Effect of two methods of irrigant agitation on the temperature and cleanliness of sodium hypochlorite associated or not with a chelator: irrigant agitation and influence in temperature

Aim: This study investigated the influence in vitro of different sodium hypochlorite (NaOCl) agitation protocols associated or not with DualRinse (HEDP) on the temperature of the solution. Methods: Forty-eight premolars were instrumented and their apical third sealed to allow a closed irrigation system. The teeth remained immersed in a basin of warm water (37°C). The teeth were divided into the groups: G1 (NaOCl+Passive Ultrasonic Irrigation (PUI)), G2 (NaOCl/HEDP + PUI), G3 (NaOCl + EasyClean (EC)) and G4 (NaOCl/HEDP + EC). The canals were filled with the respective solutions and after 180 seconds the first temperature measurement was taken (T0). Then, the solutions were agitated, following the different protocols, for 60 seconds and a new measurement was performed (T60). The temperature was measured using a digital thermometer for type "K" sensors that was inserted into the middle third of the teeth. At the end of the measurements, the teeth were sectioned and prepared for scanning electron microscopy. The dentinal wall of middle third was graded according to the amount of debris and smear layer remaining on the walls. The results were analyzed using ANOVA test and Tukey's multiple comparisons (p<0.05). Results: G1 and G2 had an average increase in temperature of 1.1°C and 1.65°C, respectively (p>0.05). EasyClean caused a decrease in the temperature of the solutions in both groups, without a significant statistical difference with T0 (p>0.05). Regarding cleaning, it was only possible to observe clean dentinal tubules in the groups with the chelator. PUI discretely increased the temperature of the solution, regardless of the solution. The opposite effect was observed after activation with EasyClean. Conclusion: The association of NaOCl with a chelating agent promoted the cleaning of the dentinal tubules

An unusual repair of perforating internal inflammatory root resorption; a case report of endodontic treatment

Internal inflammatory root resorption (IIRR) can occur as a serious complication of dental trauma which leads to progressive loss of the root structure. An early diagnosis could influence the therapeutic approach, but endodontic treatment becomes a challenge with a doubtful prognosis. The present report described an unusual clinical presentation of an IIRR with perforation resulting from a trauma four years previous. A 15-year-old female patient was presented to our service with pain in the maxillary incisor region. Intraoral radiography revealed a large radioloucent area compatible with IIRR, communicating with the periodontium in the middle third on the distal root face of the right central incisor. The root canal of the right central incisor was chemo-mechanically prepared. The calcium hydroxide (CH) intracanal medication was used and renewed periodically four times. The root canal was filled only in the cervical region to the level of resorption by the inverted gutta-percha cone technique. Clinically and radiographically, all follow-up examinations revealed an asymptomatic tooth, evidencing periapical tissue repair and new bone formation. The tooth remained asymptomatic 3 years afterwards. The present case report supports the idea of executing satisfactory intracanal decontamination by chemo-mechanical preparation, thus creating a favourable environment for tissue repair.

Could polyhexanide and chlorine dioxide be used as an alternative to chlorhexidine? A systematic review

ABSTRACT BACKGROUND: Maintenance of oral microbiota balance is the simplest way to prevent infectious oral diseases, through controlling dental biofilm. Combined use of mouthwash and mechanical removal has been shown to be a very effective way for this. OBJECTIVES: To identify clinical studies comparing the antimicrobial effect and possible adverse effects and/or side effects of chlorhexidine-based mouthwashes with those of mouthwashes containing chlorine dioxide and/or polyhexanide, for controlling oral microbiota. DESIGN AND SETTING: Systematic review designed by the stomatology sector of postgraduation in applied dental sciences of Bauru Dentistry School, University of São Paulo, Brazil. METHODS: A systematic review was conducted using online databases (PubMed, Embase, Web of Science and Science Direct) up to April 8, 2020. The search was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. RESULTS: The studies included comprised eight articles published between 2001 and 2017. A total of 295 young adults, adults and elderly people were evaluated (males 44.75% and females 55.25%). Three articles compared polyhexanide with chlorhexidine and five articles compared chlorine dioxide with chlorhexidine. No studies comparing all three mouthwashes were found. The concentrations of the study solutions were quite varied, and all rinses had an antimicrobial effect. In four studies, it was stated that no side effects or adverse effects had been found. Three studies did not address these results and only one study addressed side effects and/or adverse effects. CONCLUSION: Mouthwashes containing chlorine dioxide and polyhexanide are viable alternatives to chlorhexidine, since they reduce oral biofilm and have little or no reported side or adverse effects.

