Bonding to root canal: structural characteristics of the substrate

Area of Science:

• Endodontics
• Dental Materials Science
• Scanning Electron Microscopy

Background:

• Root canal treatment requires effective adhesion of restorative materials.
• Dentin morphology, including tubule density and orientation, influences bonding effectiveness.
• Acid etching is a common method to improve dentin surface area for bonding.

Purpose of the Study:

• To investigate in vitro the dentin morphology within root canals.
• To evaluate tubule orientation, density, and surface area increase post-etching.
• To assess hybrid layer formation and resin tag characteristics.

Main Methods:

• Thirty anterior teeth were divided into three groups.
• Scanning Electron Microscopy (SEM) was used for morphological analysis.
• Teeth were etched with 32% phosphoric acid, with some receiving a bonding system and fiber post luting.

Main Results:

• Tubule density and orientation showed significant variability within root canal sections.
• Dentin surface area increased by 202% (coronal), 156% (middle), and 113% (apical) after etching.
• Hybrid layer thickness correlated with tubule density; thinner layers formed in areas with lower density.

Conclusions:

• Acid etching enhances dentin surface area for improved bonding in root canals.
• Variability in tubule morphology affects hybrid layer formation and potentially bond strength.
• Optimizing etching protocols may be necessary for consistent bonding outcomes across root canal regions.