Document Detail

Effect of retorque on loosening torque of prosthetic screws under two levels of fit of implant-supported dentures.
MedLine Citation:
PMID:  20464315     Owner:  NLM     Status:  MEDLINE    
This study evaluated the influence of retorque on loosening torque (Lt) of prosthetic screws in implant-supported dentures with different fit levels. Ten mandibular implant-supported dentures were fabricated and then 20 cast models were then prepared using prosthetic structures to create 2 fit levels: passive fit (Pf) and misfit (Mf). Two tightening techniques were also evaluated: initial torque only (T1); and initial torque and retorque after 10 min (T2). Gold or titanium screws were used, resulting in 4 groups to each one: Pf/T1, Pf/T2, Mf/T1, Mf/T2. The Lt was measured 24 h after the tightening torque using digital torque meter. Data were analyzed statistically by two-way ANOVA and Tukey's test (alpha=0.05), separately for each screw material. For titanium screws, no significant difference (p>0.05) was found between Pf/T1 and Pf/T2, or between Pf/T2 and Mf/T2. However, statistically significant difference (p<0.05) was found between Pf/T1 and Mf/T1, and between Mf/T1 and Mf/T2. Mf reduced the Lt using T1, while and T2 increased the Lt for Mf. Retorque and fit were shown to have no significant influence on the Lt of the gold screws. Retorque application made insignificant the misfit effect on the Lt of the titanium screws, suggesting that this procedure should be performed routinely during the screw tightening in multi-unit dentures.
Aloísio Oro Spazzin; Guilherme Elias Pessanha Henrique; Mauro Antônio de Arruda Nóbilo; Rafael Leonardo Xediek Consani; Lourenço Correr-Sobrinho; Marcelo Ferraz Mesquita
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Brazilian dental journal     Volume:  21     ISSN:  1806-4760     ISO Abbreviation:  Braz Dent J     Publication Date:  2010 Jan 
Date Detail:
Created Date:  2010-05-13     Completed Date:  2010-08-18     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9214652     Medline TA:  Braz Dent J     Country:  Brazil    
Other Details:
Languages:  eng     Pagination:  12-7     Citation Subset:  D    
Department of Restorative Dentistry, Dental Materials Division, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
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MeSH Terms
Acrylic Resins / chemistry
Chromium Alloys / chemistry
Dental Abutments*
Dental Alloys / chemistry
Dental Implants*
Dental Marginal Adaptation* / classification
Dental Materials / chemistry
Dental Prosthesis, Implant-Supported*
Denture Design
Denture Retention / instrumentation
Denture, Complete, Lower
Gold Alloys / chemistry
Materials Testing
Time Factors
Titanium / chemistry
Tooth, Artificial
Reg. No./Substance:
0/Acrylic Resins; 0/Chromium Alloys; 0/Dental Alloys; 0/Dental Implants; 0/Dental Materials; 0/Gold Alloys; 12743-70-3/titanium alloy (TiAl6V4); 7440-32-6/Titanium

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