二氧化氯冲洗根管清洁效果的扫描电镜观察

目的:评价二氧化氯(ClO2)用于根管冲洗的清洁效果.方法:选择30个离体单根管前磨牙,截去牙冠后随机平分成6组(SA、SB、SC、UA、UB、UC),采用逐步后退法进行根管预备,前3组用注射器冲洗根管,冲洗剂分别为3%H2O2 0.9%NaCl、1%次氯酸钠(NaClO)和0.1%ClO2;后3组用超声波冲洗,冲洗剂分别用蒸馏水、1%NaClO和0.1%ClO2.完成根管预备后纵行劈开牙根,扫描电镜观察,记录电镜照片上根管颈1/3、中1/3、尖1/3各部位的碎屑和玷污层情况,进行统计学分析.结果:使用注射器冲洗者,碎屑和玷污层记分SC组均明显低于SA组(P＜0.05),与SB组无显著性差异(p＞0.05);用超声波冲洗者,碎屑记分3组之间无显著性差异(P＞0.05),玷污层记分UC组显著低于UA组(p＜0.05),与UB组无显著性差异(P＞0.05).结论:0.1%ClO2可用于根管冲洗,对碎屑和玷污层的清除效果优于3%H2O2 0.9%NaCl,与1%NaClO无明显不同,联合超声波冲洗效果更好.     

Internal root resorption studied by radiography, stereomicroscope, scanning electron microscope and computerized 3D reconstructive method

Abstract –  Aim and methology : Two cases of internal tooth resorption were examined. A mandibular premolar and a mandibular canine were studied after they were extracted using radiographs, a stereomicroscope (SM) and a scanning electron microscope (SEM). Lastly, 3D images of the sectioned teeth were obtained(3D).
Results : Radiographically, internal root resorption was shown as a uniform radiolucency. By SM examination, an extensive destruction of dentin was seen, while, by SEM examination, a disappearance of dentinal tubules was clear. The 3D reconstructive method revealed a circumscribed, oval-shaped defect that did not perforate the cemental layer.
Conclusions : Internal root resorption is a rare remodeling process that can be studied using different experimental methods.     

Cervical external root resorption in vital teeth

External resorptions associated with inflammation in marginal tissues present a difficult clinical situation. Many times, lesions are misdiagnosed and confused with caries and internal resorptions. As a result inappropriate treatment is often initiated. This paper provides three-dimensional representations of cervical external resorption, based on X-ray microfocus-tomographical scanning of a case, which will aid the dental practitioner in recognizing characteristic features during clinical inspection. In addition, histopathological examination reveals the cellular morphology of the adjacent tissues.     

下颌第三磨牙长距离近中移动后牙根吸收的研究

目的 通过对拔除下颌第一磨牙病例的回顾性研究,探讨第三磨牙在长距离近中移动后其牙根的吸收情况,同时比较第三磨牙牙根发育完成与否对牙根吸收的影响。方法 回顾性分析32例拔除下颌第一磨牙的病例,共41颗下颌第三磨牙。根据第三磨牙牙根的发育情况,分为A组(发育完成组)和B组(未发育完成组),采用直接数字化全景片测量矫治前后下颌第三磨牙牙根的长度,研究不同发育阶段的第三磨牙在长距离近中移动后其牙根的变化。结果 A组第三磨牙在长距离近中移动后,近远中牙根分别吸收(0.07±0.66) mm、(0.09±0.62) mm,差异没有统计学意义(P>0.05);B组第三磨牙牙根继续发育,矫治结束后长度增加,差异具有统计学意义(P<0.05);B组较A组下颌磨牙近中移动距离大,差异具有统计学意义(P<0.05)。矫治结束后A组、B组近中牙根长度差异没有统计学意义(P>0.05),但远中牙根B组较A组长,差异具有统计学意义(P<0.05)。结论 下颌第三磨牙长距离近中移动后,其牙根的吸收量较小,不具备临床意义,牙根发育情况对远中牙根存在一定影响,提示临床中磨牙缺失后要在第三磨...     

