Periodontal regeneration of transplanted rat molars after cryopreservation

The effects of cryopreservation on periodontal regeneration of transplanted rat molars were investigated histologically and histochemically in rats. Bilateral first and second maxillary molars of 4-week-old Wistar rats were gently extracted and transplanted into the abdominal subcutaneous connective tissue immediately or after cryopreservation in liquid nitrogen overnight. Donor teeth were slowly frozen by a rate-controlling freezer (program freezer) using 5% dimethylsulfoxide (DMSO) and 6% hydroxyethyl starch (HES) as cryoprotectants. One-four weeks after transplantation, they were carefully excised with the surrounding tissues. Regeneration of acellular cementum, periodontal ligament, and alveolar bone were observed 2 weeks after immediate transplantation. The pulp was repaired by the ingrowth of granulation tissue from the root apex followed by the formation of calcified tissue. The regenerated periodontal ligament was positive for alkaline phosphatase (ALP). Small or mononuclear tartrate resistant acid phosphatase (TRAP) positive cells were scattered on the newly formed alveolar bone and on the hard tissue in the pulp, but there was no external or internal progressive root resorption at 4 weeks. Cryopreserved teeth had acellular cementum with a rough surface at 1 week, but with the increase of cementoblasts and the appearance of periodontal ligament and alveolar bone, the surface became smooth at 3 weeks. Epithelial rests of Malassez (ERM) also revived. After regeneration of the periodontal tissues at 4 weeks, there was no evidence of root resorption. Although the process proceeded slowly, the cryopreserved teeth showed the periodontal regeneration substantially similar to that of the immediately transplanted teeth without progressive root resorption, indicating that they could be applicable for clinical use.     

Effects and distribution of the enamel matrix derivative Emdogain® in the periodontal tissues of rat molars transplanted to the abdominal wall

Abstract – The enamel matrix derivative Emdogain^® (EMD) has been found to promote regeneration of lost periodontal tissues. We have studied the effects and distribution of EMD in the periodontal tissues of maxillary rat molars transplanted to a subcutaneous position in the abdominal wall. The molars were transplanted with or without EMD either immediately after extraction or after drying for 30 min. After 2 days, 1, 2 or 4 weeks the rats were killed and the teeth were examined by means of light microscopy and immunohistochemistry with anti-amelogenin antibodies. Teeth transplanted immediately after extraction showed formation of alveolar bone separated from the dental roots by a periodontal space, regardless of the use of EMD. Among the teeth that were transplanted with EMD after drying for 30 min, new alveolar bone was formed in five out of eight teeth after 2 and 4 weeks. None of the teeth that were dried for 30 min and transplanted without EMD showed alveolar bone formation. Only one tooth transplanted with EMD showed root resorption after drying, while resorption was noted in all teeth transplanted without EMD. All teeth that were transplanted with EMD and none of the teeth that were transplanted without EMD showed an immunohistochemical reaction for amelogenin. After 2 days, amelogenin was precipitated on all surfaces exposed at the transplantation procedure. Later, the immunoreactive material was redistributed to cells at the root surface, where it was still demonstrable after 4 weeks. In conclusion, EMD is accumulated in cells at the root surface and promotes regeneration of the periodontal tissues of the transplanted teeth. It also seems to promote healing of root resorption.     

自体移植冻存骨髓基质细胞修复犬牙周缺损的实验

目的 观察冻存对骨髓基质细胞(bone marrow stromal cells,BMSC)体内形成牙周支持组织能力的影响.方法 在5只Beagle犬的26个实验牙位制备牙周缺损.区组随机法分成3组,空白组(8颗)植入载体胶原膜,未冻存组(9颗)和冻存组(9颗)接种未冻存或冻存细胞与胶原膜复合物,8周后观察牙周组织再生情况.结果 冻存组和未冻存组牙槽骨再生百分比分别为(83.7±10.6)%、(85.0±6.8)%,两组新生牙骨质和牙周膜百分比均为100%,差异无统计学意义(P>0.05);空白组牙槽骨再生百分比为(24.7±9.2)%,牙骨质再生百分比为(21.0±4.8)%,牙周膜再生百分比为(24.8±5.4)%,均较冻存组和未冻存组显著减少,差异有统计学意义(P<0.05).结论 冻存对BMSC体内分化形成牙周组织的能力无显著影响.     

