SEM Analysis and Chemical Optimizing Dentin Bonding in Deep Margin Elevation Procedures with Chemical Surface Conditioning and Decoupling Techniques

This research aimed to evaluate the impact of various methods for preparing dentin surfaces on the micro-shear bond strength of a three-step etch-and-rinse adhesive system, particularly in relation to Deep Margin Elevation (DME) procedures. An experimental, laboratory-based study was conducted using ۱۰۸ caries-free and crack-free human third molars. The tooth crowns were sectioned below the cementoenamel junction, and the samples were randomly divided into six groups (n=۱۸). The dentin surface preparation methods included sandblasting, acid etching, and a combination of sandblasting and acid etching. Additionally, half of the groups underwent a Decoupling with Time (DWT) protocol after adhesive curing. The Optibond FL three-step etch-and-rinse adhesive system and composite resin were utilized across all groups. Micro-shear bond strength was assessed, and the fractured surfaces were analyzed using scanning electron microscopy (SEM). The sandblasting with DWT group recorded the highest mean micro-shear bond strength, whereas the acid etching group showed the lowest. SEM findings revealed that sandblasting effectively removed the smear layer, exposed dentin tubules, and increased surface roughness, thereby improving the micromechanical interlocking between the adhesive and the dentin. The combination of sandblasting and acid etching created a favorable surface topography with exposed dentin tubules and a microporous inter-tubular dentin structure. For the use of fourth-generation adhesives, such as Optibond FL, on deep dentin in DME procedures, dentin preparation with sandblasting was more effective than ۳۷% phosphoric acid etching. Additionally, observing the DWT protocol after adhesive curing increased the bond strength to dentin.

کلیدواژه ها:

Dentin preparation ، Bond strength ، total etching adhesive ، Micro-shear ، Scanning Electron Microscopy (SEM)