术前放疗对游离皮瓣影响的实验研究

本实验选用成年新西兰白兔２４只作单侧兔耳术前放疗，剂量分别为７Ｇｙ×４（Ⅰ组）、９Ｇｙ×４（Ⅱ组）及１１Ｇｙ×４（Ⅲ组），放疗后３周行双侧耳背皮瓣游离移植术（左右换位）．术后观察皮瓣的变化及成活情况，并于术后不同时期作光镜及电镜组织学观察，并行血管铸型标本制作及扫描电镜下形态计量分析．结果显示：Ⅰ组的皮瓣成活率为７５％（６／８），Ⅱ组为６２．５％（５／８），Ⅲ组为３７．５％（３／８）．光镜显示成活皮瓣存在上皮、皮肤附件及皮下组织明显萎缩现象，电镜下核固缩、胶原纤维水肿、基底膜不完整等表现可持续至术后１年以后，血管铸型标本中发现Ⅲ组血管密度明显低于Ⅱ组     

Gluma脱敏剂治疗活髓牙全冠牙体预备后敏感症的临床疗效和扫描电镜观察

目的:探讨Gluma脱敏剂治疗金属烤瓷全冠牙体预备后敏感症的疗效及作用机理。方法:自身配对设计将15例62颗患牙随机分为Gluma治疗组和空白对照组,可视分级评价法(visualanalogscale,VAS)评价其临床疗效;制作离体牙标本,扫描电镜观察Gluma脱敏剂对牙本质小管的封闭作用。结果:Gluma脱敏剂治疗后VAS值(3.43±1.49)与治疗前(6.20±1.20)、对照组治疗后(5.87±1.47)均有显著差异(P<0.05),有效率83.87%;牙本质小管被封闭,表面均匀平整。结论:Gluma脱敏剂能缓解活髓牙全冠备牙后的敏感症状。     

即刻桩腔预备对三种根管预备方法预备的直根管根尖封闭性的影响

目的 研究三种不同根管预备方法根管预备、根管充填后即刺桩腔预备对直根管根尖封闭性的影响.方法 离体直单根管上前牙124个,其中120个随机平均分为3组(n=40),A组:不锈钢根管锉常规法;B组:G 型钻根管冠部预处理 不锈钢根管锉常规法;C组:手用Pr01raper镍钛根管锉冠向下法,刺余4个随机平均分为阴性对照组和阳性对照组.所有根管均用侧方加压法充填,即刻手持垂直加压器去除部分充填材料,然后P型钻桩腔预备.用染料渗透法评价各组根尖封闭能力.结果 B组G型钻根管冠部预处理 不锈钢根管锉常规法预备的根管和C组手用ProTaper镍钛根管锉冠向下法预备的根管即刻桩腔预备后,其根尖微渗漏较A组常规法预备的轻(P<0.05).结论 大锥度根管预备,根管充填后即刻桩腔预备的根尖封闭性较好.     

A proposal for a new classification of lesions of exposed tooth surfaces

In the presence of improved methods of identification and treatment of lesions on the exposed surfaces of teeth, it should now be acknowledged that the GV Black "classification of carious cavities" is out of date. This paper describes a new system, proposed in 1997, discussed broadly throughout the profession, and eventually modified. The system has been adopted in several regions around the world as being a useful corollary to the current developing concept of minimal intervention dentistry. It is now desirable to adopt a new approach to the identification and recording of the lesions caused by both caries and non-carious tooth loss. A major advantage arising from its adoption would be that it would encourage the profession to minimise the amount of normal healthy tooth structure that is often sacrificed in pursuit of the cavity designs as suggested by Black. The authors are members of a Project Group of the FDI Science Committee, and this paper explains the concept and offers justification for the adoption of the system.     

SEM evaluation of canal wall dentine following use of Mtwo and ProTaper NiTi rotary instruments

AIM: To compare using scanning electron microscopy (SEM) root canal walls following instrumentation in vitro with two different rotary NiTi instruments. The hypothesis was that no difference should be observable between the experimental groups in terms of debris on canal walls and surface morphology. METHODOLOGY: Twenty-four single-rooted human teeth were selected. Two types of NiTi instruments were used, Mtwo (Sweden & Martina, Padova, Italy) and ProTaper (Dentsply Maillefer, Ballaigues, Switzerland). Irrigation for both groups was performed after each instrument change with 5% NaOCl, 3% H2O2 and 17% EDTA solutions. Three different areas (coronal, middle and apical thirds) of the root canal were evaluated using SEM. The canal wall of each sample was assessed and compared using a predefined scale of four parameters, namely, smear layer, pulpal debris, inorganic dentine debris, surface profile. Data were analysed statistically using the Kruskal-Wallis test (anova). RESULTS: A statistically significant difference (P < 0.01) was found between the apical third and the middle and coronal thirds for both groups. No difference was observable between instrumentation groups. In the apical third canal walls were often contaminated by inorganic debris and by smear layer. In the apical third, the surface profile was affected by uninstrumented regions, comprising dentine depressions and grooves in which predentine was still visible. CONCLUSION: Both instruments produced a clean and debris-free dentine surfaces in the coronal and middle thirds, but were unable to produce a dentine surfaces free from smear layer and debris in the apical third. The presence of deep grooves and depression on dentine walls in the apical third may well explain the presence of less-instrumented areas.     

IN VITRO EVALUATION OF ROOT CANAL PREPARATION USING OSCILLATORY AND ROTARY SYSTEMS IN FLATTENED ROOT CANALS

Objective:

The aim of this study was to evaluate the biomechanical preparation of flattened root canals using the following systems: Endo-Eze AET stainless steel oscillatory instruments (Ultradent) and RaCe rotary NiTi instruments (FKG Dentaire).

