Morphological Evaluation of 2- and 1-step Self-etching System Interfaces with Dentin

Abstract

ßSUMMARYThis in vitro study evaluated the resin-dentin interface formed by two 2-step and two 1-step self-etching adhesive systems under SEM. Class V cavities (4 x 2.5 x 1.5 mm) were prepared on the buccal surfaces of 25 extracted intact human third molars using a carbide bur in a high-speed handpiece. Four self-etching systems with corresponding resins were used: two 2-step systems, AdheSE (Ivoclar Vivadent) and Contax (DMG Hamburg), one 1-step/2 components system Futurabond NR (Voco) and a 1-step/1 component adhesive G-Bond (GC Corp). An etch and rinse system, PQ Clear (Ultradent), was used as a control. The teeth were thermocycled (500 cycles, 5°/55°C, 30 seconds dwell time), and 2 sections were made longitudinally through the restorations with a low-speed diamond saw, producing approximately 1-mm wide samples. The samples were polished with silicon carbide paper of increasing grit (400-1000), demineralized (6N HCl, 30 seconds), deproteinized (2.5% NaOCl, 10 minutes), left to air dry for 24 hours in a desiccator under low vacuum pressure, gold sputtered and viewed under SEM (JEOL-JSM-6460LV). In the AdheSE, Contax and Futurabond NR specimens, resin tag penetration into the tubules and lateral tags could be seen. G-Bond showed different interface morphology, with a tight, thin continuous junction and almost no resin penetration into tubules. PQ Clear samples exhibited the highest number of resin tags with numerous lateral tags. A clearly defined hybrid layer was seen in the Contax and PQ Clear specimens. Investigated self-etching systems showed similar interfacial morphology with dentin, except for the 1 step/1 component adhesive G-Bond. The degree of demineralization and interaction with dentin correlated with the acidity of the selfetching primers/adhesives. Fewer resin tags were formed with self-etching primers/adhesives than with the etch and rinse system.

Effect of Surface Treatments and Different Adhesives on the Hybrid Layer Thickness of Non-carious Cervical Lesions

“…The degree of demineralization and interaction with dentin correlates with the acidity of self-etch adhesives, as observed in previous investigations. 10,11,17 In the current study, a moderate self-etch adhesive, Xeno III ( pH: 1.5), and a mild selfetch adhesive, Clearfil SE ( pH: 2.7), created similar hybrid layer thicknesses (p<0.05) ( Table 2). Xeno III created thin, infrequent resin tags in the gingival dentin of non-carious cervical lesions ( Figure 5).…”

Morphological evaluation of new total etching and self etching adhesive system interfaces with dentin

“…Radovic I, Vulicevic ZR, and Godoy GF also used 500 cycles, as it was based on the current ISO standard. [1] In the present study, 6N Hydrochloric acid was used for demineralization and 2.5% sodium hypochlorite for deproteinization. This ensured optimal exposure of the resin tags and hybrid layer and enabled viewing under the scanning electron microscope.…”

“…The intensity of the interaction of self-etching adhesive systems with dentin was mostly dependant on the acidity and aggressiveness of the primer used. [1]…”

In vitro bonding effectiveness of self-etch adhesives with different application techniques: A microleakage and scanning electron microscopic study

“…Minimal resin tag formation has been reported in one-step self-etch adhesives and resin tags are usually scant and thinner, indicating that most of the dentinal tubules remain obstructed by smear plugs, which is in contrast to etch and rinse adhesives. [3536] With the use of SEM, an excellent characterization of the ultramorphological interface is possible due to an enhanced resolution. However, polishing the restored disks followed by demineralization and deproteinization can induce artifacts.…”