraz
MF
Mesquita