A self-etching adhesive exhibited significantly lower bond strength to dentin contaminated with 25% aluminum chloride solution compared to normal dentin, but a total-etching adhesive exhibited no difference in bond strength to either contaminated or normal dentin. Longer primer application of the self-etching adhesive significantly increased the dentin bond strength of the contaminated group. SUMMARYThis study evaluated the bond strength of a totaletch and a self-etch adhesive to dentin contaminated with a hemostatic agent containing aluminum chloride (AlCl 3 ). Eighteen occlusal dentin discs were prepared from human molars. Each disc was ground and sectioned into two halves, one for normal dentin and the other for contaminated dentin. The specimens of both normal and contaminated dentin were randomly divided into three groups and treated with the following materials: 1) Excite (EX); 2) Clearfil SE Bond with 20-second primer application time (CB 20) and 3) Clearfil SE Bond with 40-second primer application time (CB 40). The microshear bond strength specimens were prepared using the resin composite Clearfil APX. The bond strengths were evaluated on a universal testing machine. Statistical analysis was performed at α=0.05. The surface micromorphology and aluminum content of the different dentin conditions were also examined. In EX, no significant difference was found between the bond strengths of normal dentin and contaminated dentin. The bond strength of CB20 to contaminated dentin was significantly lower than that to normal dentin. The

SUMMARYThe current study evaluated the micro-shear bond strength of two resin cements to astringentcontaminated dentin. Twelve occlusal dentin discs were prepared from extracted caries-free human molars and divided into two groups subjected to two types of resin cements, Panavia F (PF) and Variolink II (VL). Each disc was ground with 600 grit SiC paper and sectioned into two semi-disks, one for the normal dentin surface and the other for the contaminated dentin surface. For contaminated dentin, an astringent containing aluminum chloride was applied for two minutes and rinsed before the bonding procedures. A micro tygon tube was placed on the dentin surface following the bonding application and then filled with a resin cement. After the resin was polymerized, the specimen was kept in water for 24 hours before the micro-shear bond strengths evaluation. The micro morphology of the treated surfaces and resin-dentin interfaces were observed under a scanning electron microscope (SEM). Aluminum content under different dentin conditions was also examined. No significant differences were found between the dentin bond strengths to normal dentin and contaminated dentin surfaces in both the PF and VL groups (p>0.05). PF showed similar bond strengths to VL on normal and contaminated dentin (p>0.05). SEM observations of the VL groups revealed no C Harnirattisai • W Kuphasuk P Senawongse • J Tagami Clinical RelevanceThe contamination of the dentin surface with an astringent-containing aluminum chloride does not reduce the bond strength of either the resin cement used in conjunction with an etch-andrinse or the resin cement with a self-etching adhesive. However, the contamination probably interferes with the etching ability of the self-etching primer and the adaptation of the resin cement to the dentin surface.

SUMMARYObjective: This study evaluated the effect of an unfilled-adhesive resin (Adper Single Bond) and a filled-adhesive resin (Adper Single Bond 2) with and without a low viscosity resin (Filtek Flow) as an elastic cavity wall on marginal leakage and dentin microtensile bond strength in Class V composite restorations under unloaded and loaded conditions. Methods: V-shaped cavities were prepared on the buccal surfaces of 56 premolars lined with unfilled (Groups 1 and 3) or filled (Groups 2 and 4) adhesives with (Groups 3 and 4) and without (Groups 1 and 2) a low viscosity resin and restored with a resin composite. The restored teeth in each group were divided into two subgroups for unloaded and loaded conditions with 50N loading force for 250,000 cycles parallel to the long-axis of the tooth. Five specimens from each group were cut bucco-lingually 0.7 mm thick and subjected to a dye leakage test for four hours using 2% methylene blue dye. The tested specimens were then trimmed into dumbbell shapes at the gingival margin and subjected to microtensile testing. The remaining two specimens were cut, embedded and observed for resin/dentin interfaces under a scanning electron microscope.Results: For the microleakage test, there were no significant differences in microleakage among the groups on both the enamel and dentin margin. No statistically significant differences were found between microleakage of the loaded and unloaded groups on enamel margins for all materials. There were statistically significant differ-P Pongprueksa • W Kuphasuk • P Senawongse Clinical RelevanceThe application of filled adhesive or low viscosity resin as an elastic cavity wall had no influence on marginal leakage both at the enamel and dentin margin; however, the application had an influence on increasing the microtensile bond strength to dentin of Class V restorations. Occlusal loading significantly increased the degree of marginal leakage at the dentin margin. ences between microleakage of the loaded and unloaded groups on the dentin margin for Groups 3 and 4. For the microtensile test, the significant difference was found between Groups 1 and 4 for the unloaded groups. For the loaded groups, there were no significant differences between Groups 1 and 2 and Groups 3 and 4. There were no statistically significant differences in microtensile bond strength between the loaded and unloaded groups except for Group 2.Conclusion: The application of filled adhesive or low viscosity resin had no influence on marginal leakage at both the enamel and dentin margin but it had an influence on the microtensile bond strength to dentin of Class V restorations. Occlusal loading significantly increased the degree of marginal leakage at the dentin margin when low viscosity was applied in combination with either unfilled or filled-adhesives, but it decreased dentin bond strength in the group treated with only filled adhesive.

