Interaction of resin-modified glass ionomer cements with hydrated dentin

published_or_final_versio

Review of Matrix Metalloproteinases’ Effect on the Hybrid Dentin Bond Layer Stability and Chlorhexidine Clinical Use to Prevent Bond Failure

This review describes the relationship between dentin collagen hybrid bond layer degradation and the Matrix Metalloproteinases (MMPs) after their release by acid etch and rinse adhesives and self etching bonding adhesives that can reduce the bond stability over time. MMP-2, MMP-8 and MMP-9 are indicated as the active proteases that breakdown the collagen fibrils in the hybrid bond layer. Phosphoric acid in the acid etch and rinse bonding process and acid primers in the self etch process are implicated in the release of these proteases and their activation by several non-collagen proteins also released from dentin by the etching. MMPs are released in saliva by salivary glands, by cells in the gingival crevices to crevicular fluid and by pulpal odontoblasts cells to the dentinal fluids. These sources may affect the hybrid layer also. Evidence of the bond strength deterioration over time and the ability of Chlorhexidine to prevent bond deterioration by inhibiting MMP action are discussed. Dentin Bonding procedure utilizing Chlorhexidine for different application times and concentrations are being developed. The application of 2% Chlorhexidine to the phosphoric acid etch surface after rinsing off the acid is the only procedure that has been clinically tested for a longer period of time and shown to prevent bond strength degradation so far. The adoption of this procedure is recommended as means of improving bond stability at this time

Effects of storage media on mechanical properties of adhesive systems

Purpose: To evaluate the effects of water vs. oil storage on the mechanical properties of dental adhesives over 3 and 6 months. Methods: Adhesive resin sheets were prepared by pouring either Single Bond (SB), One-Step (OS) or Clearfil Liner Bond 2V (CL) into a mold measuring 15 x 15 x 0.8 mm. After solvent evaporation, the adhesives were light-cured, removed from the mold and trimmed to either hourglass or I-beam shapes that were used to determine the true stress (TS) and modulus of elasticity (E), respectively. Control adhesive specimens were subjected to tensile testing at 0.6 mm/minute after 24 hours of immersion in distilled water. Experimental specimens were stored at 37 C in either distilled water or mineral oil and tested after 3 and 6 months. The data were analyzed by two-way ANOVA and Tukey's test. Results: Storage in water significantly decreased the TS and E of SB and OS specimens after 3 and 6 months (P 0.05). Storage in oil significantly increased the TS of the three adhesives after 3 and 6 months (P> 0.05), and the same trend was observed for E value of CL sample (P> 0.05).17210410

Durability of resin-dentin bonds related to water and oil storage

Purpose: To evaluate the long-term effects of etching time, adhesive system and storage condition on resin bond strength to dentin. Methods: Twenty-five extracted human third molars had a flat dentin surface exposed. Two total-etch adhesives, Single Bond (SB) and One-Step (OS), and one self-etching adhesive system, Clearfil Liner Bond 2V (CL), were used. The adhesives were bonded to dentin according to their respective manufacturer's instructions. Additional groups of SB and OS systems were created, in which the phosphoric acid etching time was doubled (30 seconds). After bonding, build-up crowns were constructed incrementally with Z250 resin composite and the teeth were stored for 24 hours in distilled water at 37°C. The teeth were serially and vertically sectioned to obtain several bonded beams with approximately 0.8 mm2 of cross-sectional area. Beams were tested in microtensile (0.6 mm/minute) either immediately (control) or after storage for 6 months or 1 year in either distilled water or mineral oil. Data were analyzed by ANOVA and Tukey's multiple comparison tests. Results: Significant reductions (P< 0.05) in bond strength were observed after both long-term storage periods in water for all the materials, regardless of the etching time for SB and OS. Bond strengths were either preserved or increased in specimens stored in oil.link_to_subscribed_fulltex

Durability of resin-dentin bonds related to water and oil storage

Purpoes: To evaluate the long-term effects of etching time, adhesive system and storage condition on resin bond strength to dentin. Methods: Twenty-five extracted human third molars had a flat dentin surface exposed. Two total-etch adhesives, Single Bond (SB) and One-Step (OS), and one self-etching adhesive system, Clearfil Liner Bond 2V (CL), were used. The adhesives were bonded to dentin according to their respective manufacturer's instructions. Additional groups of SB and OS systems were created, in which the phosphoric acid etching time was doubled (30 seconds). After bonding, build-up crowns were constructed incrementally with Z250 resin composite and the teeth were stored for 24 hours in distilled water at 37 degrees C. The teeth were serially and vertically sectioned to obtain several bonded beams with approximately 0.8 mm(2) of cross-sectional area. Beams were tested in microtensile (0.6 mm/minute) either immediately (control) or after storage for 6 months or 1 year in either distilled water or mineral oil. Data were analyzed by ANOVA and Tukey's multiple comparison tests. Results: Significant reductions (P < 0.05) in bond strength were observed after both long-term storage periods in water for all the materials, regardless of the etching time for SB and OS. Bond strengths were either preserved or increased in specimens stored in oil.18631531

