Mandibulotomy fixation: a laboratory analysis.
OBJECTIVE
Mandibulotomy is an access osteotomy technique associated with significant complications. Critical evaluation of available fixation systems is required to aid in the selection of the most stable fixation method. This study was designed to provide data on the stability of traditionally used plating configurations and a low-profile 2.0-mm locking plate (mandibular locking plate, Synthes MLP; Synthes Maxillofacial, Paoli, PA).


METHODS
An in vitro red oak model was used to evaluate the stability provided by the study fixation devices. Five groups were studied as follows: group 1, two 4-hole 2.0-mm nonlocking miniplates; group 2, two 4-hole 2.0-mm mandibular locking plates; group 3, one 6-hole 2.0-mm mandibular locking plate; group 4, one 6-hole 2.4-mm nonlocking rigid plate; and group 5, control (uncut red oak blocks). Each specimen was tested with vertical loads applied over the osteotomy site. The force-versus-displacement behavior was recorded for each specimen and analyzed statistically.


RESULTS
Plate type and configuration affected the resistance to vertical peak load (kilogram/force [kgf]) and the fixation stiffness (kgf/mm). The greatest peak load (58.92 kgf) and stiffness (7.07 kgf/mm) was found with group 2 specimens. The differences in system stiffness were statistically significant (P <.05), as were the peak loads for groups 1, 2, and 3. The control group (nonosteotomized red oak) had markedly higher values of peak load and stiffness (484 kg and 83 kg/mm, respectively). Group 2 specimens exhibited increased resistance to flexion.


CONCLUSIONS
Two 2.0-mm locking plates provided the greatest resistance to vertical load.
Engroff
Stephen L
SL
Tri-County Oral-Facial Surgeons, 211 W. Beaver Avenue, State College, PA 16801, USA. engroff@tricountyoral.com
Blanchaert
Remy H
RH
von Fraunhofer
J Anthony
JA
D001696:Biomechanical Phenomena; D001860:Bone Plates; D004548:Elasticity; D004867:Equipment Design; D006801:Humans; D008334:Mandible / Q000601:surgery*; D008422:Materials Testing; D008953:Models, Anatomic; D010027:Osteotomy / Q000295:instrumentation*; D018583:Pliability; D029963:Quercus; D013314:Stress, Mechanical; D013499:Surface Properties; D016474:Weight-Bearing