Enterococcus faecalis Biofilms Eradication by Root Canal Irrigants

The aim of this study was to evaluate the minimal biofilm eradication concentration (MBEC) of sodium hypochlorite (NaOCl), chlorhexidine (CHX), EDTA, and citric and phosphoric acids after 1, 5, and 10 minutes of exposure to biofilms of Enterococcus faecalis. The biofilms grew in the MBEC high-throughput device for 24 hours at 37°C and were exposed to 10 serial two-fold dilutions of each irrigating solution. The viable cell counts were log₁₀ transformed, and a concentration of an irrigant was considered to eradicate the biofilms when it produced a reduction of ≥ 5 logarithmic units. NaOCl was the most effective agent, capable of eradicating the biofilms after 1 minute at a concentration of 0.00625%. CHX eradicated biofilm after 5 minutes at 2%. EDTA and citric and phosphoric acid solutions were not effective against the biofilms at any concentration or time tested.     

根管冲洗剂对玷污层的作用

玷污层可阻碍药物进行深层消毒,降低充填材料与根管壁的密合性,使根尖微漏显著增加．导致根管治疗失败。根管冲洗是根管治疗过程中一个重要环节,能否有效去除玷污层是其关键之一。本文就次氯酸钠,螯合剂及有机酸等常用冲洗剂对玷污层的作用进行概述,可以看出,多种冲洗剂联合使用将更加有效地去除玷污层。     

四种浓度次氯酸钠根管消毒效果的评价

目的 探讨4种浓度次氯酸钠对感染根管的消毒作用.方法 将100例慢性根尖周炎患者随机分为5组,分别使用0.25%、0.50%、1.00%、2.00%的次氯酸钠和生理盐水作为根管冲洗剂,根管预备前后,分离、培养根管内厌氧菌,观察并记录细菌形态及菌落数.结果 4种浓度次氯酸钠对感染根管均有消毒作用,生理盐水的根管消毒作用差.结论 在橡皮障未能普及的情况下,作为根管冲洗剂的次氯酸钠合适浓度为1.00%.     

Root Canal Irrigants and Medicaments in Endodontic Malpractice Cases: A Nationwide Longitudinal Observation

Introduction

The aim of this study was to assess the role of root canal irrigants and medicaments in endodontic injuries verified in Finland and to estimate the rate of such events over time.

Er:YAG激光联合次氯酸钠对粪肠球菌杀菌效果的研究

目的:比较掺铒钇铝-石榴石脉冲(Er:YAG)激光联合不同浓度次氯酸钠对根管内粪肠球菌杀菌效果的研究。方法:选择新鲜拔除的人单根管离体前磨牙建立粪肠球菌根管感染模型75个,随机分为5组,每组15个,分别进行如下处理:A组:5.25%次氯酸钠单独冲洗;B组:Er:YAG激光+5.25%次氯酸钠冲洗;C组:1%次氯酸钠单独冲洗;D组:Er:YAG激光+1%次氯酸钠冲洗。E组:空白对照。采集5组根管内的细菌进行培养计数并对结果进行卡方检验(Chi-square test)。结果:A、B、D三组均能完全杀灭根管内的粪肠球菌;C组未能完全杀灭根管内的粪肠球菌。15个培养皿中有11个可见粪肠球菌菌落。A、B、D三组间杀菌效果无差异且均显著优于C组。结论:高浓度次氯酸钠可以完全杀灭根管内的粪肠球菌,低浓度次氯酸钠不能完全杀灭根管内的粪肠球菌;Er:YAG激光可以显著增强低浓度次氯酸钠的杀菌作用。     

超声根管预备和根管封闭剂对根尖微渗漏的影响

目的 了解超声根管预备和根管封闭剂对根管治疗后根尖微渗漏的影响。方法 将79颗离体牙随机分为5个实验组和2个对照组。实验组分别用超声波，回旋手机和手法备根后分别用AH plus^TM，根充I号，氧化锌糊剂作根管封闭剂并用牙胶法作侧压充填。用2％亚甲蓝浸泡1周后纵剖牙体，体视镜下观测染料渗透长度。数据行统计学分析。结果 三种备根方法中，超声备根组根尖微渗漏最少。三种根管封闭剂中，AH plus^TM组微渗漏最少。结论 超声根管预备后根充术，同时采用AH plus^TM根管封闭剂，能有效地减少根充术后微渗漏，提高根管治疗效果。     

Root Canal Disinfection by Single- and Multiple-instrument Systems: Effects of Sodium Hypochlorite Volume,Concentration, and Retention Time