Impact of irrigation protocols with some chelators and mechanical agitation on intratubular decontamination

Abstract: This study evaluated main canal and intratubular decontamination using different irrigation solutions followed by adjunctive agitation steps for infected root canals. Sixty-eight lower incisors were contaminated with Enterococcus faecalis and allocated to groups according to canal treatment (n = 10): G1, NaOCl followed by ethylenediaminetetraacetic acid (EDTA); G2, a mixture of NaOCl with hydroxyethylidene bisphosphonate (HEBP); and G3, NaOCl followed by EDTA-T (EDTA with sodium lauryl ether sulfate). All three groups of teeth were agitated with passive ultrasonic irrigation (PUI) using saline solution, whereby G4, G5, and G6 were prepared as above, and agitation was performed using an XP-Endo Finisher instrument. Microbiological samples were collected from the root canals with paper points at three times: before and after chemomechanical preparation and after agitation. The colony-forming units (CFU)/mL count was determined, and bacterial intratubular viability was analyzed via confocal laser scanning microscopy using Live/Dead staining. Statistical analysis was performed using a Kruskal-Wallis test followed by Dunn tests. A Friedman test was applied for colony-counting data (α = 0.05). CFU/mL counting indicated equally effective decontamination in the experimental groups (p > 0.05). According to microscopy images, the use of irrigation solutions followed by agitation with the XP-Endo Finisher yielded better results. Moreover, NaOCl+EDTA-T followed by XP-Endo Finisher resulted in significantly lower viability than in the PUI-activated groups (p < 0.05). The cervical and medium thirds of the specimens presented similar results. Overall, NaOCl+EDTA-T exhibited the best intratubular antibacterial activity, mainly for canals that were subsequently agitated using XP-Endo Finisher.

Influence of EDTA and its Association with Benzalkonium Chloride on Enterococcus faecalis Adhesion to Dentin / Influencia del EDTA y su Asociación con Cloruro de Benzalconio en la Adhesión de Enterococcus faecalis a la Dentina

ABSTRACT: The aim of this in vitro study was to investigate the influence of ethylenediaminetetraacetic acid (EDTA) associated with the benzalkonium chloride (BAK) on the adhesion and formation of Enterococcus faecalis biofilms attached to coated dentin. Discs standard bovine dentin blocks were treated with the coating materials evaluated: Saline solution (control), 17 % EDTA, 17 % EDTA associated with 1 % BAK for 5 minutes and subsequently washed with saline solution. Afterwards, biofilms of E. faecalis (ATCC 29212) were grown on the surface of coated dentin blocks for time intervals of 1 hour and 7 days (n = 20) and were subsequently washed with phosphate-buffered saline (PBS). Bacterial viability and total biovolume were analyzed by confocal laser scanning microscopy (CLSM) using the Live/Dead technique. Nonparametric Kruskal-Wallis followed by Dunn tests were used to determine statistical differences (a = 5 %). The 17 % EDTA + 1 % BAK group showed significantly lower biovolume and bacterial viability values at the end of 1 hour (p < 0.05). After 7 days of contamination, the 17 % EDTA and 17 % EDTA + 1 % BAK groups showed similar results that differed statistically from those of the control group (p < 0.05). The saline solution group showed higher values. The use of BAK associated with EDTA on dentin blocks surfaces before exposure to contamination was able to interfere in the adhesion of E. faecalis to dentin. Also, dentin treatment by BAK associated with a chelating agent influences the secondary biofilm formation, which could have important effects on the long-term success of root canal treatment.