深冷冻保存对离体牙牙周膜细胞活性影响的研究

目的：探讨应用不同降温方法和不同冷冻保护液的深冷冻保存技术,对人离体牙牙周膜细胞活性的影响。方法：收集新鲜拔除的人第一或第二前磨牙25颗随机分为5组;其中4组使用含海藻糖或不含海藻糖的冷冻保护液,分别应用程序降温或快速降温至－196℃,冷冻保存一周;一组新鲜拔除牙齿为对照组。分别刮取牙根面中1／3的牙周膜组织,消化法收集细胞,台盼蓝染色,高倍镜下计数活细胞数,并计算细胞存活率。结果：不同降温方法不同冷冻保护液深冷冻保存与对照组相比,牙周膜细胞存活率无明显差异。其中,使用含海藻糖的冷冻保护液程序降温的方法牙周膜细胞存活率最高。结论：应用深冷冻技术保存牙齿,牙周膜细胞的活性无明显变化,其中使用含海藻糖的冷冻保护液程序降温的方法对牙周膜细胞的活性影响最小。     

Revascularization after cryopreservation and autotransplantation of immature and mature apicoectomized teeth.

Autotransplantation of immature teeth can have a success rate of almost 98% if the tooth is atraumatically transplanted from the donor site to a suitable acceptor site and the extraoral time is kept to a minimum. When the tooth cannot be transplanted immediately, cryopreservation and storage in a tooth bank offer new possibilities for autotransplantation. However, the effect of cryopreservation on the revascularization of transplanted teeth is still unknown. The purpose of this study was to examine revascularization in immature teeth that have an open apex and in mature teeth that have had the apex cut. The study was carried out on 16 teeth in 2 dogs; 8 teeth were removed and immediately transplanted to the contralateral position and 8 teeth were cryopreserved and transplanted 1 week later. The results show that: (1) teeth can revascularize after autotransplantation if the original pulp tissue is removed at the time of extraction, (2) there is no significant difference in the amount of revascularization between teeth stored in a tooth bank for 7 days and those immediately transplanted without freezing, and (3) there is no difference in the ingrowth of new pulpal tissue between mature apicoectomized teeth and immature teeth.     

A case of tooth autotransplantation after long-term cryopreservation using a programmed freezer with a magnetic field

This case report describes the treatment of a skeletal Class III malocclusion with autotransplantation of a cryopreserved tooth. To gain an esthetic facial profile and good occlusion, extraction of bimaxillary premolars and surgical therapy were chosen. The patient had chronic apical periodontitis on the lower left first molar. Although she did not feel any pain in that region, the tooth was considered to have a poor prognosis. Therefore, we cryopreserved the extracted premolars to prepare for autotransplantation in the lower first molar area because the tooth would probably need to be removed in the future. The teeth were frozen by a programmed freezer with a magnetic field (CAS freezer) that was developed for tissue cryopreservation and were cryopreserved in −150°C deep freezer. After 1.5 years of presurgical orthodontic treatment, bilateral sagittal split ramus osteotomy was performed for mandible setback. Improvement of the facial profile and the occlusion were achieved in the retention phase. Six years after the initial visit, the patient had pain on the lower left first molar, and discharge of pus was observed, so we extracted the lower left first molar and autotransplanted the cryopreserved premolar. Three years later, healthy periodontium was observed at the autotransplanted tooth. This case report suggests that long-term cryopreservation of teeth by a CAS freezer is useful for later autotransplantation, and this can be a viable technique to replace missing teeth.     