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SUMMARYThis study investigated the effect of two base materials with different elastic moduli (F2000 and Vitrebond) on the fracture load of machinable ceramic inlays. Standardized MOD cavities were prepared in 18 human maxillary first or second premolars. The teeth were randomly assigned to three groups of six premolars each; Group 1 (control: no base); Group 2 (base with a polyacid-modified resin composite: F2000); Group 3 (base with a resin-modified glassionomer cement: Vitrebond). The inlays were fabricated from Vitablocs Mark II using a Cerec II machine. After the inlays were cemented with Tetric Ceram and the Syntac adhesive system, using the Ultrasonic Insertion Technique (USI), they were stored in distilled water at 37°C for 24 hours prior to fracture testing in a universal testing machine using a crosshead speed of 0.5 mm/minute. The static transverse elastic moduli of base materials were measured using a threepoint bending test. The mean fracture loads and standard deviations of the Cerec inlays in Groups 1, 2 and 3 were 1.15 ± 0.39 KN, 1.13 ± 0.36 KN and 0.58 ± 0.11 KN, respectively. Statistical analysis showed that the mean fracture load of Group 3 was significantly lower than that of Groups 1 and 2 (p<.05). There was no significant difference in fracture load between Groups 1 and 2. The means and standard deviations of the elastic moduli of F2000 and Vitrebond were 15.63 ± 0.32 and 2.16 ± 0.55 GPa, respectively. The results indicated that the fracture load increased significantly as the elastic modulus of a base material increased.

ObjectiveTo evaluate the optical match between enamel and resin composites fabricated using mono‐layered and double‐layered techniques.Materials and MethodsEnamel slabs were prepared from human upper incisors and canines. Mono‐layered composite replicas were prepared from seven Filtek Z350XT and Estelite Sigma shades using silicone molds prepared from the respective enamel surfaces. Translucent and enamel shades (A2 or A3) of the two materials were produced from incisor molds for double‐layered replicas, and the groups with the best results underwent accelerated aging. Spectrophotometric evaluation was performed using CIE color system. The differences in translucency (ΔTP) and color (ΔE00) between the enamel and paired composite replicas were calculated and analyzed using parametric statistics (α = 0.05).ResultsFor the mono‐layered composites, white enamel and translucent shades of Filtek yielded the lowest ΔTP for canines (4.6) and incisors (8.9), respectively. The ΔE00 of mono‐layered replicas ranged from 5.1 to 11.8. Double‐layered Filtek replicas displayed a better 1‐day optical match with the lowest ΔTP (3.4–4.0) and ΔE00 (4.2–4.6), irrespective of each layer's thickness.ConclusionsFor canines, the lowest ΔTP of Filtek white enamel was close to the acceptable threshold (4.43). For incisors, the thicker translucent double‐layered Filtek composites demonstrated the greatest optical match before and after aging.Clinical SignificanceUpper incisors and canines have distinct enamel optical properties. Enamel layering using specific double‐layered resin composites could achieve a better optical match with upper incisor enamel.