Bilateral mandibular distraction in adult dogs with an epiperiosteal distractor.

We tested the function and efficiency of a new intraoral, bone-borne distraction device for mandibular lengthening, and the effect of bilateral transsection of the inferior alveolar arteries on osteogenesis in adult dogs. Nine adult Beagles had bilateral complete mandibular osteotomies and epiperiosteal placement of the distractor. After 7 days, the mandibles were distracted at 1 x 1mm/day, 1 x 0.5 mm/day or 2 x 0.25 mm/day for 15 or 30 days, respectively. Hemimandibles were harvested after 1, 14, or 42 days consolidation and evaluated clinically, radiographically and histologically. The mean distraction achieved was 11 mm (range 4-16 mm). New bone formation and clinical stability increased with increasing consolidation time and was independent of the distraction protocol used. Osteogenesis at the distal and proximal mandibular fragments did not differ. In 10/18 distraction sites, wound dehiscences compromised osteogenesis. The new epiperiosteal distractor permitted successful distraction osteogenesis despite complete bilateral osteotomy with section of the medullary vessels in adult dogs.

Effects of isoflurane, enflurane, and halothane on skeletal muscle microcirculation in the endotoxemic rat.

PURPOSE: The cardiovascular effects of volatile anesthetics during sepsis sets patients at high risk for hemodynamic deterioration. We compared the microcirculatory alterations in skeletal muscle under anesthesia with isoflurane, enflurane, and halothane in an endotoxemic rat preparation. MATERIALS AND METHODS: Twenty-one Sprague-Dawley rats under continuous hemodynamic monitoring and intravital microscopy of the spinotrapezius muscle were studied during two level lipopolysaccharide (0.2 mg/kg and 2 mg/kg) induced sepsis. The effects of equianesthetic concentrations (1.5 minimum alveolar concentration [MAC]) of either isoflurane [n:7], enflurane [n:7], or halothane [n:7] on microcirculatory vasoregulation were measured and histopathologic changes were evaluated. RESULTS: During low-dose endotoxemia, arteriolar vasodilation under isoflurane was nearly abolished (P < .05). At high-dose endotoxemia, this lack of vasodilatory effect was similar (P < .05). Animals receiving 1.5 MAC of enflurane during low-dose endotoxin presented a significant decrease in arteriolar diameter by -11.3 (+/-2.9%), this response was less during high-dose endotoxemia (-7.0, +/-2.9%). Halothane caused pronounced vasoconstriction by -20 (+/-3.7%) during low-dose endotoxemia and moderate but significant constriction during high-dose endotoxemia (-7.9, +/-2.6%). CONCLUSIONS: Isoflurane, enflurane, and halothane exert significantly different effects on vasoregulation of skeletal muscle arterioles in the endotoxemic rat.

[Effect of bFGF on regeneration of distracted mandibles after radiation]. / Einfluss von bFGF auf die Regeneration von distrahierten Unterkiefern nach Radiatio.

The potential of distraction osteogenesis in mandibular reconstruction has been limited by its questionable efficacy in previously irradiated bone. The possible osteogenetic effect of recombinant human basic fibroblast growth factor (bFGF) on lengthening of irradiated mandibles was investigated in beagle dogs. We studied nine adult dogs which underwent a full course of external beam radiation therapy (60 Gy/30 fractions). Six months after completion of radiotherapy, the molars were extracted bilaterally followed by bone lengthening of the mandible using an intraoral device. On postoperative day 3 and 7 we injected 10 micrograms bFGF into the osteotomy site of each right hemimandible. The left sides were used as controls. The time course in ossification of the distracted area was evaluated at 2, 4, and 6 weeks after completion of bone lengthening. The radiographs of the newly formed bone tissue were measured by digital image analysis. Corresponding to the radiographic findings, the histological examination of the removed jaws showed an earlier and more intensive bone formation in the treated side after 2, 4, and 6 weeks compared to the control side. We conclude that bFGF promotes the ossification of distracted mandibles after radiation therapy in dogs.