外伤全脱位年轻恒牙再植的临床研究

目的：观察不同离体时间的年轻恒牙再植后的成功率。方法：详细记录60颗全脱位牙离体时间、手术及牙愈合情况,对患者进行1～2年的随访。结果：60颗脱位牙（离体时间为15min～16h）再植后牙周膜愈合26颗（43．3％）,其中牙髓成活19颗（31．67％）;骨性愈合31颗（51．67％）;纤维愈合3颗。术后对38颗牙进行了根管治疗。结论：缩短脱位牙的离体时间、尽可能保存牙周膜的活性等是再植成功的重要因素。     

Effect of calcium hydroxide treatment on periodontal repair and root resorption

Abstract Pulpal application of calcium hydroxide is a common treatment for external root resorption. Several mechanisms of action have been suggested. In the present investigation, the effect of pulpal calcium hydroxide on cells at the root surface and in the periodontal ligament was studied by means of scanning-electron microscopy and light microscopy. Lateral incisors in monkeys were extracted, a groove was made- in the root surface and the teeth were then immediately replanted. The pulps of some teeth were infected by bacteria from the saliva. Application of calcium hydroxide in the root canal caused a limited necrosis of the cells resorbing dentin as well as the cells forming reparative cementum in the experimental groove. In the non-infected teeth, a temporary ankylosis developed. The high pH having a bactericidal and necrotizing effect seemed to be sufficient to explain the therapeutic effect of calcium hydroxide on root resorption.     

不同离体时间和保存液对犬离体牙牙周膜细胞活力影响的实验研究

目的:探讨完全脱位牙不同离体时间和保存液对牙周膜细胞活力的影响。方法:麻醉拔除犬牙35个,首先将20个牙随机分为5组,分别为室温干燥放置0、30、60、120、240 min组,另15个牙室温干燥放置30 min后,随机分为3组,分别放入牛奶、HBSS液,100 g/L蜂胶液中浸泡2 h。各组处理完成后,采用全牙消化法获得牙周膜细胞,并通过4 g/L台盼蓝染色法检测各组牙周膜活细胞数和存活率。结果:室温干燥放置30、60、120、240 min后,牙周膜细胞存活率依次为33.6%、23.6%、18.5%、0.8%,而0 min的牙周膜细胞存活率可达95.5%。拔后30 min,经牛奶、HBSS液和100 g/L蜂胶液中保存2 h后,牙周膜细胞均有活力,其细胞存活率大小依次为100 g/L蜂胶液、HBSS液和牛奶,其中100 g/L蜂胶液与HBSS液相比无统计学差异(P>0.05),但与牛奶组相比,均有统计学差异(P<0.05)。结论:随着离体时间延长,完全脱位牙根面牙周膜细胞活力明显下降。100 g/L蜂胶液和HBSS液保存犬牙牙周膜细胞活力优于牛奶液。     

The Effect of Long-term Dressing with Calcium Hydroxide on the Fracture Susceptibility of Teeth

Introduction

Calcium hydroxide has been widely used to treat immature teeth to achieve periodontal healing and to promote the formation of an apical barrier. However, retrospective clinical studies have shown a high incidence of cervical root fractures with long-term calcium hydroxide dressing. The alkalinity of calcium hydroxide has been suggested to weaken the root. In vitro studies using ovine teeth show conflicting results on fracture strength of dentine, although different commercial products may have influenced the results. The purpose of this study was to investigate the effects of 2 commercial products used in prior studies (Calasept Plus and UltraCal XS), as well as a new product (Calmix) that uses a nonaqueous vehicle that allows for a higher pH, on the fracture strength of dentine over time.

