根管冲洗剂次氯酸钠和氯亚明的细胞毒性

目的:评价次氯酸钠(NaOCl)和氯亚明溶液在相同有效氯浓度下的细胞毒性.方法: 按有效氯浓度为0.500 0%、0.250 0%、0.200 0%、0.150 0%、0.125 0%、0.062 5%分别配制NaOCl溶液和氯亚明溶液,使其与L929细胞接触2 h、30 min、10 min,用MTT法检测各组的细胞存活率.结果: 在所设定的浓度范围内,除高低两端组(0.500 0%-2 h及0.062 5%-30 min)外,细胞在其余各组NaOCl溶液中的存活率均大于氯亚明,差异有统计学意义(P<0.05).结论: 在0.250 0%以下的有效氯浓度范围,NaOCl溶液的细胞毒性小于氯亚明溶液.     

In vitro solubility of human pulp tissue in calcium hydroxide and sodium hypochlorite

Abstract The tissue solvent capacity of a 2% stabilized sodium hypochlorite solution (Milton®) and a commercial calcium hydroxide solution (Calasept®) was examined under in vitro conditions where autolyzed human pulp fragments weighing approximately 0.0065 g were immersed in these solutions at 37°C for periods of up to 10 days. It appeared that sodium hypochlorite was able to dissolve half the volume of pulp tissue within 1 h and the remaining tissue after 2–2 1/2 h. Calcium hydroxide dissolved half the pulp volume within 2 h, whereas it took 1 week for the remaining tissue to dissolve. These findings support the use of sodium hypochlorite as an irrigation solution during canal preparation and calcium hydroxide as a canal dressing for the purpose of creating a canal free of pulp remnants before root filling.     

Antimicrobial efficacy of endodontic irrigants from Azadirachta indica: An in vitro study

Abstract

Objective. This study analyzed the antimicrobial effect of five irrigants formulated from different parts of the tree Azadirachta indica (Neem) and compared with 2.5% sodium hypochlorite and 0.2% chlorhexidine gluconate through an agar diffusion test. Materials and methods. A clinical isolate of Candida albicans was innoculated on Sabourad Dextrose Agar and Enterococcus faecalis (ATCC 29212) on Sheep Blood Agar. Wells with 6 mm diameter were created in agar and 100 μL aliquiots of each irrigant were introduced to five different wells. After incubation, the largest uniform diameter of the inhibition zone was recorded. Results. The leaf extract of the tree and a mixture of the seed-bark powder dissolved in dimethyl sulfoxide were active against both organisms. The other neem-based irrigants, a leaf powder dissolved in dimethyl sulfoxide, aqueous bark decoction and neem oil, did not possess any antimicrobial efficacy. Sodium hypochlorite completely inhibited growth of C. albicans and the leaf extract had larger inhibition zones than chlorhexidine (p = 0.011) or the seed-bark irrigant (p = 0.008). Against E. faecalis, inhibition zones with chlorhexidine were the largest and differed significantly from sodium hypochlorite (p = 0.039), leaf extract (p = 0.008) and seed-bark irrigant (p = 0.011). Conclusions. Two neem irrigants displayed antimicrobial properties. The efficacy of the standard endodontic irrigants varied depending on the organisms tested. Clinical relevance: Neem-based endodontic irrigants may be formulated for clinical application.     

Comparison of the in vivo antimicrobial effectiveness of sodium hypochlorite and chlorhexidine used as root canal irrigants: a molecular microbiology study

Introduction

The purpose of this clinical study was to compare the antimicrobial effects of 2.5% sodium hypochlorite (NaOCl) and 0.12% chlorhexidine digluconate (CHX) when used as irrigants during treatment of teeth with apical periodontitis.

Methods

Forty-seven single-rooted single-canal teeth with necrotic pulps and asymptomatic apical periodontitis were selected for this study according to stringent inclusion/exclusion criteria. Bacterial samples were taken at the baseline (S1) and after (S2) chemomechanical preparation using 2.5% NaOCl (n = 30) or 0.12% CHX (n = 17) as the irrigant. Bacterial, archaeal, and fungal presence was evaluated by broad-range polymerase chain reaction (PCR), whereas bacterial identifications were performed by a closed-ended reverse-capture checkerboard approach targeting 28 candidate endodontic pathogens.

