[Investigation of reinforcement of the free enamel--the adhesive strength test and SEM observation by using the composite resin].

In this study, the purpose of which is to examine reinforcement of free enamel, we employed visible light-cured adhesive composite resins applied to the inner surface of free enamel and the enamel surface. An Autograph DCS-5000 was used to measure physical tensile shearing strength; a scanning electron microscope (SEM) was used to observe the fracture surface of the adhesive area between the enamel and the composite resin. Results 1. Adhesive strength on the inner surface of free enamel was about 20% lower than that of the enamel surface. Nonetheless, we judged the inner surface of free enamel to have adhesive strength. 2. SEM observation showed that breaking occurred at the boundary of the adhesive surface between the enamel and the bonding material. It is possible to expect a certain amount of reinforcement of free enamel from the use of composite resins.