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Resin-metal bonding systems: a review of the Silicoating and Kevloc systems.

The Silicoating and Kevloc systems are resin-metal attachment devices that are designed to improve bond strength and decrease microleakage at the resin-metal interface. Clinically, these systems can be used to place resin pontics and veneers, enhance cementation with resin cements, and bond the resin matrix to metal implant substructures. To provide practitioners contemplating the use of either modality with background information, a concise summary of the potential advantages of resin-metal bonding, the procedures required to establish the chemical bond, and the methods of evaluating laboratory studies are presented. Chemical bonding with these systems is technique sensitive. How the system is used may be as important to the final clinical results as is the choice of system.

Acrylonitrile↗

Identification and characterization of estrogen-like components in commercial resin-based dental restorative materials.

Recently, resin-based dental restorative materials have been targeted as potential sources of xenoestrogens, specifically bisphenol A (BPA) and bisphenol A dimethacrylate (BAD), which could contribute to overall estrogen load and result in deleterious side effects. The present study used high-pressure liquid chromatography (HPLC) to analyze twenty-eight different commercially available dental resins for the presence of BPA and/or BAD. In addition, sublines of the MCF-7 human breast tumor cell line were cultured in the presence of eluates from eleven of the dental resins and assessed for proliferative responses using the sulforhodamine B assay. Only one resin, Delton II, had detectable levels of BPA or BAD that could be verified by Fourier transform infrared spectrometry. Likewise, eluates from Delton II were the only samples that elicited a significant proliferative response in two of the MCF-7 sublines tested. Therefore, we conclude that dental resins in general do not represent a significant source of BPA or BAD exposure.

Benzhydryl Compounds↗

Silane effects on luting resin bond to a Ni-Cr alloy.

This study investigates the effect of a silane coupling agent on the shear bond strength of four commercially available resin luting systems (two of which rely on mechanical retention and two which have a chemical bond to metal) when bonding a prepared Ni-Cr alloy to etched bovine enamel. Silane application reduced the bond strengths of the two chemically adhesive resins and increased the bond strength of one of the mechanically retained resins. For the other mechanically retained resin, silane application did not significantly increase the bond strength but the plane of fracture changed from resin/metal to resin/enamel: from this an increase in metal resin bond strength can be inferred.

Acid Etching, Dental↗

Bond strengths of lingual orthodontic brackets bonded with light-cured composite resins cured by transillumination.

A method of curing light-cured composite resins by transillumination to cement acid-etched fixed partial dentures was adapted to bond solid mesh-backed lingual orthodontic brackets. Results of this investigation showed that the bond strengths of the orthodontic brackets bonded with light-cured composite resins were significantly less (P less than 0.05) than the bond strengths of the orthodontic brackets cemented with traditional adhesives and orthodontic composite resins. Notwithstanding, the bond strengths achieved with the transilluminated light-cured composite resins should be adequate to withstand the forces of mastication and orthodontic movements. There was no correlation of bond strengths of the brackets cemented with the transilluminated light-cured composite resins when compared to the faciolingual widths of the teeth.

Acrylic Resins↗

Effect of time on tensile bond strength of resin cement bonded to dentine and low-viscosity composite.

OBJECTIVES: The purpose of this study was to evaluate the tensile bond strength (TBS) of Panavia F resin cement (PF) applied on dentine pre-treated with ED Primer (ED) and Clearfil Liner Bond 2V (CLB) coated with a layer of low-viscosity composite Protect Liner F (PLF) at 10 min, 24 h and 12 months after curing. METHODS: The labial surfaces of 60 bovine lower incisors were ground to obtain a flat dentine surface, allowing a demarcation of a 4.0 mm-diameter area with adhesive tape. The teeth were randomly divided in six groups; ED was applied in groups A I, A II and A III and CLB was applied, followed by PLF, in groups B I, B II and B III. A resin composite rod with a wire loop was luted directly to the prepared surface of each group with PF. The specimens of groups A I and B I were submitted to TBS test after 10 min. Groups A II and B II were submitted to TBS test after 24 h storage and groups A III and B III were submitted to TBS test after 12 months storage. Each specimen was inspected by SEM and classified according to the failure mode. Additionally, two representative specimens of each failure mode were sectioned for a composite/dentine interface SEM evaluation. RESULTS: No significant statistical differences were observed among the groups at 10 min and 24 h. Groups A III and B III presented the lowest TBS values (p<0.05) after 12 months storage. PF on resin-coated dentin (PLF) showed the highest TBS values and was statistically different to PF on dentine for all the groups. The fracture pattern was generally cohesive on the adhesive/hybrid layer for groups A I, A II and A III and cohesive on composite resin for B I, B II and B III. SIGNIFICANCE: The use of a less hydrophilic self-etching system to pre-treat dentine, coating with a low-viscosity composite layer prior luting with resin cement, may provide a protection of the hybridised complex, allowing a dentine seal during the 12 months storage period.

