ABSTRACT
Objective@#To explore the best indication for veneers and to improve the repair success rate by investigating the effects of different types of dentin exposure on the shear bond strength of cast porcelain veneers with two new veneer bonding systems.@*Methods@#Bonding interfaces with 0%, 25%, 50%, 75% and 100% dentin exposure were designed and fabricated. The bonding interfaces were divided into groups A, B, C, D and E. Sixty 4-mm x 4-mm x 2-mm (length x width x thickness) ceramic specimens were bonded by using two bonding systems, The VN-A, VN-B, VN-C, VN-D and VN-E groups were bonded with Variolink bonding system, and the PF-A, PF-B, PF-C, PF-D and PF-E were bonded with Panavia F bonding system (six specimens per group). The bonded specimens were stored in a distilled water bath at (37 + 1)℃ for 24 hours. The fracture load was tested by a universal testing machine, and the fracture type was observed by scanning electron microscopy.@*Results @#The VN-A (25.14 ± 3.40 MPa), VN-B (22.54 ± 4.48 MPa), VN-C (19.59 ± 2.21 MPa), PF-A (20.61 ± 2.42 MPa), PF-B (18.08 ± 4.11 MPa), PF-C (17.06 ± 2.29 MPa) groups’ shear bond strengths were above 17 MPa. The VN-A group had the highest shear bond strength value. There was no statistically significant difference in bond strength between the VN-A group and the VN-B and VN-C groups (P > 0.05) or the PF-A and PF-B groups (P > 0.05); however, the differences between VN-A and the VN-D and VN-E groups (P < 0.05) and between PF-A and the PF-C and PF-D and PF-E groups (P < 0.05) were statistically significant. The differences between the VN-A group and PF-A group (P < 0.05) were statistically significant. The fracture modes of the VN-A, PF-A, VN-B, PF-B, and VN-C groups mainly included resin cement cohesive failure and mixed failure; the VN-D, VN-E, PF-C, PF-D and PF-E groups were dominated by interface failure and mixed failure.@*Conclusion@#When the dentin exposure is greater than 50%, the shear bond strength value of the veneer was significantly affected. To obtain a better clinical effect, the dentin exposure rate should be less than 25%.
ABSTRACT
PURPOSE: This study examined the recovery of the dentin-resin bonding strength, and the difference in the bonding strength after applying pH hemostatic agents at various pH. MATERIALS AND METHODS: Bosmin, Hemodent, Astregedent, and Visine were used as the hemostatic agents in this study. The Bosmin, Hemodent, and Astrigedent hemostatic agents are acidic, and the Visine hemostatic agent is neutral and is used as a decongestant. Ninety human molar teeth were used as the specimen. The teeth were sectioned using a diamond wheel until the dentin was exposed and wet ground by silica paper. The specimens were divided into two groups according to the hemostatic agent used. The specimens were then subdivided into 9 groups according to the application of re etching (R group) or rinsing only (N group). A commonly used resin bonding procedure was used in the control group. The resin bonding procedure was managed dentin using celluloid capsule. In addition, the shear bond strength was measured using an Instron. RESULTS: In general, samples with the applied hemostatic agent, with the exception of Visine, had a slightly weak bond that was similar to the control group. In addition, the rinsing only (N) group had slightly weak bond that was similar to the re etching (R) group. CONCLUSION: The application of a hemostatic agent on the dentin surface does not affect the shear bond strength after application for a short time. In addition, rinsing only can recover the shear bond strength making other management procedures redundant, particularly re etching.
Subject(s)
Humans , Dentin , Dentin-Bonding Agents , Diamond , Hydrogen-Ion Concentration , Imidazoles , Molar , Silicon Dioxide , ToothABSTRACT
The purpose of this study was to compare in vitro shear bonding strength with three different enamel surface preparations: (1) 30% sulfated polyacrylic acid with 0.3M lithium sulfate (2) 40% sulfated polyacrylic acid with 0.3M lithium sulfate (3) 37% phosphoric acid. 105 extracted human premolar teeth were divided into each three groups of 35. Metal brackets were bonded to teeth in the three groups. The same self curing resin was used for all groups. A shearing force was applied to the teeth. After debonding, bases of bracket and enamel surfaces were examined under steroscopic microscope to determine the failure modes. Statistical analysis of the data was carried out with one way ANOVA and Student t-test. The results were as follows. 1. Shear bond strength values for the 30% polyacrylic acid and 40% polyacrylic acid group were approximately two thirds of the phosphoric acid group. It maintains clinically acceptable but not enough bond strength. 2. There was no statistically significant difference in shear bond strengths between 30% and 40% polyacrylic acid group. 3. The failure modes of brackets had some differences. In polyacrylic acid groups, the percentage of adhesive/enamel failure was higher than that of adhesive/bracket interface failure. On the contrary in phosphoric acid groups, the results were reversed. Further study of bond strength could be required. If polyacrylic acid enamel conditioning is used clinically.
Subject(s)
Humans , Bicuspid , Dental Enamel , Lithium , ToothABSTRACT
To investigate the effects of different surface conditioning methods on the shear bonding strength of glass-infiltrated ceramic to dentine, 24 glass-infiltrated ceramic testing-pieces were divided into four groups randomly. Among them 3 groups were treated with A(sandblasting+silance), B(etching+silace) or C(silance), separately, while group D was set as the control. Bonding the ceramic pieces to dentine with Super-Bond and the shear bonding strengths was measured. The results showed that the shear bonding strength of group D was lower than that of group A, B and C (P0.05). It is suggested that surface conditioning using combined sandblasting with silance can remarkbly improve the shear bonding strength of glass-infiltrated ceramic to dentine.