ABSTRACT
Objective To observe the effect of hyperbaric oxygen therapy (HBOT) on mineral density and biomechanics of new-formed bone in distraction gap.Methods The mandibles were subjected to osteotomy and distractors were placed bilaterly in 30 rabbits,which were divided randomly into 2 groups.After 5 days for latency,the mandibles were distracted at a rate of 0.8 mm/day for 10 days,and then for consolidation.After surgery,group A received HBOT with daily distraction,whereas group B only distracted without HBOT served as control group.The animals in groups A and B were sacrificed 1 wk,2 wk,4 wk of consolidation,respectively.The mandibles were harvested and subjected to examination for new bone formation,and bone mineral density (BMD) and biomechanics of newly formed bone in the distraction gap.Results At one week of consolidation,no significant differences were observed between the BMD of newly formed bone in the two groups (P＞0.05);however,at the other time points,BMD of newly formed bone in group A was significantly higher than that in group B (P＜0.05).Moreover,at 4 weeks of consolidation,the strength,maximum fragile energy and modulus of elasticity of newly formed bone in group A were significantly higher than those in group B (P＜0.05).Conclusions The results suggest that HBOT improves mineral density and strength of new formed bone in distraction gap.
ABSTRACT
Objective To explore the effect of elastic outside distraction on microvessel density and to illustrate the mechanism correcting inverted nipples. Methods Three female 3-month-old minipigs,with 12 nipples each,were employed.4 nipples of each minipig were remained without distraction were control group,and the other 8 nipples were continuously distracted with inverted nipple correction instruments.Corresponding nipples were excised at 2,4,8 and 12 weeks after traction.The excised nipple specimens were employed with immunohistochemical staining to detect the expression of vascular endothelial cells growth factor (VEGF) and CD34 in those tissues,and the percentageof positive cells and microvessel density (MVD) changes were counted.Results The expression of CD34 and VEGF in the experimental groups increased at 2 weeks after tracted,and reached at the peak at 4 weeks,then gradually decreased during 8 to 12 weeks after tracted.While those were weakly positive in control group.Compared with the control group,the integral optical density of VEGF-positive cells and MVD were significantly different (P＜0.01),and there was a significantly positive correlation between MVD and VEGF.Conclusions Continuous elastic outside distraction can promote the expression of VEGF and CD34 in female minipig nipple and enhance angiogenesis,which increases oxygen supply locally,and therefore those local tissue proliferation may be one of key mechanisms of correcting the inverted nipple by continuous elastic outside distraction.
ABSTRACT
ObjectiveTo observe the effect of continuous elastic outside distraction on female minipig nipples and their supporting tissues,and to investigate its mechanism to correct inverted nipples.MethodsThree female 3-month-old minipigs with 12 nipples were employed.4 nipples of each minipig were remained without distraction as control group,and the other 8 nipples were continuously distracted with inverted nipple correction instruments.Corresponding nipples were excised at 2,4,8 and 12 weeks after traction.Before excision,the diameters and heights of nipples were measured with a vernier caliper.Then the excised nipple specimens were employed for HE staining to observe the change of their tissue structure and the number counting of capillaries.ResultsThe volumes of nipples all obviously increased after traction,as compared with control group,and diameters and heights of nipples were significantly different (P＜0.01).In addition,there was a trend that nipple height increased with traction time.Under light microscope,the traction group showed that epidermis thickened,basal cells,fibroblasts and capillary significantly proliferated.Capillary counts compared with the control group were significantly different (P＜0.01).ConclusionsContinuous elastic outside distraction can promote the proliferation of female minipig nipple and areola papillaris.