IntroductionThis ex vivo study evaluated the intracanal bacterial reduction promoted by chemomechanical preparation using a single-file technique varying the volume, concentration, and retention time of sodium hypochlorite (NaOCl) irrigation in comparison with a multifile system.MethodsPalatal roots from extracted maxillary first molars were selected and anatomically matched based on microcomputed tomographic analysis for group distribution. The canals were contaminated with a fresh mixed bacterial culture grown in anaerobiosis and recently obtained from a tooth with apical periodontitis. Specimens were divided into 4 groups of 24 each according to the following preparation protocols: REC-6LOW (Reciproc R50 instrument [VDW, Munich, Germany], 6% NaOCl, low irrigant volume), REC-2.5LOW (R50, 2.5% NaOCl, low irrigant volume), REC-2.5HI (R50, 2.5% NaOCl, high irrigant volume), and BR-2.5HI (BioRaCe [FKG Dentaire, LaChaux-de-Fonds, Switzerland], 2.5% NaOCl, high irrigant volume). The total time of preparation was recorded. Intracanal bacteriologic samples were taken before and after preparation; DNA was extracted and subjected to quantitative polymerase chain reaction.ResultsBacteria were detected in 22 initial samples from the REC-2.5LOW group and in 23 from the other groups. Intragroup analysis showed that all tested preparation protocols were highly effective in significantly reducing the intracanal bacterial counts (P < .001). Intergroup comparison of bacterial reduction levels revealed a statistically significant difference between BR-2.5HI and REC-2.5LOW (P < .05). Counts of bacteria were 2.5 times significantly higher in REC-2.5LOW compared with BR-2.5HI. No other significant differences were found in quantitative findings (P > .05).ConclusionsThe concerted effects of multiple instruments, the high volume of irrigation, and the long retention time of NaOCl irrigant had a positive influence on intracanal disinfection during chemomechanical preparation.     

Outcome of Endodontic Retreatment Using 2 Root Canal Irrigants and Influence of Infection on Healing as Determined by a Molecular Method: A Randomized Clinical Trial

IntroductionThis study compared the clinical and radiographic outcome of endodontic retreatment of teeth with apical periodontitis using either 1% sodium hypochlorite (NaOCl) or 2% chlorhexidine digluconate (CHX) as the irrigant. The influence of residual infection detected by a molecular method on the outcome was also examined.MethodsFifty-two root-filled teeth with apical periodontitis were randomly assigned into 2 groups according to the irrigant used during retreatment. Root canal microbiological samples taken before (S1) and after (S2) preparation using either NaOCl or CHX irrigation and after calcium hydroxide medication (S3) were subjected to 16S ribosomal RNA gene-based real-time quantitative polymerase chain reaction (qPCR) to quantify total bacteria. The periapical status was scored using the periapical index and dichotomized as healed (<3) or not healed (≥3) at the 1- and 4-year follow-up.ResultsForty-five (NaOCl, n = 20; CHX, n = 25) and 33 teeth (NaOCl, n = 16; CHX, n = 17) were available at the 1- and 4-year follow-up, respectively. After 1 year, 65% in the NaOCl group and 64% in the CHX group healed, with no differences between them (P > .05). At the later follow-up, the corresponding figures were 81% and 82%, respectively (P > .05). Canals that yielded qPCR-negative results in S3 had a higher healing rate (79%) than qPCR-positive canals (45%, P < .05). The mean bacterial load increased from S2 to S3 in half of the unhealed cases (P < .05). All S3-positive canals containing <3.12 × 10³ bacterial cell counts healed. Increasing the apical level of the root canal filling influenced the outcome (P < .05).ConclusionsNo significant differences in the clinical outcome between 1% NaOCl and 2% CHX were found. Bacterial persistence at the time of filling as detected by qPCR significantly affected the outcome.     

口腔医学生临床前离体牙及人工根管根管治疗教学研究

目的：通过离体牙、人工根管培养实习医生了解并掌握根管治疗的标准程序和方法。方法：选择正畸患者拔除离体牙36颗、牙髓病及牙周病拔除离体牙42颗,人工根管4颗,分组采用常规改良逐步后退法、冠向逐步深入法进行根管处理、预备及充填,观察实习医生根管治疗掌握情况及模拟治疗效果。结果：离体牙采用改良逐步后退法时,前牙根管治疗成功率〉前磨牙〉磨牙（P〈0.05）;离体牙磨牙组中,采用冠向逐步深入法成功率高于逐步后退法（P〈0.01）。结论：采用人工根管可以直观的辅助实习医生体会弯曲根管的治疗,结合离体牙进行根管治疗训练可以提高加深实习医生对根管解剖结构、不同根管治疗方法的了解,对于实习医生临床前培养有明显效果。     

