Document Detail

Contraction stress and physical properties development of a resin-based composite irradiated using modulated curing methods at two C-factor levels.
MedLine Citation:
PMID:  17681596     Owner:  NLM     Status:  MEDLINE    
OBJECTIVES: The objective of this study was to verify the influence of curing methods on contraction stress, stress rate and degree of conversion (DC) of a restorative composite at two C-factor levels. METHODS: For the stress test, composite was applied between two for 15 min from diameter glass rods mounted in a servohydraulic machine, and stress was monitored for 10 min from the beginning of light curing. Stress rates were calculated as the change in stress versus time at each second. DC was measured by micro-FTIR. Four curing methods were tested at two C-factor levels (1.5 and 3.0): continuous light (CL), soft-start (SS) and two pulse delay methods using different initial irradiances--150 mW/cm(2) (PD150) and 80 mW/cm(2) (PD80). Results were analyzed by ANOVA and Tukey's test (alpha=0.05). RESULTS: For the stress test, at CF 1.5, PD80 presented the lowest mean value, statistically different from the others. PD150 also showed a mean value statistically inferior to CL. At CF 3.0, no statistical difference was observed among CL, SS and PD150. PD80 presented statistically lower stress values compared to CL and SS. Stress values at CF 3.0 were statistically higher than those at CF 1.5 for all curing methods. CL presented the highest maximum stress rate, followed by SS, PD150 and PD80, for both C-factors. In the DC test, no difference was observed among the methods and between the C-factor levels. SIGNIFICANCE: Modulated curing methods were shown to be effective in reducing contraction stress rate, without compromising the DC of the restorative composite. C-factor was shown to influence negatively the stress rate and the amount of stress generated.
Leonardo G Cunha; Roberta C B Alonso; Carmem S C Pfeifer; Lourenço Correr-Sobrinho; Jack L Ferracane; Mário Alexandre C Sinhoreti
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-08-02
Journal Detail:
Title:  Dental materials : official publication of the Academy of Dental Materials     Volume:  24     ISSN:  0109-5641     ISO Abbreviation:  Dent Mater     Publication Date:  2008 Mar 
Date Detail:
Created Date:  2008-02-01     Completed Date:  2008-06-11     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  8508040     Medline TA:  Dent Mater     Country:  England    
Other Details:
Languages:  eng     Pagination:  392-8     Citation Subset:  D    
Department of Restorative Dentistry, University of Campinas-UNICAMP, Piracicaba, São Paulo, Brazil.
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MeSH Terms
Analysis of Variance
Composite Resins / chemistry*,  radiation effects*
Dental Marginal Adaptation
Dental Stress Analysis*
Materials Testing
Phase Transition
Spectroscopy, Fourier Transform Infrared
Statistics, Nonparametric
Reg. No./Substance:
0/Composite Resins; 0/Filtek Z250

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