显微CT在根管峡区研究中的应用

目的：探讨显微CT在根管峡区形态定性定量研究中的应用。方法：收集单根上颌前磨牙,显微CT扫描及三维重建后,筛选出五颗有根管峡区的牙,分析峡区横断面百分比以及横断面峡区类型,测量峡区至釉牙骨质界距离（DcEJ）以及至解剖根尖距离（DApex）,并分析峡区根管的结构模型指数（SMI）。结果：峡区横断面百分比为81．8％,其中完全峡区（CI）占72．8％,部分峡区（PI）占9％;DCEJ为（0．79±0．55）mm,DApex为（1．55±0．86）m;峡区根管的SMI为1．20±0．43。结论：显微CT结合三维重建技术能够对根管峡区形态进行定性定量分析,是研究根管峡区较理想的方法。     

Four-year Outcome of Nonsurgical Root Canal Retreatment Using Cone-beam Computed Tomography: A Prospective Cohort Study

IntroductionThe purpose of this prospective study was to investigate the 4-year outcome and prognostic factors of nonsurgical root canal retreatment determined by measuring the volumetric change of periapical radiolucencies on cone-beam computed tomographic (CBCT) scans.MethodsNinety-seven endodontically treated teeth from 80 patients diagnosed as apical periodontitis and indicated for root canal retreatment were included. Retreatment was performed by 7 endodontic specialists using a standardized treatment protocol. The teeth were reexamined clinically and radiographically 48–67 months after retreatment. The volume of preoperative and postoperative periapical radiolucencies on CBCT images was independently measured by 2 examiners. Radiographic outcome is presented in 4 categories: absence, reduction, enlargement, or unchanged. Reduction or enlargement was determined when the volumetric change of radiolucency was 20% or more. Multivariate logistic regression was performed for predictor analysis.ResultsSixty-two teeth (63.9%) from 50 patients returned for follow-up. Fifty-eight teeth were included in the prognostic analysis, all of which were symptom free. The 4 remaining teeth that had been extracted because of fracture were excluded. The total volume of periapical radiolucencies at 4 years postoperatively decreased by 94.6% compared with that preoperatively (P < .001), with an average reduction of 83.4% (95% confidence interval, 69.2%–97.5%). The periapical radiolucencies were determined as absence in 44 teeth (75.9%), reduction in 10 teeth (17.2%), unchanged in 1 tooth (1.7%), and enlargement in 3 teeth (5.2%). Tooth type was identified as an outcome predictor (P < .05).ConclusionsThe 4-year outcome of endodontic retreatment is predictable, with a significant volumetric reduction in periapical radiolucencies.     

A Microcomputed Tomography Scanning Study of Root Canal Space: Changes after the Ultrasonic Removal of Fractured Files

This in vitro study aimed to investigate the effect of ultrasonic removal of endodontic fractured files on tooth structure. Fifty-three canine roots were cleaned and weighed. They were scanned by a microcomputed tomography scanner producing two-dimensional images that were reconstructed into two-dimensional slices, and, finally, the canal volume was measured. In a control group, canals were prepared to F5-size ProTaper (Dentsply Ltd, Surrey, UK). In three experimental groups, F5-fractured files were ultrasonically removed from three root canal locations: coronal, middle, and apical. All roots were reweighed and rescanned. Reconstruction and analysis were performed to remeasure the canal volume. The differences in root mass (weight) and canal volume between before and after treatment were calculated. The highest change increase in canal volume was found when fractured files were removed from the apical part followed by middle and coronal. A positive correlation existed between canal volume and root mass changes. Microcomputed tomography scanning can reliably determine changes in canal volume resulting from fractured-file removal.     

