RESUMEN
This study aimed to evaluate the chemical interaction of collagen with some substances usually applied in dental treatments to increase the durability of adhesive restorations to dentin. Initially, the similarity between human dentin collagen and type I collagen obtained from commercial bovine membranes of Achilles deep tendon was compared by the Attenuated Total Reflectance technique of Fourier Transform Infrared (ATR-FTIR) spectroscopy. Finally, the effects of application of 35% phosphoric acid, 0.1M ethylenediaminetetraacetic acid (EDTA), 2% chlorhexidine, and 6.5% proanthocyanidin solution on microstructure of collagen and in the integrity of its triple helix were also evaluated by ATR-FTIR. It was observed that the commercial type I collagen can be used as an efficient substitute for demineralized human dentin in studies that use spectroscopy analysis. The 35% phosphoric acid significantly altered the organic content of amides, proline and hydroxyproline of type I collagen. The surface treatment with 0.1M EDTA, 2% chlorhexidine, or 6.5% proanthocyanidin did not promote deleterious structural changes to the collagen triple helix. The application of 6.5% proanthocyanidin on collagen promoted hydrogen bond formation.
Asunto(s)
Colágeno Tipo I/química , Inhibidores de la Metaloproteinasa de la Matriz , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Diente/patología , Grabado Ácido Dental/métodos , Animales , Bovinos , Colágeno/química , Dentina/química , Dentina/metabolismo , Recubrimientos Dentinarios/farmacología , Humanos , Enlace de Hidrógeno , Péptidos/química , Proantocianidinas/química , Espectrofotometría/métodosRESUMEN
O objetivo deste estudo foi analisar a distribuição de tensões de von Mises em uma prótese parcial fixa de três elementos em metalocerâmica e em dois sistemas de cerâmica pura através de carregamento estático aplicado em modelos matemáticos bidimensionais obtidos pelo método de elementos finitos. A partir da imagem de uma peça anatômica de estudo, os desenhos foram confeccionados e suas imagens vetorizadas foram exportadas para o programa MSC/PATRAN e a análise foi feita utilizando-se um carregamento de 100N distribuídos em 17 pontos das superfícies oclusais dos modelos. Em todos os modelos as maiores concentrações de tensões localizaram-se no interior dos pinos e na região médio-inferior dos conectores. Os dois sistemas cerâmicos se comportaram satisfatoriamente em comparação à metalocerâmica.
Asunto(s)
Análisis de Elementos Finitos , Fenómenos Biomecánicos , Dentadura Parcial Fija , Aleaciones de Cerámica y Metal/normas , Modelos TeóricosRESUMEN
AIM: The aim of this study was to evaluate how cavity preparation and primer application methods influence the adhesion of composite resin to dentin using a self-etching system. METHODS AND MATERIALS: Forty-eight extracted, sound human molars were divided into six groups (n=8) according to the method used for the surface preparation of the teeth (#600-grit paper disc, diamond bur, and Er:YAG laser) and the primer application method utilized (active or passive). Following the adhesive procedure using a self-etching system, 5 mm high composite buildups were created with Z-250 composite resin. After storage in water at 37 degrees C for 24 hours, the specimens were vertically sectioned into serial 1 mm2 sticks and tested for microtensile strength (micro-TBS). Nine additional molars were prepared for morphological analysis using scanning electron microscopy (SEM). RESULTS: Statistical analysis showed surface preparation technique (p < 0.00) and primer application methods (p < 0.001) do influence bond strength of the self-etching system tested. The best adhesion was achieved with specimens having the dentin ground with sandpaper followed by those ground with diamond burs. The worst bonding was obtained with Er:YAG laser ablated dentin. The active primer application method increased bonding performance compared to the passive method. CONCLUSIONS: Within the limitations of the study, it can be stated surface treatment can influence the bond strength of the self-etching system tested and the active primer application method is more effective in achieving success in bonding to dentin compared with the passive application method. CLINICAL SIGNIFICANCE: Clinicians should use the active application method to apply a mild acidic self-etching primer along with an appropriate tooth surface preparation to facilitate the bond strength between dentin and composite resin.
