ABSTRACT
PURPOSE: To evaluate marginal leakage of bulk fill flowable composite resin filling with different curing time by using microcomputed tomography technology. MATERIALS AND METHODS: 30 previously extracted human molars were randomly divided into 6 groups based upon restorative system and different curing time. Class II cavities (vertical slot cavities) were prepared. An individual metallic matrix was used to build up the proximal wall. The SonicFill or SureFil SDR flow was inserted into the preparation by using 1 bulk increment, followed by light polymerization for different curing times. The different exposure times were 20, 40, and 60 seconds. All specimens were submitted to 5,000 thermal cycles for artificial aging. Micro-CT scanning was performed by using SkyScan 1272. One evaluator assessed microleakage of silver nitrated solution at the resin-dentin interface. The 3D image of each leakage around the restoration was reconstructed with CT-Analyser V.1.14.4. The leakage was analyzed with the Mann-Whitney test. RESULTS: Significant differences were observed between the light curing times, but no significant differences were found between the bulk fill composite resins. Increasing in the photoactivation time resulted in greater microleakage in all the experimental groups. Those subjected to 60 seconds of light curing showed higher microleakage means than those exposed for 20 seconds and 40 seconds. CONCLUSION: Increasing the photoactivation time is factor that may increase marginal microlekage of the bulk fill composite resins. Further, micro-CT can nondestructively detect leakage around the resin composite restoration in three dimensions.
Subject(s)
Humans , Aging , Composite Resins , Molar , Polymerization , Polymers , Silver , X-Ray MicrotomographyABSTRACT
Obiective To study controUing method for curing time of the materials based on isocyanate, and perfect making means and operating rules of transmitting apparatus for the wounded, Methods According to the controlling principles of the rate of chemical reaction, the influencing factors' were studied such as catalyzer, ambient temperature, mixture level of materials and materials volume by experiment. Results By the results of experiments, ambient temperature hasn't an effector impact on eufing time of isocyanate, catalyzer and mixture level of materials only have a little effect or impact on initial reaction time, but materials volume is an important factor of all. Conclusion By the means of experiments, the curing time of isocyanate is only influenced by the volume of materials, and the character is very useful to transmitting apparatus for the wounded in field battle or on-site emergency rescue.
ABSTRACT
OBJECTIVES: This study investigated the hypothesis that increasing light-curing time would leave the oxygen-inhibited layer (OIL) of the adhesive thinner, and in turn, result in lower shear bond strength (SBS) than those obtained by the routine curing procedures. METHODS: 120 human extracted posterior teeth were randomly divided into three groups for bonding with three adhesives: All Bond 2(R), One Step(R), and Adper Prompt(R). They were subsequently divided into four subgourps with different light-curing time (10, 20, 30 and 60 s). The assigned adhesives were applied on superficial occlusal dentin according to the manufacturer's instructions and cured with one of the four curing times. Composite resin cylinder, 2.35 mm in diameter, were built on the cured adhesive and light-cured for 40 s. SBS were measured after 24 h from the bonding using a universal testing machine (crosshead speed 1.0 mm/min). The relative thickness of the OIL and the degree of conversion (DC) were determined from the adhesive on a slide glass using FT-NIR in an absorbance mode. Data were analysed with One-way ANOVA and Duncan's multiple test (p 0.05), those of All Bond 2 decreased significantly (p 0.05). Although the DC of All-Bond 2 were statistically not different with increasing cure time (p > 0.05), those of One-Step and Adper Prompt showed an increasing trends with increasing cure time (p < 0.05). CONCLUSIONS: Increasing light-curing time did not affect on the relative thickness of the OIL of the adhesives, and in turn, on the SBS to dentin.
Subject(s)
Humans , Adhesives , Dentin , Glass , ToothABSTRACT
OBJECTIVES: This study investigated the hypothesis that increasing light-curing time would leave the oxygen-inhibited layer (OIL) of the adhesive thinner, and in turn, result in lower shear bond strength (SBS) than those obtained by the routine curing procedures. METHODS: 120 human extracted posterior teeth were randomly divided into three groups for bonding with three adhesives: All Bond 2(R), One Step(R), and Adper Prompt(R). They were subsequently divided into four subgourps with different light-curing time (10, 20, 30 and 60 s). The assigned adhesives were applied on superficial occlusal dentin according to the manufacturer's instructions and cured with one of the four curing times. Composite resin cylinder, 2.35 mm in diameter, were built on the cured adhesive and light-cured for 40 s. SBS were measured after 24 h from the bonding using a universal testing machine (crosshead speed 1.0 mm/min). The relative thickness of the OIL and the degree of conversion (DC) were determined from the adhesive on a slide glass using FT-NIR in an absorbance mode. Data were analysed with One-way ANOVA and Duncan's multiple test (p 0.05), those of All Bond 2 decreased significantly (p 0.05). Although the DC of All-Bond 2 were statistically not different with increasing cure time (p > 0.05), those of One-Step and Adper Prompt showed an increasing trends with increasing cure time (p < 0.05). CONCLUSIONS: Increasing light-curing time did not affect on the relative thickness of the OIL of the adhesives, and in turn, on the SBS to dentin.
Subject(s)
Humans , Adhesives , Dentin , Glass , ToothABSTRACT
The purpose of this study is to evaluate the polymerization ability of three different light sources by microhardness test. Stainless steel molds of 1, 2, 3, 4 and 5 mm in thickness of 7 mm in diameter were prepared. The hybrid composite Z100 was packed into the hole of the mold and curing light was activated for designated time. Three different light sources, conventional halogen, light emitting diode, and plasma arc, were used for curing of composite. Two different curing times applied; one is to follow the manufacturer's recommendation and the other is to extend the curing time of LED and plasma arc for balancing the light energy with halogen. Immediately after curing, the Vickers hardness was measured at the bottom of specimen. The results were as follows. 1. The composite cured with LED showed equal to higher microhardnesss than halogen. 2. The composite was cured with plasma arc by manufacturer's recommendation showed lowest microhardness at all thickness. However, when curing time was extended, microhardness was higher than the others. In conclusion, this study suggested that plasma arc needs properly extended curing time.