Results

All S1 samples were PCR positive for bacterial presence but negative for both archaea and fungi. Both NaOCl- and CHX-based protocols were significantly effective in reducing the bacterial levels and number of taxa. No significant differences were observed between them in all tested parameters including the incidence of negative PCR results in S2 (40% for NaOCl vs 47% for CHX, p = 0.8), reduction in the number of taxa per canal (p = 0.3), and reduction in the bacterial levels (p = 0.07). The most prevalent taxa in S2 samples from the NaOCl group were Propionibacterium acnes, Streptococcus species, Porphyromonas endodontalis, and Selenomonas sputigena. In the CHX group, the most prevalent taxa in S2 were Dialister invisus, Actinomyces israelii, Prevotella baroniae, Propionibacterium acidifaciens, and Streptococcus species.

Conclusions

Treatment protocols using irrigation with either NaOCl or CHX succeded in significantly reducing the the number of bacterial taxa and their levels in infected root canals, with no significant difference between these substances.     

不同冲洗液对根尖溢出碎屑的影响

目的： 比较根管预备后不同冲洗液对根尖溢出碎屑的影响。方法：58颗正畸拔除的单根牙随机分为4组,常规根管预备后,采用不同冲洗液冲洗,对照组(A组)：7颗、蒸馏水冲洗;实验组每组17颗,B组：1% NaOCl冲洗;C组：2.5% NaOCl冲洗;D组：17% EDTA冲洗。收集冲洗后的冲洗液,通过紫外可见分光光度计检测吸光度（OD）值,比较其根尖溢出碎屑的含量。采用SPSS 13.0软件包对结果进行统计学分析。结果：冲洗前、后的OD差值分别为对照组A组0.012、B组0.122、C组0.393、D组0.021,B、C、D 3组冲洗前、后的差值与对照组相比,均有显著差异（P<0.05）。其中,C组最高,与B、D 2组相比,均差异显著（P<0.05）。结论：冲洗液能增加根尖溢出碎屑的含量,2.5%NaClO冲洗液产生较多的根尖溢出碎屑,1% NaOCl、17%EDTA溶液是临床上较理想的冲洗液。     

Evaluation of tissue reaction, cell viability and cytokine production induced by Sealapex Plus

Objective

The aim of this study was to investigate the effects of mineral trioxide aggregate (MTA), Sealapex, and a combination of Sealapex and MTA (Sealapex Plus) on the reaction of subcutaneous connective tissue of rats, and on cell viability and cytokine production in mouse fibroblasts.

Material and Methods

The tissue reaction was carried out with dentin tubes containing the materials implanted in the dorsal connective tissue of rats. The histological analysis was performed after 7 and 30 days. Millipore culture plate inserts with polyethylene tubes filled with materials were placed into 24-well cell culture plates with mouse fibroblasts to evaluate the cell viability by MTT assay. ELISA assays were also performed after 24 h of exposure of the mouse fibroblasts to set material disks.

Results

Histopathologic examination showed Von Kossa-positive granules that were birefringent to polarized light for all the studied materials at the tube openings. No material inhibited the cell viability in the in vitro test. It was detected IL-6 production in all root-end filling materials. MTA and Sealapex Plus induced a slight raise of mean levels of IL-1ß.

Conclusions

The results suggest that Sealapex Plus is biocompatible and stimulates the mineralization of the tissue.     

