J. Yamashita et al., A COMPARISON OF IN-VIVO AND IN-VITRO STRAIN WITH POSTERIOR FIXED PARTIAL DENTURES, The Journal of prosthetic dentistry, 77(3), 1997, pp. 250-255
Purpose. Deformation of fixed partial dentures during function has bee
n related to clinical failures. However, such deformation has not been
measured quantitatively, and the effect on deformation of the viscoel
astic behavior of peridental structures is not well understood. The pu
rpose of this study was to determine the strain distribution of fixed
partial dentures during function and to compare the biomechanical beha
vior of fixed partial dentures in vivo and in vitro. Material and meth
ods. Three conventional posterior fixed partial dentures and two compl
ete crowns were fabricated. Both in vivo and in vitro strain measureme
nts of each of the five prostheses were recorded by a strain gauge met
hod. A static load was produced through occlusal force in vivo and wit
h a universal testing machine in vitro. Results. The resulting differe
nce between the strain distribution for the two crowns in vivo and in
vitro was negligible, but the whole fixed partial denture demonstrated
a substantial amount of strain in vivo. Conclusions. The results of t
his study suggest that serious problems with strain may occur in a lon
g-span mandibular posterior fixed partial denture.