Acrylic Resins↗

Tensile bond strength of a composite resin cement for bonded prosthesis to various dental alloys.

The development of composite resin cements that chemically bond to dental alloys has improved the construction of resin-bonded prostheses. Composite resins can be selected for various situations, but specific clinical situations may require different alloys. This study evaluated the ability of a composite resin cement to bond to various dental alloys of different compositions. Ten pairs of disks for each alloy (two NiCr, two NiCrBe, one CuAl, one gold type IV, and one gold for metal ceramic) were bonded to a composite resin cement after air abrasion was performed with aluminum oxide. The disks were then rinsed in tap water and were ultrasonically cleaned in distilled water for 2 minutes. The tensile tests exhibited greater values for alloys ultrasonically cleaned, and the best results were recorded by NiCr and NiCrBe alloys.

Aluminum↗

Microleakage of Class V resin-modified glass ionomer and compomer restorations.

STATEMENT OF PROBLEM: Resin-modified glass ionomers and polyacid-modified resin composites (compomers) have been introduced to provide esthetic restorations. However, there is concern about the marginal sealing ability of these materials, especially at the dentin (cementum) aspects of restorations. PURPOSE: This in vitro study evaluated the microleakage of Class V restorations made with resin-modified glass ionomers or a compomer. MATERIAL AND METHODS: Thirty noncarious human molar teeth were used. Standardized kidney-shaped Class V cavity preparations were placed in the buccal and lingual surfaces at the cementoenamel junction. Teeth were randomly assigned to 3 experimental groups of 10 teeth each and restored as follows: group 1, Fuji II LC; group 2, Vitremer; and group 3, Dyract. In all cases, the manufacturers' instructions were strictly followed. All materials were placed in a single increment. Unfinished restorations were immediately coated with the respective manufacturers' sealer or varnish and this was either light cured for 20 seconds or allowed to air-dry. After 24 hours, teeth were finished to contour and to the cavosurface margins, coated with nail varnish except for 1 mm around the restoration margin, thermocycled (1000x, 5-55 degrees C) and placed in a solution of 2% basic fuchsin dye for 24 hours at room temperature. The staining along the tooth restoration interface was recorded. RESULTS: Kruskal-Wallis 1-way analysis of variance revealed significant differences among all restorative materials for the overall, occlusal, and gingival scores (P =.03, P =.01, P =.01, respectively). Occlusal and gingival scores for each matched pair of restorative materials using the Wilcoxon test showed statistically significant differences between Fuji II LC glass ionomer cement and Dyract composite, both for the occlusal (P =.005) and gingival (P =.005) margins and also as an overall evaluation (P =.01), with Fuji II LC showing the least dye penetration. Vitremer revealed dye penetration scores not significantly different from Fuji II LC glass ionomer cement or Dyract composite. CONCLUSION: Resin-modified glass ionomers showed less or similar microleakage than the polyacid-modified composite resin tested.

Analysis of Variance↗

Fluoride release from glass ionomer cements and resin composites coated with a dentin adhesive.

