A comparison of in vivo and in vitro strain with posterior fixed partial dentures.
OBJECTIVE
Deformation of fixed partial dentures during function has been related to clinical failures. However, such deformation has not been measured quantitatively, and the effect on deformation of the viscoelastic behavior of peridental structures is not well understood. The purpose of this study was to determine the strain distribution of fixed partial dentures during function and to compare the biomechanical behavior of fixed partial dentures in vivo and in vitro.


METHODS
Three conventional posterior fixed partial dentures and two complete crowns were fabricated. Both in vivo and in vitro strain measurements of each of the five prostheses were recorded by a strain gauge method. A static load was produced through occlusal force in vivo and with a universal testing machine in vitro.


RESULTS
The resulting difference 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 this study suggest that serious problems with strain may occur in a long-span mandibular posterior fixed partial denture.
Yamashita
J
J
Tokyo Medical and Dental University, Faculty of Dentistry, Japan.
Shiozawa
I
I
Takakuda
K
K
D000328:Adult; D000368:Aged; D001641:Bicuspid; D001732:Bite Force; D003442:Crowns; D000044:Dental Abutments; D003799:Dental Stress Analysis; D003830:Denture, Partial, Fixed; D005260:Female; D006047:Gold Alloys; D006801:Humans; D008297:Male; D008334:Mandible; D008875:Middle Aged; D008963:Molar
D006047:Gold Alloys