In order to find out the causes that produce failures in restorative therapy with inlays, in our survey we mainly concentrated upon the way in which the tensions generated by functional efforts are transmitted to the dental structures. Our operating method consisted in conceiving a mathematic method, represented by the necessity of experimenting in vitro the efforts of dental periodontal tissues that were exposed to a mechanical effort. Our conclusions demonstrate that the nature of the coronarian restorative material influences the biomechanics behavior of the dental tissues and, consequently, the durability in time of inlays. The way in which these structures respond to functional efforts will influence the stress induced by the surrounding structures.