Effect of C-factor on Bond Strength to Cavity Wall

Abstract

The purpose of this study was to evaluate the effect of C-factor on a resin-composite bond strength to a Class I cavity wall using three adhesive systems. Box-form occlusal cavities, 3mm wide, 5mm long, 2mm deep (C-factor=3.1), were prepared on flat dentin surfaces of human molars. For controls walls of cavities were removed in order to make flat dentin walls for bonding (C-factor=0.2). Each specimen was restored with one of three adhesives: Clearfil Mega Bond (Kuraray Medical), Single Bond (3M ESPE) or Clearfil Tri-S Bond (Kuraray Medical); followed by bulk filling or build up using Z100 resin composite (3M ESPE). After 600mW/cm² light-curing for 40s, specimens were stored in water maintained at 37 degrees centigrade for 24 hours under the dark condition. A specimen was cut parallel to cavity floor obtaining beams having bonding area of approximately 1mm². Control specimens were also cut obtaining beams. The micro-tensile bond strength (μ-TBS, MPa) was determined for flat dentin and cavity wall specimen. Data (n=9) were analyzed using Bonferroni test. Clearfil Mega Bond, Single Bond and Clearfil Tri-S Bond showed significantly lower μ-TBS to the cavity wall compared with the flat wall dentin group (p<0.05). Bonding to Class I cavity wall was affected by C-factor.