改良猪小肠黏膜下层可吸收膜在兔下颌骨缺损早期愈合中的作用

目的:建立两种尺寸兔下颌骨骨缺损模型,研究改良猪小肠黏膜下层(small intestinal submucosa,SIS)可吸收膜在骨缺损早期愈合中的屏障作用。方法:将12只新西兰大白兔随机分组,于双侧下颌骨各制备一个深度均为2 mm、直径为5 mm或8 mm的A、B两种圆形骨缺损,并分别给予以下处理:覆盖SIS膜(简称S)、覆盖Bio-Gide膜(简称G)和不做任何处理(简称O), 得到AS、AG、AO、BS、BG和BO共6组(n=4)24个样本。术后4周取材,进行大体、微型CT(Micro-CT)和组织学观察,采用单因素方差分析法对数据进行统计学分析,评估各组骨缺损早期愈合的情况。结果:大体标本观察显示术后4周SIS膜完整,未见明显降解,Bio-Gide不完整,与周围组织融合;AS、BS和AG三组中屏障膜均平整覆盖于骨面,下方骨质较硬,BG组Bio-Gide向中央凹陷,下方骨质相对松软;AO、BO两组骨面明显凹陷,有大量纤维结缔组织。Micro-CT三维重建图显示,AS、BS、AG和BG四组均可见大量新生骨小梁,BG组中央凹陷区新生骨小梁稀疏,AO、BO组仅在缺损底部有少量新生骨小梁。Micro-CT定量结果显示,AS组骨体积分数(new bone percentage,BV/TV)(39.10%±0.79%)和骨密度(bone mineralized density,BMD)(517.73±11.22) mg/cm ³]显著高于AO组26.67%±1.12%,(319.81±8.00) mg/cm ³,P<0.05],但与AG组38.15%±0.91%,(518.65±7.48) mg/cm ³]差异无统计学意义(P>0.05)。BS组BV/TV(34.90%±1.35%)和BMD(409.09±8.14) mg/cm ³]显著高于BO组23.63%±2.07%,(171.00±16.24) mg/cm ³,P<0.05],但与BG组33.40%±1.06%,(412.70±8.6) mg/cm ³]差异无统计学意义(P>0.05)。组织学观察显示,AO和BO组有大量脂肪空泡,仅有少许散在新生骨组织,相对稀疏,未形成岛状,与天然骨组织界限清楚。AS和AG两组可见大量新生骨组织形成,骨小梁呈岛状,表面衬有成排的成骨细胞,可见血管形成,与周围自体骨组织界限不清。BS和BG组也可见大量新生骨组织,但较AS、AG组稀疏,与周围自体骨组织界限清晰。结论:在下颌骨骨缺损早期愈合中,SIS可吸收膜和Bio-Gide可吸收膜均发挥良好的屏障作用,其效果无明显差异,但本实验中SIS膜在一定程度上对于下颌骨缺损修复空间的维持能力更好。

Barrier effect of improved porcine small intestinal submucosa absorbable membrane on early healing of mandibular defects in rabbits

Objective: To evaluate the barrier effect of an absorbable barrier membrane made by small intestinal submucosa (SIS) compared with Bio-Gide collagen membrane. Methods: 12 healthy New Zealand male white rabbits were randomly assigned. A or B round bone defects with a depth of 2 mm and a diameter of 5 mm or 8 mm was made in each rabbit’s mandibular. The following treatments were given respectively: covered with SIS membrane (S), covered with Bio-Gide membrane (G) and blank control (O). Then we got six groups: AS, AG, AO, BS, BG, and BO (n=4). After 4 weeks, the rabbits were sacrificed. The specimens were examined by naked-eye observation, new bone percentage (BV/TV) and bone mineralized density (BMD), which were measured and analyzed by Micro-CT. The data were analyzed with one-way ANOVA. Results: After 4 weeks, Bio-Gide membranes were fused with the surrounding tissue while SIS membranes held the form with no significant degradation. In the AS, BS and AG groups, the absorbable membranes smoothly covered on the new bone. While in the BG group, Bio-Gide membranes collapsed to the center of the bone defects. The 3D reconstruction of Micro-CT showed that a large number of newly formed trabeculae were found in the four groups of AS, BS, AG, and BG. In the central subsidence area of the BG group, the newly formed trabeculae were sparse. However only a small amount of new bone trabecula appeared at the bottom of the defects in groups AO and BO. Micro-CT quantitative results showed that BV/TV (39.10%±0.79%) and BMD (517.73±11.22) mg/cm ³] of AS group were significantly higher than those of AO group 26.67%±1.12%, (319.81±8.00) mg/cm ³] (P < 0.05), and there was no significant difference between AS group and AG group 38.15%±0.91%, (518.65±7.48) mg/cm ³] (P>0.05). BV/TV (34.90%±1.35%) and BMD (409.09±8.14) mg/cm ³] of BS group were significantly higher than those of BO group 23.63%±2.07%, (171.00±16.24) mg/cm ³] (P < 0.05). Meanwhile, there was no significant difference between BS and BG groups 33.40%±1.06%, (412.70±8.6) mg/cm ³] (P > 0.05). HE staining analysis revealed that significant bone formation was achieved in the AS, AG, BS and BG groups, and trabecular bone of AS and AG groups were thicker and denser. In AO and BO group, there were scattered new bone tissues in edges of host bone, and no coarse trabecular bone formed. Conclusion: In the early healing of two sizes bone defects in rabbit mandibular, SIS membrane and Bio-Gide membrane have a similar barrier effect in guided bone regeneration. And SIS membrane's ability to maintain space for bone regeneration seems to be better.