RESUMEN: El objetivo del estudio consistió en investigar in vitro, la influencia del ácido etilendiamino-tetraacético (EDTA) con cloruro de benzalconio (BAK) en la adhesión y formación de biopelículas de Enterococcus faecalis a la dentina. Discos de dentina bovina fueron tratadas con solución salina (control), 17 % de EDTA, 17% de EDTA asociado con 1 % de BAK durante 5 minutos y lavadas con solución salina. Las biopelículas de E. faecalis (ATCC 29212) se cultivaron sobre los discos de dentina durante intervalos de tiempo de 1 hora y 7 días (n = 20), lavados con solución salina tamponada con fosfato (PBS). La viabilidad bacteriana y el biovolumen total se analizaron mediante microscopía de barrido por láser (CLSM) utilizando la técnica Live / Dead. Se realizó prueba no paramétrica de Kruskal-Wallis, seguida por Dunn con una diferencia estadística (a = 5 %). El grupo de 17 % EDTA + 1 % BAK mostró valores significativamente menores de biovolumen y viabilidad bacteriana al final de 1 hora (p < 0,05). Después de 7 días de contaminación, los grupos de 17 % EDTA y 17 % EDTA + 1 % BAK mostraron resultados similares que diferían estadísticamente del grupo control (p < 0,05). La solución salina mostró valores más altos. La asociación de BAK con EDTA antes de la contaminación interfirió en la adhesión de E. faecalis. Además, el tratamiento de la dentina por BAK asociado con EDTA influye en la formación de biopelículas secundarias, lo que podría tener efectos importantes sobre el éxito a largo plazo del tratamiento del conducto radicular.

Resistência à fadiga cíclica e torcional dos instrumentos reciprocantes W File e X1 Blue File / Cyclic and torcional fatigue resistance of W File and X1 Blue file reciprocating instruments

Objetivo: O objetivo deste estudo foi avaliar a resistência à fadiga cíclica e torcional dos sistemas reciprocantes WFile 25.07 (WF, TDKaFile, Cidade do México, México) e X1 Blue File 25.06 (X1 BF, MK Life, Porto Alegre, Bra- sil) à temperatura corporal. Material e Métodos: Foram utilizados 40 instrumentos reciprocantes WFile 25.07 (WF 25.07) e X1 BF 25.06 (n=20, cada grupo). O teste de fadiga cíclica foi realizada à temperatura corporal (36±1°C). Os instrumentos foram ativados com movimento reciprocante em um canal artificial de aço inoxidável com ângulo de 60o e 5mm de raio de curvatura (n=10). O teste torcional avaliou o torque e o ângulo de rotação necessários para a fratura dos instrumentos (n=10) nos 3mm iniciais da parte ativa do instrumento, de acordo com a norma ISO 3630-1. Os fragmentos fraturados foram avaliados em microscopia eletrônica de varredura (MEV). Os dados obtidos foram submetidos aos testes estatísticos de Kolmogorov-Smirnov e t de Student, sendo utilizado o nível de significância de 5%. Resultado: O X1BF25.06 apresentou maior tempo e número de ciclos para a fratura do que o WF 25.07 (p<0,05). O teste de torção demonstrou que o WF 25.07 apresentou maior torque do que o X1 BF 25.06 (p<0,05). Em relação ao ângulo de rotação, o X1 BF 25.06 apresentou maiores valores do que o WF 25.07 (p<0,05). Conclusão: O X1 BF apresentou maior resistência à fadiga cíclica e maior ângulo para a fratura do que o WF 25.07. Entretanto, o WF 25.07 apresentou maior torque para a fratura do que o X1 BF 25.06 (AU).

