RESUMO
PURPOSE: For contemporary hydrophilic resin adhesive systems, bonding to dentin is improved if the substrate is maintained in a hydrated state following acid-etching. The purpose of this study was to compare the dentin shear bond strengths of two single-bottle adhesives (one acetone-based and one ethanol-based) applied under different etched-dentin conditions: dry, wet, or dry and re-wetted with different solutions. MATERIALS AND METHODS: Bovine incisors (N = 120) were mounted in acrylic, polished to 600-grit, and randomly assigned to 12 groups (n = 10). Dentin was etched for 15 seconds using 35% phosphoric acid, rinsed, and either blot-dried, air-dried, or air-dried and re-wetted with different solutions (distilled water, Gluma Desensitizer, Aqua-Prep, and 5% glutaraldehyde in water). Two adhesives (Single Bond and Prime & Bond NT) were applied to each of the surface conditions following manufacturers' instructions. After adhesive application and curing, composite was applied in a No. 5 gelatin capsule and light-cured. Specimens were loaded in shear, using an Instron at 5 mm per minute. Shear bond strengths were calculated by dividing the failure load by the bonded surface area. Data were subjected to analysis of variance (ANOVA) and a post hoc Tukey test. RESULTS: Mean shear bond strengths ranged from 12.5 to 26.6 MPa for Single Bond and from 5.6 to 14.7 MPa for Prime & Bond NT. Significant differences were found in both groups of materials (p < .001). The three highest mean bond strengths were obtained (in order) on dentin that was re-wetted with Gluma Desensitizer, re-wetted with Aqua-Prep, or never dried. Differences between these surface conditions were not statistically significant for either material.
Assuntos
Colagem Dentária , Adesivos Dentinários/química , Dentina/ultraestrutura , Agentes Molhantes/química , Acetona/química , Condicionamento Ácido do Dente , Análise de Variância , Animais , Bis-Fenol A-Glicidil Metacrilato/química , Bovinos , Resinas Compostas/química , Análise do Estresse Dentário/instrumentação , Etanol/química , Glutaral/química , Metacrilatos/química , Ácidos Fosfóricos/administração & dosagem , Ácidos Polimetacrílicos/química , Distribuição Aleatória , Solventes/química , Estatística como Assunto , Estresse Mecânico , Propriedades de Superfície , Água/químicaRESUMO
As the use of adhesive restorative materials has increased during the last several years, interest in adhesive materials that release fluoride has also grown. The purpose of this study was to measure fluoride release from several adhesive restorative materials and to evaluate its effect on dentin resistance to demineralization and on bacterial metabolism in a modified in vitro system. Standardized cavities (1.8 mm in diameter) were prepared in bovine teeth that had been ground to dentin. One cavity in each tooth was restored with one of the following restorative systems: (a) Single Bond and Z100; (b) Single Bond and Tetric Ceram; (c) Fuji Bond LC and Z100; (d) Fuji Bond LC and Tetric Ceram; (e) Fuji II LC; or (f) Fuji IX GP. The other cavity in each tooth was "restored" with wax as a control. For each restorative system, 12 specimens were evaluated for fluoride release during the first 24 hrs after restoration placement. Dentin adjacent to the restored sites was subjected to lactic acid challenge (pH 4.3) for 3 hrs, after which calcium release was measured. Another 12 specimens in each group were stored for 24 hrs in de-ionized water, and were exposed to an S. mutans suspension (1:1 THB/de-ionized water and 50 mM glucose, A660 = 0.2) for 6 hrs, followed by calcium release and pH measurement. Bulk specimens of each material were also made and stored in water. Fluoride released from Fuji Bond LC, Fuji IX GP, and Fuji II LC in bulk was significantly greater than from the other materials. In the restored dentin specimens, increased resistance to demineralization from a lactic acid challenge was directly related to fluoride release. The same effects were seen as a result of the S. mutans challenge. While fluoride release from restorative materials increased the resistance of dentin to demineralization in this system, the clinical relevance of the findings is not known.
Assuntos
Materiais Dentários/farmacologia , Restauração Dentária Permanente , Dentina/efeitos dos fármacos , Fluoretos/farmacologia , Desmineralização do Dente/induzido quimicamente , Animais , Bovinos , Restauração Dentária Permanente/métodos , Concentração de Íons de Hidrogênio , Técnicas In Vitro , Ácido Láctico/farmacologia , Distribuição Aleatória , Streptococcus mutans/metabolismo , Streptococcus mutans/patogenicidade , Desmineralização do Dente/microbiologiaRESUMO
Recently, simple radiometers for measuring the intensity of dental curing lights have been introduced. This study examined the relationship among light intensity measurements by three radiometers, distance of curing tip from composite resin, and resin polymerization (as indicated by microhardness). Light intensity measurements, which decreased with increasing distance from the curing tip, were strongly correlated with composite resin hardness. Reduced light intensity produced softer composite resin, particularly on the bottom of specimens (2-mm depth). The different radiometers provided similar indications of the changes in light intensity at various curing distances.