Marginal adaptation of class V composite restorations submitted to thermal and mechanical cycling

Objective This study evaluated the effect of the margin location and an adhesive system on the marginal adaptation of composite restorations. Material and Methods Class V cavities were prepared in bovine teeth with the gingival margin on the dentin and the incisal margin on the enamel. The cavities were restored with a micro-hybrid composite resin using an etch-and-rinse [Single Bond 2 (SB)] or a self-etching adhesive [Clearfil SE Bond (CL)]. After finishing and polishing the restorations, epoxy replicas were prepared. The marginal adaptation was analyzed using scanning electronic microscopy (SEM, 500 x magnification). The higher gap width in each margin was recorded (T0). After the first evaluation, the samples were submitted to thermal cycling (2,000 cycles of 5°C±2°C followed by 55°C±2°C – T1) and mechanical cycling (100,000 cycles of 50 kN and 2 Hz – T2). Replicas of samples were rebuilt after each cycling and analyzed under SEM. The data were submitted to Mann-Whitney, Wilcoxon and Friedman testing (α=0.05). Results The SB presented higher gaps in the dentin than the enamel, while there was no difference between the substrate for the CL. In the dentin, the CL showed better marginal sealing than the SB. The opposite occurred in the enamel. There were no significant differences between the baseline, thermal and mechanical cycling for any experimental condition. Conclusions The outcomes of the present study showed that the adhesive system and margin location have an important effect on the marginal adaptation of composite restorations

Effect of cavity preparation design on the fracture resistance of directly and indirectly restored premolars

e aim of this study was to evaluate the fracture resistance of human premolars with extensive cavity preparations of the inlay and onlay types, for performing direct and indirect composite resin restorations. Methods: Eight-four premolars were divided into 7 groups (n=12): G1=intact teeth; G2=inlay/Filtek Z-250 direct; G3=inlay/ Filtek Z-250 light polymerized indirectly; G4=inlay/Solidex; G5=onlay/ Filtek Z-250 direct; G6=onlay/ Filtek Z-250 light polymerized indirectly; G7=onlay/ Solidex. Indirect Filtek Z-250 restorations were light activated using the EDG-lux oven. All samples were submitted to axial compression load in a Universal Testing Machine until fracture. The data were submitted to the one-way ANOVA and Tukeys test (a=0.05). Results: The results (N) were: G6-1938a, G5-1570ab, G7-1285b, G1-1215b, G4-1174b, G3-1146b and G2-1112b. The onlay cavities restored indirectly with Filtek Z-250 presented significantly higher fracture resistance (G6) than the other groups, except for onlay restorations made directly with Filtek Z-250 (G5), which, in turn, did not differ significantly from the other groups. However, the onlay restorations made with Filtek Z-250 led to more catastrophic failure modes. Conclusions: 1. Adhesive inlay restorations, irrespective of the type of composite resin and light-activation technique used, restored the fracture resistance of intact teeth

Postoperative Sensitivity In Class I Composite Resin Restorations In Vivo.

This study evaluated the postoperative sensitivity of posterior Class I composite resin restorations, restored with a self-etching or a total-etch one-bottle adhesive system. One hundred four restorations were replaced by one clinician in 52 patients. Each patient received two restorations. After cavity preparations were completed under rubber-dam isolation, they were restored using Clearfil SE Bond or Single Bond and a resin-based restorative material (Filtek Z250). Sensitivity was evaluated at 0 and 7 days and 6 months using cold stimuli, and recorded using a visual analogue scale. If sensitivity was experienced on day 7, patients were also contacted on days 14 and 30 to assess the degree of sensitivity. The scores were analyzed as nonparametric data by means of the Friedman and Wilcoxon tests. No statistically significant differences in sensitivity were found between the two adhesives systems at days 0 and 7 or at 6 months. No spontaneous postoperative sensitivity was reported. The adhesives systems used in this study showed no differences in postoperative sensitivity, and did not show spontaneous sensitivity after 6 months.853-

Effect of cavity preparation design on the fracture resistance of directly and indirectly restored premolars

Aim: The aim of this study was to evaluate the fracture resistance of human premolars with extensive cavity preparations of the inlay and onlay types, for performing direct and indirect composite resin restorations. Methods: Eight-four premolars were divided into 7 groups (n=12): G1=intact teeth; G2=inlay/Filtek Z-250 direct; G3=inlay/ Filtek Z-250 light polymerized indirectly; G4=inlay/ Solidex; G5=onlay/ Filtek Z-250 direct; G6=onlay/ Filtek Z-250 light polymerized indirectly; G7=onlay/ Solidex. Indirect Filtek Z250 restorations were light activated using the EDG-lux oven. All samples were submitted to axial compression load in a Universal Testing Machine until fracture. The data were submitted to the one-way ANOVA and Tukey’s test (a=0.05). Results: The results (N) were: G6-1938a, G5-1570ab, G7-1285b, G1-1215b, G4-1174b, G3-1146b and G2-1112b. The onlay cavities restored indirectly with Filtek Z-250 presented significantly higher fracture resistance (G6) than the other groups, except for onlay restorations made directly with Filtek Z-250 (G5), which, in turn, did not differ significantly from the other groups. However, the onlay restorations made with Filtek Z-250 led to more catastrophic failure modes. Conclusions: 1. Adhesive inlay restorations, irrespective of the type of composite resin and light-activation technique used, restored the fracture resistance of intact teeth

Effect Of The Adhesive Application Mode And Fiber Post Translucency On The Push-out Bond Strength To Dentin.

This study evaluated the effect of the adhesive application mode and fiber post translucency on the push-out bond strength to dentin. Bovine roots were endodontically treated, and 10 roots were used for each adhesive application mode: PB (Prime&Bond 2.1), PB + SC (Self-cure activator), PB + SBM (Scotchbond Multi-purpose adhesive system), BB (Brush&Bond), BB + CAT (chemical catalyst), and BB + SBM. The translucent Light-Post and Aestheti-Post were cemented. The roots/cemented posts were transversally sectioned to originate three thirds (cervical, middle, and apical). The push-out test was performed, and the failure mode of fractured specimens was analyzed. There was no difference between the fiber posts. For PB and BB, the use of hydrophobic adhesive resin SBM increased post bond strength. The use of SC and CAT catalyst did not affect the push-out bond strength values. The apical third presented the lowest bond strengths.331078-8

Kinetics Of Conversion Of Two Dual-cured Adhesive Systems.

The aim of this study was to evaluate the kinetics of conversion of Scotchbond Multi-purpose Plus (3M ESPE, St Paul, MN) and Prime&Bond NT (Dentsply De Trey, Konstanz, Germany) used in light-cured, self-cured, or dual-cured versions. The adhesive systems were used in the light-cured version (without the use of chemical initiator) or mixed with its respective chemical initiator either with light activation (dual-cured) or not (self-cured). The degree of conversion (DC) was monitored as a function of time during 5 minutes with a Fourier transform infrared spectrometer equipped with an attenuated total reflectance device. Light-cured and dual-cured modes of Scotchbond Multi-purpose Plus presented the highest DC at 5 minutes. The addition of the self-cure activator (dual-cured mode) to Prime&Bond NT reduced the DC. For the self-cured versions, only the Scotchbond Multi-purpose Plus presented any polymerization reaction at 5 minutes. For the two bonding systems tested, it appears that light curing of the adhesive is important in order to reach a high DC in the first moments after the bonding procedure.341115-