The effect of load cycling on nanoleakage of deproteinized resin/dentin interfaces as a function of time

• Published in: Dental materials 2008-07, Vol.24 (7), p.867-873
• Main Authors: Yamazaki, Paula C.V, Bedran-Russo, Ana Karina B, Pereira, Patricia N.R
• Format: Article
• Language: English
• Subjects: Acid Etching, Dental - methods; Advanced Basic Science; Animals; Bisphenol A-Glycidyl Methacrylate - chemistry; Cattle; Collagen - ultrastructure; Composite Resins - chemistry; Dental Leakage - classification; Dentin - ultrastructure; Dentin-Bonding Agents - chemistry; Dentistry; Materials Testing; Mechanical cyclic loading; Methacrylates - chemistry; Microscopy, Electron, Scanning; Nanoleakage; Oxidants - chemistry; Random Allocation; Resin Cements - chemistry; SEM; Silver Staining; Sodium hypochlorite; Sodium Hypochlorite - chemistry; Stress, Mechanical; Surface Properties; Temperature; Time Factors; Water - chemistry
• ISSN: 0109-5641; 1879-0097
• DOI: 10.1016/j.dental.2007.11.005

Abstract Objectives To evaluate the effects of cyclic loading on nanoleakage as a function of time at resin–dentin interfaces with and without removal of collagen. Methods Bovine flat mid-coronal dentin received one of the following surface treatments: (1) acid-etch or (2) acid etched + 5% NaOCl for 2 m. The teeth were then bonded with Single Bond (3M ESPE), Scotchbond Multi-Purpose (3M ESPE), One-Step Plus (Bisco) or All-Bond 2 (Bisco) adhesive systems and restored with Z250 composite. Half of the bonded teeth were randomly assigned to receive 200,000 cycles of loading at 50 N. Teeth were sectioned into 1 mm × 1 mm thick slices and stored in distilled water for 24 h and 6 months. After water storage, beams were prepared for nanoleakage evaluation and observed under the SEM. Data were statistically analyzed using three-way ANOVA and Fisher's PLSD test ( p < 0.05). Results Use of NaOCl did not affect nanoleakage at the interface of all adhesive systems ( p > 0.05) when compared to their respective controls. After 6 months of immersion in water, except for One Step Plus, collagen-depleted groups and control groups presented similar leakage values. After cyclic loading, the deproteinized group revealed a higher degree of silver nitrate deposits when compared to the control group ( p < 0.05). All four adhesive systems presented a high degree of silver nitrate deposits after 6 months of water storage. Significance The hybrid layer is important as a stress-absorbing layer and it may not represent the weak link for initiation of the nanoleakage phenomenon.