Assessment of antibacterial activity of 2.5% NaOCl,chitosan nano-particles against Enterococcus faecalis contaminating root canals with and without diode laser irradiation: an in vitro study

Objective: This study was done to evaluate the antibacterial effect of chitosan nano-particles (CNPs) root canal irrigant as a new alternative to Sodium hypochlorite (NaOCl) for disinfection of root canals inoculated with Enterococcus faecalis, with and without laser activation.

Methodology: Sixty single rooted human premolars were decoronated, prepared and had their apical foramina sealed. E. faecalis were incubated in the root canals for 15 days. The teeth were then randomly divided into two experimental groups (n?=?30) according to the disinfection protocol used. In Group I: disinfection was performed using the irrigant solutions only (Saline, 2.5% NaOCl, CNPs). Whereas in Group II, disinfection was done using the same irrigants followed by Diode laser at (980-nm) at 2 W output for 5?×?5?s. Intra-canal bacterial samples were taken before and after canal disinfection to determine the CFU count.

Results: In group I, 2.5% NaOCl was as effective as CNP in eradication and significantly more effective than Saline (p?=?0.008) in eradication of E. faecalis. In Group II, either 2.5% NaOCl or CNP in combination with diode laser irradiation showed a similarly high effect in bacterial eradication.

Conclusions: Within the parameters used in this study, a combination therapy consisting of irrigation followed by diode laser irradiation should be utilized as an effective treatment modality for eliminating E. faecalis from root canal systems.     

河套灌区覆膜沟灌对加工番茄生长效应与品质的影响

针对传统灌溉中存在不足,在内蒙古河套灌区研究了沟灌覆膜和无覆膜形式对加工番茄植株生育指标、品质、水分生产率、地上植株干物质积累量和番茄产量以及经济效益的影响。结果表明:覆膜处理对沟灌措施下的番茄植株的株高相比无覆膜处理增加达43%,茎粗增加达45%,番茄红素分别增加6.5%～25.4%;水分生产率及地上植株干物质的积累也分别提高了56%和22%,植株产量增长了1848.15～2768.89 kg·667m^-2,农民也得到了692.75～1592.75元·667m^-2的增产收入。因此在沟灌加工番茄生产中采取覆膜种植能有效促进生长并能取得良好的经济效益。     

滴灌条件下枣树耗水规律的研究

试验通过研究枣树的茎流来预测其耗水量,为合理灌溉提供科学依据。利用植物茎流计在滴灌条件下测定枣树的茎流变化,结果表明2010年5月15日的最大值出现在中午12∶00,达到1 834.28 g·h^-1,6月26日的最大茎流速率在13∶00,达到4 861.89 g·h^-1,7月20日最大值出现在15∶00,达到6 385.88 g·h^-1,8月10日最大茎流出现在16∶00,达到5 816.86 g·h^-1;最小茎流都是出现在凌晨4∶00～8∶00。5月份的日平均累计流量比较小,枣树在这个月的日平均耗水量反而最小,到了7、8月份,随着温度的升高和雨季的结束,枣树耗水量明显增加,8月的日平均耗水累计量最高;通过相关分析,地表最高温度和最高气温对枣树的茎流量影响较大。研究得出：土壤含水量是影响茎流的变化主要因素,其它环境因子对茎流的影响也很重要。     

基于控墒补灌的春小麦滴灌制度研究

为优化北疆绿洲区滴灌春小麦的灌溉制度,采用控墒补灌法研究了不同灌水量对滴灌春小麦光合特征、干物质分配及水分利用效率的影响。结果表明,拔节～开花期小麦株高、干物质积累量和叶面积指数均随着灌水量的增加显著（P<0.05）升高。小麦旗叶各时期净光合（Pn）、气孔导度（Gs）和蒸腾速率（Tr）增加显著（P<0.05）升高,而胞间CO₂浓度（Ci）变化趋势相反;过量灌溉T5各时期Gs均有所降低,Pn和Tr成熟期下降显著（P<0.05）;亏缺灌溉（T1）Pn峰值提前至孕穗期,各时期WUE均最低、LS最高。干物质向籽粒的分配、花前同化物转运率和对籽粒的贡献率随墒度随灌水量增加显著（P<0.05）降低。二次曲线拟合表明,灌水量为371 mm时可取得7 450 kg·hm^-2的高产,灌溉频率约每7 d灌1次是本地区春小麦的最佳灌溉方案。     