Analysis of the reaction of subcutaneous tissues in rats and the antimicrobial activity of calcium hydroxide paste used in association with different substances

The aim of this study was to evaluate the subcutaneous tissue response in rats and the antimicrobial activity of intracanal calcium hydroxide dressings mixed with different substances against E. faecalis. Fifty four rats were divided into three experimental groups according to the vehicle in the calcium hydroxide treatment: 0.4% chlorohexidine in propylene glycol (PG), Casearia sylvestris Sw in PG and calcium hydroxide+PG (control group). The pastes were placed into polyethylene tubes and implanted into the subcutaneous tissue. After 7, 14 and 30 days, the samples were processed and histologically evaluated (hematoxylin and eosin). The tissue surface in contact with the material was analyzed, and the quantitative analysis determined the volume density occupied by the inflammatory infiltrate (giant cells, polymorphonuclear cells and mononuclear cells), fibroblasts, collagen fibers and blood vessels. For the antimicrobial analysis, 20 dentin blocks infected with E. faecalis were treated with calcium hydroxide pastes in different vehicles; 0.4% chlorhexidine in PG, PG, extract from Casearia sylvestris Sw in PG and a positive control (infection and without medication) for 7 days. The efficiency of the pastes was evaluated by the live/dead technique and confocal microscopy. The results showed that 0.4% chlorhexidine induced a higher inflammatory response than the other groups. The Casearia sylvestris Sw extract showed satisfactory results in relation to the intensity of the inflammatory response. In the microbiological test, there were no statistical differences between the evaluated intracanal dressings and the percentage of bacterial viability was between 33 and 42%. The control group showed an 86% viability. Antimicrobial components such as chlorhexidine or Casearia sylvestris Sw did not improve the antimicrobial activity against E. faecalis in comparison to the calcium hydroxide+PG treatment. In addition, the incorporation of chlorhexidine in the calcium hydroxide paste promoted the highest inflammatory response.     

The effects of sodium hypochlorite and calcium hydroxide on tissue dissolution and root canal cleanliness

In this in vitro study, we investigated the efficacy of sodium hypochlorite (NaOCl) and calcium hydroxide (Ca(OH)₂) in dissolving necrotic tissue and cleaning root canals. In the first part of the study, 0.5% NaOCl solution and Ca(OH)₂ paste and solution were tested with samples of necrotic bovine muscle in different treatment modes and for different periods. The necrotic tissue was weighed before and after the test and the percentage of weight change calculated. In the second part of the study, 40 extracted single-rooted human teeth were hand instrumented and then subjected to different irrigation regimens. The cleansing efficacy in root canals of 0.5% NaOCl with Ca(OH)₂ pretreatments and ultrasonics was examined using scanning electron microscopy. A solution of 5% NaOCl was significantly more effective than 0.5 % NaOCl as a solvent of necrotic tissue. Calcium hydroxide was an effective solvent for necrotic tissue as a paste but not as a solution. Pretreatment of necrotic tissue with Ca(OH)₂ increased its solubility in 0.5% NaOCl. While 5 % NaOCl plus ultrasonic irrigation produced cleaner root-canal walls at the middle and apical thirds, 0.5% NaOCl used with the same technique achieved no root-canal cleaning. However, pretreatment of root canals with Ca(OH)₂ paste increased the effectiveness of 0.5% NaOCl plus ultrasonic irrigation, except in the coronal third of the root canal.     

Comparative evaluation of fracture resistance among conventional versus herbal irrigants in root canal treated teeth: In vitro study

To evaluate the efficacy of conventional irrigants and herbal extracts materials which helps to resist fracture of endodontically treated teeth. 75 maxillary human permanent incisor teeth instrumented using ProTaper rotary files till apical size(F4). Instrumented samples divided into 5 groups with n = 15 based on various irrigants used. Group I: normal saline, Group II: 5% sodium hypochlorite (NaOCl), Group III: 2% chlorohexidine, Group IV: 10% Azadirachta indica (neem extract) and Group V: 10% Ocimum sanctum (tulsi extract).After that, root canals were proceeded to be filled by using single gutta-percha cone and Sealapex sealer. Specimens were then prepared and loaded until root fracture occurred. Maximum mean flexural strength of dentin (fracture resistance) was obtained from group treated with 2% chlorohexidine and 10% neem extract. Least fracture resistance was observed with 5% NaOCl. Herbal irrigants can be used as an alternative to NaOCl as they exhibit high fracture resistance.     

