Effect of light sources and curing mode techniques on sorption, solubility and biaxial flexural strength of a composite resin.
Adequate polymerization plays an important role on the longevity of the composite resin restorations.


OBJECTIVE
The aim of this study was to evaluate the effect of light-curing units, curing mode techniques and storage media on sorption, solubility and biaxial flexural strength (BFS) of a composite resin.


METHODS
Two hundred and forty specimens were made of one composite resin (Esthet-X) in a stainless steel mold (2 mm x 8 mm Ø), and divided into 24 groups (n=10) established according to the 4 study factors: light-curing units: quartz tungsten halogen (QTH) lamp and light-emitting diodes (LED); energy densities: 16 J/cm² and 20 J/cm²; curing modes: conventional (CM) and pulse-delay (PD); and permeants: deionized water and 75% ethanol for 28 days. Sorption and solubility tests were performed according to ISO 4049:2000 specifications. All specimens were then tested for BFS according to ASTM F394-78 specification. Data were analyzed by three-way ANOVA followed by Tukey, Kruskal-Wallis and Mann-Whitney tests (α=0.05).


RESULTS
In general, no significant differences were found regarding sorption, solubility or BFS means for the light-curing units and curing modes (p>0.05). Only LED unit using 16 J/cm² and PD using 10 s produced higher sorption and solubility values than QTH. Otherwise, using CM (16 J/cm²), LED produced lower values of BFS than QTH (p<0.05). 75% ethanol permeant produced higher values of sorption and solubility and lower values of BFS than water (p<0.05).


CONCLUSIONS
Ethanol storage media produced more damage on composite resin than water. In general the LED and QTH curing units using 16 and 20 J/cm² by CM and PD curing modes produced no influence on the sorption, solubility or BFS of the tested resin.
School of Dentistry, Federal University of Goiás, Goiânia, GO, Brazil. andreia.assiscarvalho@gmail.com
Andreia Assis
AA
Carvalho
Francine do Couto Lima
Fdo C
Moreira
Rodrigo Borges
RB
Fonseca
Carlos José
CJ
Soares
Eduardo Batista
EB
Franco
João Batista de
JB
Souza
Lawrence Gonzaga
LG
Lopes
D000042:Absorption; D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry / Q000528:radiation effects*; D055117:Curing Lights, Dental; D000431:Ethanol / Q000737:chemistry; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000379:methods*; D008422:Materials Testing; D058105:Polymerization / Q000528:radiation effects; D012995:Solubility; D018709:Statistics, Nonparametric; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry
D003188:Composite Resins; D014867:Water; D000431:Ethanol