Observations of acoustic streaming fields around an oscillating ultrasonic file.

The steady acoustic streaming generated around straight and precurved oscillating ultrasonic files driven by the Piezon-Master 400 unit was examined in the free field and in small channels using a stereomicroscope. In addition, the effect of file-wall contact on streaming production was also investigated. The results indicated that the ultrasonic files can generate acoustic streaming both in the free field and in the small channel. Higher velocity streaming was observed when smaller size files were employed and when the file was precurved. Light file-wall contact did not totally inhibit streaming while severe file-wall contact inhibited movement of the file and, as a result, no streaming was observed. The positions and length scales of the streaming vortices appeared to be influenced by the presence of boundaries. In the free field, two rows of vortices were situated along the sides of the file while in the small channel, the vortices were positioned above the surface of the file. These results indicated that it is possible for acoustic streaming to occur in a confined space as in a root canal provided that severe file-wall contact is avoided. It is therefore recommended that light filing or allowing the file to freely vibrate during some stage of treatment should be carried out in order to generate streaming in the root canal.     

XP-endo Finisher effectively reduces hard-tissue debris accumulated in root canals with isthmus after preparation with a reciprocating file system

This study compared the accumulated hard-tissue debris (AHTD) after preparation with WaveOne Gold (WOG) to XP-endo Shaper (XPS), without and with a supplementary step using XP-endo Finisher (XPF) using clinically applicable irrigation. Twenty-four mesial roots with two canals and single foramen were micro-CT-scanned and matched. Scans were also taken after preparation with WOG or XPS, and after XPF. Irrigation with 2.5% NaOCl (total: 17 ml per canal) and 17% EDTA (2.5 ml per canal) was performed using a 30ga Max-I-Probe needle placed up to the working length. Morphological parameters were calculated and compared within and among groups. XPF significantly reduced unprepared area within XPS and WOG groups, and AHTD within WOG (p < 0.05). There were no significant differences between WOG and XPS after preparation and after XPF (p > 0.05). In conclusion, WOG and XPS produced a similar volume of AHTD, but the supplementary step with XPF decreased the AHTD in the WOG group.     

Measurements of temperature generated by ultrasonic file in vitro

Abstract The temperature rise of the irrigant in the root canal during free vibration of the ultrasonic file was studied in vitro in 10 human teeth. The mean temperature rise was found to be 0.6°C. The minimal temperature increase may not significantly contribute to the effectiveness of ultrasonic root canal instrumentation.     

根管超声冲洗的计算流体动力学分析

目的 应用计算机模型分析当超声工作尖位于根管内一定深度时冲洗液的计算流体动力学特点,以期为临床应用提供参考.方法 首先使用扫描激光振测系统扫描超声工作尖,分析其在一定功率下的振动特点.然后应用ICEM CFD 18.0软件建立根管超声冲洗模型,设置超声工作尖放置的位置为距根尖止点1 mm,通过FLUENT 18.0软件...     

Systemic,prophylactic and local applications of antimicrobials in endodontics: an update review

Antibiotics were first discovered in the late 1920s but were not routinely used clinically until the early 1940s during the Second World War. They can be used as an adjunct to endodontic treatment in a number of ways‐systemically, prophylactically and locally. There are few real indications for the systemic use of antibiotics in conjunction with endodontic treatment. They are only needed when the body's efforts at fighting bacteria are failing. Use of antibiotics to prevent infection (antibiotic prophylaxis) may prevent some case of bacterial endocarditis. Therefore, prophylaxis is recommended for individuals in high‐risk and moderate‐risk categories. Another mode of application of antibiotics is local application as intracanal medicaments and root canal irrigants.     

Deposition of calcified tissue around an overextended gutta-percha cone: case report

CASE REPORT: Root canal treatment was performed in a mandibular right second premolar with a periapical lesion and apical resorption. The root canal was prepared with K-files using the step-back technique and 3% NaOCl as an irrigant; during obturation gross overfilling of gutta-percha occurred. The tooth was permanently restored with a post and core along with a crown. Although healing of the periapical lesion occurred and the patient reported that he was symptom-free, the tooth was extracted after 4 years because of a subgingival root fracture. Following extraction the tooth was examined with SEM. The examination revealed the presence of newly formed calcified tissue at resorption sites on the root apex. This newly formed tissue extended from the surface of the root around the apex to the extruded gutta-percha cone to which it was well adapted, forming a bridge between the cone and the root.     