Susceptibility of Actinomyces israelii to antibiotics, sodium hypochlorite and calcium hydroxide

Actinomyces israelii has been repeatedly implicated as a cause of failure of endodontic therapy. This study investigated the antimicrobial effect of antibiotics as well as intracanal medicaments, sodium hypochlorite solution and calcium hydroxide, on this important pathogen. Growth of A. israelii was inhibited by low concentrations of antibiotics, yet high concentrations were not bactericidal for A. israelii over 1 week. When A. israelii was exposed for 2-6 weeks at concentrations equivalent to clinical serum levels, the antibiotics were lethal. The results reveal a species - specific antibiotic tolerance for A. israelii. Both sodium hypochlorite solution and calcium hydroxide were found to be highly eifective in killing A. israelii.     

Influence of EDTA and dentine in tissue dissolution ability of sodium hypochlorite

This study verified whether ethylenediaminetetraacetic acid (EDTA) influences the pulp tissue dissolution capability of different concentrations of NaOCl, in the presence of dentine. NaOCl and EDTA solutions were simultaneously mixed in flasks either containing a dentine disc or those not containing a dentine disc. Previously weighed bovine pulp tissues were immersed in the solutions for 5, 15 and 30 min. The weight loss was measured. The dissolution tests were performed in triplicate. Univariate analysis of variance, along with further Tukey's honestly significant difference pairwise comparisons, was used to verify the effect of EDTA, different concentrations of NaOCl, dentine and time of incubation on the tissue dissolution. Higher concentrations of NaOCl increased the tissue dissolution. EDTA reduced the capacity of NaOCl to dissolve pulp tissue, even in presence of dentine. Dentine negatively affects the capacity of NaOCl to dissolve pulp tissue. In conclusion, the presence of EDTA and dentine negatively affects the tissue dissolution ability of NaOCl.     

Biological response of epithelial and connective tissue cells to titanium surfaces with different ranges of roughness: An in-vitro study

ObjectivesThis study aimed to investigate how titanium (Ti) surface with different range roughness created by industrial machining influence the biological response of primary human gingival fibroblasts (HGFB) and keratinocytes (HGKC) in terms of cell proliferation and cytotoxicity.MethodsFour Ti surfaces of different roughness ranges were investigated: smooth (S: 0.08–0.1 µm), minimally rough (MM: 0.3–0.5 µm), moderately rough (MR: 1.2–1.4 µm) and rough (R: 3.3–3.7 µm). Discs topography and surface roughness were evaluated by scanning electron microscopy (SEM) and non-contact profilometer. Both cell lines were cultured, expanded, and maintained according to their supplier’s protocols. Cell proliferation and cytotoxicity were evaluated at days 1, 3, 5, and 10 using cell viability and cytotoxicity colorimetric assays. Data were analysed via two-way ANOVA, one-way ANOVA and Tukey’s post hoc test (p = 0.05 for all tests).ResultsBoth cell lines showed comparable initial proliferation activity of 70–86% for all the investigated roughnesses. HGKC showed better and higher proliferation % with S surface at all time points than all the other investigated surfaces which was significantly higher than MM at day 3 and higher than all the other investigated surfaces at day 5 and 10. On the other hand, HGFB exhibited the best proliferation with both MM and R surfaces with no significant differences from the other two surfaces (S and MR). Different surface roughnesses and exposure times showed significant effect on cell proliferation in both cell lines. Cytotoxicity for both cell lines was generally the highest on day 3, with the following order from highest to lowest: S (19.86%)> R> MR> MM for HGKC and MM (39.48%)> MR> S> R for HGFB. Different exposure times showed a significant effect on cell cytotoxicity in both cell lines and a significant effect of surface roughness in HGFB.SignificanceAll investigated roughness levels were sufficiently biologically compatible with cells representative of the major population of the soft tissue surrounding dental implants. However, the S surface was most cytotoxic to HGKC, while the MM surface was most cytotoxic to HGFB cells.     