Root and periodontal tissue development after allogenic tooth transplantation between rat littermates

Oral Diseases (2011) 17 , 379–386 Objective: The study was designed to investigate the development of roots and periodontal tissues after allogenic tooth transplantation between rat littermates by micro‐computed tomography (micro‐CT) and histology. Materials and Methods: The upper right second molars in 2‐week‐old rats were extracted and immediately transplanted into the upper right first molar socket of rat littermates under anesthesia. The upper left second molars in 2‐week‐old recipient rats were used as a control. The rats were fixed and tissues analyzed at 0, 4, 8, or 12 weeks after transplantation. Root development of seven rats in each group was analyzed quantitatively using micro‐CT. Periodontal tissue formation was examined qualitatively by histologic methods. Results: Roots developed after allogenic transplantation, but they were significantly shorter than control roots. The number of roots varied from one to four in transplanted teeth, while it was consistently four in control teeth. Periodontal tissue formation in transplanted teeth was equivalent to that of the control teeth. Conclusion: Allogenic transplantation between rat littermates permits root development and periodontal tissue formation.     

Attachment formation after transplantation of teeth cultured with enamel matrix derivative in dogs

Background: Implantation of cultured cells may be applied for periodontal regeneration in the future. However, a donor is essential in each case and tooth extraction is required to obtain the periodontal ligament–derived cell. We developed a novel regenerative technique combining tissue culture and transplantation of teeth. The purpose of this study is to evaluate the effect of enamel matrix derivative (EMD) on periodontal healing using this technique in dogs. Methods: A total of 32 incisors from seven beagle dogs were used. The periodontal ligament and cementum 5 mm from the coronal part of the roots were removed, whereas those in the apical part were preserved. Teeth were transplanted after the following treatments: 1) culture with application of EMD to the root surface for 6 weeks (n = 11); 2) culture without application of EMD for 6 weeks (n = 11); and 3) immediately transplanted without culture as control (n = 10). Eight weeks after transplantation, periodontal healing was analyzed. Results: The downgrowth of junctional epithelium on the roots of the EMD and culture groups was significantly smaller than that in the control group (P <0.01). Most of the root‐planed surfaces in the EMD group were covered with new cementum (72.2% ± 8.6%). This was significantly greater than that in the culture (29.1% ± 22.9%) and control groups (0.3% ± 1.1%). Conclusions: Transplantation of tissue‐cultured teeth decreased epithelial downgrowth and increased connective tissue attachment on the root‐planed surface. Furthermore, EMD could remarkably increase the new connective tissue attachment in this periodontal regenerative technique.     

Regeneration of periodontal tissues following experimentally induced periodontitis in rats: a comparison of sucrose-rich and conventional diets

The purpose of the present study is to elucidate influences of diet on periodontal regeneration following experimental periodontitis in rats. S-D rats were divided into two groups, which were fed either a conventional diet (group A) or a sucrose-rich diet (group B). Experimental periodontitis was produced by placement of elastic bands between maxillary molar teeth. After one week, the elastic bands were removed and the animals were sacrified by perfusion fixation with formalin immediately, 1, 3, or 5 days, or 1, 2, 3, 4, 6, or 8 weeks after the removal. Sections of the teeth and surrounding tissue were examined by light microscopy. Three days after the removal, in both groups, granulation tissues with many inflammatory cells were covered by epithelial cells; the attachment site to the root surface was located more apically than the cemento-enamel junction. Distinct periodontal pockets were formed by five days after the removal in group A. In group B, the infiltrations of inflammatory cells were more prominent than in group A. Six weeks after the removal in both groups, an epithelium which resembled long junctional epithelium rather than pocket epithelium became thicker. Eight weeks after the removal, the findings were similar to those of six weeks in group A. However, a severe inflammatory cell concentration was found in group B. These results suggest that periodontal wound healing is markedly influenced by diet, and that this experimental system is useful for studying dynamic changes in both pocket and long junctional epithelia.     

Does removal of the original pulp tissue before autotransplantation influence ingrowth of new tissue in the pulp chamber?