Variations in the power output of the Piezon-Master 400 ultrasonic endodontic unit

The present study was undertaken to see if there was any variability in the power output of Piezon-Master 400 ultrasonic files when driven using different generators, tranducers and file holders. The displacement amplitude of the oscillating tip of the file in air was used as a measure of the power output. The results showed that there was considerable variability in the power output of Piezon-Master 400 ultrasonic files of similar size and length when driven using different generators, transducers and file holders. In consideration of this, it is recommended that a calibration device be incorporated in the ultrasonic unit so that the operator will have some knowledge of when the unit is working at its maximum efficiency.     

An in vitro evaluation of the antimicrobial efficacy of irrigants on biofilms of root canal isolates

AIM: The bactericidal effect of four antimicrobial agents was investigated against single-species biofilms derived from a range of root canal isolates. METHODOLOGY: Single-species biofilms of Prevotella intermedia, Peptostreptococcus micros, Streptococcus intermedius, Fusobacterium nucleatum and Enterococcus faecalis were generated on membrane filter discs and subjected to 15 min or 1 h incubation with 5 p.p.m. colloidal silver, 2.25% sodium hypochlorite (NaOCl), 0.2% chlorhexidine, 10% iodine or phosphate buffered saline (PBS) as a control. The antimicrobial activity of the agents was neutralized and the bacterial cells were harvested from the discs by vortexing, serially diluted in reduced transport fluid, plated on fastidious anaerobe agar containing 5% horse blood, incubated anaerobically and colony-forming units calculated. RESULTS: Iodine and NaOCl were more effective than chlorhexidine except against P. micros and P. intermedia where they were all 100% effective. Iodine and NaOCl elicited a 100% kill after 1 h incubation for all strains used. However, after 15 min, they showed differing bactericidal effects depending on the strain. None of the agents were effective against F. nucleatum after 15 min but NaOCl, iodine and chlorhexidine were all effective after 1 h. Colloidal silver was generally ineffective. CONCLUSIONS: The effectiveness of a particular agent was dependent on the nature of the organism in the biofilm and on the contact time. NaOCl was generally the most effective agent tested, followed by iodine. However the clinical efficacy of these agents must be considered in light of the complex root canal anatomy and polymicrobial nature of root canal infections.     

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%.     

Physical mechanisms governing the hydrodynamic response of an oscillating ultrasonic file

Ultrasonically driven vibrating files are known to enhance the efficiency of root canal debridement. This paper presents a phenomenological view of the hydrodynamic response of an oscillating ultrasonic file and the relationship between the file response and various physical factors such as file size and curvature, file surface properties, file velocity amplitude, root canal geometry, and the type of irrigant. Relevant hydrodynamic properties include the propensity of a file to produce stable and transient cavitation, steady streaming, and cavitation microstreaming. These relationships were explored by experiment. Sonoluminescence was employed as an indicator of transient cavitation activity and photographic analysis was utilized as a means for detecting steady streaming, microstreaming, and stable cavitation. Measurements failed to indicate any strong correlation between registered driving power and the propensity to produce transient cavitation. Files that were pitted or possessed salient edges were very effective at generating transient cavitation. When observed, transient cavitation activity generally occurred near the tip of the straight file, provided the wall-loading did not inhibit file motion. In all cases studied, steady streaming and stable cavitation were observed to varying degrees, depending on the amount of file to wall contact. Stable cavitation was probably enhanced by the addition of moderate amounts of dissolved gas into the irrigant. Although the imposition of file–wall contact served to inhibit the production of transient cavitation, this action had relatively little effect on the ability of a file to produce a nominal level of streaming, microstreaming, and stable cavitation. The relationship between these hydrodynamic properties and the process of root canal debridement is addressed. Observations suggest that it is not prudent to ascribe enhanced cleaning effects to any one phenomenon, for it is likely that several factors are involved to varying degrees depending on the local conditions of application.     

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??Objective    To evaluate and compare the amount of debris and irrigant extrusion quantitatively by using rotary nickel-titanium ??Ni-Ti?? instrument and sonic handpiece in root canal preparation. Methods    Forty freshly extracted human teeth were selected??which were with single canals??having similar canal length and curvature??due to orthodontics therapy and periodontitis in Department of Oral and Maxillofacial Surgery of China Medical University Stomatology Hospital during October 2012 to January 2014. They were separated into two groups based on Ni-Ti instruments ProTaper and sonic handpiece and mounted in a debris collection apparatus. After each instrument change??1 mL of NaClO was used as the irrigant and the amount of irrigant extruded was measured by EP tube. The EP tube was weighed using an electronic microbalance to determine its weight. After drying in an incubator for five days??the EP tube was weighed again. Compare the amount of debris and irrigant extrusion quantitatively. Results    The median of the amount of irrigant??in the group of ProTaper it was 116.24 mg??in the group of sonic handpiece it was 13.76 mg. The rotary Ni-Ti instrumentation techniques extruded significantly more irrigant than sonic handpiece??P < 0.05??. The median of the amount of debris??in the group of ProTaper it was 4.87 mg??in the group of sonic handpiece it was 0.63 mg. The rotary Ni-Ti instrumentation techniques extruded significantly more debris than sonic handpiece??P < 0.05??. Conclusion    The sonic handpiece extrudes significantly less irrigant and debris than the rotary Ni-Ti instrumentation techniques. It has a good clinical application prospects.     

