Correlation of bond strength with surface roughness using a new roughness measurement technique

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Surface Science

Background:

• Dental restorations often involve bonding resin composites to amalgam.
• Surface characteristics of the substrate significantly influence the bond strength of dental materials.
• Accurate measurement of surface roughness is crucial for understanding bonding mechanisms.

Purpose of the Study:

• To investigate the correlation between shear bond strength and surface roughness of set amalgam.
• To evaluate the impact of different measurement directions of surface roughness on this correlation.
• To compare the bond strength of PENTA-containing and PENTA-free adhesive systems to amalgam.

Main Methods:

• Set amalgam surfaces were mechanically roughened using abrasive papers (80 and 600 grit).
• Surface roughness parameters (Ra, true profile length) were measured parallel and perpendicular to polishing scratches.
• Shear bond strength was determined at the bonding agent/amalgam interface using a knife-edge test.

Main Results:

• The correlation between bond strength and surface roughness was significantly higher when roughness was measured parallel to polishing scratches.
• Measurements perpendicular to polishing scratches showed a significantly lower correlation.
• No significant difference in shear bond strength was observed between PENTA-containing and PENTA-free adhesive systems.

Conclusions:

• Shear bond strength of resin composite to amalgam is significantly correlated with surface roughness measured parallel to polishing scratches.
• The conventional measurement of surface roughness perpendicular to scratches yields a weaker correlation.
• The direction of surface roughness measurement is critical for predicting bond strength in dental applications.