ABSTRACT
Objective: To determine the shear bond strength of different adhesive systems to superficial and deep dentin under simulated pulpal pressure. Methods: Occlusal surfaces of 72 sound extracted noncarious human molars were ground to obtain flat dentin surfaces(36 superficial and 36 deep dentin). Each dentin groups was randomly asssigned into 3 groups(n = 12): Clearfil SE Bond(SE), Clearfil S3 Bond(S3) and Prime&Bond NT(PB). All of samples were tested under simulated pulpal pressure. After bonding procedures with 3 adhesives respectively,all samples were covered with nail vanishi. The shear bond strength was tested after the samples stored for 24 h under simulated pulpal pressure. Results: The bond strength of PB to superficial and deep was (17. 11 ± 2. 71) and(11. 13 ± 3. 60) MPa(P ＜ 0. 05),that of SE (16. 53 ± 5. 29) and (14. 78 ± 4. 53) MPa(P＞ 0. 05),S3 (9. 08 ± 1. 74) and (8. 43 ± 1. 41) MPa(P＞ 0. 05). Conclusion: Bond strengths of phosphoric acid etching system decreases with an increase of dentin depth, that of two-step self-etch adhesive system is not affected by the depth.
ABSTRACT
Statement of problem: Limited research on flowable resin has been undertaken on its application directly on dentin associated with the adhesive systems. Purpose: This study was to evaluate the shear bond strength and fracture aspect of flowable resin on human dentin with various types of dentin bonding adhesives with thermocycling effect. Materials and methods: Filtek-Flow(3M ESPE, USA) was used as flowable resin and Eighty human molars were randomly divided into 4 groups : three dentin bonding adhesives (Scotchbond-Multipurpose: 3-step conventional system, One-Step: One-bottle system, Prompt L-Pop: All-in-one, self-etching primer) and 32% etching treatment without bonding adhesive as a control group. For evaluating their durability of bonding, each group was subdivided : storaging in the water at 37 degree C(24 hours) and thermocycling (0degree C-55degree C, 30 seconds intervals, 1000 cycle). Shear bond strength tests were performed and resin-dentin interface and fracture mode were observed. Results were analysed by one-way ANOVA and Scheffe's multiple range test. Results and Conclusion: 1. At 0 cycle, the mean shear bond strength of One-Step exhibited the highest value of all groups(p0.05). After 1000 thermocycling, One-Step exhibited higher value than other groups(p0.05). 2. The shear bond strength of each group was significantly decreased after thermocycling except Scotchbond-Multipurpose(p>0.05). 3. The most common failure mode was adhesive type and mixed type, next in order.