Interaction of resin-modified glass-ionomer cements with moist dentine

Objectives. The objective of this study was to report on a novel phenomenon that occurs when resin-modified glass-ionomer cements (RMGICs) are bonded to moist human dentine. Methods. Dentine surfaces from extracted third molars were abraded with 180-grit SiC paper. Ten teeth were prepared for each of the two RMGICs tested (Fuji II LC, GC Corp. and Photac-Fil Quick, 3M ESPE). RMGIC buildups were made according to the manufacturers' instructions. After storage at 37°C, 100% humidity for 24 h, the bonded specimens were cut occlusogingivally into 0.9×0.9 mm beams. Dentine surfaces bonded with the two RMGICs were examined along the fractured RMGIC/dentine interfaces. Additional beams fractured within the RMGICS and at 3 mm away from the interfaces were used as controls. The fractured beams were examined using scanning electron microscopy (SEM), field emission-environmental SEM (FE-ESEM) and transmission electron microscopy (TEM). Results. SEM and FE-ESEM revealed numerous solid spherical bodies along the RMGIC/dentine interfaces. By contrast, no spherical bodies could be identified within the RMGIC fractured 3 mm distant from the bonded interface. TEM and energy dispersive X-ray analyses performed on carbon-coated ultrathin sections showed that these solid spherical bodies consisted of a thin aluminum and silicon-rich periphery and an amorphous hydrocarbon core within the air voids of the original resin matrix. Conclusion. The spherical bodies probably represent a continuation of GI reaction and poly(HEMA) hydrogel formation that results from water diffusion from the underlying moist dentine. Their existence provides evidence for the permeation of water through RMGIC/dentine interfaces. © 2004 Published by Elsevier Ltd.link_to_subscribed_fulltex

Bond strength, biaxial flexural strength and flexural modulus of dentin bonding systems exposed to water

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Purpose: This study evaluated the effects of storage time on dentin bond strength, biaxial flexural strength, and flexural modulus of four adhesive systems. Materials and Methods: The following adhesive systems were tested: Easy Bond, Scotchbond SE, Single Bond Plus, and Scotchbond Multi-Purpose. Sixty human third molars were used for the microtensile bond strength test (n=15). The adhesives were applied to flat occlusal dentin surfaces according to the manufacturers' instructions and a Filtek Supreme resin composite block (6 mm high) was incrementally built up. After 24 h, the teeth were prepared for the bond strength test. The specimens were stored for one week, six months, and one year in distilled water. At the end of each storage period, the specimens were tested under tension (0.5 mm/min) until failure occurred. For the biaxial flexural test, resin discs of each adhesive (0.6 mm thick and 6.0 mm in diameter) were prepared in silicon molds (n=10). The discs were stored for the same storage periods in distilled water prior to testing in a universal testing machine (1.27 mm/min). Data were analyzed using two-way analysis of variance and Tukey's test (alpha=0.05). Results: Bond strength values decreased significantly after six months and one year of water storage only for Scotchbond SE (from 48.1 +/- 11.0 to 24.5 +/- 15.3 MPa after one year). The storage time did not affect the flexural strength or modulus for any adhesive tested. Conclusion: Water storage for six months or one year can reduce the dentin bond strength of adhesives; however, the results are product-dependent. No changes in flexural strength or modulus of the adhesives tested were observed after storage of any duration. (C) 2014 Published by Elsevier Ltd.49109114Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CAPES [3110/2010]CNPq [305777-2010-6

Interaction of resin-modified glass-ionomer cements with moist dentine

Objectives. The objective of this study was to report on a novel phenomenon that occurs when resin-modified glass-ionomer cements (RMGICs) are bonded to moist human dentine. Methods. Dentine surfaces from extracted third molars were abraded with 180-grit SiC paper. Ten teeth were prepared for each of the two RMGICs tested (Fuji II LC, GC Corp. and Photac-Fil Quick, 3M ESPE). RMGIC buildups were made according to the manufacturers' instructions. After storage at 37 degreesC, 100% humidity for 24 h, the bonded specimens were cut occlusogingivally into 0.9 x 0.9 mm beams. Dentine surfaces bonded with the two RMGICs were examined along the fractured RMGIC/dentine interfaces. Additional beams fractured within the RMGICS and at 3 mm away from the interfaces were used as controls. The fractured beams were examined using scanning electron microscopy (SEM), field emission-environmental SEM (FE-ESEM) and transmission electron microscopy (TEM). Results. SEM and FE-ESEM revealed numerous solid spherical bodies along the RMGIC/dentine interfaces. By contrast, no spherical bodies could be identified within the RMGIC fractured 3 mm distant from the bonded interface. TEM and energy dispersive X-ray analyses performed on carbon-coated ultrathin sections showed that these solid spherical bodies consisted of a thin aluminum and silicon-rich periphery and an amorphous hydrocarbon core within the air voids of the original resin matrix. Conclusion. The spherical bodies probably represent a continuation of GI reaction and poly(HEMA) hydrogel formation that results from water diffusion from the underlying moist dentine. Their existence provides evidence for the permeation of water through RMGIC/dentine interfaces. (C) 2004 Published by Elsevier Ltd.32752153