Histological and Histomorphometric Analysis of the Bone–Screw Interface in the Mandibular Body After Using a 2.0-mm Miniplate System: An Experimental Study in Dogs

Abstract

To evaluate the bone-screw interface in a 2.0-mm miniplate system used for rigid internal fixation (RIF). Nine adult mongrel dogs were subjected to unilateral continuous defect through an osteotomy between the lower third and fourth premolars. The control contralateral side remained untreated. Two 4-hole miniplates were placed bilaterally according to the Arbeitgeimeinschaft für Osteosynthesefragen manual. Miniplates adapted to the alveolar processes were fixed monocortically with 6.0-mm-long titanium alloy screws, whereas miniplates placed near the mandible base were fixed bicortically. At 2, 6, and 12 weeks, mandible segments enclosing the RIF were removed, fixed in formalin, ground-sectioned, and stained with toluidine blue. Under conventional light microscopy, proportions of bone-to-screw contact (BSC) were determined, and data were compared by analysis of variance. At 2 weeks, for both groups, the area between threads exhibited necrotic bone with multiple cracks and absence of bone cells and blood vessels. At 6 and 12 weeks, new Haversian systems progressively replaced necrotic bone. At each time point, no significant differences were seen between screws placed in the same miniplate or between groups. The proportions of BSC were statistically similar at 2 and 6 weeks and lower at 12 weeks. The results suggested that in this model, osteotomy did not significantly alter bone repair adjacent to the screw surface.