A new method for volumetric measurement of orthodontically induced root resorption craters

This method was designed to quantify root resorption on human premolar root surfaces induced by orthodontic forces by volume. Light (25 g) or heavy (225 g) orthodontic forces were applied to 20 first maxillary premolars in 10 human subjects. The contralateral teeth of the subjects served as controls. All teeth were extracted after 28 d of experimentation and prepared for imaging. A pair of stereo scanning electron microscopy (SEM) images (+/-3 degrees ) of resorption craters was captured and imported into an image analysis software package. The images were aligned and grayscale depth maps of the craters were generated. Correction for errors due to residual tilt and curvature of the cementum surface using shading correction was performed. Thresholding was used to obtain a measure of both the cementum surface height and the average depth of the crater. The depth of the crater was the difference in these values. Crater volumes were obtained by multiplication of the average of this difference by area of the crater. Calibration of this volumetric measurement against standardized calculated known volumes on metallic rods showed good accuracy and reproducibility. In the experimental teeth, heavy forces caused threefold more resorption than light forces (P < 0.01). There was also more root resorption evident in the experimental teeth compared with the control teeth in both the light and heavy force groups.     

手用ProTaper镍钛器械根管清理效果的扫描电镜研究

目的评价新型镍钛根管预备器械——手用ProTaper预备后牙根管的效果。方法选择因正畸治疗而拔除的成对上颌前磨牙20对共40个,随机分为2组进行根管预备。A组为实验组,采用手用ProTaper和冠根向深入法预备根管;B组为对照组,采用镍钛手用K锉Nitiflex和平衡力技术预备根管;记录根管预备时间。纵剖根管后,扫描电镜下观察根尖段、根中段、根管口段的碎屑和玷污层。结果在根尖和根中段,A组的碎屑和玷污层均较B组少,差异具有显著性意义(P<0.05)。在根管口段,两组间无显著性差异(P>0.05)。两组间根管预备时间无统计学差异(P>0.05)。结论手用ProTaper镍钛器械配合有效的冲洗液,具有良好的根管清理效果,是值得推广的新型手用根管预备技术。     

异常牙根形态对正畸治疗前后前牙根吸收的影响

目的 调查异常牙根形态在正畸治疗前后对牙根吸收的影响。方法 随机选择经直丝弓矫治技术完成的病例153例,分析患者治疗前后的全口曲面断层片,将前牙按根形态分为正常组、短根组、钝根组、弯根尖组及滴管状根组5组,以Levander和Malmgren的牙根吸收分级法记录每个前牙牙根根吸收程度,将牙根根吸收程度及其改变的频数进行统计分析。结果 前牙中异常根形态的发生率为16.92%,以弯根尖与钝根最为常见;根形态异常组与正常组的根吸收均值间在正畸治疗前有显著性差异（P<0.05）,正畸治疗后亦有显著性差异（P<0.01）,其中短根组根吸收值最高,其次为滴管状根组;根形态异常组在正畸治疗前后的根吸收发生率均较正常组高,差异有显著性（P<0.01）。结论 异常牙根形态能显著增加牙根吸收的发生率和严重程度。     

Ultrastructural morphologic pattern in the roots of deciduous teeth in different stages of physiologic resorption

AimThis study was conducted to assess the ultrastructural morphological pattern of resorption in the hard tissues of the root of deciduous teeth at different stages of resorption.Material and methods35 extracted deciduous teeth in different stages of resorption were collected. Standardized photos of the teeth were taken from all the aspects. The remaining root length (RRL) as described by the distance between the trough of the cervical line and the deepest point of resorption on the root surface was measured. Teeth were grouped into 4 groups based on the RRL. After surface preparation, the teeth were mounted in clear self cured acrylic. The teeth were then analysed for the ultrastructural morphology in different of stages of physiologic resorption using Smart SEM Version 5.05, Carl Zeiss NTS Ltd, Germany.ResultsUltrastructurally stage 1 is characterized by the presence of individual isolated resorption craters in the apical region. They however increase in the number in the furcal region. As the process continues further along the different stages, these craters deepen, which at higher magnifications shows the lacunae housing the odontoclasts following a linear path of resorption. The pattern clearly describes single large odontoclast leading the path of resorption with other odontoclasts following the path in linear manner.ConclusionThe cellular and ultrastructural changes are affected by the stages of resorption and each stage have the characteristic features that depict the resorptive process.Clinical significanceThis study provides the knowledge of comprehensive morphologic pattern which is characteristic of each stage of physiologic resorption.     

