中文摘要：

目的 ：通过影像学和组织形态学观察,比较脱位牙的再植位点与自然愈合拔牙创的牙槽骨高度,并观察保留或刮除牙周膜对再植脱位牙的牙槽骨骨量影响。方法：选取3只成年雄性健康Beagle犬,间隔拔除其下前牙3颗,并将每只实验犬的前牙分成3组,有牙周膜再植组（T1）,无牙周膜再植组（T2）,拔牙创自然愈合组（T3）。4个月后处死Beagle犬,切取实验位点组织块,Micro-CT扫描分析,制作硬组织磨片,HE染色后在光学显微镜下进行组织学观察及形态学观察。结果：Micro-CT分析显示,T1组骨小梁数量（Tb.N）多于其他两组（P〈0.05）,差异有统计学意义,而T2和T3组差异无统计学意义;骨小梁间隙（Tb.Sp）在T1组间隙明显小于T2组,差异有统计学意义（P〈0.05）,T2和T3组间差异无统计学意义;骨量比（BV/TV）、骨小梁厚度（Tb.Th）等骨微参数,各组间差异无统计学意义。HE染色显示,在所有试验位点颊侧牙槽嵴发生垂直骨降低,但三组间骨量吸收值的差异无统计学意义。在距颊侧牙槽嵴顶以下1 mm位置处的颊侧骨壁的水平宽度,T2和T3组间具有统计学意义（P〈0.05）;而在2、3 mm两个水平位置处,各组间差异均无统计学意义。结论：牙拔除后20 min内,牙再植回拔牙窝中,相比于自然愈合,可以保留更多牙槽骨骨量,而进一步保留再植牙的牙周膜活性,更有利于颊侧新骨形成。

英文摘要：

Objective： This experimental study aimed to assess changes occurred in the alveolar ridge following methods of tooth replantation with/without periodontal ligament（PDL）, and to compare them against natural healing without inter-ventions. Methods： A randomized control trial was designed. Three beagle dogs were used in this study. Mandibular ante-rior teeth were extracted between every other tooth. Three extraction sites of each dog were randomly assigned to three treatment groups as follows： tooth replantation with PDL（T1）, tooth replantation without PDL（T2）, and natural healing（T3）.Four months after surgery, the dogs were sacrificed and tissue blocks containing the extraction socket were dissected, the microstructural changes at the alveolar ridges were evaluated by Micro-CT and a 3-dimensional image was constructed.The microstructural measurements including the trabecular number（Tb.N）, bone volume fraction（BV/TV）, trabecular thick-ness（Tb.Th）, and trabecular separation（Tb.Sp）. After that, tissue samples were fixed and mounted and stained with hema-toxylin-eosin. The histologic studies and morphological measurements were performed by using an optical microscope and a digital image software. Results： Tb.N increased significantly in T1 as compared with T2 and T3（P0.05）, but there was no significant difference between T2 and T3. Tb.Sp decreased significantly when T1 compared with T2（ P0.05）, while BV/TV and Tb.Th did not show significant difference between each group. Descending of the buccal wall height occurred in all groups, but no significant difference among them. As for the horizontal changes in the buccal wall, a significant differ-ence was found at 1mm below the crest of ridge in T2 and T3（P0.05）, while no statistical difference was found between other groups. Conclusions： Our study demonstrates tooth replantation with preservation of periodontal ligament takes more advantage in preventing buccal wall from resorption. Compared to the natural healing site,