Relative efficiencies of various wiring configurations commonly used in open reductions of fractures of the angle of the mandible.
Many fractures of the angle of the mandible require direct intraosseous fixation in addition to intermaxillary fixation. In the past, various configurations of intraosseous wiring were used both at the lower and upper borders of the mandible. This study investigated which of four configurations offers the greatest mechanical resistance to a typical displacing force. Twelve baboon mandibles were cleared of all soft tissues and sectioned in the midline, and the most distal erupted molar tooth was extracted. Jigs were constructed to ensure that each mandible was sectioned in a standard fashion and that holes for wiring were drilled at a standard distance from the cut line. Mandibular halves, wired under standard conditions, were placed in an Instron tensile testing machine and subjected to a constant force that simulated the action of the major elevator muscles. Graphic recordings of force versus displacement were made. The results were subjected to an analysis of covariance, and to Scheffe's test for multiple comparisons. Results indicate that under experimental conditions, without jagged fracture surfaces, upper border mandibular wiring is less efficient than lower border wiring. At the lower border, a figure-of-eight wire is more effective than a combination figure-of-eight and straight wire, and at the upper border, the figure-of-eight wire is more effective than the straight wire.
Fisher
I T
IT
Department of Maxillo-facial and Oral Surgery, University of Witwatersrand, Johannesburg, Republic of South Africa.
Cleaton-Jones
P E
PE
Lownie
J F
JF
D000818:Animals; D001864:Bone Wires; D003799:Dental Stress Analysis; D004526:Efficiency; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D008337:Mandibular Fractures / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D008410:Masticatory Muscles / Q000502:physiology; D008422:Materials Testing; D009984:Orthopedic Fixation Devices; D010215:Papio; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength