磷酸锌水门汀基在内漂白中的抗渗漏作用

目的研究髓室内漂白时，磷酸锌水门汀基对抗过氧化氢渗漏的作用。方法对离体牙行内漂白，用分光光度法检测过氧化氢渗漏量。结果漂白前平齐釉牙骨质界水平制备磷酸锌水门汀基，过氧化氢渗漏量显著减少。结论磷酸锌水门汀基是防治内漂白后牙颈部外吸收的一种有效方法     

菌斑及其产物对豚鼠牙周组织的影响

４０只豚鼠分成４组，在下切牙区龈沟分别灌注Ｇ－菌内毒素（ＬＰＳ）、Ｇ＋菌脂磷壁酸（ＬＴＡ）、龈下菌斑（ＰＬ）及生理盐水（ＮＳ），於１、２、３、６、８周分批处死观察。结果：ＮＳ对照组除１、２周牙龈出现少量炎症细胞外，未见其他异常；ＬＰＳ组１周很快出现牙龈炎症和明显骨吸收，４、５周炎症渐消退并有新骨形成；ＬＴＡ组菌斑和牙石沉积明显，而炎症与骨吸收较弱，３周即渐恢复；ＰＬ组既见菌斑牙石形成，又有炎症反应及骨吸收，持续时间较长，６、８周仍见轻度炎症。它们作用于牙周组织的不同特点，为进一步阐明牙周病的发病机理提供实验依据。     

消炎痛对豚鼠实验性牙周炎的抑制作用──组织学观察

本研究选用丝线缝扎和高糖食料结合以形成实验性牙周炎，用不同剂量的消炎痛喂养豚鼠以观察其对牙周炎的抑制作用，光镜和电镜观察组织学变化。结果表明，牙周炎组在实验的第１、２、４和８周龈固有层均出现不同量的巨噬细胞，淋巴细胞和浆细胞，第４和８周时在骨吸收陷窝和骨髓腔内有大量破骨细胞，破骨细胞内含丰富的溶酶体，线粒体和粗面内质网；消炎痛治疗Ⅰ组（ＩＮＤ－１）牙周组织变化较Ｐ组减轻，成骨细胞增多；消炎痛治疗２组（ＩＮＤ－２）牙龈炎症和牙槽骨变化较ＩＮＤ－１组明显减轻，破骨细胞减少，成骨细胞增多；消炎痛治疗３组（ＩＮＤ－３）与ＩＮＤ－２组作用相似。提示在以后的研究中使用ＩＮＤ－２组剂量的消炎痛喂养豚鼠对牙周炎的抑制作用较好。     

脉冲Nd：YAG激光用于狗牙活髓切断术的实验研究

目的：观察脉冲Ｎｄ∶ＹＡＧ激光照射狗牙活髓切断术后断面的牙髓组织愈合情况。方法：动物分成３组，每组５个牙。一组对照，一组切髓后激光照射断面，条件４０Ｈｚ、６０ｍＪ（２．４Ｗ），另一组切髓后激光照射断面，条件为４０Ｈｚ、４０ｍＪ（１．６Ｗ）。各组均用盖髓剂盖髓。分别于３、１５、４５ｄ处死动物，组织切片光镜观察。结果：能量参数为４０Ｈｚ、６０ｍＪ（２．４Ｗ）、照射时间５ｓ的Ｎｄ∶ＹＡＧ激光对切髓术后牙髓组织具有良好的促进愈合作用，牙髓炎性反应小、牙本质桥形成良好。而能量参数为４０Ｈｚ、４０ｍＪ（１．６Ｗ）、照射时间１０ｓ的激光照射断髓面，对牙髓组织则产生不可逆转的损伤作用。结论：一定能量的Ｎｄ∶ＹＡＧ激光对切髓术有促进愈合作用。激光对牙髓组织的损伤程度更多取决于激光照射时间，而非输出功率。应用脉冲Ｎｄ∶ＹＡＧ激光切髓时，应严格控制照射时间     