滴灌次数对冬小麦根系生长及时空分布的影响

以新冬18号为材料,利用双管分根管栽法,模拟田间试验研究了拔节期后不同滴灌次数W₁（6次）、W₂（7次）、W₃（9次）、W₄（11次）（每次内、外管分别滴30 mm）对0～100 cm土层含水量,0～100 cm土层初、次生根干重和长度、根系活性分布及产量的影响。结果表明,随滴灌次数及总滴灌量的增加,0～40 cm土层的含水量增加,并延缓该土层的初生根干重和根长的衰减、促进次生根干重和根长增长,增加孕穗期至花后20 d初、次生根干重密度、根长密度及根系活性,而对40～100 cm土层根系的生长影响较小。小麦产量和水分利用效率均以W₄最高,分别为25.5 g·管^-1和1.36 kg·m^-3 。当滴灌量少、湿润土层浅时,小麦深层初、次生根生长易受严重抑制,且根系分布浅,初生根提前衰老,导致千粒重降低而减产。     

Comparison of Sealer Penetration Using the EndoVac Irrigation System and Conventional Needle Root Canal Irrigation

Introduction

The aim of this study was to compare the effect of the EndoVac irrigation system (SybronEndo, Orange, CA) and conventional endodontic needle irrigation on sealer penetration into dentinal tubules.

Methods

Forty single-rooted, recently extracted human maxillary central incisors were randomly divided into 2 groups according to the irrigation technique used: conventional endodontic needle irrigation and EndoVac irrigation. All teeth were instrumented using the ProFile rotary system (Dentsply Maillefer, Ballaigues, Switzerland) and obturated with gutta-percha and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany) labeled with fluorescent dye. Transverse sections at 1, 3, and 5 mm from the root apex were examined using confocal laser scanning microscopy. The total percentage and maximum depth of sealer penetration were then measured.

Results

Mann-Whitney test results showed that EndoVac irrigation resulted in a significantly higher percentage of sealer penetration than conventional irrigation at both the 1- and 3-mm levels (P < .05). However, no difference was found at the 5-mm level. The 5-mm sections in each group showed a significantly higher percentage and maximum depth of sealer penetration than did the 1- and 3-mm sections (P < .05).

Conclusions

The EndoVac irrigation system significantly improved the sealer penetration at the 1- to 3-mm level over that of conventional endodontic needle irrigation.     

Spectrophotometric Determination of Irrigant Extrusion Using Passive Ultrasonic Irrigation,EndoActivator, or Syringe Irrigation

Introduction

Sodium hypochlorite (NaOCl) irrigation is critical to endodontic success, and several new methods have been developed to improve irrigation efficacy (eg, passive ultrasonic irrigation [PUI] and EndoActivator [EA]). Using a novel spectrophotometric method, this study evaluated NaOCl irrigant extrusion during canal irrigation.

Methods

One hundred fourteen single-rooted extracted teeth were decoronated to leave 15 mm of the root length for each tooth. Cleaning and shaping of the teeth were completed using standardized hand and rotary instrumentation to an apical file size #40/0.04 taper. Roots were sealed (not apex), and 54 straight roots (n = 18/group) and 60 curved roots (>20° curvature, n = 20/group) were included. Teeth were irrigated with 5.25% NaOCl by 1 of 3 methods: passive irrigation with needle, PUI, or EA irrigation. Extrusion of NaOCl was evaluated using a pH indicator and a spectrophotometer. Standard curves were prepared with known amounts of irrigant to quantify amounts in unknown samples.

Results

Irrigant extrusion was minimal with all methods, with most teeth showing no NaOCl extrusion in straight or curved roots. Minor NaOCl extrusion (1–3 μL) in straight roots or curved roots occurred in 10%–11% of teeth in all 3 irrigant methods. Two teeth in both the syringe irrigation and the EA group extruded 3–10 μL of NaOCl.

