The effect of bonding system and composite type on adaptation of different C-factor restorations.
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This study evaluated the effect of two adhesive systems and four resin-based composites on the marginal sealing and cavity wall adaptation of restorations with different C-factors. Cylindrical cavities, 1 mm deep and 3 mm in diameter (C-factor=2.3) or 2 mm in diameter (C-factor=3), were prepared on superficial bovine dentin surfaces. The teeth were restored with Clearfil SE Bond or Single Bond adhesive system followed by hybrid (Photo Clearfil Bright or Z100) or flowable (Filtek Flow or Estelite LV) resin composite. After thermocycling, a dye penetration test was carried out to evaluate the degree of marginal leakage and cavity-wall gap formation. Cavity-wall gap formation increased when the C-factor increased from 2.3 to 3, except for Estelite LV resin composite. In terms of marginal sealing, Clearfil SE Bond showed better performance than Single Bond. When using Clearfil SE Bond, flowable composites improved resin composite adaptation to the cavity wall compared with hybrid composites. (+info)
Adhesive analysis of voids in Class II composite resin restorations at the axial and gingival cavity walls restored under in vivo versus in vitro conditions.
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OBJECTIVES: Adhesive analysis, under the scanning electron microscope of microtensile specimens that failed through the adhesive interface, was conducted to evaluate the amount of voids present at the axial versus gingival cavity walls of class II composite restorations restored under in vivo and in vitro conditions. METHODS: Five patients received class II resin composite restorations, under in vivo and in vitro conditions. A total of 14 premolar teeth yielded 59 (n=59) microtensile adhesive specimens that fractured through the adhesive interface. The fractured surfaces of all specimens were examined and the % area of voids was measured. RESULTS: Voids at the adhesive joint were highly predictive of bond strengths. An increase in the number of voids resulted in a decrease in the microtensile bond strength. The area of voids at the adhesive interface was as follows: in vivo axial 13.6+/-25.6% (n=12); in vivo gingival 48.8+/-29.2% (n=12); in vitro axial 0.0+/-0.0% (n=19) and in vitro gingival 11.7+/-17.6% (n=16). SIGNIFICANCE: Composite resin may bond differently to dentin depending upon the amount of voids and the cavity wall involved. The bond to the gingival wall was not as reliable as the bond to the axial wall. An increase in the amount of surface voids was a major factor for reducing microtensile bond strengths of adhesive to dentin. (+info)
Clinical performance of chairside CAD/CAM restorations.
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BACKGROUND: The CEREC system (Sirona Dental Systems GmbH, Bensheim, Germany) is marking its 20th year of clinical service. The author reviews the literature on the effectiveness of this chairside CAD/CAM system. TYPES OF STUDIES REVIEWED: The author identified and reviewed clinical studies from 1985 through 2006 that included CEREC-generated inlays, onlays or crowns. These studies were conducted in both private practice and university settings. The author summarized the findings as they relate to postoperative sensitivity, restoration fracture, color match, margin adaptation and clinical longevity. RESULTS: Although postoperative sensitivity was reported, it was due to mainly occlusal interferences. Long-term postoperative sensitivity was not a reported problem. Similar to other ceramic restorations, restoration fracture is the primary mode of failure for CEREC-generated restorations. Although margin wear is detected consistently, consequences of the wear leading to restoration failure were reported rarely. The survival probability of CEREC-generated restorations was reported to be approximately 97 percent for five years and 90 percent for 10 years. CLINICAL IMPLICATIONS: The low rate of restoration fracture and long-term clinical survivability document the effectiveness of the CEREC system as a dependable, esthetic restorative option for patients. (+info)
Effect of spherical silica filler addition on immediate interfacial gap-formation in Class V cavity and mechanical properties of resin-modified glass-ionomer cement.