根管治疗中应用Nd:YAG 激光的扫描电镜观察

目的 探讨Nd：YAG激光在根管治疗中的应用。方法 选用28个离体单根牙，随机分为4组。对照组不做处理。常规组进行根管扩大和根管冲洗，激光组经根管扩大后，用Nd：YAG激光1．5W，20pps分别照射15s和30s，并用扫描电镜观察。结果 激光照射15s组玷污层被去除，牙本质小管封闭和半封闭。激光照射30s组牙本质过分熔融，牙本质小管口开放。结论 Nd：YAG激光在根管治疗中的应用是可行的。     

Meta analysis of the treatment-related factors of external apical root resorption

OBJECTIVE: To elucidate possible treatment-related etiological factors--such as, duration of treatment and apical displacement--for external root resorption. DESIGN: Meta-analysis of the available English-language literature. INCLUSION & EXCLUSION CRITERIA: Papers with a sample size > 10, fixed appliances, pre- and post-operative radiographs, and apical displacement recorded were included. History of trauma, prior root resorption and endodontic treatment were excluded. Appropriateness of these selections was tested with a 'funnel plot' analysis. OUTCOME MEASURE: Correlations between root resorption, apical displacement, and treatment duration. RESULTS: Mean apical root resorption was strongly correlated with total apical displacement (r = 0.822) and treatment duration (r = 0.852). CONCLUSION: The treatment-related causes of root resorption appear to be the total distance the apex had moved and the time it took.     

Prevalence of different periapical lesions associated with human teeth and their correlation with the presence and extension of apical external root resorption

AIM: The aim of this study was to determine the prevalence of various periapical pathologies and their association with the presence and extent of apical external inflammatory root resorption in human teeth. METHODOLOGY: One hundred and four root apices from extracted teeth with periapical lesions were examined. Semi-serial sections of soft tissue lesions were stained with HE. The lesions were classified as noncystic or cystic, each with different degrees of acute inflammation: 0, 1, 2 and 3, increasing in severity. The root apices were analysed by SEM. External root resorption was classified according to site, as periforaminal or foraminal, and the extension of the resorbed area graded in increasing area as 0, 1, 2 or 3. RESULTS: Cysts accounted for 24.5% of the samples, 84% of which were associated with marked inflammation. The most prevalent diagnosis was noncystic periapical abscess with varying degrees of severity (63.7%). Periapical granuloma was not a frequent finding. SEM analysis showed that 42.2% of the root apices had periforaminal resorption extending over 50% of their circumference. When the foraminal resorption was evaluated, 28.7% had resorption affecting >50% of the periphery. Only 8.9% of the samples showed no periforaminal or foraminal resorption. CONCLUSIONS: In the sample of extracted teeth investigated, 24.5% of the periapical lesions were cysts. Most periapical lesions (84.3%) displayed acute inflammation, whether cystic or not. Periforaminal resorption was present in 87.3% of the cases, and foraminal resorption in 83.2%. Periforaminal and foraminal resorptions were independent entities. There was no association between external root resorption and the nature of the periapical lesions.     

External root resorption in patients with secondary bone-grafting of alveolar clefts

Abstract External root resorption as a complication to bone grading of alveolar clefts is described and a treatment procedure evaluated. The root resorption was related to possible etiologic factors. In this study a total of 419 cleft sides in 354 patients were treated with iliac bone grafting. External dental root resorption was diagnosed radiographically in 16 teeth. Thirteen of these teeth were treated at the Dental Faculty, University of Oslo. The treatment procedure was a combination of enclodontic treatment and a surgical flap operation to remove granulation tissue in the resorptive defect. Non-zinc silver amalgam was used for the restoration of the defects. Arrest of the lesions was achieved in 11 teeth, evaluated 18–36 months post-operatively. The resorption described is progressive in nature and shows a characteristic localization in the cervical area of the tooth.     

三种根管封闭剂根管封闭性能的实验研究

目的：比较三种根管封闭剂的根管封闭能力。方法：选择103颗单根离体牙,根管预备后随机分为3组,分别用AH-plus根管封闭剂＋牙胶（A组）、Cortisomol根管封闭剂＋牙胶（B组）、EndoREZ双固化UDMA树脂根管封闭剂＋牙胶（C组）侧方加压法充填根管,扫描电镜观察封闭剂与根管结合情况,并进行染色法微渗漏实验,观察3、7、30d染色线长度。结果：扫描电镜下观察,树脂类封闭剂与根管壁结合紧密,染色法发现Cortisomol组染色3、7、30d较其它两组微渗漏值高,3、7d无显著性差异（P〉0．05）,30d时有显著性差异（P〈0．05）。结论：树脂类根管封闭剂根管封闭性能较好。     

Root resorption and its association with alterations in physical properties, mineral contents and resorption craters in human premolars following application of light and heavy controlled orthodontic forces