Materials and Methods:

Twenty extracted human mandibular incisors were randomly assigned to two groups: Group 1 - Instrumentation with oscillatory Endo-Eze AET files (oscillatory technique); Group 2 - Instrumentation with rotary NiTi RaCe files (rotary technique). The teeth were decoronated, had their apices and coronal openingssealed with sticky wax and were embedded in crystal-clear orthophtalic polyester resin. The roots were sectioned transversally with diamond discs at 10 mm (middle third) and 5 mm (apical third) from the apex and the segments were reassembled for instrumentation. The sections were photographed before and after root canal instrumentation and evaluated with respect to whether the original root canal shape was modified by instrumentation. To evaluate the differences in the root canal shape before and after biomechanical preparation, scores were given regarding the instruments touch on the intracanal walls.

Results:

In middle third of the root canals instrumented with the rotary system, there was a change in the original canal anatomy (p<0.05), with formation of a protuberance in the mesiodistal direction. This protuberance did not occur when the oscillatory instrumentation was used. The oscillatory system had better results in the middle and apical thirds as evaluated by Dunn’s multiple-comparison test (p>0.05).

Conclusion:

Under the tested conditions, Endo-Eze oscillatory system yielded the instrumentation of all flattened root canal walls, maintaining the canal original shape throughout the biomechanical preparation, and was more effective than RaCe rotary system.     

根管锥度和循环疲劳对牙根力学性能的影响

目的：分析根管预备锥度和循环疲劳对离体牙根力学性能的影响。方法：将32颗离体下颌第一前磨牙随机分成4组,每组8颗牙齿,截冠后将每组的牙根分别预备成0.02、0.04、0.06、0.08锥度,使用侧方加压充填根管。随后每组中随机抽取4颗牙根做循环疲劳实验,疲劳前后均做扫描电镜观察牙根表面形态,最后对所有牙根进行抗压强度测试。结果：各锥度组随锥度的增大牙根抗压强度值有降低趋势,但无统计学差异（P〉0.05）;疲劳实验后0.08锥度牙根表面裂纹明显多于疲劳前,疲劳实验中实验组和对照组两组离体牙根抗压强度值无统计学差异（P〉0.05）;且疲劳和锥度两因素之间没有交互作用（P〉0.05）。结论：根管预备后锥度在0.08以内对牙根的整体抗压性能和抗疲劳性能无明显影响。     

CLEANING ABILITY OF CHLORHEXIDINE GEL AND SODIUM HYPOCHLORITE ASSOCIATED OR NOT WITH EDTA AS ROOT CANAL IRRIGANTS: A SCANNING ELECTRON MICROSCOPY STUDY

The aim of this study was to evaluate the cleaning efficacy of 2% chlorhexidine gluconate gel (CHX) compared to 2.5% sodium hypochlorite solution (NaOCl) associated or not with 17% EDTA used as irrigants during the biomechanical preparation. Fifty freshly extracted single-rooted human teeth with complete apex formation were randomly divided into five groups: G1 - sterile saline, G2 - 2.5% NaOCl, G3 - 2% CHX, G4 - 2.5% NaOCl + EDTA and G5 - 2% CHX + EDTA. The specimens of G1 were subdivided into two control groups. The teeth were decoronated and the coronal and middle root thirds were prepared with Gates-Glidden burs, and the apical third was reserved to manual instrumentation. All procedures were performed by a single operator. In all groups, 2 mL of irrigant was delivered between each file change. The teeth were sectioned and prepared for analyses under scanning electron microscopy (SEM). SEM micrographs were graded according to a score scale by two examiners. Data were analyzed statistically by Kruskal-Wallis and Dunn tests at 1% significance level. The best results were obtained in the groups in which the irrigant was used followed by the chelating agent. No statistically significant difference was observed among G4, G5 and the positive control group (p<0.01). The groups G2 and G3 were significantly different from the others, presenting the worst cleaning capacity. In conclusion, the use of the chelating agent is necessary to obtain clean canal walls, with open tubules and no heavy debris. The use of 2% chlorhexidine gluconate gel alone is not able to remove the smear layer.     

Non-surgical root canal treatment of Dens invaginatus: reports of three cases

Dens invaginatus is a rare developmental malformation of teeth showing a deep infolding of enamel and dentine which may extend deep into the root. To date, conventional root canal therapy, endodontic surgery and extraction have been reported as treatment modalities, when the pulpo-dentinal complex of such teeth is affected. In the present report, non-surgical endodontic treatment of three maxillary lateral incisors with invaginatus (DI) is discussed. The Tri Auto ZX rotary system was used for shaping the root canals of two affected teeth and the Profile system was used in the third. Teeth with periradicular lesions received calcium hydroxide as an interim therapy. Two teeth were obturated with gutta percha points and AH Plus sealer using cold lateral compaction. In the third case, obturation was accomplished using a coated carrier system (Thermafil) due to the specific shape of the root canal system. Twelve months postoperatively all teeth were asymptomatic with resolution of the periapical radiolucency on two affected teeth, as confirmed radiographically. Healing was achieved without any need for further surgical intervention.     

Influence of preparation design and spacing parameters on the risk of chipping of crowns made with Cerec Bluecam before cementation

Purpose

To evaluate the influence of the preparation design and spacing parameters on the risk of chipping of crowns made by CEREC Bluecam before cementation.