The purpose of this study is to monitor structural response in intact teeth and teeth with structural loss using a noninvasive fiber optic microbend (FOMB) sensor. In this study a miniature fiber optic microbend sensor is fabricated and tested on intact tooth specimens, tooth specimens in which one-third crown structure was removed, tooth specimens in which access cavity was prepared and tooth specimens in which access cavity and root canal were prepared. The microbend sensor displayed a direct relationship between the applied load and the output light intensity. The rate of change in light intensity with increase in loads corresponded with the structural response of the tooth. This experiment highlights the potential of FOMB sensor technology to quantitatively monitor tooth structural loss during post endodontic restorations.