冷光牙齿漂白技术对活髓牙牙髓影响的病理观察

目的 探讨冷光牙齿漂白技术对活髓牙牙髓的影响.方法 选择因正畸需要拔除的40颗活髓牙,对照组(10颗)不做任何处理拔除,其余30颗牙采用冷光漂白后分别即刻拔除(15颗)和漂白7 d后拔除(15颗).40颗牙齿均制作病理切片,镜下观察牙髓组织形态.结果 所有活髓牙漂白前后均未发现有任何临床症状.漂白后即刻拔除组、7 d后拔除组以及对照组在镜下均表现为正常的牙髓组织结构,与对照组相比漂白后即刻拔除组及7 d后拔除组牙髓组织均无明显改变.结论 冷光牙齿漂白技术对活髓牙牙髓无明显不良影响,是一项安全可靠的漂白技术.     

Beyond冷光牙齿漂白技术对人牙髓影响的组织病理学研究

目的 探讨Beyond冷光牙齿漂白技术对牙髓的影响.方法 选择因正畸要拔除的40颗活髓牙,对照组(10颗)不做任何处理拔除,其余30颗采用Beyond冷光漂白后分别即刻拔除(15颗)和漂白七天后拔除(15颗).40颗牙齿均制作病理切片,镜下观察牙髓组织形态.结果 所有活髓牙漂白前后均未发现有任何临床症状.漂白后即刻拔除组、七天后拔除组以及对照组在镜下均表现为正常的牙髓组织结构,漂白组较对照组牙髓组织无明显改变.结论 Beyond冷光牙齿漂白技术对活髓牙牙髓无明显不良影响,是一项安全可靠的漂白技术.     

固齿膏对豚鼠实验性牙周炎的抑制作用──组织学观察

选取豚鼠作实验，分为正常对照组（Ｎ）、牙周炎对照组（Ｐ组）、消炎痛对照组（ＩＮＤ组）和固齿膏治疗组（Ｇｕ组）四组，用光镜和电镜观察组织学变化。结果表明：Ｎ组和其它三组在实验开始时牙周组织基本正常；Ｐ组在２周时有大量淋巴细胞和巨噬细胞浸润，牙槽骨开始出现吸收现象，４周时骨吸收明显，有大量破骨细胞，其中含丰富的溶酶体、线粒体和粗面内质网，成骨细胞少且合成蛋白的能力降低；Ｇｕ组和ＩＮＤ组变化较Ｐ组小，破骨细胞较少，破骨能力降低，而成骨细胞较多，且成骨能力增强。提示固齿膏和消炎痛都有抑制豚鼠实验性牙周炎的作用。     

先有反复的机构创伤后与边缘性牙周炎协同对猴牙周组织的影响

本实验以成年恒河猴为实验动物其目的：（１）观察创伤先于炎症时，协同破坏因素理论的意义；（２）单纯创伤对牙周组织的影响。结果提示：（１）尽管创伤先于炎症作用，协同破坏因素并未产和更多的软组织附着水平丧失，也不改变炎症播散途径，肝下袋，但可产生更多的牙槽骨丧失；（２）单纯创伤不引起牙周炎，不产生牙周袋，可引起牙槽骨破坏。     

切牙髓腔近远中径的测定

本研究对８０例１５～８０岁正常人作切牙组ｘ线摄片。经定点测量后，统计显示，颈部髓腔宽１７ｍｍ，根中１／２处髓腔宽１．０ｍｍ，距根尖０．５ｍｍ处髓腔宽０．１７ｍｍ。颈部髓腔宽１．４ｍｍ，根中１／２处髓腔宽０．８ｍｍ，距根尖０．５ｍｍ处髓腔宽０．１１ｍｍ。颈部髓腔宽０．７ｍｍ，根中１／２处髓腔宽０．４ｍｍ，距根尖０．５ｍｍ处髓腔宽０．０９ｍｍ。颈部髓腔宽０．９ｍｍ，根中１／２处髓腔宽０．４ｍｍ，距根尖０．５ｍｍ处髓腔宽０．０８ｍｍ。本文对其结果进行了应用性讨论。     

内漂白致牙颈部外吸收的研究

无髓牙变色影响美观，需得到有效的治疗，内漂白是治疗无髓变色牙的主要方法之一，但近年来不断有内漂白后出现牙颈部外吸收的报道，对此，人们进行了深入的研究，成为有关无髓变色牙漂白的一个活跃的研究课题，本文对内漂白常用漂白剂的毒性，内漂白后牙颈部外吸收的发生机理及其防治作一综述。     

Invasive cervical resorption: an analysis of potential predisposing factors.

OBJECTIVE: An investigation was undertaken to assess potential predisposing factors to invasive cervical resorption. METHOD AND MATERIALS: A group of 222 patients with a total of 257 teeth displaying varying degrees of invasive cervical resorption were analyzed. Potential predisposing factors, including trauma, intracoronal bleaching, surgery, orthodontics, periodontal root scaling or planing, bruxism, delayed eruption, developmental defects, and restorations were assessed from the patients' history and oral examination. RESULTS: Of the potential predisposing factors identified, orthodontics was the most common sole factor, constituting 21.2% of patients and 24.1% of teeth examined. Other factors were present in an additional 5.0% of orthodontically treated patients (4.3% of teeth), and these consisted principally of trauma and/or intracoronal bleaching. Trauma was the second most frequent sole factor (14.0% of patients and 15.1% of teeth). Trauma in combination with intracoronal bleaching, orthodontics, or delayed eruption constituted an additional 11.2% of patients (10.6% of teeth). Intracoronal bleaching was found to be the sole potential predisposing factor in 4.5% of patients and 3.9% of teeth, and an additional 10.4% of patients and 9.7% of teeth showed a combination of intracoronal bleaching with trauma and/or orthodontics. Surgery, particularly involving the cementoenamel junction area, was a sole potential predisposing factor in 6.3% of patients and 5.4% of teeth. Periodontal therapy, including deep root scaling and planing, showed a low incidence, as did other factors, such as bruxism and developmental defects. The presence of an intracoronal restoration was the only identifiable factor in 15.3% of patients and 14.4% of teeth, while 15.0% of patients and 16.4% of teeth showed no identifiable potential pedisposing factors. CONCLUSION: These results indicated a strong association between invasive cervical resorption and orthodontic treatment, trauma, and intracoronal bleaching, either alone or in combination.     

The management of postbleaching cervical resorption

Cervical resorption has been repeatedly associated with intracoronal bleaching procedures. This report reviews literature associated with postbleaching resorption, a case, and a rationale for management. We observed cervical resorption upon recall of an intracoronal bleaching case. It was successfully treated with a calcium hydroxide "recalcification" procedure. Twenty-three months later, no further resorption has been observed.     

Efficacy of intracoronal bleaching techniques with different light activation sources

AIM: To evaluate ex vivo the efficacy of 35% hydrogen peroxide for intracoronal bleaching when activated by LEDs, halogen lamp or by the walking bleach technique. METHODOLOGY: Forty extracted human maxillary central incisors had their crowns resected 1 mm below the amelo-cemental junction and were submitted to artificial staining in centrifuged rat haemolysed blood. A 2-mm thick glass ionomer cervical plug was placed inside the canal, at the level of the amelo-cemental junction. Samples were divided randomly into five groups: group I received 35% hydrogen peroxide gel activated by LEDs. Group II received 35% hydrogen peroxide gel activated by a halogen lamp-based light curing unit. Group III received 35% hydrogen peroxide gel followed by the walking bleach technique. Group IV was neither artificially stained nor bleached (positive control) and group V was stained, but not bleached (negative control). The shade of the teeth was assessed visually by three independent and calibrated evaluators, before and after bleaching. The results were analysed using Kruskal-Wallis one-way analysis of variance and Dunn's post-test. RESULTS: No statistical differences regarding sample shades were found amongst groups for the tested internal bleaching techniques (P > 0.05). CONCLUSIONS: Hydrogen peroxide for intracoronal bleaching when activated either by LEDs, halogen lamp or by the walking bleach technique presented similar efficacy.     