Introduction: The aim of this study was to evaluate the cyclic and torsional fatigue resistance of reciprocating single-file systems W File 25.07 (WF, TDKaFile, Mexico City, Mexico) and X1 Blue File 25.06 (X1 BF, MK Life, Porto Alegre, Brazil) at body temperature. Materials and Methods: Forty reciprocating instruments of the W File 25.07 (WF 25.07) and X1 BF 25.06 (n=20) were used. Cyclic fatigue tests were performed at body temperature (36° ± 1°C). The instruments were reciprocated until fracture occurred in an artificial stainless steel canal with a 600 angle and a 5-mm radius of curvature (n=10). The torsional test evaluated the torque and angle of rotation at failure of new instruments (n=10) in the portion 3 mm from the tip according to ISO 3630-1. The fractured surface of each fragment was observed by using scanning electron microscopy (SEM). Data were analyzed using one-way ANOVA and Tukey tests, and the level of significance was set at 5%. Results: X1 BF 25.06 had significantly higher time and NCF to failure than WF 25.07 (P<0.05). The torsional test showed that WF 25.07 had significantly greater torsional strength (p<0.05). In relation to angular rotation, the X1 BF 25.06 showed higher angular rotation values to failure than WF 25.07 (p<0.05). Conclusion: The X1 BF 25.06 had the highest cyclic fatigue resistance and highest angular rotation values to fracture in comparison with WF 25.07. However, WF 25.07 showed higher torsional resistance to fracture than X1 BF 25.06 (AU).

Consequences of chemical residue formation during potentiation of final irrigation - in vitro study

Seeking to increase the efficiency of endodontic irrigation, the association of different solutions as final irrigant has been investigated, such as sodium hypochlorite with chlorhexidine. The literature shows that the combination of these substances leads to the formation of a brownish precipitate, but does not reveal measurements of the intensity of this precipitate and its consequences. Aim: The present study aimed to evaluate the change in dentin color and the obliteration of the dentinal tubules after the association of sodium hypochlorite (NaOCl) with chlorhexidine (CHX) in the final irrigation. Methods: Fifty sterile human lower premolars were prepared with a ProDesign R 35.05 files and divided into 6 groups. Four different NaOCl concentrations (0.5%; 1%, 2.5% and 5.25%) associated with 2% CHX were tested, in addition to 2 control groups, using only 2.5% NaOCl and 2% CHX, respectively. After the final irrigation protocol, the dentin color change was evaluated by spectrophotometry immediately and after 24 hours, and the dentinal tubule obliteration was assessed by scanning electron microscopy. Results: It was possible to verify that regardless the NaOCl concentration used when associated with CHX, a chemical residue was formed, with consequent dentin pigmentation and tubular obstruction. There was a trend towards increased dentin pigmentation and tubular obstruction due to the deposition of the chemical residue formed by this association. Conclusion: It can be concluded that all concentrations of NaOCl associated with CHX caused color changes and tubular obstruction, being proportional to the concentration of NaOCl used

Sweetness Taste Preference Levels and Their Relationship to the Nutritional and Dental Caries Patterns among Brazilian Preschool Children

Objective: To evaluate the sweetness taste preference levels and their relationship with the nutritional and dental caries patterns among preschool children. Material and Methods: The participants of this cross-sectional study were 191 children aged 4 to 5 years, who were regularly attending public Child Education Centers of a city southern Brazil. Children's preference for sugar was evaluated by the Sweet Preference Inventory; caries prevalence, according to the World Health Organization criteria, and nutritional status, by anthropometric weight and stature measurements, in accordance with child growth standards of the World Health Organization. Results: High levels of sweetness preference were identified. The majority of children (67.5%) opted for the most concentrated sucrose solutions. Excess weight was recorded in 27.7% of the preschoolers. The prevalence of caries was 51.8%, with the mean dmf-t equal to 1.92 (± 2.72) and the decayed (c) component responsible for 94.2% of the index. No significant association between sweetness preference and the nutritional or the oral health patterns could be established. In addition, no association between excess weight and dental caries was identified. The diseases studied were only associated with sociodemographic variables. Excess weight was associated with maternal age (p=0.004) and caries experience with family income (p=0.013). Conclusion: No significant associations could be stablished between the sweetness taste preference and the diseases studied, nor between excess weight and dental caries. However, the findings of high patterns of sweet preference, excess weight and untreated caries experience, highlight the need for the implementation of integrated public policies aimed at controlling both nutritional and of oral health problems in the studied population.