Abstract – In an attempt to extend the indication area for autotransplantation of vital teeth, two possibilities can be proposed: (i) The enlargement of the apical foramen, with the aim to facilitate revascularization and ingrowth of new tissue. The ingrowth of tissue will eliminate the need for endodontic treatment when mature teeth are transplanted and (ii) the cryopreservation of teeth in case they cannot be transplanted immediately to the receptor site. Teeth with an ideal stage of root formation can be cryopreserved to perform transplantation later. Although pulpcell cultures survive crypreservation in vitro, the pulp tissue cannot survive the cryopreservation procedures when it is kept inside the pulpchamber. Therefore, the pulp tissue has to be removed before cryopreservation. It has been demonstrated that revascularization and ingrowth of new tissue can occur in an empty pulp chamber ( 1 ). The aim of this study was to find out if revascularization and ingrowth of new pulp tissue is influenced by removal of the original pulp tissue before autotransplantation. Twenty nine single‐rooted teeth from three adult beagle dogs were transplanted after resection of the root tip. One group of teeth (n = 14) had the pulp tissue removed before transplantation. The other group (n = 15) had the original pulp left in situ. The transplanted teeth were histologically analysed 90 days post‐transplantation. In the group with the tissue left in situ, 12 teeth (80%) showed a pulp chamber totally filled or at least 1/3 to 2/3 filled with viable tissue. In the group with the pulp tissue removed, 11 teeth (79%) had no or little vital tissue in the pulp chamber. The necrotic masses that develop in the original pulp tissue immediately after transplantation are a possible stimulating factor in the repair process of the pulp. As a conclusion, it can be stated that in case of autotransplantation of teeth, it is advisable to leave the pulp tissue in situ to stimulate the revascularization and ingrowth of new tissue after transplantation.     

Effects of polyglactin mesh combined with resorbable calcium carbonate or replamineform hydroxyapatite on periodontal repair in dogs

Abstract This study evaluates periodontal repair and biomaterial reaction following implantation of a polyglactin mesh with or without porous resorbable calcium carbonate (RCC) or porous replamineform hydroxyapatite (RHA) in conjunction with reconstructive surgery. Ligature- and surgically-induced interproximal periodontal defects of left and right mandibular premolar teeth in 7 dogs were used. Bilaterally, mesial defects of the 2nd, 3rd and 4th premolar teeth were treated with polyglactin mesh, polyglactin mesh and RHA. or polyglactin mesh and RCC. respectively. The polyglactin mesh, shaped according to the contour of the defect, was adapted to the experimental teeth: its coronal margin positioned immediately apical to the cemento-enamel junction. Gingival flap margins were adapted and sutured to cover the polyglactin mesh completely. Clinical healing was generally uneventful. The dogs were sacrificed to provide block sections for histologic evaluation at 1, 3, 6, 12, 26, 32 and 56 weeks following wound closure. Generally, cementum regeneration was observed beginning at week 6 in all groups. Bone regeneration was observed from week 3 in polyglactin mesh-treated groups, and from week 6 in polyglactin mesh + RCC or polyglactin mesh + RHA treated groups. Bone regeneration appeared enhanced in polyglactin mesh + RCC or polyglactin mesh + RHA treated defects at week 12 and 26, with little difference between the three experimental conditions at week 56. Polyglactin mesh degradation was observed at week 3 and appeared complete at week 12. The RHA did not appear to resorb, while the RCC was gradually replaced by bone from week 3. Within limitations of the study conditions, periodontal regeneration was observed following implantation of a polyglactin mesh with or without RCC or RHA in conjunction with reconstructive surgery. As a conclusion, there seems to be no significant difference in periodontal regeneration after 12 months of healing between the group treated with the membrane only, and the group treated with the membrane and the bone substitution material. Changes in connective fiber orientation over the 1st 12 weeks of healing may suggest that “fibrous encapsulation” observed in earlier studies may only represent a transient stage in periodontal regeneration.     

