Comparative study of the mechanical resistance of 2 separate plates and 2 overlaid plates used in the fixation of the mandibular condyle: an in vitro study.
OBJECTIVE
The objective of this study was to carry out a comparative evaluation of the mechanical resistance of 2 rigid internal fixation techniques for fractures of the mandibular condyle using miniplates.


METHODS
Forty polyurethane resin replicas of human hemimandibles were used. The hemimandibles were sectioned to simulate a high subcondylar fracture and then stabilized with 2 fixing techniques using 2.0-mm system plates and screws. The fixation techniques were 2 separate 4-hole plates with 8 screws, and 2 overlaid 4-hole plates with 4 screws. Each system was submitted to load tests, with the application of the load in mediolateral and anteroposterior directions in an Instron 4411 universal assay machine (Instron, Norwood, MA).


RESULTS
Load values and peak displacement were measured. Means and standard deviations were evaluated by analysis of variance (P < .05) and Tukey tests, in which it was verified that the antero-posterior peak load value was affected by the arrangement of the plates on the models, although no differences were observed between the groups for the mediolateral peak load. The arrangement of the plates did not have any influence on peak displacement. Similarly, the final value of the mediolateral load was not affected by the arrangement of the plates on the model.


CONCLUSIONS
The experimental model with 2 separate plates was statistically superior to the model with 2 overlaid plates only in relation to anteroposterior peak load. Despite showing superiority in mediolateral peak load and peak displacement, there was no statistical difference between the groups for these parameters.
Gealh
Walter Cristiano
WC
MSc Student, Dental School, State University of Sao Paulo (Julio de Mesouita Filho) UNESP-Arasatuba, Campo Mourão, Paraná, Brazil. waltergealh@gmail.com
Costa
Julyano Vieira
JV
Ferreira
Geovane Miranda
GM
Iwaki Filho
Liogi
L
D001696:Biomechanical Phenomena; D001860:Bone Plates; D001863:Bone Screws; D003799:Dental Stress Analysis / Q000295:instrumentation; D004867:Equipment Design; D004868:Equipment Failure; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D006801:Humans; D008335:Mandibular Condyle / Q000293:injuries* / Q000601:surgery; D008337:Mandibular Fractures / Q000601:surgery*; D008422:Materials Testing; D008953:Models, Anatomic; D011140:Polyurethanes / Q000737:chemistry; D013314:Stress, Mechanical
D011140:Polyurethanes