Evaluation of the antimicrobial activities of chlorhexidine gluconate,sodium hypochlorite and octenidine hydrochloride in vitro

The objective of this study was to compare the antimicrobial activity of sodium hypochlorite (NaOCl), chlorhexidine gluconate (CHX) and octenidine hydrochloride (OCT) in different concentrations against endodontic pathogens in vitro. Agar diffusion procedure was used to determine the antimicrobial activity of the tested materials. Enterococcus faecalis, Candida albicans and the mixture of these were used for this study. In the agar diffusion test, 5.25% NaOCl exhibited better antimicrobial effect than the other concentrations of NaOCl for all strains. All concentrations of OCT were effective against C. albicans and E. faecalis. Some 0.2% CHX was ineffective on all microorganisms. Antibacterial effectiveness of all experimental solutions decreased on the mixture of all strains. Decreasing concentrations of NaOCl resulted in significantly reduced antimicrobial effect.     

In vitro solubility of human pulp tissue in calcium hydroxide and sodium hypochlorite.

The tissue solvent capacity of a 2% stabilized sodium hypochlorite solution (Milton) and a commercial calcium hydroxide solution (Calasept) was examined under in vitro conditions where autolyzed human pulp fragments weighing approximately 0.0065 g were immersed in these solutions at 37 degrees C for periods of up to 10 days. It appeared that sodium hypochlorite was able to dissolve half the volume of pulp tissue within 1 h and the remaining tissue after 2-2 1/2 h. Calcium hydroxide dissolved half the pulp volume within 2 h, whereas it took 1 week for the remaining tissue to dissolve. These findings support the use of sodium hypochlorite as an irrigation solution during canal preparation and calcium hydroxide as a canal dressing for the purpose of creating a canal free of pulp remnants before root filling.     

An in vitro spectroscopic analysis to determine the chemical composition of the precipitate formed by mixing sodium hypochlorite and chlorhexidine

Introduction

The purpose of this in vitro study was to determine the chemical composition of the precipitate formed by mixing sodium hypochlorite (NaOCl) and chlorhexidine (CHX) and the relative molecular weight of the components.

Methods

Using commercially available CHX gluconate, a 2% solution was formed and mixed in a 1:1 ratio with commercially available NaOCl producing a brown precipitate. The precipitate as well as a mixture of precipitate and pure CHX diacetate was then analyzed using one-dimensional and two-dimensional NMR spectroscopy.

Results

The one-dimensional and two-dimensional NMR spectra were fully assigned in terms of chemical shifts of all proton and carbon atoms in intact CHX. This permitted identification of two major CHX breakdown products, neither of which are parachloroaniline (PCA). Both products are related to PCA in that they are parasubstituted benzene compounds. Based on NMR data and a proposed mechanism of CHX breakdown, the products appear to be parachlorophenylurea (PCU) and parachlorophenylguanidyl-1,6-diguanidyl-hexane (PCGH).

Conclusions

Based on this in vitro study, the precipitate formed by NaOCl and CHX is composed of at least two separate molecules, all of which are smaller in size than CHX. Along with native CHX, the precipitate contains two chemical fragments derived from CHX (PCU and PCGH), neither of which are PCA.     

Effectiveness of calcium and sodium hypochlorite in association with reciprocating instrumentation on decontamination of root canals infected with Enterococcus faecalis

The aim of this study was to evaluate the antimicrobial activity of sodium and calcium hypochlorite utilising reciprocating instrumentation. Sixty root canals were inoculated with E. faecalis for 14 days. Samples were divided into six groups according to decontamination protocol: G1: no treatment, G2: distilled water, G3: 2.5% sodium hypochlorite, G4: 2.5% calcium hypochlorite, G5: 5.25% sodium hypochlorite and G6: 5.25% calcium hypochlorite. Instrumentation was performed with Wave One reciprocating system (Dentsply Sirona Endodontics, York, PA, USA) in groups G2 to G6. Colony‐forming units (CFUs) counting was performed and the data were subjected to Anova and Tukey (α  =  0.05). Group 1 and 2 showed the highest mean contamination, with a significant difference between them (P < 0.05). Groups 3, 4, 5 and 6 showed the lowest contamination means with no significant difference between them (P < 0.05). Sodium and calcium hypochlorite, in association with reciprocating instrumentation, can be an effective decontamination protocol in root canals infected with E. faecalis.     