Relationship between file size and stiffness of stainless steel instruments

Abstract The purpose of this study was to evaluate the relationship existing between file size and stiffness for three endodontic files of different cross-sections. Three groups of instruments were tested: Flexofiles from the Maillefer company. K Files and K-Flex from the Kerr company. Flexofiles have a triangular cross-section, K Files a square cross-section, and K-Flex instruments a rhombus cross-section from size 15 to size 40. For each group, 10 files from size 15 to size 40 were compared according to ANSI/ADA specification N° 28 for bending moment evaluation. There was a statistical difference between the three groups: the square cross-section K files presented a larger bending moment than the rhombus cross-section K Flex, which presented a higher bending moment than the triangular cross-section Flexofiles. There was an exponential relationship between file size and bending moment.     

口康含漱液用于超声根管预备抗菌效果的研究

目的探讨口康与超声联合应用杀灭感染根管内厌氧菌的效果。方法将60例慢性根尖周炎患者共60个患牙随机分为3组,每组各20个患牙,A组常规法手持器械根管预备和常规针筒式根管冲洗,B、C组均用超声法进行根管预备并分别以生理盐水、口康作为超声冲洗液,根管预备前后分别取样进行厌氧培养。结果B组厌氧菌减少程度明显大于A组(P<0.05);C组厌氧菌减少程度明显大于B组(P<0.01),显著大于A组(P<0.001)。结论超声在根管杀菌方面有独特的优势,口康可有效杀灭感染根管内厌氧菌,是一种较理想的根管超声冲洗液。     

声波手机与机用镍钛器械根管预备过程中根尖冲洗液及碎屑溢出比较研究

评价机用镍钛器械与声波手机根管预备过程中冲洗液及碎屑溢出根尖情况。 方法    选取2012年10月至2014年1月在中国医科大学附属口腔医院口腔外科门诊因正畸治疗需要或牙周炎症拔除的单根管离体牙（长度与弯曲度相近）40颗作为研究样本,随机分为ProTaper组（使用机用ProTaper镍钛锉进行根管预备）和Sonic handpiece组（使用MM1500声波手机及其配套的Rispisonic和Shaper锉进行根管预备）,并将离体牙安装到碎屑及液体收集装置。在根管预备过程中每换用一号器械时,用1 mL次氯酸钠溶液进行根管冲洗,用EP管收集根尖溢出冲洗液及碎屑,称重;恒温箱内干燥5 d后再次称重。比较两组根尖冲洗液及碎屑溢出情况。 结果    根尖冲洗液溢出量的中位数：ProTaper组为116.24 mg,Sonic handpiece组为13.76 mg,两组差异有统计学意义（P < 0.05）。根尖碎屑溢出量的中位数：ProTaper组为4.87 mg,Sonic handpiece组为0.63 mg,两组差异有统计学意义（P < 0.05）。结论    使用声波手机在根管预备时产生的根尖冲洗液及碎屑溢出均明显少于使用机用镍钛器械;声波手机具有较好的临床应用前景。     

Effect of ultrasonic instrumentation on Bacteroides intermedius

Abstract Two physical mechanisms of ultrasound, cavitation and acoustic streaming, were investigated in an ultrasonic endodontic unit. In addition, the potential of ultrasonic instrumentation for disruption of Bacteroides intermedius was examined at various time intervals. The ultrasonic file could not generate cavitation within the recommended power settings indicated for endodontic purposes. However, there was evidence of acoustic streaming. The latter phenomenon resulted in destruction of 21.6%, 30.4% and 92.9% of test bacteria after 1, 5 and 15 min sonication respectively. It appears that ultrasonic instrumentation of root canals has little bactericidal effect.     

