| Objective1, Establishing a goat model of bilateral mandibular distraction osteogenesis for evaluating the effect of resorbable calcium sulphate material on early bony consolidation in distraction osteogenesis.2, To confirm whether calcium sulphate would affect the serum calcium concentration or not.MethodsEight goats were devided randomly into two groups: calcium sulfate group(A),control group(B). All animals underwent bilateral mandibular distraction osteogenesis then an internal distraction device was applied to the mandibular body after. In the calcium sulfate group, a total of 3 mm gap was distracted initially. The solidifiable,injectable calcium sulfate pasta were injected into this gap whereas the distracted bones in the control groups were closed up without any gap and intervention. After 5 days'latency period, distraction was commenced at a rate of 0.5 mm/12h for 7 days in the test group and 10 days in the control group. Serum alkaline phosphatase(S-ALP) and serum calcium concentration were measured before operation and at 3,6,9,11,14days after operation. All the animals were sacrificed 6 weeks after distraction. The appearance of the samples,radiological changes,bone mineral density,breaking load,undecalcified and decalcified histology were examined.ResultsAll animals recovered satisfactorily, and the distraction device was well tolerated fixed firmly. Clinical observation: When the hauling ended, all of the goats' mandible were forward prominent and the occlusions were disorder but with nomal foodintaking. In the control group, an animal's left surgery region has got slight infection but was cured with the helps of antibiotics and change of dressing. The remaining surgery regions grew well with no malunion as effusion,flare,disruption. The distracted gap of all mandibles were lengthened about 10±1mm successfully with new bone filled,consecutive periosteum. The lingual surface of all mandibles was smoother and harder than buccal. X-ray: All specimens showed progressive calcification of distracted area between mandibular segments and the bone cortex had coalesced completely. Radiodensity was lower in the control group and highest in the calcium sulfate group. There was no partially high radiodense of CS area in the distracted zone. Histological investigations: New bone was also generated from the edges to the center of the distracted zone in both group. The amount of new bone formation in group A was slightly greater than that in group B. An large abundance of osteoblasts with woven bone was seen in group A and with no CS remaining.Serum alkaline phosphatase and serum calcium concentration tests: Both group's serum alkaline phosphatase increased with different extents, and the test group increased more significantly than the control group (P <0.05). But there was no statistical difference between group A and group B with regard to the serum calcium concentration. Bone Mineral Density: The BMD values were higher in the group A than group B with a statistical significance of P<0.05. Biomechanical test:Three-point bending test showed that the breaking load values in the test group (279±24.3N) were higher than the control group (234±11.7N) with a statistical significance of P<0.05. Histomorphometric analysis:Statistical analysis of the percentage of new bone trabeculae area in the distraction gap revealed that a greater amount of new bone was observed in group A compared with the group B(P<0.05).ConclusionsThe application of solidifiable,injectable calcium sulfate could facilitate early bony consolidation, and the applying resorbable calcium sulphate on local scale have little effect on impacting the serum calcium concentration. |
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