Influence of a Simulated Oral Environment on Dentin Bond Strength of Two Adhesive Systems

Purpose: To evaluate in vitro the influence of different clinical conditions (temperature, relative humidity) on dentin bond strength.

Materials And Methods: Two different bonding systems were studied, ScotchBond Multi-Purpose Plus (SBMP) and Clearfil SE Bond (SE Bond). In the first part of the study, the different environmental conditions were: ambient conditions, i.e. 20 degrees C/30% relative humidity (RH), 30 degrees C/50% RH, 30 degrees C/65% RH, 33 degrees C/80% RH and 35 degrees C/95% RH. In the second part, the different interfaces (dentin/primer, primer/adhesive and adhesive/composite for SBMP and primer/adhesive, adhesive/composite for SE Bond) were also studied in order to explain the results obtained in the first part of the study. After the bonding procedure, a composite cylinder (Z100) was bonded to the surface using a Teflon mold (diameter: 3 mm/height: 5 mm). The different specimens were tested in a shear bond mode after a 24-hour storage in distilled water at 37 degrees C.

Results: For SBMP, the shear bond strengths decreased when temperature/RH increased. The average values were very low when the 35 degrees C/95% RH conditions were simulated. A study of the interfaces showed that the primer/adhesive interface was the most sensitive to the environmental conditions simulated. For SE Bond, a decrease occurred but only at the highest temperature/humidity conditions. The interface study did not provide an explanation of the results obtained in the first part of the study.