Endodontic Retreatment Using Dynamic Navigation: A Case Report

IntroductionDynamic navigation systems are used in dental implantology to optimize the accuracy of dental implant placement.MethodsA 30-year-old man was seen at the endodontic clinic of the Universidad Autónoma de Yucatán for pain in the left maxillary lateral incisor. A previously treated tooth with symptomatic apical periodontitis was diagnosed. The patient accepted treatment, and after signing an informed consent form, minimally invasive coronal access was performed through a zirconia crown. Then a post removal was performed with an ultrasonic tip to 2 mm before the apical gutta-percha limit, and the removal of material was completed manually with a K-file.ResultsThis case report demonstrates the use of dynamic navigation to remove a post from under a zirconia crown for the retreatment of a failing root canal procedure. The removal of fiber posts from endodontically treated teeth can present a unique challenge for clinicians. Numerous techniques and instrument kits are recommended for the removal of fiber posts, but the risk of excessive root structure damage is a major concern because the ability to differentiate the color difference between peripheral dentin and a bonded fiber post can complicate the accuracy of the removal.ConclusionsThe dynamic navigation system enabled minimally invasive removal of the fiber post with a high degree of accuracy, thus ensuring that there was no unnecessary removal of root structure. Dynamic navigation using real-time monitoring could reduce the attendant risk of iatrogenic errors in complex treatment cases.     

Comparison of the Efficacy of NeoNiTi,ProTaper, and Reciproc Files in the Retreatment of Curved Root Canals: a CBCT Assessment

ObjectiveEffective tools and methods are applied during root canal retreatment to eliminate root canal obturation materials and preserve the initial root canal anatomy. The present study compared the efficacy of Reciproc, Neoniti, ProTaper, and Hedstrom files in the retreatment of curved root canals.Material and methodsIn the present in vitro study, 100 root canals with 25‒45º curvatures were used. After the samples were initially prepared and examined by CBCT, the root canals were obturated with gutta-percha and randomly assigned to four groups (n=25). A retreatment was carried out in each group with NeoNiTi, ProTaper, Reciproc, and Hedstrom files. CBCT examinations were carried out again under the same conditions. The samples were evaluated at 3-, 6-, and 9-mm distances from the apex on the first and the second CBCT image for root canal transportation and remaining gutta-percha in the root canals. The time required for retreating each canal in each sample was recorded. One-way ANOVA and corresponding non-parametric tests were applied for data analysis.ResultsThe root canal transportation in the NeoNiTi group was lower than that in the other groups and significantly different from the ProTaper group (P<0.05). There was a remaining gutta-percha after retreatments in all the four groups, which was not statistically significant (P>0.05).ConclusionDespite the fact that the NeoNiTi file produced less transportation than other file systems evaluated in the retreatment of curved root canals, all the files were very effective at the clinically acceptable levels.     

Desocclusol和氯仿辅助去除根充材料的体外研究

目的 研究Desocclusol和氯仿辅助去除根充材料的能力,为临床根管再治疗寻找新型的根充物辅助溶剂提供依据.方法 选择因正畸需要拔除的离体上颌双根双根管第一前磨牙40颗,经开髓、根管预备后随机分为4组,每组10颗牙,20个根管.A组:普通根充糊剂和牙胶尖根充后用Desocclusol和K锉去除根充物.B组:普通根充糊剂和牙胶尖根充后用氯仿和K锉去除根充物.C组:碧兰CORTISOMOL永久性根充糊剂和牙胶尖根充后用Desocclusol和K锉去除根充物.D组:碧兰CORTISOMOL永久性根充糊剂和牙胶尖根充后用氯仿和K锉去除根充物.分别记录各组成功去除根充物的根管数、操作时间、失败情况及原因.各组之间操作时间的比较采用t检验.结果 4组成功去除根充物的根管数分别为18、19、20、18个.操作时间比较,A组与B组差异无统计学意义(P＞0.5),A组与C组差异无统计学意义(P＞0.5),C组少于D组(P＜0.01),B组少于D组(P＜0.01).结论 Desocclusol是有效的根充物的辅助溶剂.     

Volumetric Changes in Apical Radiolucencies of Endodontically Treated Teeth Assessed by Cone-beam Computed Tomography 1 Year after Orthograde Retreatment

Introduction

Cone-beam computed tomography (CBCT) allows us to assess in 3 dimensions the location and size of periapical radiolucencies. We aimed to assess by CBCT scans the volumetric changes of periapical radiolucencies in endodontically treated teeth 1 year after orthograde retreatment.