OBJECTIVES: This laboratory study compared the effect of surface coatings on patterns and amounts of fluoride released from four glass ionomer cements and two fluoride-containing resin composites. METHODS: Twelve cylinders of each material were prepared in a polyethylene mold. The experimental groups (n = 6) were coated with one layer of an adhesive resin (3M Scotchbond Multipurpose Adhesive), while the control groups (n = 6) remained uncoated. Cumulative fluoride release into deionized water was measured on days 1, 2, 3, 7, 14, 21 and 28 using an ion analyzer. Total fluoride release after 28 days was analyzed for significant differences among materials using one-way ANOVA and Student-Newman-Keuls test (p < 0.05). RESULTS: The total amounts of fluoride release from the coated samples were found to be significantly less than the uncoated samples for all materials, except Solitaire. The uncoated samples released a total amount of fluoride of between 2.3 and 85.4 ppm, while the coated samples released a total amount of fluoride of between < 0.2 and 24.1 ppm. Similar patterns of fluoride release were found in coated and uncoated samples. SIGNIFICANCE: The results indicated that the application of a dentin adhesive coating did not completely prevent fluoride release from glass ionomer cements and fluoridated resin composites, although the amounts were significantly less. Clinically, it suggests that a continued release of fluoride from glass ionomer cements and fluoridated resin composites is possible after placing a thin layer of resin adhesive. The clinical significance of these findings is not known.

Analysis of Variance↗

In vitro study of 24-hour and 30-day shear bond strengths of three resin-glass ionomer cements used to bond orthodontic brackets.

Interest in using composite resin-glass ionomer hybrid cements as orthodontic bracket adhesives has grown because of their potential for fluoride release. The purpose of this pilot study was to compare shear bond strengths of three resin-glass ionomer cements (Advance, Fuji Duet, Fuji Ortho LC) used as bracket adhesives with a composite resin 24 hours and 30 days after bonding. The amount of adhesive remaining on the debonded enamel surface was scored for each adhesive. Mesh-backed stainless-steel brackets were bonded to 100 extracted human premolars, which were stored in artificial saliva at 37 degrees C until being tested to failure in a testing machine. The hybrid cements, with one exception, had bond strengths similar to those of the composite resin at 24 hours and 30 days. Fuji Ortho LC had significantly lower bond strengths (ANOVA p < or = 0.05) than the other adhesives at 24 hours and 30 days when it was bonded to unetched, water-moistened enamel. Adhesive-remnant scores were similar for all cements, except for cement Fuji Ortho LC when it was bonded to unetched enamel. The resin-glass ionomer cements we tested appear to have bond strengths suitable for routine use as orthodontic bracket-bonding adhesives.

Acid Etching, Dental↗

Future directions in bonding resins to the dentine-pulp complex.

Resin-based materials are rapidly becoming the primary restorative material to replace tooth structure and the low percentage of biological problems reported for resin-based restorations is testimony to their relative biocompatibility. Despite considerable advances in the understanding of the mechanisms, which govern the integration of resin composite materials with the dentine-pulp complex, considerable potential for improvement remains. Most of these improvements centre around a better understanding of the biological and microbiological risks of resin materials and will only be possible with improved in vitro and in vivo models. There are also a number of possible future developments in materials, clinical techniques and diagnostic methods that may improve the long-term success and reliability of resin-based restorations. The remainder of this paper describes the most likely avenues for future improvements.

Biocompatible Materials↗

A clinical evaluation of posterior composite resin restorations.

There is a trend towards manufacturers seeking to provide dentists with a single, all-purpose composite resin, usually of the small particle hybrid type. This three-year clinical study compared the clinical performance of three different types of composite resin used in posterior teeth and identified several modes of failure. Of the 330 restorations (three composite resins and one amalgam control) initially placed in 72 patients, 223 restorations in 48 patients were available for evaluation at three years. Modified clinical criteria for assessing the restorations were able to discriminate among the composite resins. A microfilled composite and a small particle hybrid exhibited increasing evidence of marginal fracture (crevice) with time. In addition, the small particle hybrid showed evidence of wear at the margins more frequently than the other materials. Of the restorations available for assessment, four restorations of each of these two types of composite resin required replacement during the study. Coarse particle hybrid restorations showed evidence of wear but little evidence of marginal fracture.

Acrylic Resins↗

Effect of primers containing copper salts on bonding of TBB resin to enamel.

