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
Purpose
To evaluate the bone–screw interface in a 2.0-mm miniplate system used for rigid internal fixation (RIF).
Materials and Methods
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.
Results
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.
Conclusion
The results suggested that in this model, osteotomy did not significantly alter bone repair adjacent to the screw surface.
⁎Graduate Student, Department of Oral and Maxillofacial Surgery and Periodontology, Faculty of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
†Assistant Professor, Division of Oral Histology, Faculty of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
‡Associate Professor, Department of Oral and Maxillofacial Surgery and Periodontology, Faculty of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
§Professor, Department of Oral and Maxillofacial Surgery and Periodontology, Faculty of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
∥Formerly, PhD Student, Department of Oral and Maxillofacial Surgery and Periodontology, Faculty of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil; Currently, Adjunct Professor, Ponticifal Catholic University of Parana, Parana, Curitiba, Brazil.
¶Associate Professor, Department of Oral and Maxillofacial Surgery and Periodontology, Faculty of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
Address correspondence and reprint requests to Dr Sverzut: Department of Oral and Maxillofacial Surgery and Periodontology, Faculty of Dentistry of Ribeirão Preto, University of São Paulo, Av do Cafe, s/n—Campus USP, 14040-904 Ribeirão Preto, SP, Brazil
This work was supported by The State of São Paulo Research Foundation (FAPESP grant 02/06855-3 for C.E.S.).
ABSTRACT