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

Histologic and Histometric Analysis of Bone Repair at the Site of Mandibular Body Osteotomy and at the Bone-Screw Interface After Using a Biodegradable 2.0-mm Internal Fixation System

The aim of the study was to evaluate histologically and histometrically the bone repair at the mandibular body osteotomy and at the bone-screw interface after using a biodegradable 2.0-mm internal fixation system. Six dogs were subjected to an osteotomy in the mandibular body, which was stabilized by applying a fixation device manufactured with poly-L-DL-lactic acid (70:30). The dogs were euthanized at 2 and 18 weeks. Each screw was sectioned along its long axis, and the osteotomy sites were divided into 3 parts: the upper part was labeled the tension third (TT); the lower part, compression third (CT); and the part between the TT and CT, intermediary third (IT). Histologic analysis showed areas of direct contact between the screw surface and the parent lamellar bone at 2 weeks. At 18 weeks, 3 microscopically distinct layers at the bone-screw interface were noted. At the osteotomy sites, union between the bone fragments was observed at 18 weeks. Statistically significant differences in the newly formed bone among TT, IT, and CT (P = 0.019) were observed. In conclusion, the biomechanical environment created by the biodegradable IF system used in this study facilitated bone repair at the osteotomy site.

Comparative study of bone repair in mandibular body osteotomy between metallic and absorbable 2.0 mm internal fixation systems. Histological and histometric analysis in dogs: a pilot study

The objective of this study was to compare the bone repair along a mandibular body osteotomy stabilized with 2.0 mm absorbable and metallic systems. 12 male, adult mongrel dogs were divided into two groups (metallic and absorbable) and subjected to unilateral osteotomy between the mandibular third and fourth premolars, which was stabilized by applying two 4-hole plates. At 2 and 18 weeks, three dogs from each group were killed and the osteotomy sites were removed and divided equally into three parts: the upper part was labelled the tension third (TT), the lower part the compression third (CT), and the part between the TT and CT the intermediary third (IT). Regardless of the treatment system, union between the fragments was observed at 18 weeks and the CT showed more advanced stages of bone repair than the TT. Histometric analysis did not reveal any significant differences among the 3 parts or systems in the distance between bone fragments at 2 weeks. Although at 18 weeks the proportions of newly formed bone did not differ among TT, IT and CT, significantly enhanced bone formation was observed in all sections for the metallic group. The patterns of repair were distinct between treatments.

Release of metals from osteosynthesis implants as a method for identification: post-autopsy histopathological and ultrastructural forensic study

Metal structures--especially of stainless steel, titanium and their alloys (biomaterials)--are widely used in orthopaedic practice and the subject of constant study in bioengineering and preventive medicine. This study presents the first experience of forensic research into the presence of permanent tissue variations around metal implants in various bone structures for the purpose of identification, with particular reference to skeletal remains or severely decomposed corpses in the absence of other identifying elements. The evaluation was conducted on 12 corpses who had undergone osteosynthesis intra-vitam, whose implants were still in place or had been removed, in comparison with five controls who had never undergone osteosynthesis. Bone fragments taken during autopsy were subjected to histopathological and scanning electron microscope-energy dispersive electroscopy examination in order to reveal and characterise any metal particles originating from osteosynthesis. The study enabled the discovery of intra-bone metal particles in tissues treated by osteosynthesis even in bone areas where the implants had been removed and even where there were no longer any radiological signs of their application. These results are therefore of considerable forensic importance, especially in the area of identification, providing a valid means of recognition beyond that of the well-established use of in situ metal implants.