The effect of primers containing copper salts on adhesion between enamel and stainless steel was studied in a trial to improve durability of TBB type resin cements. Bovine enamel surfaces were treated with 10% phosphoric acid, then with acetone primers containing copper salts, and finally bonded with TBB resins. Tensile strengths of the bonded specimens were measured after thermocycling testing in water and compared with those obtained for commercial composite type resin cements. A combination of a primer containing copper (II) methacryloyloxyethyl succinate and 4-META/MMA-TBB resin was most effective in improving the durability, and superior to the commercial resin cements. The mean and lowest bond strength values of 21 MPa and about 12 MPa, respectively, were retained after 2,000 thermocycles.

Acrylic Resins↗

In vitro evaluation of bond strength and surface roughness of a resin-paint material.

This study investigated the stability of a resin-paint material (Master Palette)--which was developed for chairside shade modification of composite restorations--by evaluating its bond strength to indirect resin composite and surface degradation. Bond strength was evaluated with four surface treatments including an application of methylene chloride, airborne particle abrasion with 50 microm aluminum oxide, and additional applications of bonding agents after air-abrasion. The surface roughness (Rz value) of both the resin-paint and indirect resin composite before and after thermo-cycling (4-60 degrees C, 50,000 cycles) was also evaluated. All data were statistically analyzed by two-way ANOVA and Boneferroni's test (p=0.05). It was found that bond strength was improved by bonding agent application (14.9+/-1.9 MPa to 18.6+/-2.2 MPa, p<0.0054) after thermo-cycling. As for surface roughness, its results after thermo-cycling (2.7+/-0.2 microm, p<0.001) demonstrated that the resin-paint needed further improvements to maintain the original surface texture.

Acrylic Resins↗

Influence of mechanical properties of two resin cements on durability of bond strength to dentin after cyclic loading.

The purpose of this study was to evaluate how the different mechanical properties of two luting agents (acrylic resin cement and resin composite cement) influenced their bond strength to dentin, after cyclic loading that simulated chewing. Stainless steel rods were bonded to the flattened dentin surfaces with each luting agent. After immersion in water for 24 hours, half the specimens of each group were tested for tensile bond strength and the remaining half were subjected to a vertical load (75.6 N, 1.2 Hz) using an acrylic stylus--which upon contact with the specimen would rotate counterclockwise and then counter-rotate. Bond strength of the resin composite cement with self-etching was found to be significantly lower than the other adhesive systems. After 100,000 cycles, the bond strength of resin composite cement was significantly decreased while acrylic resin cement showed no decrease in bond strength.

Acid Etching, Dental↗

Field-emission scanning electron microscopy of resin-dentin interface morphology of seven dentin adhesive systems.

PURPOSE: The purpose of this study was to evaluate the resin-dentin interface morphology of 7 resin-based dentin adhesive systems (Solid Bond, EBS-Multi, PermaQuik, One Coat Bond, Gluma One Bond, Prime & Bond NT/NRC, and Clearfil Liner Bond 2V). MATERIALS AND METHODS: Fourteen dentin disks 1.0 mm thick were obtained from superficial occlusal dentin of extracted human third molars, and finished with wet 600-grit silicon carbide paper. Two dentin disks were bonded using each of the adhesives above according to the manufacturers' instructions, and a thin layer of flowable resin composite was applied. The specimens were kept in tap water for 24 h at 37 degrees C, and then assigned to one of two observational techniques: a fracture technique and an acid-base technique. Fracture technique: shallow grooves were cut, fixed in 10% buffered formalin, and dehydrated in an ascending ethanol series up to 100%, critical-point dried, and fractured along the prepared grooves. Acid-base technique: the specimens were embedded in epoxy resin, sectioned through the center, polished with diamond paste down to 0.25-micron particle size, and treated with 10% orthophosphoric acid for 10 s and 5% sodium hypochlorite for 5 min. All the specimens were mounted on aluminum stubs, gold sputter coated, and observed using field-emission scanning electron microscopy (FE-SEM). RESULTS: All the dentin adhesive systems showed hybrid layer formation, but the thickness varied depending on the bonding system used. The self-etching priming systems (Prime & Bond NT/NRC and Clearfil Liner Bond 2V) showed the thinnest hybrid layer at 1 to 2 microns, whereas the "single-bottle" system (Gluma One Bond) exhibited the thickest hybrid layer at 8 to 16 microns. CONCLUSION: The ultramorphological structures of dentin bonding systems are determined by the composition of each system. Characterization of the interface of the adhesive system using the fracture technique provides additional information regarding the pattern of resin infiltration in some dentin bonding systems.