Asunto(s)
Resinas Compuestas , Recubrimiento Dental Adhesivo/métodos , Preparación de la Cavidad Dental/métodos , Recubrimientos Dentinarios , Láseres de Estado Sólido , Cementos de Resina , Preparación de la Cavidad Dental/instrumentación , Fracaso de la Restauración Dental , Análisis del Estrés Dental , Dentina/ultraestructura , Humanos , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Diente Molar , Capa de Barro Dentinario , Propiedades de Superficie , Resistencia a la TracciónRESUMEN
AIM: The aim of this study was to evaluate the influence of chlorhexidine on microleakage of composite restorations in class V cavities prepared with a carbide bur (CB) and a erbium:yttrium-aluminum-garnet (Er:YAG) laser. METHODS AND MATERIALS: Cavity preparations were created on the buccal surfaces of 48 bovine incisors using different methods then equally dividing them into four groups. Groups I and II were prepared with a #56 CB in a high speed handpiece while Groups III and IV were prepared with a Er:YAG laser at 350m J/4Hz on enamel and at 80.24 J/cm2 on dentin. The cavity preparations were rinsed with 2% chlorhexidine solution before the application of Clearfill SE Bond system and placement of a Z100 composite resin restoration. After 24 hours, the teeth were polished, thermocycled, and sealed with cosmetic varnish. The samples were then immersed in 2% methylene blue for four hours and sectioned in the buccolingual direction to determine the degree of microleakage. RESULTS: After statistical analysis (Kruskal-Wallis, p<0.05), no significant differences were verified among the tested groups and between the evaluated cervical or incisal margins of the restoration. CONCLUSION: The use of the chlorhexidine did not interfere with the adhesion process regardless of whether a CB or the Er:YAG laser were used to prepare class V cavities when restored with the tested self-etching adhesive system.
Asunto(s)
Antiinfecciosos Locales/efectos adversos , Clorhexidina/efectos adversos , Resinas Compuestas , Preparación de la Cavidad Dental/instrumentación , Terapia por Láser , Dióxido de Silicio , Circonio , Animales , Bovinos , Colorantes , Filtración Dental/diagnóstico , Filtración Dental/etiología , Filtración Dental/prevención & control , Adaptación Marginal Dental , Restauración Dental Permanente/métodos , Recubrimientos Dentinarios , Erbio , Azul de Metileno , Microscopía Electrónica de Rastreo , Cementos de ResinaRESUMEN
OBJECTIVE: The aim of this study was to test the effect of Er:YAG laser irradiation on the marginal sealing of root cavities restored with two glass ionomer cements. BACKGROUND DATA: For preventing secondary root caries, new technologies for dental caries removal, such as the Er:YAG laser irradiation, have been proposed. METHODS: Forty-five human teeth were used. Artificial root caries were induced using a microbiological model (Streptococcus mutans). The lesions were removed by three different methods: conventional technique using burs (controls; groups 1 and 2); Er:YAG laser irradiation using dentine preparation parameters (250 mJ, 4 Hz, 80.6 J/cm2; groups 3 and 4); irradiation with the dentine preparation parameters followed by surface conditioning parameters (60 mJ, 2 Hz, 19.2 J/cm2; groups 6 and 7). After each preparation method, three teeth were prepared for scanning electron microscopy morphological observation. The remaining teeth were restored by conventional glass ionomer cement (G1, G3, and G5) or resin modified glass ionomer cement (G2, G4, and G6). After restoration, the samples were thermocycled (1,000 cycles) and prepared for microleakage test. RESULTS: Scores of less infiltrated samples were observed in groups treated by Er:YAG laser, and the smallest infiltration occurred in the group treated by the dentine preparation parameter, followed by cavity restoration with resin-modified glass ionomer (p < 0.05). CONCLUSION: Our results suggest that root caries removal by Er:YAG laser irradiation, followed by restoration with resin-modified glass ionomer cement, is a suitable choice for dental root caries restoration.