根管冲洗液对粪肠球菌作用的研究进展

粪肠球菌是一种最常见的导致根管治疗失败的细菌,如何控制根管内的粪肠球菌是研究的热点。根管冲洗剂是杀灭和抑制粪肠球菌的有效方法之一,本文就根管内粪肠球菌的感染特点、常用根管冲洗液以及冲洗剂联合使用对其的作用等方面作一综述。     

The effect of QMix, an experimental antibacterial root canal irrigant, on removal of canal wall smear layer and debris

Introduction

This study examined the ability of two versions of QMix, an experimental antimicrobial irrigant, on removal of canal wall smear layers and debris using an open canal design.

Methods

Cleaned and shaped single-rooted human root canals were irrigated with NaOCl as the initial irrigant and one of the following as the final irrigant: (1) QMix I (pH = 8), (2) QMix II (pH = 7.5), (3) distilled water, (4) 17% EDTA, and (5) BioPure MTAD (Dentsply Tulsa Dental Specialties, Tulsa, OK). Smear and debris scores were evaluated in the coronal, middle, and apical thirds of longitudinally fractured canal spaces using scanning electron microscopy and analyzed using Cochran-Mantel-Haenszel statistic.

Results

Smear scores, when the overall canal was considered, differences were observed among groups except groups 1 versus 4 and groups 2 versus 4. After adjusting for canal levels, all groups differed significantly from each other (p < 0.005) with the exception of groups 2 versus 5. For the debris scores, no significant difference was observed among the treatment groups when the overall canal was considered and after adjusting for the effect of canal level.

Conclusion

Within the limitations of an open-canal design, the two experimental QMix versions are as effective as 17% EDTA in removing canal wall smear layers after the use of 5.25% NaOCl as the initial rinse.     

根管冲洗液和黏结剂对金属桩核黏固后根管微渗漏影响的析因分析

目的 探讨根管冲洗液和黏结剂对金属桩核黏固后根管冠方微渗漏的影响,以及二者对于根管冠方微渗漏的交互作用。方法采用两因素析因设计方法,将90颗完成根管充填的离体下颌前磨牙进行桩道预备,经常规制作钴铬桩核后,分为6组,每组15颗。根管冲洗液（因素A）选取3种：A1为无冲洗液（75%乙醇棉球清洁）,A2为3%H2O2+0.9%NaCl溶液,A3为15%乙二胺四乙酸（EDTA）+5.25%NaClO溶液;黏结剂（因素B）选取2种：B1为聚羧酸锌水门汀,B2为玻璃离子水门汀。按照A1B1、A1B2、A2B1、A2B2、A3B1、A3B2分别对6组进行处理,桩核黏固完成后的所有样本浸泡于印度墨水中3周,然后沿颊舌向中线位置纵行劈开,在体视显微镜下拍照并测量染料渗入根管的最大长度,以此评价微渗漏的大小。采用SPSS 13.0软件对结果进行析因分析。结果 A1B1、A1B2、A2B1、A2B2、A3B1、A3B2组染料渗入长度分别为（1 192.59±417.84）、（1 317.38±527.35）、（1 429.33±482.68）、（1 026.79±459.49）、（1 448.29±561.02）、（1 922.47±678.86）μm,A2B2组微渗漏程度最轻,A3B2组最重;不同冲洗液之间微渗漏的差异有统计学意义（P<0.05）,不同黏结剂之间的差异没有统计学意义（P>0.05）,但根管冲洗液和黏结剂对于微渗漏的发生有交互作用（P<0.05）。结论 黏固金属桩核时,3%H2O2+0.9%NaCl溶液冲洗根管联合玻璃离子水门汀黏结剂在减少微渗漏的发生方面有一定优势;15%EDTA和5.25%NaClO联合玻璃离子水门汀会加重根管微渗漏的发生。     

Removal of separated instruments from unfavourable locations: Case reports using the HBW ultrasonic ring or a surgical approach

Two patients were admitted to the dental clinic to evaluate two right mandibular first molars (both FDI no. 46). In Case 1, there was an accidental instrument separation, which was thought to have been bypassed; however, the instrument was located beyond the apical foramen, in the alveolar bone. The 1-week follow-up revealed that the fragment was close to the inferior alveolar nerve, thus allowing surgical removal to be performed. In Case 2, two separated instruments located in the apical third of the mesiobuccal and mesiolingual canals were removed using the HBW ultrasonic ring coupled to ISO 10 and 15 hand instruments. The 3-month and 1-year follow-ups (Case 1), and the 2-year and 3-year follow-ups (Case 2) showed a favourable evolution in both cases. It can be concluded that both the surgical approach and the HBW ultrasonic ring are viable options for the removal of separated instruments in unfavourable locations.