Factors Related to Loss of Root Canal Filled Teeth

Objectives : This case-control study characterized factors related to loss of root canal filled (RCF) teeth among members of the Kaiser Permanente Dental Care Program, a dental health maintenance organization based in Portland, Oregon. Methods : Individuals were identified who were enrolled continuously from January 1, 1987, through December 31, 1994, underwent initial root canal therapy on a permanent tooth (excluding third molars) in 1987 or 1988, had a clinical examination within two years after endodontic access, and were at least 21 years old at access. Patients who lost the RCF tooth by December 31, 1994, were defined as cases (n=96); those who did not were defined as controls ( n =120). Computerized data, dental radiographs, and chart entries were reviewed to ascertain variables of interest, and multivariable logistic regression was used to describe differences between the groups. Results : RCF teeth of cases had fewer proximal contacts at access than RCF teeth of controls (odds ratio=2.7; 95% Cl=1.4, 5.1). Cases were older (odds ratio=1.4; 95% Cl=1.1, 1.9 per 10-year increase) and more likely to have had a facial injury than controls (odds ratio=3.6; 95% Cl=1.2, 10.5). Cases also had more missing teeth (odds ratio=1.5; 95% Cl=1.0, 2.1) and more plaque (odds ratio=1.7; 95% Cl=1.0, 2.6). Conclusion : Conditions evident during treatment planning may help dentists assess patients' chances of losing an RCF tooth.     

不同根管处理方法对根管壁抗折力影响的研究

目的　比较预备与不预备的根管以及预备后充填与不充填的根管抗折力。方法　将 30颗人尖牙随机分为 2个实验组和 1个对照组 ,每组 10颗。实验组从牙颈部截去牙冠后进行根管预备。第 1组以Ultra为封闭剂 ,采用冷侧压方法充填 ;第2组根管预备后不充填 ;第 3组根管不作任何处理。所有标本进行抗剪切强度试验。结果　第 2组与其他 2组间差异有显著性 (P <0 .0 0 1) ,抗折应力值最低 (12 6 .182MPa) ;第 1组抗折应力值最大 (15 3.4 97MPa) ;第 1组和第 3组之间无统计学差异 (P>0 .0 5 )。结论　预备后不充填的根管抗折力低于未处理组和完善根管治疗组。使用封闭剂根充后的管壁抗折力增强。     

Use of Cone-beam Computed Tomography to Evaluate Root Canal Morphology and Locate Root Canal Orifices of Maxillary Second Premolars in a Chinese Subpopulation

Introduction

The aim of this study was to investigate root canal morphology and locate root canal orifices of maxillary second premolars in a Chinese subpopulation using cone-beam computed tomographic imaging.

Methods

A total of 392 cone-beam computed tomographic images of maxillary second premolars were obtained from 238 patients who required a preoperative assessment for implant surgery or orthodontic treatment. The number of roots and root canals and root canal configuration were investigated and categorized using Vertucci's criteria. The distance between the root canal orifice and the anatomic apex and the distance between root canal orifices in those teeth with 2 root canals were measured and evaluated. The Fisher exact test was used to analyze the correlation between the number of roots and sex.

Results

Among the 392 teeth, 86.5% (n = 339) had 1 root; 45.4% (n = 178) of the teeth had 1 root canal, and 54.3% (n = 213) had 2 root canals that ranged from type II–type V. The majority of teeth with 2 root canals showed a type IV canal configuration (n = 79, 20.2%) followed by type II (n = 64, 16.3%), type III (n = 45, 11.4%), and type V (n = 25, 6.4%). Only 1 tooth had 3 root canals. No significant difference was found between the number of roots and sex (P > .05). Among the 213 teeth with 2 root canals, the most frequent distribution of the distance between the root canal orifice and the anatomic apex was 5–10 mm (n = 157). The distance between the 2 orifices of 189 teeth was 1–4 mm.

Conclusions

The frequency of teeth with 2 root canals was high in maxillary second premolars. The internal morphology of teeth with 2 root canals was variable. This study provided useful information about the root canal morphology of maxillary second premolars in a Chinese subpopulation.     