Conclusions

The spectrophotometric method used in this study proved to be very sensitive while providing quantification of the irrigant levels extruded. Using the PUI or EA tip to within 1 mm of the working length appears to be fairly safe, but apical anatomy can vary in teeth to allow extrusion of irrigant.     

An Evaluation of the Accuracy of Labeling of Percent Sodium Hypochlorite on Various Commercial and Professional Sources: Is Sodium Hypochlorite from These Sources Equally Suitable for Endodontic Irrigation?

Introduction

The shelf life of sodium hypochlorite (NaOCl) is limited, and a previous article showed that there can be a discrepancy between the expected concentration of free available chlorine (FAC) and the actual FAC concentration in NaOCl solutions intended for endodontic irrigation. The current study investigates the FAC content of domestic and professional NaOCls and evaluates the influences of dilution and storage on FAC concentration.

Methods

First, domestic and professional NaOCls not obtained from manufacturers were iodometrically titrated. Then, NaOCls were diluted with demineralized water or tap water and stored at 4°C or 18°C and analyzed at baseline and 2 and 22 weeks. Statistical analyses included paired samples, independent samples t tests and repeated multivariate analysis of variance. Correlations were calculated with the Pearson or Spearman rank correlation test. A P < .05 was considered significant.

Results

Label specifications of domestic NaOCl were very imprecise (ie, <5% NaOCl). Domestic NaOCl contained 1.8%–3.5% NaOCl (w/v). Professional NaOCl varied from 14.3% relative less FAC than specified on the label to 23.5% relative more FAC than specified. After 22 weeks, the relative average loss of FAC in all conditions was 5.4% FAC (P = .002). Dilution, diluents, or storage temperature had no effect on the decline of FAC caused by aging.

Conclusions

There is a great variation in NaOCl concentrations, with domestic NaOCl being the least accurate. NaOCl can be stored up to 5 months. The FAC concentration of domestic NaOCl is unpredictable, and, therefore, it appears less suitable for clinical application as root canal irrigant.     

Apical extrusion of debris: a literature review of an inherent occurrence during root canal treatment

Extrusion of intracanal debris as well as irrigants is a common occurrence during root canal treatment, and no instrument or technique has thoroughly solved this problem. Because flare‐ups may arise with any irritation directed towards periapical tissues, a shaping or irrigation technique should minimize the risk of apical extrusion, even though it may not be prevented. There has been a rapid evolution of root canal instruments and irrigation systems through the last decade, and many have been assessed for their debris extrusion potential. The purpose of this review was to identify publications regarding the evaluation of debris, bacteria and irrigant extrusion during root canal treatment. A PubMed, Ovid and MEDLINE search was conducted using the keywords “apical extrusion”, “debris extrusion” and “endodontic treatment”. The literature search extended over a period of more than 30 years up to 2012. Content of the review was limited to apical extrusion of debris and irrigants, extrusion of liquid by irrigation methods and bacterial extrusion. Issues relevant to apical extrusion were obtained by further search in the reference sections of the retrieved articles. The review provides an update on the current status of apical extrusion.     

一种检测根管冲洗效率模型的构建及应用

目的：构建红墨水检测根管内冲洗液交换效率的模型,检验其检测冲洗液交换效率的一致性和准确性,并使用此模型评估不同因素对冲洗液交换效率的影响。方法：将一个单弯树脂根管用PtoTaper预备至F2,分别使用红墨水和葡萄糖作为示踪剂,再按针头和流速分为3组进行冲洗实验,冲洗完毕后将残留液吸出测吸光度值,计算出剩余率。结果：相同条件下红墨水组剩余率与葡萄糖氧化酶法组剩余率差异无统计学意义（P＞0．05）;两种方法对剩余率的测定,组内相关系数大于0．75;红墨水的检出限小于葡萄糖氧化酶法;红墨水组中高流速组剩余率低于低流速组（P＜0．01）,平口针头组剩余率低于侧方开口针头组（P＜0．01）。结论：红墨水的检测准确性和葡萄糖氧化酶法一样,二者对于同一检测对象具有检测一致性,红墨水可准确检测的范围大于葡萄糖氧化酶法,不同针头设计和冲洗速度对冲洗液交换效率有影响。