Methods

Forty-five root-filled teeth with persistent apical periodontitis requiring endodontic orthograde retreatment from 37 individuals were included in the study. The research protocol was approved by the VU University Medical Center Amsterdam ethics committee (2007/265), and the participants signed a letter of consent. We made 2 CBCT scans for every patient, the first one before retreatment and the second one a year later. Two observers measured independently the volume of radiolucencies on CBCT images by using the AMIRA software. The intraclass correlation coefficient was used to evaluate interobserver agreement, and the Wilcoxon signed rank test was used to assess pretreatment and post-treatment volume size.

Results

The intraclass correlation coefficients were 0.994 and 0.998 for the scans before retreatment and 1 year after, respectively. The recall rate was 78% for the teeth and 73% for the patients. The volumetric change in periapical radiolucencies 1 year after retreatment was statistically significant (z = −3.112, P < .005). The volume of periapical radiolucencies reduced in 20 teeth (57%), remained unchanged in 8 (23%), and increased in 7 (20%).

Conclusions

One year after endodontic orthograde retreatment, the volume of periapical radiolucencies reduced significantly in 57% of the teeth.     

Outcomes of Nonsurgical Retreatment and Endodontic Surgery: A Systematic Review

IntroductionThe purpose of this systematic review was to compare the clinical and radiographic outcomes of nonsurgical retreatment with those of endodontic surgery to determine which modality offers more favorable outcomes.MethodsThe study began with targeted electronic searches of MEDLINE, PubMed, and Cochrane databases, followed with exhaustive hand searching and citation mining for all articles reporting clinical and/or radiographic outcomes for at least a mean follow-up of 2 years for these procedures. Pooled and weighted success rates were determined from a meta-analysis of the data abstracted from the articles.ResultsA significantly higher success rate was found for endodontic surgery at 2–4 years (77.8%) compared with nonsurgical retreatment for the same follow-up period (70.9%; P < .05). At 4–6 years, however, this relationship was reversed, with nonsurgical retreatment showing a higher success rate of 83.0% compared with 71.8% for endodontic surgery (P < .05). Insufficient numbers of articles were available to make comparisons after 6 years of follow-up period. Endodontic surgery studies showed a statistically significant decrease in success with each increasing follow-up interval (P < .05). The weighted success for 2–4 years was 77.8%, which declined at 4–6 years to 71.8% and further declined at 6+ years to 62.9% (P < .05). Conversely, the nonsurgical retreatment success rates demonstrated a statistically significant increase in weighted success from 2-4 years (70.9%) to 4–6 years (83.0%; P < .05).ConclusionsOn the basis of these results it appears that endodontic surgery offers more favorable initial success, but nonsurgical retreatment offers a more favorable long-term outcome.     

Outcome of Nonsurgical Root Canal Retreatment Procedures Obturated with Warm Gutta-percha Techniques: A Longitudinal Clinical Study

IntroductionTo evaluate the success rate of nonsurgical root canal retreatment at the 2–3-year follow-up and identify the possible prognostic factors.MethodsPatients who underwent root canal retreatment at a university dental clinic were contacted for clinical and radiographic follow-up. The retreatment outcomes in these cases were based on clinical signs, symptoms, and radiographic criteria. Inter- and intraexaminer concordances were calculated using Cohen's kappa coefficient. The retreatment outcome was dichotomized into success or failure according to strict and loose criteria. The radiographic success criteria consisted of complete resolution or absence of a periapical lesion (strict criteria) or a reduction in the size of an existing periapical lesion at recall (loose criteria). χ² tests were used to evaluate possible variables associated with retreatment outcomes (age, sex, tooth type, location, contact points, periapical status, quality of previous and final root canal filling, previous and final restoration, number of visits, and complications).ResultsOverall, 129 teeth (113 patients) were included in the final evaluation. The success rate was 80.6% under strict criteria and 93% under loose criteria. Molars, teeth with an initially higher periapical index score, and teeth with >5 mm periapical radiolucency had a lower success rate according to the strict criteria model (P < .05). When the loose success criteria were used, teeth with larger (>5 mm) periapical lesions and those that had been perforated during retreatment showed a lower success rate (P < .05).ConclusionsThe present study demonstrated that nonsurgical root canal retreatment is a highly successful procedure after an observation period of 2–3 years. Treatment success is primarily affected by the presence of large periapical lesions.     

