Abstract
Acid-etched enamel can be damaged by careless instrumentation during the application of bonding agents. In such a case, the adhesive strength of the resultant bonding agent may be impaired to a considerable degree, resulting in an unfavorable marginal integrity. The effects of applied pressure to the acid-etched enamel on the adhesive strength of the bonding agent were examined microstructurally. The influence of pressure was marked. For example, when a sponge pellet was used to apply the pressure, an adhesive strength of ca. 190kg/cm2 resulted following the applied pressure of 0.01-0.03g. However, it decreased to ca, 100 and 50kg/cm2 when the applied pressure was 2-3g and 7-10g, respectively. Therefore, the bonding agent should be applied as carefully as possible.