Histological evaluation of three-dimensional rectangular grid plates in treatment of mandibular fractures: an experimental study

AIM OF THE WORK: Evaluate the efficacy of 3D rectangular grid plates in treatment of mandibular fractures in comparison to the more commonly used locking plates. SUBJECTS AND METHODS: This experimental study was conducted on sixteen mature male Mongrel dogs (ranged from 1-2 years old), weighting about 15-20 kg each. A linear fracture was done using surgical sagittal saw with aid of mallet and chisel in the right side of the mandible in the premolar molar area for each animal of the study under general anesthesia. The animals were divided into two groups: Group A was fixated with 3D rectangular grid plate and six 7 mm monocortical screws and Group B was fixated with two locking plates; the inferior plates fixated with 11 mm bicortical screws and the superior one fixated with 7 mm monocortical screws. The bone formation and remodeling is assessed using histomorphometric analysis of bone biopsy. RESULTS: Group A subjects showed significantly less bone formation than group B (26.78±4.3 vs 48.4±10.3 respectively in postoperative week 4 P<0.005 and 28.119±10.507 vs 51.109±11.348 respectively in postoperative week 12 P<0.005). The surface area of the fracture was also significantly lower in group A than in group B (0.317 ± 0.065 vs 0.485 ± 0.105 respectively in postoperative week 4 P<0.005 and 0.287 ± 0.105 vs 0.511 ± 0.115 respectively in postoperative week 12 P<0.005). CONCLUSIONS: Fixation with 3D rectangular grid plates demonstrated a bone healing pattern characterized by closer fracture segment approximation and reduced callus formation, consistent with primary bone healing, as evidenced by histological and histomorphometric analysis, compared with locking plates.