Rigid fixation and strain patterns in the pig zygomatic arch and suture

• Published in: Journal of oral and maxillofacial surgery Vol. 55; no. 5; pp. 496 - 504
• Main Authors: Freeman, John A, Teng, Shengyi, Herring, Susan W
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.05.1997
• Subjects: Animals; Bite Force; Bone Plates; Cranial Sutures - physiology; Cranial Sutures - surgery; Dentistry; Electromyography; Female; Immobilization - physiology; Mastication; Masticatory Muscles - physiology; Stress, Mechanical; Swine; Swine, Miniature; Temporal Bone - physiology; Temporal Bone - surgery; Zygoma - physiology; Zygoma - surgery
• ISSN: 0278-2391; 1531-5053
• DOI: 10.1016/S0278-2391(97)90701-1

Purpose: In orthognathic surgery, rigid fixation is routinely used to hold together bone fragments that may experience heavy forces from attached masticatory muscles. Internal fixation plates are assumed to hold bony parts rigidly, but the mobility at such sites subjected to normal masticatory function has not been measured. The purpose of this study was to investigate in vivo the degree to which a linear plate immobilizes separated bones, specifically sutures. Materials and Methods: Three female miniature pigs (Sus scrofa) had 1.3-mm Synthes titanium plates placed across the suture in the zygomatic arch. Foil strain gauges were used to record load deformation in the zygomatic and squamosal (temporal) bones and across the vertical and horizontal parts of the suture. Strain was recorded in vivo during mastication and in anesthetized pigs with electrical stimulation of masticatory muscles. Results: Strain at the suture was not reduced from normal levels. The plate induced increases in strain within the bones, but the changes were slight. Conclusion: The results indicate that linear “rigid fixation” does not immobilize sutures.