漂白剂对牙颈部硬组织影响的扫描电镜研究

目的：观察漂白剂直接作用于牙颈部后牙的结构变化。方法：选用几种不同的漂白剂，直接作用于牙颈部，应用扫描电镜观察漂白剂引起的牙本质、釉质、牙骨质的结构变化。结果：牙颈部的牙骨质、牙本质均有结构上改变，釉质变化不明显。结论：提出预防牙颈部外吸收的措施，使临床上能安全、有效地应用漂白技术     

冠内漂白对牙龈组织自由基含量的影响

目的：对狗牙冠内经３０％过氧化氢液漂白后，研究其牙龈组织中超氧化物歧化酶（ｓｕ－ｐｅｒｏｘｉｄｅｄｉｓｍｕｔａｓｅ，ＳＯＤ）、丙二醛（ｍａｌｏｎｄｉａｌｄｅｈｙｄｅ，ＭＤＡ）的含量变化。方法：用光化学扩增法测定ＳＯＤ；用硫代巴比妥酸比色法测定ＭＤＡ。结果：随漂白时间延长，ＳＯＤ含量逐渐下降，ＭＤＡ含量则逐渐增加，支持氧自由基的损伤机制。结论：冠内漂白引起牙龈组织中自由基含量增加，可损伤牙周组织。这种损伤可能是短暂的，也可能转变为慢性局部刺激因素，与其它因素协同作用，导致牙颈部外吸收     

Histological characterization of bleaching-induced external root resorption in dogs.

External root resorption occasionally develops after intracoronal bleaching with hydrogen peroxide. In this study, an experimental model was established to study thermocatalytic bleaching-induced root resorption in dogs. Histological examination after 6 months revealed that 18% of the teeth had root resorption lesions. The lesions could be divided into three types. In type I, root excavations were associated with a dense inflammatory cell infiltrate. Type II lesions were characterized by granulation tissue formation. In type III, the lesions were filled with reparative cementum. The three types probably represent different phases of one process. Calcium hydroxide had no effect on the occurrence or type of resorption. The instability of hydrogen peroxide and the presence of inflammatory resorption lesions 6 months postoperatively suggest hydrogen peroxide-induced toxic radicals or denaturants as potential irritants.     

Radicular penetration of hydrogen peroxide during intra-coronal bleaching with various forms of sodium perborate

The development of external cervical root resorption following internal bleaching of discoloured pulpless teeth is associated with the use of hydrogen peroxide. The aim of the study was to determine radicular penetration of hydrogen peroxide following intracoronal bleaching with various forms of sodium perborate, 63 extracted human incisors were root filled and stained artificially. Standardized cementum defects were created on the mesial and distal aspects of the root directly below the cemento-enamel junction (CEJ). Using the walking bleach technique all teeth were bleached for a 6-day period, with replacement of the bleaching paste after days 1 and 3. Sodium perborate monohydrate (MH), trihydrate (TRH) or tetrahydrate (TH) was mixed with H₂O₂ or H₂O and subsequently placed intracoronatly 1 mm below the labial CEJ. The teeth were divided into six groups:

• I. MH + H₂O₂(30%)(n=12);
• II. TRH + H₂O₂(30%)(n=12);
• III. TH + H₂O₂(30%)(n=12);
• IV. TH + H₂O(n=12);
• V. TH + H₂O gel(n=12);
• VI. no bleaching paste (n= 3).

At baseline and at days 1, 3 and 6 the amount of H₂O₂ taken up from the surrounding medium of each root was indirectly recorded and calculated as p.p.m. Almost all teeth of the experimental groups showed leakage of hydrogen peroxide compared to those of the control group. The radicular penetration of hydrogen peroxide was significantly higher in teeth of groups I and III than in those of groups IV and V (P≤ 0.001). In conclusion, the amount of hydrogen peroxide leakage depends, among other factors, on the form of sodium perborate used. The risk of post-bleaching cervical root resorption may be diminished by using sodium perborate tetrahydrate in conjunction with H₂O.     