An in vitro assessment of type,position and incidence of isthmus in human permanent molars

Root canal anatomical complexities, such as isthmus, may limit the action of the endodontic instruments, irrigant solutions and intracanal medications, leading to endodontic treatment failure.

Objectives

This in vitro study assessed the type, position and incidence of isthmus in human permanent molars.

Material and Methods

One hundred and twenty eight upper and lower first and second permanent molars were analyzed. The roots were embedded in transparent resin, and then split at different distances from the apex (1.0-2.5-4.0-5.5-7.0 mm). Following the sample examination in stereomicroscope, the data were submitted to chi-square statistical test at a 5% significance level.

Results

The highest isthmus incidence was at 7.0 mm from the root apex in all samples, except the distal root of lower molars (at 5.5 mm). In upper and lower molars, type V (complete isthmus with a continuous opening between the two main root canals) was the most common classification of isthmus (28.8%). In the mesial root of first and second mandibular molars, type IV had the highest incidence (36% and 23.9%, respectively).

Conclusion

It was concluded that isthmus was widely found in flat roots, with a low percentage in areas close to the apex. In upper and lower molars, these structures were most frequently found at 7 mm from the apex.     

Viscoelastic and chemical properties of dentine after different exposure times to sodium hypochlorite,ethylenediaminetetraacetic acid and calcium hydroxide

This study aims to evaluate the viscoelastic and chemical properties of dentine after different durations of exposure to 5.25% NaOCl, 17% EDTA and Ca(OH)₂ solutions, and NaOCl in alternating combination with EDTA. Standard dentine bars were randomly assigned to: (i) formal‐saline control‐1; (ii) NaOCl; (iii) EDTA; (iv) NaOCl/EDTA; (v) formal‐saline control‐2; (vi) Ca(OH)₂ pH 12.6; and (vii) Ca(OH)₂ pH 9.8. Groups 1‐–4 underwent 10 min cycles of soaking and dynamic mechanical analysis up to 120 min. Groups 5–7 underwent similar tests at days 7, 14, 28 and 84. FTIR spectra of dentine discs exposed to the same regimens assessed surface chemistry. NaOCl or Ca(OH)₂ (pH 12.6) solutions reduced the organic (N‐H[1], N‐H[3], C=0) peak components of dentine. This study demonstrated that accumulative damage of dentine could be facilitated by alternated exposure to NaOCl and EDTA. Exposure of dentine to Ca(OH)₂ (pH12.6) for 7 days reduced viscous behaviour, inferring increased potential for fatigue failure.     

Tissue responses to an experimental calcium phosphate cement and mineral trioxide aggregate as materials for furcation perforation repair: a histological study in dogs

The aim was to evaluate histologically the inflammatory reactions and tissue responses to an experimental tricalcium phosphate cement (TCP) and mineral trioxide aggregate (MTA) when used as repair materials in furcation perforations in dogs. Perforations were performed in 24 mandibular premolars of six anaesthetised dogs and filled either with ProRoot MTA (grey) or TCP. The root canals were subsequently shaped and filled, and the access cavities were closed with a bonded composite resin. The animals were killed at 12 weeks. After radiological examination, the teeth and surrounding structures were processed for light microscopy. Concerning the grades of inflammation, MTA exhibited significantly better results than TCP (chi-square test according to Pearson). No furcation was free of inflammatory cells. Mild inflammation was observed in nine of twelve cases with MTA and only twice in those with TCP. No significant differences were revealed between MTA and TCP in terms of bone reorganization or deposition of fibrous connective tissue (Mantel-Haenszel chi-square test). The grade of radiological examination corresponded with the grade of inflammation or differed by only one grade plus or minus. Perforations located in the furcation of teeth remain an endodontic and a periodontal problem with an uncertain prognosis, in spite of the promising modern materials applied.