Assessing the Iatrogenic Contribution to Contamination During Root Canal Treatment

IntroductionAsepsis in endodontics aims to control all potential sources of infection. Inadvertent introduction of bacteria into the root canal system may occur when the aseptic chain is breached during treatment. Therefore, measures are taken to prevent such microbial access and establish an aseptic environment. This study aimed to assess potential bacterial contamination and the potential risk of iatrogenic introduction from 7 sites comprising surfaces, instruments, and files acquired during the treatment of 30 vital, pulpitic teeth.MethodsBacterial samples were collected from access burs, files, endodontic rulers, rubber dam surfaces, gloves, and instruments. Genomic DNA was extracted and quantified by quantitative polymerase chain reaction. Bacterial types were determined using next-generation sequencing.ResultsHigh frequencies of contamination and microbial numbers were encountered in all sample types examined.Thirty-eight percent of the initial files introduced into the root canal had significant levels of bacteria at the point of obturation, including endodontic pathogens. Around half of the rubber dam surfaces were contaminated with substantial bacterial loads at the time of obturation, and bacteria were also detected in 20%–30% of gloves, instruments, and rulers before obturation. Next-generation sequencing revealed the predominant oral or endodontic origin of these contaminants, with the following genera identified: Streptococcus, Rothia, Granulicatella, Cutibacterium, Corynebacterium, Peptostreptococcus, and Fusobacterium. Together, these findings highlight the potential risk of reintroducing endodontically relevant bacteria during treatment.ConclusionsGloves, rubber dams, instruments, and files acquire bacterial contamination during treatment at high frequencies and loads. This highlights the potential risk of iatrogenic contamination at the clinically vulnerable point of canal obturation. Measures to address these may improve clinical outcomes.     

上颌第三磨牙根形态与根管形态的研究

目的：寻找上颌第三磨牙根形态及根管形态的规律。方法：使用传统的牙透明技术,充分显露该牙髓腔外形,在体式显微镜下读取根管系统的形态,并统计分类。结果：103颗上颌第三磨牙,融合根占72%,分叉根占28%;完全融合型牙根单根管（1-1型）多见,不完全融合牙根中双根管（2-2）和三根管（3-2;3-3）为主;分叉根型中近中颊根分为双管型常见;根尖分歧和根管侧枝在各型根管中均可见到。结论：上颌第三磨牙融合根常见,但根管形态多样。     

前牙牙根及根管形态的研究进展

目前,对有外伤、牙髓炎或根尖周炎的前牙进行根管治疗后行桩冠修复已非常普及并被患者普遍接受.本文通过回顾近年来对上下颌前牙牙根及根管解剖形态的大量系统研究,阐述了各前牙牙体牙根及根管解剖特征、根管分型和各根管类型的发生率,并分析了上下颌前牙根管治疗的注意点.     

Contribution of Root Canal Treatment to the Fracture Resistance of Dentin

Introduction

Although the strength and toughness of dentin decrease with age, no study has explored if restorative treatments are a contributing factor.

有瘘型根尖周炎的氩离子激光手术及一次程根管充填的临床疗效观察

目的 :探讨 Ar+激光手术加一次程根管充填治疗有瘘型根尖周炎的处理方法及疗效 ,为临床提供一种新的根管消毒法 .方法 :应用 Ar激光技术及一次程根管充填术对 87例有瘘型根尖周炎患牙进行治疗和临床观察分析 .结果 :成功 70例 ,进步 9例 ,总有效率达 90 .8% .结论 :证实了 Ar+激光临床根管治疗的有效性、安全性和实用性 ,不失为一种新的临床根管消毒方法 ,在临床具有应用前景。     

Root and Root Canal Morphology in Maxillary Second Molar with Fused Root from a Native Chinese Population

Introduction

Root fusion is an anatomic variation in maxillary second molars (MSMs); however, the nature of this canal morphology as it relates to its root anatomy has not been fully clarified. The purpose of this study was to investigate the relationship between features of fused roots and root canal anatomy in MSMs using micro–computed tomographic imaging.

Methods

One hundred eighty-seven extracted MSMs were scanned with the μCT50 (Scanco Medical, Bassersdorf, Switzerland), and their root and canal morphology was classified and analyzed using the classifications proposed by Yang and Vertucci. The number and position of canals that merged were recorded and compared among different root fusion types.

Results

One hundred eight (57.75%) MSMs had 3 separate roots, and 79 (42.25%) had fused roots. Of the 79 fused roots, 22 showed partial canal merging, and 6 had complete canal merging. Canal merging was found with teeth with 3-root fusion more often than in those with 2-root fusion (P < .05). Of 28 merged canals, 16 occurred between mesiobuccal and distobuccal canals and 9 among mesiobuccal, distobuccal, and palatal canals.

Conclusions

MSMs with fused roots may present a complicated root canal system as a result of canal merging.