Bone induction capacity of the periosteum and neonatal dura in the setting of the rat zygomatic arch fracture model.

Objectives: Osteogenic properties of the dura and periosteum are thought to contribute to the regenerative capacity of membranous bone tissue. The purpose of this investigation was to elucidate (1) whether dura without underlying neural tissues can induce osteogenesis, (2) to what extent the periosteum participates in membranous bone healing, and (3) the difference between dura-induced and periosteum-induced osteogenesis.

Methods: A standardized 2-mm defect was created within the middle portion of each zygomatic arch in 30 Wistar albino rats. The rats were divided into 3 groups, 10 animals in each group. In group 1, the periosteum was removed and neonatal dura grafts were transplanted onto the zygomatic arch bone defect circumferentially. In group 2, the overlying periosteum was preserved. In group 3, the periosteum was removed. At 3 and 10 weeks, animals from each group were killed, and specimens were obtained. Data were collected from the 3-dimensional computed tomographic scans and histologic studies to compare the extent of bony repair.

Results: Fracture sites demonstrated osteogenesis associated with chondrogenesis in groups 1 and 2 and only limited osteogenesis with no chondrogenesis in group 3. In some animals in group 3, cortical bone ends underwent resorption. In groups 1 and 2, bone defects were obliterated by the formation of the mature compact bone at 10 weeks postoperatively. The difference between bone regeneration in these groups was not significant (P =.16). In group 3, the defects failed to heal by bony union, and in most of the samples the fibrous union was observed instead. The difference between groups 1 and 3 was significant (P =.03). The difference between groups 2 and 3 was not significant (P =.09).

Conclusions: The trend toward significance is in agreement with the current clinical practice of preserving periosteum in the manipulations of the membranous bone defects. Newborn dura can exert a potentiating effect on osteogenesis.