Shear bond strength of resin modified glass ionomer cement bonded to different tooth-colored restorative materials.

AIM: The aim of this study was to determine in vitro the shear bond strength (MPa) and the type of bond failure when resin-modified glass ionomer cement (RMGIC) was bonded with different tooth-colored restorative materials. METHODS AND MATERIALS: The RMGIC tested was Fuji II LC (FL) and the tooth-colored restorative materials used were composite resin Point-4 (P4), Compomer Dyract AP (DY), and Ormocere Admira (AD). A total number of 60 FL specimens were prepared using Teflon molds. The specimens were divided into six equal groups. Each group of ten specimens was bonded to a tested tooth-colored restorative material as follows: Group I--etched FL bonded to P4; Group II--non-etched FL bonded to P4; Group III--etched FL bonded to DY; Group IV--non-etched FL bonded to DY; Group V--etched FL bonded to AD; and Group VI--non-etched FL bonded to AD. The specimens were stored in distilled water at 37 degrees C for 24 hours. The shear bond strength was measured in a universal testing machine, and the fractured surfaces were examined under a stereomicroscope. RESULTS: The results of the shear bond strength indicated the lowest mean value (14.46 MPa) was in Group III, and this was significantly different from the values of other groups (p<0.05). However, Groups V and VI recorded the highest mean values (24.5 MPa and 28.39 MPa) which were significantly different (p<0.05) when compared to other groups. Groups I, II, and IV showed no significant difference with mean values of 20.06, 19.99, and 20.1 MPa which were significantly different from other groups (p<0.05). CONCLUSION: AD showed the highest shear bond strength to RMGIC. All groups demonstrated a cohesive failure in FL except for Group IV where a cohesive failure in DY was recorded. AD showed good shear bond strength when laminated with FL.

Effect of different bonding conditions on the shear bond strength of two compomers to bovine dentin.

AIM: Despite the improvements to compomer materials, the bond strength of these materials remains inferior to "composite/resin bonding" systems and limits their clinical use. The purpose of this study was to evaluate the effect of acidic conditioning with phosphoric acid and Prompt L-Pop (PLP) on the shear bond strength of two compomers Dyract AP (DAP) and Composan Glass (CG) to dentin. METHODS AND MATERIALS: Sixty extracted bovine teeth were used to test the shear bond strength of two compomers to flat dentin labial surfaces. The dentin specimens were randomly assigned to six groups of ten specimens each: Group 1: DAP and Prime & Bond NT (PBNT); Group 2: DAP/PBNT with a 15 second dentin etch prior to bonding; Group 3: DAP placed with PLP adhesive; Group 4: CG and Compobond NE (CBNE); Group 5: CG/CBNE with a 15 second dentin etch; and Group 6: CG placed with PLP adhesive. The specimens were stored at 37 masculineC with 100% humidity for 24 hours then mounted and sheared using an Instron Universal Testing Machine at a cross head speed of 0.5 mm/min. The results were recorded in Mega Pascals (MPa). The sheared specimens were examined under a light microscope, and the type of failure (adhesive, cohesive, or mixed) was recorded. RESULTS: The mean dentin shear bond strength value (MPa) for the groups was: Group 1 (11.6+/-3.9); Group 2 (13.2+/-3.3); Group 3 (12.4+/-2.0); Group 4 (13.0+/-4.3); Group 5 (19.3+/-3.7); and Group 6 (13.1+/-3.0). One way analysis of variance (ANOVA) and Tukey HSD post-hoc tests detected a significantly higher bond strength (P = 0.003) for group 5. For groups 1, 3, 4, and 6, the mode of failure was mostly adhesive. When acid etching of dentin was performed (groups 2 and 5), cohesive fracture within dentin was the predominant mode of failure. Acid etching and the use of PLP significantly reduced the number of adhesive fractures and reduced variability in the shear bond strength results. CONCLUSIONS: Acid etching significantly increased the shear bond strength of CG to dentin but did not affect DAP. The application of PLP resulted in a shear bond strength not statistically different from PBNT or CPNE. CG bond to dentin is improved with acid etching using phosphoric acid. However, PLP provided no significant improvement in the shear bond strength of DAP and CG.

Shear bond strengths and microleakage of four types of dentin adhesive materials.

The aim of this investigation was to compare the microleakage of composite resin (Z-100) and shear bond strength to bovine dentin using different types of adhesive systems (Scotch Bond Multi-Purpose, All-Bond 2, One-Step, and Perma Quick) to compare and correlate microleakage to shear bond strength. For the microleakage aspect of the study, 20 class V were prepared (bovine incisors) with 90-degree cavosurface margins and were located at the cemento-enamel junction using a template. Each dentin bonding system was applied to five cavities following the manufacturer's instructions and restored with Z-100 composite resin. After 24 hours of storage in distilled water at 37 degrees C, the teeth were immersed in 2% basic fuchsin dye. All teeth were sectioned in a mesiodistal direction using a diamond saw, and each section was then inspected under a stereomacroscope. For the shear bond strength aspect of the study, 20 bovine incisors were centrally horizontally mounted in Teflon mold with cold cure acrylic resin. Flat labial dentin surfaces were prepared using different grit silicon carbide abrasive wheels. Five specimens were used for each of the bonding agent systems. Each specimen was bonded with restorative composite resin (Z-100) and applied to the treated dentinal surface through a split Teflon mold. All specimens were stored in distilled water at 37 degrees C for 24 hours. The bonds were stressed using shear forces at a crosshead speed of 0.5mm/min using an Instron Universal testing machine. Findings indicate none of the systems tested in this study were free from microleakage. Scotch bond multi-purpose achieved the best seal, with One-Step being second best, while All-Bond 2 and Perma Quick had the poorest seal. However, there were significant differences among the shear bond strengths of the four bonding systems tested. Scotch Bond Multi-Purpose has a higher bond strength to composite resin when compared to the other dentin adhesives. The study also concluded there is no association between microleakage and shear bond strength.