Delayed replantation after submucosal storage in order to prevent root resorption after replantation. An experimental study in monkeys

The purpose of this study was to determine the root resorption pattern of teeth autotransplanted to a submucosal site and to determine whether root resorption after replantation could be prevented by delayed replantation of teeth after submucosal storage in order to regenerate damaged periodontal ligament. Permanent teeth were extracted in green Vervet monkeys. One group of teeth was transplanted to a submucosal site and examined histologically in situ. Another group of teeth was autotransplanted to submucosal sites, recovered and replanted either 2 or 6 weeks later. The animals were sacrificed 8 week after replantation and examined histometrically. The following histologic parameters were registered: surface resorption, inflammatory resorption, replacement resorption (ankylosis), periapical inflammatory changes and downgrowth of pocket epithelium. Teeth autotransplanted to submucosal sites developed surface and inflammatory resorption. In half of the cases where teeth were transplanted with a vital periodontal ligaments new formation of bone took place adjacent to the transplant. Delayed replantation after submucosal burial was not found to inhibit the development of ankylosis, but changed the resorption type from direct apposition of bone upon the root surface to apposition of bone after initial resorption.     

Re-innervation in the canine periodontal ligament of replanted teeth using an antibody to protein gene product 9.5: an immunohistochemical study

The re-innervation process in the periodontal ligament of replanted canine teeth was examined by immunohistochemistry for protein gene product 9.5 (PGP 9.5), a general marker for neurons, and by electron microscopy. Within 1 week of replantation, the periodontal fibers had regenerated, filling the narrow spaces between the alveolar bone and the root surface around the cervical and apical regions. Near the root apex, however, no PGP 9.5-immunopositive nerve fibers were found in the regenerated periodontal ligament except for those in the alveolar half of the ligament. At 2 weeks after replantation, many nerve fibers positive for PGP 9.5 had ascended the periodontal ligament from the thick nerve bundles located near the root apex. Fine nerve endings showing complicated ramification were also present in the apical region. By 3 or 4 weeks after replantation, the vascular network was regenerated and principal periodontal fibers were re-established throughout the entire length of the periodontal ligament. The extensively ramified PGP 9.5-immunopositive structures had increased in thickness and density and showed characteristic tree-like profiles by 3 weeks. Electron microscopy confirmed that most of these structures were Ruffini-like endings, and demonstrated that such nerve terminals were almost regenerated by 4 weeks post-replantation. These results indicated that, in the periodontal ligament of replanted canine teeth, the regeneration of the nerve fibers including mechanosensory receptors first showed signs of regeneration by 2 weeks following tooth replantation and proceeded rapidly thereafter. Regeneration of the periodontal ligament including fiber architecture as well as vascular and neural elements was almost complete by 4 weeks after replantation.     

Reinnervation in the canine periodontal ligament of replanted teeth using an antibody to protein gene product 9.5: an immunohistochemical study

Abstract— The re-innervation process in the periodontal ligament of replanted canine teeth was examined by immunohistochemistry for protein gene product 9.5 (PGP 9.5), a general marker for neurons, and by electron microscopy. Within 1 week of replantation, the periodontal fibers had regenerated, filling the narrow spaces between the alveolar bone and the root surface around the cervical and apical regions. Near the root apex, however, no PGP 9.5-im-munopositive nerve fibers were found in the regenerated periodontal ligament except for those in the alveolar half of the ligament. At 2 weeks after replantation, many nerve fibers positive for PGP 9.5 had ascended the periodontal ligament from the thick nerve bundles located near the root apex. Fine nerve endings showing complicated ramification were also present in the apical region. By 3 or 4 weeks after replantation, the vascular network was regenerated and principal periodontal fibers were re-established throughout the entire length of the periodontal ligament. The extensively ramified PGP 9.5-immunopositive structures had increased in thickness and density and showed characteristic treelike profiles by 3 weeks. Electron microscopy confirmed that most of these structures were Ruffini-like endings, and demonstrated that such nerve terminals were almost regenerated by 4 weeks post-replantation. These results indicated that, in the periodontal ligament of replanted canine teeth, the regeneration of the nerve fibers including mechanosensory receptors first showed signs of regeneration by 2 weeks following tooth replantation and proceeded rapidly thereafter. Regeneration of the periodontal ligament including fiber architecture as well as vascular and neural elements was almost complete by 4 weeks after replantation.     

