ABSTRACT
The use of soft-start photoactivation to reduce shrinkage stress has become widespread in restorative dentistry. However, an increased susceptibility to ethanol degradation of polymers formed by pulse-delay photoactivation was reported. It was hypothesized that reductions in flexural strength after ethanol storage were related not only to low curing rates, but also to the radiant exposure employed. A commercial composite was subjected to different curing protocols (continuous at high irradiance, continuous at low irradiance, and pulse-delay) and radiant exposures (6, 12, and 24 J/cm2). After 48 h, differences in degree of conversion were minimal and no differences in strength were detected among specimens stored in water. Ethanol storage caused significant strength reductions in pulse-delay and low irradiance specimens that received 6 J/cm2. The results suggest that when low irradiances or pulse-delay methods are used, a relatively high radiant exposure is necessary to originate a polymer network structure similar to that obtained by continuous high irradiance photoactivation.
Subject(s)
Composite Resins/chemistry , Composite Resins/radiation effects , Ethanol/chemistry , Light , Water/chemistry , Materials Testing , Photochemistry , Pliability , Tensile StrengthABSTRACT
PURPOSE: To compare the retention of a multi-use bonding agent (OptiBond) to a conventional sealant (Delton) used as pit and fissure sealants. MATERIALS AND METHODS: An informed consent was obtained from 38 subjects aged 11-17 yrs. Delton, a self-cured sealant, was applied to 86 teeth, and OptiBond, a dual-cure glass filled adhesive, was applied to 85 teeth, under cotton roll isolation and saliva ejector. Each subject received both sealing materials, randomly assigned to the sides of the mouth. The sealed teeth were followed up to 30 months. Clinical evaluation was performed by two examiners and the retention was classified as failure or success. RESULTS: Statistical analysis based on a stratified Cox proportional hazards regression model indicated that OptiBond had better clinical performance than Delton (P < 0.001).
Subject(s)
Dental Bonding , Dentin-Bonding Agents/therapeutic use , Pit and Fissure Sealants/therapeutic use , Adhesives/chemistry , Adhesives/therapeutic use , Adolescent , Bicuspid , Bisphenol A-Glycidyl Methacrylate/chemistry , Bisphenol A-Glycidyl Methacrylate/therapeutic use , Child , Confidence Intervals , Dental Caries Susceptibility , Dentin-Bonding Agents/chemistry , Female , Follow-Up Studies , Humans , Male , Molar , Observer Variation , Proportional Hazards Models , Resin Cements/chemistry , Resin Cements/therapeutic use , Treatment OutcomeABSTRACT
To evaluate multi-use bonding systems as the sole material for sealing pits and fissures, this study compared the performance of three adhesives (OptiBond, All-Bond 2 and Scotchbond MP Plus) with respect to microleakage. Each material was applied to 12 teeth with dry-etched surfaces, and to 12 teeth with contaminated-etched surfaces (1 microliter of human plasma). Each group of 12 sealed teeth was divided into three subgroups, and each of these was subjected either to thermal cycling (4,000 cycles at 5-55 degrees C), to thermal and load cycling (4,000 plus 300,000 cycles) or to no cycling. The teeth were placed in a 50% AgNO3 solution, rinsed, immersed in a developing solution and exposed to a fluorescent light. Subsequently, each of the 72 crowns was sectioned at three different positions, generating 432 cross-sections. The severity of dye penetration on each cross-section was evaluated by two methods. An ANOVA was used to assess the main effects of the three factors (product, surface condition and cycling), as well as for their interactions on the severity of microleakage. The results obtained under both evaluation methods demonstrated that OptiBond had the best performance under either dry or contaminated surfaces, while All-Bond 2 and Scotchbond MP Plus performed similarly, with greater microleakage intensity on contaminated etched enamel compared to OptiBond.