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The aim of this study was to investigate how the addition of silanized spherical silica filler (SF) would influence the formation of summed, immediate interfacial gaps in Class V tooth cavities. Resin-modified glass-ionomer cement (RMGIC) is usually used for Class V restorations. As such, the following aspects of RMGIC were examined in correlation with summed interfacial gaps in the tooth cavity: setting shrinkage of cement in the Teflon mold, as well as mechanical properties in terms of compressive strength, diametral tensile strength, and flexural strength. Spherical silica filler was added to the RMGIC powder (Fuji II LC EM). For comparison purpose, untreated spherical silica filler (UF) was added too. When compared with the control (i.e., original RMGIC mixed with manufacturer-recommended powder/liquid ratio), the addition of SF significantly decreased the formation of summed interfacial gaps in Class V cavities in the immediate condition. In particular, addition of 10 wt% SF increased the compressive strength by 56%, while diametral tensile strength was increased by 28% and flexural strength by 26%. (+info)
Influence of elasticity on gap formation in a lining technique with flowable composite.
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The purpose of this study was to investigate the effect of flowable composites as liners for direct composite restorations, with key focus on the elastic moduli of flowable and condensable composites. After treating the composite mold cavity surface with an adhesive system, one of the flowable composites was placed as a 1 mm-thick layer on the cavity floor and irradiated for 20 seconds. The rest of cavity was subsequently filled with a condensable composite and irradiated for 40 seconds. Gap formation at both interfaces--between the cavity floor and flowable composite, and between the flowable and condensable composites--was examined. No gaps were detected at the interface between the cavity floor and flowable composite. Gap percentage at the interface between the flowable and condensable composites was dependent on the difference in elastic modulus. It was concluded that flowable composite with high elastic modulus could inhibit gap formation between flowable and condensable composites. (+info)
Contraction gap versus shear bond strength of dentin adhesive in sound and sclerotic dentins.
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To evaluate the effect of a dentin adhesive on sclerotic dentin, contraction gap width and shear bond strength were measured. Dentin cavity wall was pretreated with an experimental dentin bonding system with and without a dentin primer, or with a commercial dentin bonding system. In the experimental dentin bonding groups, contraction gap width of sclerotic dentin was significantly smaller than that of sound dentin when the cavity was not primed with glyceryl monomethacrylate. For each individual tooth, the correlation between contraction gap width and shear bond strength was insignificant. In conclusion, the bonding efficacy of dentin bonding systems to sclerotic dentin was superior to that of sound dentin. Further, it was determined that it was impossible to detect the interaction between the polymerization contraction stress of resin composites and the efficacy of dentin adhesives by measuring bond strength. (+info)
Effect of thermocycling on interfacial gap-formation in Class V cavities and mechanical properties of spherical silica filler addition to resin-modified glass ionomer restorations.
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The effects of thermocycling at 20,000 cycles and addition of silanized spherical silica filler (SF) on resin-modified glass ionomer cement (RMGIC) restorations were investigated. A RMGIC added with an untreated spherical silica filler (UF) was used as a comparison. Marginal gaps in Class V tooth cavities, compressive strength, diametral tensile strength, flexural strength, and shear bond strengths to enamel and dentin were examined. All thermocycled samples showed decreased frequency of marginal gap formation as compared to the 24-hour samples, with reduction of 73% to 95%. At the immediate condition, after 24 hours, and after thermocycling, the addition of 10 wt% SF yielded the most favorable results in terms of marginal gap formation in Class V cavities, compressive strength, flexural strength, and shear bond strength to enamel. Diametral tensile strength and flexural strength were also increased significantly by the addition of 5 wt% SF. Further, shear bond strength tests showed that the addition of SF had no effect on bonding capability to enamel and dentin. (+info)
One-year clinical evaluation of five single-step self-etch adhesive systems in non-carious cervical lesions.
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This study evaluated the clinical performance of five single-step self-etch adhesive systems over a one-year follow-up period in 98 restorations. Independent evaluations were performed at baseline (one week), after three months, six months, and one year, by two trained examiners using the modified US Public Health Service rating criteria. Color match, marginal integrity, anatomical form, surface roughness, marginal or interfacial staining, postoperative sensitivity, and secondary caries were evaluated. Results were analyzed using the Kruskal-Wallis test at a significance level of p<0.05. After one year, the restorations were re-evaluated and 100% retention rate was recorded. No caries were detected in association with any of the restorations. Marginal adaptation was the only measure that showed a slight deterioration over time, and there were no significant differences in this factor among the adhesive systems tested (p=0.464). (+info)