Assessment of the Separation Incidence of Reciprocating WaveOne Files: A Prospective Clinical Study

Introduction

Despite metallurgical advancements in the nickel-titanium file manufacturing process, file separation remains a concern. The purpose of this prospective clinical study was to assess the separation incidence of the reciprocating WaveOne file (Dentsply Tulsa Dental Specialties, Tulsa, OK) when used to prepare root canals of posterior teeth.

Methods

File separation incidence was assessed over an 18-month period in which 4 experienced and calibrated endodontists performed conventional endodontic treatment on posterior teeth using the WaveOne file system. The separation incidence was determined based on both the number of teeth and the number of canals instrumented during this time period.

Results

A total of 2,215 canals (711 teeth) were treated. Three instruments (two 21.06 and one 25.08) separated during use and were deemed to be irretrievable. The overall instrument separation incidence in relation to the number of canals shaped was found to be 0.13% (0.42% teeth).

Conclusions

Based on the results of this study, the incidence of endodontic instrument separation when using the WaveOne reciprocating file was considerably low.     

Effectiveness of Three Different Retreatment Techniques in Canals Filled With Compacted Gutta-Percha or Thermafil: A Scanning Electron Microscope Study

IntroductionThis study evaluated the root canal wall morphology under scanning electron microscopy magnification after removal of 2 types of root canal fillings by using ultrasonic tips, nickel-titanium (NiTi) rotary instruments, and hand K-files.MethodsThirty-six extracted roots were filled by using AH Plus (DeTrey-Dentsply, Konstanz, Germany) as a sealer with Thermafil (Tulsa Dental Products, Tulsa, OK) (18 roots) or warm vertically condensed gutta-percha (18 roots). All fillings were removed up to the middle third by using Gates Glidden drills. The retreatment was completed by using K-files (group 1), M-Two NiTi rotary instruments (group 2), or ESI ultrasonic tips (group 3) in 12 roots each. Root canals were irrigated by using 10% ethylenediaminetetraacetic acid and 2.5% NaOCl. The samples were split longitudinally and observed by scanning electron microscopy (100–2000×). The presence of smear layer, filling debris, and the surface profile was evaluated in each picture. Kruskal-Wallis (analysis of variance) and Mann-Whitney tests were used to evaluate the differences between the obturation techniques, the 3 retreatment methods, and the canal thirds (P < .05).ResultsResin sealer tags were observed inside dentinal tubules. No statistical differences (P > .05) were found among the 3 retreatment methods. No statistical differences were observed between Thermafil and vertically compacted warm gutta-percha for each group or between the coronal third used as control, middle, and apical thirds.ConclusionsAll retreatment techniques showed similar performances in terms of smear layer morphology, debris, and surface profile. None of them completely removed filling debris from dentinal tubules of apical third.     

Retrograde Instrumentation of Surgically Resected Roots Using Controlled Memory Files: A Human Cadaver Study

IntroductionThe purpose of this study is to evaluate the amount of residual obturation material of retroinstrumented surgically resected roots using controlled memory files and to evaluate the incidence of adverse treatment outcomes.MethodsThirty maxillary anterior teeth in human cadavers were selected, and nonsurgical root canal treatment was performed on these teeth. A standardized 4-mm osteotomy and a 3-mm root resection with as close to 0° bevel as possible were made on each tooth. A microsurgical diamond tip was used to create a 1- to 2-mm starting point for each retropreparation. A 25/06 and 30/06 VTaper 2H were bent at about 90° angle to mimic the clinical and anatomic restrictions and used to create a retropreparation to a depth of 14 mm. Micro–computed tomography scans were taken and analyzed for volume and percentage of residual obturation material at 5 and 10 mm. In addition, the incidences of instrument separation and crack and ledge formation in the teeth were recorded.ResultsThe median volume of residual obturation at 5 and 10 mm was 0.18 mm³ (interquartile range, 0.36 mm³) and 1.97 mm³ (interquartile range, 1.99 mm³), respectively. The overall incidence of file separation during retropreparation was 13.33% (4/30). Among the cases analyzed with micro–computed tomography, none showed crack or ledge formation.ConclusionsRetroinstrumentation of surgically resected roots using controlled memory files cleans the canal effectively with relatively low adverse treatment outcomes. Although this novel technique is limited in application, it is a safe and effective way to achieve a deep, clean retropreparation.     