前牙内收移动与根尖外吸收的关系及其评价方法

根尖外吸收是正畸治疗后常见的并发症,其发生率为0%～100%。其由多种因素引起,大致可分为生物学因素和机械因素。生物学因素包括遗传易感性、系统性疾病、性别、药物摄入等,机械因素包括正畸力的大小、类型、持续时间,牙移动的量和类型,牙的超限移动。本文对前牙内收移动与根尖外吸收的关系及其评价方法做一综述。     

乳牙根管充填材料对根尖周组织的影响

目的：观察乳牙根管充填材料对周围组织的影响，比较其临床应用的合理性。方法：以一端封闭，另一端开放的硅胶管模拟乳牙根管，无菌条件下分别充填氧化锌丁香油糊剂，氢氧化钙糊剂和碘仿糊剂。分别埋入Wistar大白鼠背部皮下组织内。于术后不同时间处死大白鼠获取组织标本，光镜下观察其急性和慢性炎症反应。结果：碘仿糊剂对组织炎性刺激反应最小，氧化锌和氢氧化钙糊剂均刺激反应较大，氧化锌糊剂刺激反应消失较快。结论：根据3种材料的与组织生物相容性特点选择治疗方法。     

The fibrillar structure of cement lines on resorbed root surfaces of human teeth

The cement lines between reparative cementum and resorbed dentin or cementum in human teeth were observed by light microscopy and scanning electron microscopy combined with NaOH maceration. The NaOH maceration was used to remove interfibrillar substances and to observe the fibrillar architecture of the cement lines directly. Light microscopy showed that the cement lines were rich in proteoglycans with mucopolysaccharides, but deficient in collagen fibrils. The cement lines were artificially broken after treatment with hyaluronidase, which digests some of the mucopolysaccharides, but digests no collagen fibrils. Scanning electron microscopy showed that fibril intermingling occurred only in some places between reparative cementum and resorbed tissue. These findings suggested that the proteoglycans in cement lines mediate the attachment between new and old mineralized tissue.     

不同粘结剂对纵折牙根粘结后再植的疗效观察

目的：通过2种粘结剂处理纵折牙根进行粘结后再植术，了解不同黏结剂对后牙纵折愈合类型的影响。方法：3只Beagle犬的前磨牙48个牙根，分成3组，分别用Clearfil SE Bond（CE组，n=18）和SuperBond C＆B（SE组，n=18）进行粘结后再植，与正常牙根再植组（CC组，n=12）进行对照。术后16周处死动物，采集牙根一牙槽骨标本，按照”8等分法”和Andreasen愈合标准，记录各位点组织愈合情况，按有利愈合和不利愈合分类量化各组组织学愈合类型，并对各组牙根余留半径长按照0-4级评分，比较有效愈合率和余留牙根半径。结果：CE、SE、CC三组有效愈合率分别为：51％、31％、59％。余留半径评分分别为：3．38、2．47、3．59。CE组比SE组更能有效促进纵折牙根的愈合。结论：Clearfil SE Bond AP-x粘结系统能有效降低炎症性吸收和置换性吸收的发生率，提高后牙纵折粘结后再植术的手术成功率。     

人工牙排列位置对下颌全口义齿固位及支持组织的影响

采用ＣＴ－数字化仪－ＣＡＤ系统建立了下颌无牙颌骨及其义齿的３个三维有限元模型，探讨在Ｈｅ力，口周肌力作用下，下颌人工牙排列位置对义齿固位和支持组织应力分布的影响，并测量了１０例口周肌动力及传统型全口义 工牙排列位置的差异。结果表明；Ｈｅ力作用下，人工牙排列干剩余牙槽嵴顶及水平偏离槽嵴顶舌，颊侧３ｍｍ，对牙骨应力分布无明显影响，但后牙位于下颌骨外斜嵴区对支持组织有利；正中Ｈｅ时，磨牙排列于牙槽嵴顶颊     

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内收前牙在安氏Ⅱ类错猞畸形（上颌前突）及双颌前突患者正畸治疗中是不可或缺的步骤。内收前牙的关键在于能够高效移动牙齿的同时将对牙齿及其支持组织的损害减小至最低限度,然而临床上牙槽骨吸收、牙根吸收及牙龈退缩等现象在上述患者中很常见,有时甚至影响到正畸治疗的整体效果。本文对正畸内收前牙所导致牙体及牙周组织的不利改建及可能原因进行综述。     