生物活性玻璃引导牙周组织再生的研究

目的 :评价生物活性玻璃倍骼生应用于引导牙周组织再生的效果。方法 :于 4只beagle犬的前磨牙区 ,2 4个牙位 ,运用人工去骨及正畸结扎丝结扎法建立重度牙槽骨水平缺损模型 ,植入生物活性玻璃倍骼生 ,同体对照 ,术后 6周对新生骨与牙根结合界面进行临床观察和组织学切片。另一实验 3只beagle犬的前磨牙区 ,18个牙位 ,于 2 4周对新生骨与牙根结合界面进行X射线能谱分析。结果 :实验组有牙周新附着形成 ,可见新生牙槽骨、牙骨质样组织和牙周韧带生长。空白对照组未见新生骨 ,胶原纤维稀疏 ,排列不规则。胶原膜联合生物骨组 ,新生牙槽骨的钙 /磷比值 (1.72± 0 .14 ) ,接近正常对照组的钙 /磷比值 (1.79± 0 .0 4 )。结论 :生物活性玻璃倍骼生具有较强骨诱导活性 ,术后 6周可有效地提高牙周组织再生。     

Tooth auto-transplantation with double periodontal ligament stimulation to replace periodontally compromised teeth

BACKGROUND: The healing process of autotransplantation puts 2 different tissues in competition: the ligament on the root surface and the bone tissue of the alveolus. This study shows the effects of a protocol with 2 surgical stages, which promote ligament repair, inhibit adhesion between bone and dental root, and reduce the occurrence of the ankylosis-root resorption phenomenon. METHODS: Forty-three patients, 33 to 73 years old, received 47 transplantations of mature teeth (including retained teeth) during a 5-year period. During the first surgical step, the transplanted tooth is extracted, measured, immediately replaced in its origin site, and maintained with an original suture technique. The alveolus to which the tooth will be transplanted is adapted after extraction of the periodontally compromised tooth. The second surgery occurs at day 14, when regeneration of periodontal ligament (PDL) is at a maximum (first stimulation). The tooth is transplanted in its new alveolus and retained using the same suture technique to avoid a rigid splint and to create mechanical stimulation of the PDL (second stimulation). RESULTS: The results were 95.75% positive with normal PDL, with a 4.25% failure rate (transplant loss) and no ankylosis. Mean probing reduction was 8.37 +/- 3.0 mm. Mean radiographic bone gain was 7.73 +/- 4.32 mm. CONCLUSIONS: This study suggests that auto-transplantation with double PDL stimulation can be a viable treatment in clinical practice, especially to replace teeth with large periodontal lesions, deep furcation defects, and/or root fractures. This study shows the high potential of stimulated PDL to regenerate alveolar bone and periodontal structures in severe destruction sites.     

Ⅱ°根分叉病变动物模型构建的研究

目的　观察杂种狗下颌前磨牙Ⅱ°根分叉病变自然修复过程及其病理状态下牙周组织的修复能力 ,探讨慢性根分叉病变动物模型的制备方法。方法　将 4只杂种狗的下颌双侧第 2、3、4前磨牙颊侧翻瓣后凿出6mm× 6mm× 3mm的牙槽骨缺损 ,对照组直接缝合牙龈 ,实验组于骨缺损区置入牙胶后缝合。分别于术后第 4、6、8、10周进行形态学和组织学观察。结果　对照组 4周就可观察到增大的牙骨质细胞出现在缺损部位的冠方 ,并有新生的类牙骨质形成。 6周时缺损部位冠方出现少量新生的牙槽骨。随着时间的推移 ,牙骨质的量逐渐增多 ,牙槽骨骨小梁变得细密 ,到 10周基本形成正常组织结构。实验组 4周时有炎症细胞浸润、牙周袋形成 ,在 8周时甚至有龈下脓肿形成 ;10周时牙龈仍有炎症、牙周袋 ,并出现骨吸收现象。结论　根分叉病变研究中 ,可以在急性损伤制备根分叉缺损的基础上结合局部因素诱导形成一个近似临床牙周根分叉病变表现的实验模型。     

