ABSTRACT
The aim of this study was to evaluate in vitro the flexural strength of direct composite resin (Z-250 FiltekTM - 3M/ESPE) and second-generation laboratory composite (II CeseaD(ST) - Kuraray) associated or not with glass fibers(Fibrex -coronal - Angelus), changing the curing light source (L.E. Demetron 1 - Kerr and Strobolux - EDG). Fifty-six specimens of the composites F and C were constucted using a stainless-steel split ring molds and divided into eight groups: G1 - Composite Z-250/No fiber/LED; GII - Composite Z-250/No fiber/Strobolux (SRT); GIII - Composite Z-250/Fibrex-coronal (FBC)/LED; GIV - Composite Z-250/FBC/STR; GV - Composite CeseaD(ST) II/No fiber/LED; GVI - Composite CeseaD(ST) II/No fiber/STR; GVII - Composite CeseaD(ST) II/FBC/ LED; GVIII - Composite CeseaD(ST) II/FBC/STR. The specimens were subjected to the flexural strength in a universal testing machine equipped with a cell load of 500Kgf at a crosshead speed of 1±0.5 mm/min. The data were submitted to Tukey's Test (p = 0.01).The mean of flexural strength was in MPa: G1 - 187,91 ± 32, 78; GII - 196,76 ± 31,15; GIII - 208, 27 ± 18,79; GIV - 218,02 ± 15,76; GV - 101,72 ± 11,25; GVI - 103,05 ± 9,56; GVII - 164,76 ± 12,54 e GVIII - 176,75 ± 47,03. The direct composite showed the highest flexural strength values in all groups; the light source did not affect the flexural strength of the composites; fiber reinforcemente increased the flexural strength of both composites; however this increase was statistically significant only for the laboratory-processed composite
Subject(s)
Composite Resins , Curing Lights, Dental , Dental Materials , In Vitro Techniques , Data Interpretation, StatisticalABSTRACT
The aim of this study was to evaluate the influence of different light sources on the bond strength of indirect resin composite restorations cemented with a dual-cure resin cement. The superficial dentin of human third molars was exposed and acid-etched and an adhesive system was applied (Single Bond 2). Four-mm-thick indirect resin composite restorations (Gradia) were fabricated and cemented using a dual-cure resin cement (Rely X). Four light sources were used to polymerize the cement: QTH - Optilux 401; LED1 - L.E.Demetron 1; LED2 - Optilight CL; and LED3 - Ultralume 5. The teeth were stored for 24 h and then sectioned, yielding stick-shaped specimens for each group with a bonded area of 1.0 mm². The specimens were then tested in a universal testing machine, at a crosshead speed of 1 mm/min. Data were analyzed using ANOVA. Bond strength mean values were: QTH: 22.5 (± 8.4); LED1: 22.7 (± 9.4); LED2: 21.4 (± 10.2); and LED3: 27.3 (± 13.8). No statistically significant difference was observed among the experimental groups. The bond strength values when the cement was polymerized using different LED lights were equivalent to the values when the QTH light was used. It can be concluded that the variety of light sources used in the present study did not influence the bond strength of indirect resin composite restorations cemented with a dual-cure resin cement.