Effect of cervical coating of ethyl cellulose polymer and metacrylic acid copolymer on the radicular penetration of hydrogen peroxide during bleaching

Abstract Extraradicular leakage of oxidizing agents during bleaching is an undesirable event and thus need to be prevented. The effect of external cervical coating of ethyl cellulose (EC) and metacrylic acid copolymer (MAC) on the radicular penetration of hydrogen peroxide during intracoronal bleaching was examined. Single rooted human premolars extracted for orthodontic reasons were used. The cementum covering the cemento-enamel junction was mechanically removed and the teeth treated endo-dontically and bleached with 30% hydrogen peroxide. Radicular hydrogen peroxide penetration was measured before coating the teeth and after applications of 1–3 layers of EC or 3 layers of MAC external cervical coatings. It was found that the radicular penetration of 30% hydrogen peroxide was related to the number of layers of cervical EC coatings. Application of one layer of EC did not reduce the hydrogen peroxide penetration. Two and three layers of EC reduced the hydrogen peroxide penetration by 38% and 85% respectively. Three layers of MAC reduced the radicular hydrogen peroxide penetration in 83%. Statistically, a highly significant difference was found between the teeth coated with three layers of either EC or MAC and the noncoated teeth (p< 0.001). It was concluded that application of ethyl cellulose or metacrylic acid copolymer to exposed cervical root surfaces may effectively prevent extraradicular leakage of bleaching agents.     

Effect of cervical coating of ethyl cellulose polymer and metacrylic acid copolymer on the radicular penetration of hydrogen peroxide during bleaching.

Extraradicular leakage of oxidizing agents during bleaching is an undesirable event and thus need to be prevented. The effect of external cervical coating of ethyl cellulose (EC) and metacrylic acid copolymer (MAC) on the radicular penetration of hydrogen peroxide during intracoronal bleaching was examined. Single rooted human premolars extracted for orthodontic reasons were used. The cementum covering the cemento-enamel junction was mechanically removed and the teeth treated endodontically and bleached with 30% hydrogen peroxide. Radicular hydrogen peroxide penetration was measured before coating the teeth and after applications of 1-3 layers of EC or 3 layers of MAC external cervical coatings. It was found that the radicular penetration of 30% hydrogen peroxide was related to the number of layers of cervical EC coatings. Application of one layer of EC did not reduce the hydrogen peroxide penetration. Two and three layers of EC reduced the hydrogen peroxide penetration by 38% and 85% respectively. Three layers of MAC reduced the radicular hydrogen peroxide penetration in 83%. Statistically, a highly significant difference was found between the teeth coated with three layers of either EC or MAC and the noncoated teeth (p < 0.001). It was concluded that application of ethyl cellulose or metacrylic acid copolymer to exposed cervical root surfaces may effectively prevent extraradicular leakage of bleaching agents.     

Invasive cervical resorption: clinical and radiological diagnosis and treatment of 3 cases

Invasive cervical resorption is a relatively uncommon form of external root resorption. Etiologic factors include trauma, orthodontic treatment, intracoronal bleaching, and inflammation, but invasive cervical resorption is often idiopathic. There may be no external signs of this disorder, and the resorptive lesion is often detected by routine radiographic examination. This article describes the clinical and radiological diagnoses and treatment modalities of invasive cervical resorption in 3 patients. Two of the 3 cases were incidental radiographic findings and the teeth concerned were symptom free. One case was symptomatic due to periodontal infection. Computed tomography (CT) evaluation was performed in the 2 symptom-free patients. Thus, exact size and localization of the resorptive lesions were obtained. In 2 cases, root canal treatment was performed, and in the other case the resorptive defect was sealed with mineral trioxide aggregate.