This study aims to demonstrate the effect of dental explorer on demineralized enamel. Bovine teeth were divided perpedinculary towards their long axis. Each section were provided with 2 grooves, parallels to the teeth's axis. These sections were exposed to an acid solution for 7 days. After this period just one of the grooves of each section was probed ahd then, the demineralization was continued for one more wee. Then we could compare the lesions depths of demineralization of the probed grooves and the non probed grooves. The probed grooves presented an increased lost of enamel structure, more than the non probed grooves. It was concluded that the careless use of dental explorer on diagnosis of fissures caries cause mechanical damage to enamel already softened as a result of a carious attack.