The purpose of this study was to investigate the effect of calcium hydroxide on dentin bonding strength of various dentin bonding systems as a function of time in composite resin restoration.

Dentin adhesives used in this study were Scotchbond Multipurpose, Single Bond, SE Bond and Prompt L-Pop. Flat dentin surfaces adjacent to pulp chamber were created, then Ca(OH)₂ and saline were mixed and applied on dentin surface of experimental group, then IRM was used to cover the mixture on dentin surface and the specimens were stored at 36.5℃ for experiment period (7 days, 30 days). After removing IRM and Ca(OH)₂, each dentin adhesives were treated on dentin surfaces.

Composite resin (Z-250, 3M) was placed with 5 mm height and was light-cured for 20 seconds. After stored in distilled water for 24 hours, each dentin-composite bonded spicemen was embedded in epoxy resin and sectioned into 1.0 × 1.0 mm² cross section composite-dentin beams. Specimen was mounted on zig of Universal testing machine and µTBS test was performed. SEM analysis was performed to examine the fractured surfaces.

The results suggested that applying calcium hydroxide did not show significant difference in dentin bonding strength.