Periodontal repair in dogs Healing patterns in large circumferential periodontal defects

This report describes the healing patterns of large circumferential periodontal defects in the beagle dog. Approximately 5 mm large periodontal defects were created around the mandibular premolars (P2, P3 and P4) in 13 animals. The root surfaces were then instrumented to remove all cementum and the wounds immediately closed by replacing and suturing the flaps just coronal to the cemento-enamel junction. Block biopsies were harvested after 4 weeks. Most of the surgically denuded root surface healed with connective tissue repair. Cementum formation and regeneration of alveolar bone was limited and averaged approximately 30% and 20%, respectively, of the defect height. Almost all teeth exhibited root resorption. Ankylosis was observed in 1/3 of the teeth. There was no difference in the healing response between the 3 premolars or their buccal and lingual surfaces. The range of healing responses indicates that a biological potential exists which makes this model useful for testing the effect of various root and wound conditioners in (1) enhancing cementum formation on the root surface, (2) increasing regeneration of alveolar bone and (3) preventing aberrant healing events such as root resorption and ankylosis. Conversely, whether such agents may compromise wound healing and result in reduced connective tissue repair may concomitantly be tested.     

碱性成纤维细胞生长因子对犬牙周成纤维细胞样细胞增殖影响的体内研究

目的　观察碱性成纤维细胞生长因子(bFGF)对犬牙周成纤维细胞样细胞增殖的影响。方法　选用4只成年杂种犬,将其上颌两侧的前磨牙(P1-3)、第一磨牙(M1)、下颌两侧的前磨牙(P2-4)、第一磨牙(M1)作为实验牙。在每个象限4个实验牙的近中根颊侧人工制备“U”形骨缺损,并设计为4组,即对照组、bFGF组、ePTFE组、bFGF+ ePTFE组。每周手术1次,每次手术做1个象限的4个牙位,连续4次。完成4次手术后1周处死动物。动物处死前1 h注射尿嘧啶脱氧核苷(BrdU),标本行免疫组化染色,显微镜下计数BrdU标记的成纤维细胞样细胞。结果　各组中BrdU+细胞数均于术后2周最多,术后3、4周显著减少。术后1、2周,bFGF组和bFGF+ePTFE组的BrdU+细胞明显多于对照组和ePTFE组。结论　牙周术后2周是牙周功能细胞增殖的活跃期,bFGF的局部应用可明显促进牙周愈合早期牙周功能细胞的增殖,从而促进牙周再生。     

Histochemical study of the influence of transplanted teeth with periodontal ligament on the binding of peanut agglutinin in rat dorsal skin

Our previous study showed that the expression of carbohydrate residues in junctional epithelium (JE) after resection is closely related to attachment and stratification along the dental root surface. However, the influence of the periodontal ligament on carbohydrate expression has still not been clarified. In this study we examined the relationship between the presence of periodontal ligament and the expression of carbohydrate residues on epithelium regenerating along root surfaces. We transplanted extracted rat molars with or without periodontal ligament tissue, repeatedly frozen and thawed teeth with ligament and demineralized teeth without ligament into the dorsal skin of rats. After 2, 3, 5, 7, 10, 14 or 21 d, dorsal cutaneous tissues containing transplanted teeth were resected, fixed, decalcified and embedded in paraffin. Serial sections were stained histochemically with the HRP-conjugated lectin. peanut agglutinin (PNA) to observe the expression of carbohydrate residues in regenerating epithelium. Histochemical observation revealed that lectin binding reactions were changed from the characteristics of skin to those of JE when the regenerating epithelium was attached and stratified along the tooth with unfrozen or frozen tissue. These results suggested that the structural formation and expression of PNA in regenerating epithelium around the root surface were influenced by not only the tooth but also by the periodontal ligament.