Adhesives↗

Micromorphological study of resin-dentin interface of non-carious cervical lesions.

This study examined the interfaces between two dentin adhesives, namely, One Coat Bond, Clearfil SE Bond and a resin-modified glass ionomer cement (Fuji II LC) and the dentin of non-carious cervical lesions (NCCLs) with FE-SEM, and compared them with the interfaces produced with "normal" dentin. Fifteen human premolars each with a buccal NCCL were used. Cervical cavities were prepared on the lingual surface of the same teeth for the normal (control) dentin. All lesions and prepared cavities were cleaned with a slurry of pumice and water. The teeth were randomly divided among the three products that were applied according to the manufacturers' instructions. For the resin-bonded specimens, the cavities were restored with resin composite. All specimens were stored in 37 degrees C tap water. Resin-bonded specimens were observed using FE-SEM after treatment with 10% phosphoric acid, and 10% phosphoric acid and 5% sodium hypochlorite (NaOCl). The resin-modified glass ionomer cement (RM-GIC) specimens were observed after 10% phosphoric acid and 5% NaOCl treatment. The hybrid layer could be observed for the two adhesive systems in all specimens, but the thickness varied depending on the bonding system used and the dentin substrate. The results suggested that the hybrid layer produced in normal dentin was slightly thicker than that of NCCLs. Further, the hybrid layer thickness decreased in all specimens after NaOCl treatment.

Bicuspid↗

Simulated oral environment and microleakage of Class II resin-based composite and sandwich restorations.

PURPOSE: To evaluate the influence of the simulation of intra-oral conditions on the interfacial microleakage of Class II composite restorations. MATERIALS AND METHODS: 40 Class II cavities were prepared on freshly extracted human third molars and filled with a direct resin composite technique (SBMP+ + Z100) or open sandwich technique (Fuji II LC + SBMP+ + Z100). Extreme intra-oral conditions were simulated (35 degrees C/95% of relative humidity) and compared with ambient conditions (20 degrees C/40% RH). After thermocycling (2,000 cycles--5 and 55 degrees C), 2 hours immersion in silver nitrate aqueous solution and embedding into epoxy resin, samples were longitudinally sectioned. The extent of microleakage was expressed as a percentage of silver penetration of enamel and dentin interfaces. The influences of environmental conditions and restorative technique were evaluated by a two-way ANOVA and the comparison between the different groups with a Fisher PLSD test. RESULTS: In comparison with values obtained in ambient conditions, the simulation of extreme environmental conditions resulted in increased silver penetration percentages for direct resin composite restorations. On the contrary, the open sandwich technique, using resin-modified glass-ionomer cements, did not seem sensitive to excessive "temperature/relative humidity" parameters. Restorations made with resin-modified glass-ionomer cements used in the open sandwich technique appear to be more tolerant towards "temperature/relative humidity" parameters, which simulated intra-oral conditions, compared with modern adhesive systems.

Analysis of Variance↗

Microleakage of a new dental adhesive comparing microfilled and hybrid resin composites.

The objective of this study was to evaluate the in vitro microleakage of a new adhesive system, Syntac. Class V preparations were cut at the cementoenamel junction in 20 extracted bovine incisors and 20 extracted human incisors. One group of 10 human and 10 bovine teeth was restored with Syntac and a microfilled posterior resin composite; the other group was restored with Syntac and a hybrid resin composite. Microleakage was evaluated at 1 week with a 45Ca radioisotope method. No statistically significant differences between human and bovine substrates were found with either resin composite. The Syntac/hybrid resin restorations leaked less than did the Syntac/microfilled resin restorations at the gingival (dentin) margin in the bovine teeth; however, this difference was not statistically significant.

Acrylates↗