A novel ultrasonic tip for removal of filling material in flattened/oval-shaped root canals: a microCT study

Abstract The aim of this study was to evaluate the influence of a novel ultrasonic tip as an auxiliary method for removing filling material from flattened/oval-shaped canals. The null hypothesis tested was that this method does not influence removing the filling material in flattened/oval-shaped canals. Forty-five mandibular incisors were selected and randomly divided into three experimental groups (n = 15) according to different protocols for removing root canal filling material. Group R: Reciproc R25/.08, Group RC: Reciproc R25/.08 + Clearsonic tip, and Group CR: Clearsonic tip + Reciproc R25/.08. The teeth were scanned pre and post-operatively by means of a micro-computed tomography system. Data were analyzed using non-parametric Kruskal-Wallis and Dunn tests (p < 0.05). The percentage of residual root canal filling material between the experimental groups was examined. Statistically significant differences between the experimental groups were found in the root canal. Group R had the highest percentage of residual root canal filling material when compared with Groups RC and CR. The lowest percentage of residual root canal filling material was observed in Group CR. In the apical third of the root canal, statistically significant differences were found between the different protocols. The use of the ClearSonic tip followed by the Reciproc 25/.08 file to remove filling material resulted in the lowest percentage of residuals in the whole root canal and in the apical third.

Analysis of the antimicrobial and anti-caries effects of TiF4 varnish under microcosm biofilm formed on enamel

Abstract Titanium tetrafluoride (TiF4) is known for interacting with enamel reducing demineralization. However, no information is available about its potential antimicrobial effect. Objectives This study evaluated the antimicrobial and anti-caries potential of TiF4 varnish compared to NaF varnish, chlorhexidine gel (positive control), placebo varnish and untreated (negative controls) using a dental microcosm biofilm model. Material and Methods A microcosm biofilm was produced on bovine enamel previously treated with the varnishes, using inoculum from human saliva mixed with McBain saliva, under 0.2% sucrose exposure, for 14 days. All experiments were performed in biological triplicate (n=4/group in each experiment). Factors evaluated were: bacterial viability (% dead and live bacteria); CFU counting (log10 CFU/mL); and enamel demineralization (transverse microradiography - TMR). Data were analysed using ANOVA/Tukey's test or Kruskal-Wallis/Dunn's test (p<0.05). Results Only chlorhexidine significantly increased the number of dead bacteria (68.8±13.1% dead bacteria) compared to untreated control (48.9±16.1% dead bacteria). No treatment reduced the CFU counting (total microorganism and total streptococci) compared to the negative controls. Only TiF4 was able to reduce enamel demineralization (ΔZ 1110.7±803.2 vol% μm) compared to both negative controls (untreated: ΔZ 4455.3±1176.4 vol% μm). Conclusions TiF4 varnish has no relevant antimicrobial effect. Nevertheless, TiF4 varnish was effective in reducing enamel demineralization under this model.

Do different strains of E. faecalis have the same behavior towards intracanal medications in in vitro research?

