Microleakage of Class II posterior composite restorations with gingival margins placed entirely within dentin.
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PURPOSE: Composite restorations are more frequently being placed with margins apical to the cementoenamel junction. However, margins within dentin are prone to microleakage. The purpose of this in vitro study was to evaluate various restorative procedures in terms of their ability to reduce microleakage in posterior composite restorations with gingival margins within dentin. We also examined the effect of staining time on microleakage. MATERIALS AND METHODS: Mesio-occlusal and disto-occlusal preparations were made in 50 extracted molars. Teeth were randomly assigned to receive 1 of 5 treatments followed by restoration with Z100 composite resin: acid etch (control); Clearfil SE Bond; Prompt-L-Pop; Vitrebond/Scotchbond Multipurpose Plus (closed-sandwich technique); or Geristore/Tenure (open-sandwich technique). After 48 hours of water storage followed by sectioning buccolingually, 1 restoration from each tooth was randomly assigned to either 2- or 4-hour immersion in 50% by weight silver nitrate solution. Restorations were removed and gingival floors analyzed to determine the percentage of surface area stained in each of 3 0.5-mm wide zones. RESULTS: Repeated measures ANOVA did not reveal statistically significant differences in staining for 2 and 4 hours. Compared with the control group, Clearfil SE bond produced statistically significant reductions in leakage in all 3 zones. Prompt-L-Pop did not reduce leakage significantly except in zone 3 (closest to the pulp). Vitrebond and Geristore both reduced microleakage in zones 2 and 3, but the reduction was greater with the use of Vitrebond. CONCLUSION: Both Clearfil SE Bond and Vitrebond in a closed-sandwich technique were effective methods for reducing microleakage within dentin. (+info)
In vitro evaluation of marginal leakage in bonded restorations, with mechanical or chemical-mechanical (Carisolv) removal of carious tissue.
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This study carried out an in vitro evaluation and comparison of the occurrence of marginal leakage in bonded restorations using mechanical or chemical-mechanical (Carisolv) removal of carious tissue. For that purpose, 40 extracted decayed human molars were divided into 4 groups: GI (burs + Prime & Bond NT + TPH), GII (Carisolv + Prime & Bond NT + TPH), GIII (burs + SBMP + Z100) and GIV (Carisolv + SBMP + Z100). After accomplishment of the restorations and thermal cycling, the teeth were exposed to dye, sectioned and qualitatively evaluated. The results demonstrated that the system of removal of carious tissue did not influence the results of microleakage at any of the cavity margins. At dentinal margins, use of the Prime & Bond NT + TPH restorative system allowed the occurrence of less microleakage than the SBMP + Z100 system. (+info)
Low-shrinkage composite for dental application.
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In modern research, development of monomers that reduce shrinkage of composite materials remains an ongoing quest and perennial challenge. The purpose of this study, therefore, was to analyze the shrinkage behaviour of an innovative composite material for dental restorations based on a monomer with a new chemical formulation, known as silorane. To this end, shrinkage stress development during curing, gel point, and coefficient of near linear fit of contraction stress/time were evaluated after polymerizing the material with 10 different curing regimes. Shrinkage stress varied between 1.4 MPa after a 10-second curing in a pulsed regime to 4.4 MPa after curing for 40 seconds with a high energy curing unit, Bluephase. Pearson correlation analysis showed that with respect to the tested curing units, shrinkage stress correlated significantly with energy density (0.89), irradiance (0.70), curing time (0.51), coefficient of near linear fit of contraction (0.70), and gel point (-0.60). Silorane exhibited low shrinkage stress values in comparison to regular methacrylate composites. Nevertheless, stress due to thermal contraction when the light exposure ended was not negligible-but could be reduced by applying the appropriate curing strategy. (+info)
Comparative evaluation for microleakage between Fuji-VII glass ionomer cement and light-cured unfilled resin: a combined in vivo in vitro study.
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Glass ionomer cement, besides being used as restorative material, can also be used as pit and fissure sealant. The use of glass ionomer cement as pit and fissure sealant has added benefit by its fluoride-releasing property that results in increased resistance of the fissures to demineralize. The capacity of a sealant to prevent microleakage into the fissure is important, since microleakage may initiate and support a carious lesion beneath the sealant. The study was carried out to compare marginal microleakage between Fuji-VII glass ionomer cement (G C Corporation, Tokyo, Japan) and the conventional light-cured unfilled resin as pit and fissure sealants (3M Concise, 3M Dental Products, St. Paul, USA). The dye used was 2% methylene blue (Qualigens Fine Chemicals, Mumbai, India). The teeth were sectioned and studied under the stereomicroscope. The result revealed that there was no difference in microleakage (P > 0.05) between the two materials. (+info)
The effect of thermal stress on bonding durability of resin composite adaptation to the cavity wall.