Planned Apical Preparation Using Cone-Beam Computed Tomographic Measures: A Micro-Computed Tomographic Proof of Concept in Human Cadavers

IntroductionThis study assessed the amount of unprepared surface areas at the apical 4-mm segment of the root canal after a planned preparation based on cone-beam computed tomography (CBCT) measurements.MethodsEighteen posterior mandible segments were obtained from cadavers and scanned using CBCT and micro-computed tomographic (micro-CT) imaging. CBCT images were used to measure the largest initial canal diameter from 29 root canals of premolars at 1, 2, 3, and 4 mm short of the apical foramen. Each measurement was used to select a master apical instrument with size/taper that was 1 diameter larger to prepare the apical 4 mm of each particular root canal. A post-preparation micro-CT scan was obtained, and the unprepared canal areas were calculated.ResultsA very high amount of surface areas over the apical 4 mm of the root canal was included in the final preparation (mean >90%). The unprepared areas ranged from as low as 3.7% to a maximum of 14.6% (mean and median, 9.2% and 9.1%, respectively).ConclusionsThe proposed planned apical root canal preparation resulted in optimized root canal shaping with a substantial amount of prepared surface areas. The protocol used also resulted in a conservative canal enlargement using final instruments that were 1 size larger than the initial largest canal diameter.     

Accuracy of High-resolution Small-volume Cone-Beam Computed Tomography in the Diagnosis of Vertical Root Fracture: An In Vivo Analysis

IntroductionThe purpose of this in vivo study was to evaluate the accuracy of small-volume cone-beam computed tomographic (CBCT) imaging compared with conventional periapical radiography (CPR) in the diagnosis of vertical root fractures (VRFs) using exploratory surgery as the reference standard.MethodsEighty-two dental records of 85 teeth with suspected VRFs that underwent CPR, CBCT imaging, and exploratory surgery were included. Two observers assessed CPR and CBCT images independently for the presence or absence of root fractures, and findings from the exploratory surgery were considered the reference standard. Diagnostic sensitivity, specificity, accuracy, and the receiver operating characteristic curve values were obtained. The effect of single- and multirooted teeth on diagnostic accuracy as well as the association between clinical symptoms and the presence of VRFs were also assessed.ResultsVRFs were surgically detected in 64 of the 85 teeth (75.3%), of which 62.5% were multirooted and 76.6% had intracanal posts. CBCT imaging was more sensitive and accurate (65.6% and 64%) than CPR (27.3% and 40.5%). Both CPR and CBCT diagnostic accuracies were higher in single- than multirooted teeth. Pain on percussion, a localized periodontal pocket, and tooth mobility were associated with the presence of VRFs (P < .05; odds ratio = 4.15, 13.5 and 4.1, respectively).ConclusionsThe accuracy of CBCT imaging for the diagnosis of VRFs was poor, although it was higher than with CPR. Multirooted teeth in the presence of intracanal posts may limit its diagnostic value.     

新型机用不锈钢锉Gentlefile根管成形能力的体外研究

目的:比较一种独特的机用不锈钢旋转系统——Gentlefile(GF)和Protaper(PT)在J形模拟根管中的成形能力.方法:将33个带有J形模拟根管的树脂块根据尖端直径分成3组,分别将其预备至GF Red(#23)、PT F2(#25)、GF Blue(#26).使用牙科手术显微镜以及相关软件采集并处理预备前后图...     

Ultrastructural Examination of Failed Molar Retreatment with Secondary Apical Periodontitis: An Examination of Endodontic Biofilms in an Endodontic Retreatment Failure

A light and electron microscope examination of the resected root tip of a failing endodontically re-treated lower molar was examined. The tooth had been initially treated 10 years ago and then re-treated 2 years ago. The resected root tip was sectioned axially, and thin sections were examined through the entire length of the specimen. Thin sections were examined with a transmission electron microscope. The thin sections were randomly chosen along the isthmus areas between the mesiobuccal and mesiolingual canals. Our findings suggest that a complex, variable, multispecies biofilm was present the entire length of the specimen.