The Effect of Crown Lengthening on the Outcome of Endodontically Treated Posterior Teeth: 10-year Survival Analysis

IntroductionThe purpose of this study was to investigate the effect of a crown lengthening (CL) procedure and the crown-root ratio after CL on the long-term survival of endodontically treated teeth (ETT).MethodsPermanent posterior teeth with opposing dentition that had received adequate nonsurgical root canal treatment (NSRCT) and a full-coverage crown between January 1, 2006, and January 1, 2016 were included in this retrospective study. The data collected included dates of the NSRCT, time of extraction if extracted, age, sex, location, the crown-root ratio after CL, and the presence of a lesion. All included ETT were divided into 2 groups:

• 1.the CL group, CL was indicated and performed after NSRCT before crown placement and
• 2.the control group: ETT with adequate ferrule after NSRCT. Data were analyzed using the Kaplan-Cox regression model (α = 0.05).

Results5-year survival rates of ETT in the control and CL groups were 88.6% and 82.2%, respectively (P > .05). The 10-year survival rates of ETT in the control and CL groups were 74.5% and 51%, respectively (P < .05). ETT that received the CL procedure after NSRCT were almost 2.3 times more likely to get extracted compared with ETT that did not need the CL procedure at the 10-year follow-up (hazard ratio = 2.29, P < .05). Also, ETT with an inadequate crown-root ratio (1:1) after CL showed the lowest survival rate (40%) compared with ETT with an adequate crown-root ratio (<1:1).ConclusionsA crown-root ratio of 1:1 after osseous CL may affect the long-term survival of ETT. Despite the promising survival rate of ETT with an adequate crown-root ratio after CL, the long-term survival of NSRCT with an inadequate crown-root ratio (1:1) should be considered in the treatment planning phase. Also, it is worth mentioning that the results of the present study should be evaluated in future prospective studies.     

年轻恒牙震荡和移位后牙髓与牙根变化的临床研究

年轻恒牙外伤后,牙髓坏死和牙根吸收在牙齿震荡和牙齿移位中的发生率及发生的时间;牙根的表浅性吸收,置换性吸收,炎症性吸与外伤类型的关系。方法从１９８４－１９９６年在北京医科大学附属口腔医院儿科就诊的２０１例前牙外伤发生牙震荡和牙移位患者的病历资料中选择７９例１５７颗无冠折根折的外伤牙,并且如果有牙松动者使用全牙Ｈｅ     

聚乳酸复合材料及乳前牙根部牙本质的力学性能研究

目的:测试不同比例聚乳酸/羟基磷灰石(PLLA/HA)复合材料及乳前牙根部牙本质的力学性能,为乳前牙根管桩的制作提供参考.方法:熔融共混法制备不同比例的PLLA/HA复合材料,按照HA质量分数不同分为PLLA、PLLA-1％HA、PLLA-3％HA、PLLA-5％HA、PLLA-7％HA共5组,采用电子万能试验机测试其...     

The Influence of Periodontal Status on Endodontically Treated Teeth: 9-year Survival Analysis

Introduction

The aim of this study was to investigate the effect of periodontal status at the time of nonsurgical root canal treatment (NSRCT) on the survival rate of endodontically treated teeth (ETT).

Effect of placement of occlusive membranes on root resorption and bone regeneration during healing of circumferential periodontal defects in dogs

Previous studies indicate that root resorption is a frequent sequela to significant amounts of periodontal repair in animal models. A model was developed in labrador dogs to study periodontal wound healing in large circumferential defects in the absence of influence from the oral environment. A polytetrafluorethylene membrane of 1 micron pore size (GORE-TEX) was used to occlude cells from specific tissues from populating the healing dentin-connective tissue wound. 3 modalities were studied: (1) control, in which no membrane and therefore no cell occlusion was used, (2) flap occlusion, in which the internal surface of the flap was lined with the membrane preventing contribution of cells from the flap, (3) bone occlusion, in which the reduced alveolar bone was lined with the membrane preventing contribution from bone cells. Wound closure included total submergence of teeth and membranes. The membranes remained incorporated and no exposure of membranes or teeth occurred during the 3 months healing period. Histology revealed bone regrowth in all 3 treatment modalities. It is suggested that inductive elements in the connective tissue or dentin, or bone cells from periosteum were responsible for bone regrowth in the bone membrane treatment modality. No significant difference was seen for root resorption between the 3 treatment modalities. This study found that physical occlusion of cells from the inside of the surgical flap, or from the pre-existing bone, is not sufficient to prevent root resorption in periodontal wound healing.     