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This study evaluated the effect of thermal stress on marginal sealing and cavity wall adaptation using two adhesive systems. Cylindrical cavities were prepared in superficial dentin of bovine incisors and bonded with Clearfil SE Bond or Single Bond adhesive. Cavities were bulk-filled with Photo Clearfil Bright or Filtek Flow resin composite and light-cured for 40 seconds. Specimens were thermocycled for 0, 500, or 5000 times. A dye penetration test was carried out to determine adaptation to the cavity wall. Dye penetration length was calculated as a percentage of the total cavity wall length. Clearfil SE Bond showed excellent marginal sealing and cavity wall adaptation regardless of composite type up to 500 cycles of thermal stress. As for the Single Bond groups, significantly greater marginal leakage occurred after 500 cycles. At 5000 cycles of thermal stress, both adhesive systems showed significantly decreased marginal integrity compared with the 0 cycle group. (+info)
Priming effects of triethylene glycol and triethylene glycol monomethacrylate on dentin bonding.
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The objective of this study was to evaluate the effects of triethylene glycol (TEG) and triethylene glycol monomethacrylate (TEGMA) solutions as dentin primers on dentin bonding. To this end, wall-to-wall polymerization contraction gap width of a resin composite in a cylindrical dentin cavity and shear bond strength to a flat dentin surface were measured. Dentin was pretreated with an experimental dentin bonding system - consisting of 0.5 M ethylenediaminetetraacetic acid conditioner, TEG or TEGMA primer, and Clearfil Photo Bond bonding agent - prior to resin composite filling. When the cavity was primed with an aqueous solution of 35 vol% TEG, 35 or 45 vol% TEGMA for a few seconds, contraction gap formation was prevented completely. Then, among these three gap-free groups, there were no significant differences in shear bond strength. It was thus shown that both TEG and TEGMA were highly effective dentin primers, completely preventing contraction gap formation even when they were applied for only a few seconds. (+info)
Clinical evaluation and interfacial morphology observation of Xeno III self-etching resin bonding and restorative system.
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This study was a clinical trial of a one-step, total priming and bonding system, Xeno III. Thirty restorations were placed in minimally invasive V-shaped, Class V cervical cavities. Immediately after placement, baseline records were made after restorations were assessed using modified Ryge/USPHS criteria. Subsequently, restorations were evaluated at recall intervals up to 18 months. Additionally, the measurement of tensile bond strength and the FE-SEM observation of resin-tooth interface were performed in vitro. At 18 months, all restorations were classified as clinically satisfactory and assigned with an Alpha rating. Tensile bond strength of Xeno III was not significantly different from that of Clearfil SE Bond. Resin-enamel/dentin interface was very tight, with the presence of a very thin hybrid layer at the superficial dentin. Based on the results obtained, the Xeno III resin bonding system seemed promising as a one-step, self-etch adhesive. (+info)
The use of amorphous calcium phosphate composites as bioactive basing materials: their effect on the strength of the composite/adhesive/dentin bond.
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BACKGROUND: Amorphous calcium phosphate (ACP) composites release calcium and phosphate ions in aqueous environments, which may lead to deposition of apatitic mineral in tooth structure. The authors evaluate the strength of the composite/adhesive/dentin bond shear bond strength (SBS) for ACP basing-composites after various periods of water aging. METHODS: The authors made the experimental composites by using two resin matrices with various ACPs or a commercial strontium ion-leachable glass. They applied successive coats of a dentin adhesive and basing composite to an acid-etched dentin surface and photopolymerized them. They added a commercial resin-based composite and light cured it. They determined the specimens' SBS after they were aged in water for various periods at 37 degrees C. RESULTS: The SBS of the ACP composites was 18.3 +/- 3.5 megapascals, independent of filler type, resin composition and water-aging interval. After 24 hours of water aging, 92.6 percent of surfaces showed the adhesive failure. After two weeks of water aging, adhesive/cohesive failures were predominant in unmilled and milled ACP composites. CONCLUSIONS: The SBS of ACP composites appears to be unaffected by filler type or immersion time for up to six months. The type of adhesive failure occurring with prolonged aqueous exposure is affected by filler type. CLINICAL IMPLICATIONS: These materials may be effective remineralizing/antidemineralizing agents and may be clinically applicable as adhesives, protective liners and bases, orthodontic cements and pit-and-fissure sealants. (+info)