OBJECTIVES: To study the effect of different orthodontic force levels on cementum, investigating from the point of view of its physical properties, alterations in the mineral components, type and location of the resorption craters and the exploration in 3D of space. DESIGN: In vivo human premolars subjected to heavy and light forces were employed for this study. After a period of movement they were analyzed for hardness and elasticity. Also, the mineral composition measuring Ca, P and F of the cementum root surface was investigated. A new method for volumetric analysis of resorption craters was developed. RESULTS: There were no significant differences for hardness and elastic modulus between the light and heavy force groups and no significant effects for different tooth positions. Significant inter-individual variation in the Ca, P and F concentrations was noted. Force-related data showed that mean volume of the resorption crater in light-force group was 3.49-fold greater than the control group, and the heavy-force group 11.59-fold more than control group. The heavy force group had 3.31-fold greater total resorption volume then light force group. Buccal cervical and lingual apical regions demonstrated significantly more resorption craters than the other regions. The 2D measurements were strongly correlated to 3D measurements. CONCLUSION: The application of light and heavy forces did not show any statistically significant differences in hardness and elastic modulus when compared with untreated teeth. The inconsistent increase or decrease of Ca, P and F contents between control and experimental teeth at sites of compression and tension were difficult to explain. There was more resorption by volume in the heavy force group as compared with the light group and controls. Our data also suggested that the high-pressure zones might be more susceptible to resorption after 28 days of force application.     

釉质酸蚀后牙面脱矿与再矿化的扫描电镜观察

目的:观察牙釉质酸蚀后在离体状态下和一段时间内在口腔环境中的结构变化,探讨牙釉质脱矿与再矿化的形态学改变.方法:选择因正畸需要拔除健康第一前磨牙病例10例,40个牙,使用YY0269-1995型酸蚀剂对拟拔除的第一前磨牙颊侧釉质酸蚀60 8,左侧上、下颌第一前磨牙为A组,A组再分为A1、A2组,A1组酸蚀后即刻拔除,制作扫描电镜观察标本,A2组,第一前磨牙酸蚀后即刻拔除,置37℃恒温蒸馏水中浸泡1个月后制作电镜标本观察.右侧上、下颌第一前磨牙为B组,第一前磨牙酸蚀后在口内存留1个月后拔除,用相同的方法进行观察,并比较A、B两组牙釉质形态学变化.结果:A组的牙釉质表面松软,不规则,多孔隙,表面呈蜂窝状改变;B组的牙釉质表面有大量矿物质沉积,孔隙变小,矿化物颗粒细小,沉积不均匀.结论:牙釉质脱矿后,在口腔环境中可发生再矿化,但矿化程度是有限的,提示在临床上应注意酸蚀时间及酸蚀范围.     

正畸治疗中快速远中移动尖牙的CBCT研究

目的：研究正畸治疗过程中快速移动尖牙术后牙根的吸收和改建。方法选取安氏Ⅱ类错成年患者15例,减数双侧上颌第一前磨牙,牙周膜牵引成骨术快速远中移动尖牙26颗,术前及术后3个月分别拍摄CBCT,测量牙根长度及牙槽骨的改建情况。结果26颗尖牙在2至3周内快速远中移动到位,尖牙快速远中移动术后3个月无明显的牙根吸收,尖牙近中骨组织密度正常。结论快速移动尖牙安全有效,可缩短正畸疗程。     

Risk factors for root resorption of second molars associated with impacted mandibular third molars

External root resorption (ERR) affecting mandibular second molars (M2) may occur when the adjacent third molar (M3) is impacted in close proximity. This retrospective cohort study aimed to assess the presence, severity, and location of ERR on M2 due to M3 using cone beam computed tomography (CBCT) scans and to identify associated factors. The angle between the axis of M2 and M3 was measured. ERR on M2 was classified as absent, slight, moderate, or severe. The location of contact between M3 and M2, the size of the dental follicle, and patient demographic characteristics were recorded. A total of 433 patients with 640 M3 were included. A male predilection was found with regard to ERR (P = 0.0004). ERR was identified on 31.9% of M2 and was slight in 30.2%, moderate in 1.4%, and severe in 0.3% of cases. The presence of ERR was associated with direct contact between M2 and M3 (P < 0.0001), the angle between M2 and M3 (P < 0.0001), the inclination of M3 (P = 0.001), and the location of contact (P = 0.0005). This study showed ERR to be a frequent finding. ERR is associated with a mesioangular position of M3 in more than one third of cases, and a proximity ≤0.5 mm between M2 and M3 favours ERR.