Effect of bisphosphonates and gallium on dentin resorption in vitro

Abstract Replacement resorption may follow the replantation of an avulsed tooth. Currently there is no effective treatment for replacement resorption. The purpose of this study was to investigate the effect of bisphosphonates and gallium nitrate, which have been shown to reduce bone resorption, on cells which resorb dentin. Osteoclast-like cells were obtained by culturing cells from prenatal chick tibeas. These cells were seeded onto slices of human dentin which had been soaked in either saline (control), or solutions of 10^–5 M 1-hydroxyethylidene-1, 1-bisphosphonic acid (EHBP), 10^–6 M dichloromethylene bisphosphonic acid (Cl₂MBP), or 10^–6 M gallium nitrate. Resorption was measured by counting the number of resorptive lacunae produced by the cells. Results indicated that the experimental groups did not differ significantly from each other, but each exhibited significantly reduced resorption compared with saline controls (p<0.01). These results suggested that the experimental treatment reduced dentinal resorption by the osteoclast-like cells, and that these agents might be useful to prevent or at least postpone replacement resorption in avulsed teeth.     

Effect of GBR and fixture installation on gingiva and bone levels at adjacent teeth

Guided bone regeneration (GBR) is frequently used in oral implantology. It is unclear to what extent GBR affects the periodontium of adjacent teeth. Therefore, the present study quantifies changes in the proximal gingiva and bone levels at these teeth in 30 patients. Staged surgery involved a standard GBR treatment, randomly using resorbable membranes with a bone substitute or non-resorbable membranes with or without a bone substitute, followed by fixture installation at 6 months and abutment connection a further 6 months later. The data were sampled at each surgery and analysed using MANOVA. Twelve months after GBR, there was on average a small but statistically significant amount of proximal gingival recession (0.75 mm) and bone resorption (0.34 mm) observed, of which 50% was the result of GBR surgery. No significant differences were found between the different GBR treatment modalities. It is concluded that GBR treatment may have a small negative effect on the levels of the free gingival margin and alveolar bone at adjacent teeth, which is in most patients not clinically relevant.     

Effect of systemic tetracycline and amoxicillin on inflammatory root resorption of replanted dogs' teeth

Abstract— The use of systemic penicillin after an avulsion injury has been recommended as a way to decrease the occurrence of resorption complications. Our previous study has shown systemic tetracycline to possess anti-resorptive properties independent of potential anti-bacterial actions. The purpose of this study was to compare histologically the effectiveness of tetracycline and amoxicillin in limiting inflammatory root resorption (IR) secondary to pulpal infection, in replanted dogs' teeth. Thirty root canals in five dogs were infected with plaque. The roots were extracted, the lingual mid-roots were shaved with a fissure bur ensuring cemental damage and immediately replanted. Dogs were given either tetracycline hydro-chloride or amoxicillin, administered orally, on the day of extraction and replantation and for the following 6 days. The control group was teeth in these animals treated in the same manner but where no antibiotics were given. After approximately 6 months, the dogs were sacrificed and the teeth prepared for histologic evaluation. The shaved root surface was identified in cross-sections and eight equidistant points along the cut root surface were evaluated for healing (H) or IR in eight sections per tooth. For the tetracycline group, H averaged 67.22% and IR 32.!8%, which was not statistically different from the amoxicillin group with H averaging 56.88% and IR 43.12%. The tetracycline group was superior to the control group with H= 27.86% and IR=72.14%. Since tetracycline has been shown to have anti-resorptive properties in addition to the antibacterial properties demonstrated here, it could be considered as an alternative to amoxicillin after avulsion injuries.