Abstract: The aim of this study was to evaluate the antimicrobial action of different endodontic pastes against Enterococcus faecalis ATCC 29212, isolated from the urinary tract, and compare the action with E. faecalis ATCC 4083, isolated from the root canal. For this purpose, dentin blocks were infected for 21 days with both bacteria at different time-intervals to ensure there would be no cross contamination. After this period, blocks were immersed in the test medications for 7 days, according to the following groups: CH/S, CH/P, CH/CMCP, CH/CHX, CH/DAP and TAP. Images of the samples were captured with a confocal microscope and the percentage of live cells was computed by means of the Bioimage program. The ATCC 29212 strain was shown to be more resistant to CH/SS, Calen, CH/DAP, and TAP than the ATCC 4083 strain. The antimicrobial action of the medications against each strain were divergent concerning the order of susceptibility. The authors concluded that the strains behaved in a different manner: in general, those extracted from the urinary tract were more resistant to the tested medications. Therefore, when E. faecalis must be used for in vitro research in endodontics, we suggest the use of ATCC 4083 strain to obtain results that are closer to the clinical reality.

Intradentinal antimicrobial action and filling quality promoted by ultrasonic agitation of epoxy resin-based sealer in endodontic obturation

Abstract The aim of this study was evaluate the influence of ultrasonic activation (UA) of AH Plus to improve canal and isthmus filing, and analyse the antimicrobial effect against Enterococcus faecalis within dentinal tubules. Material and Methods: Thirty mesial roots of mandibular first molars were selected and divided into 2 groups (n = 15): with and without UA of the sealer. Then the root canals were filled by using the single cone technique, and the specimens were sectioned at 2, 4 and 6 mm from the apex for stereomicroscope and confocal laser scanner microscopy (CLSM) analysis. In addition, 30 bovine incisors were contaminated with Enterococcus faecalis and divided into 3 groups (n = 10). The specimens were obturated by using the single cone technique with (G1) and without (G2) UA of the sealer and G3 as the control group. All were sectioned into 6 mm-long cylinders and stained with LIVE/DEAD to assess bacterial viability by CLSM. Results: The UA of the sealer significantly reduced the presence of unfilled areas in the canal and isthmus area in all sections (p<0.05), and there was a significant increase in sealer penetration in both canals and isthmuses (p<0.05). As regards gaps, a significant reduction was found at 2 and 6 mm in the isthmus area of the UA group (p<0.05). Moreover, UA of the sealer significantly reduced bacterial viability in the superficial dentine when compared with the other groups (p<0.05). Conclusion: Ultrasonic activation of the AH Plus sealer promoted a better quality of root canal filling and increased the intratubular penetration of sealer, especially in the isthmus area. Additionally, ultrasonic activation of the sealer increased the intradentinal antimicrobial action against Enterococcus faecalis, mainly in the superficial dentine of the root canal.

Effect of ultrasound streaming on the disinfection of flattened root canals prepared by rotary and reciprocating systems

Abstract New technical and scientific developments have been advocated to promote the success of the endodontic treatment. In addition to rotary and reciprocating systems, irrigating solution agitation has been suggested and passive ultrasonic irrigation (PUI) is the most used. Objective: To evaluate, in vitro, the effect of ultrasound streaming (US) in the disinfection of flattened root canal systems prepared by the ProTaper, BioRaCe and Reciproc systems, utilizing the microbiological culture. Methodology: Extracted human mandibular incisors (n=84) were used. Suspensions of Enterococcus faecalis (ATCC 29212) were standardized and inserted along with the teeth immersed in brain-heart infusion (BHI) broth. The contamination was made following a protocol during 5 days. The teeth were randomly divided into six groups: G1, ProTaper Universal; G2, ProTaper Universal with US; G3, BioRaCe; G4, BioRaCe with US; G5, Reciproc; and G6, Reciproc with US. Irrigation was performed with saline solution. After biomechanical preparation, microbiological samples were performed with sterilized paper points, which were diluted and spread on BHI agar; after 48 h, the colony forming units (CFU/mL) were counted for each sample. Results: Groups using ultrasonic agitation presented a greater antibacterial effect than the other ones, even using saline solution as irrigant. The ProTaper Universal system showed the best antibacterial activity of the tested systems (median of 0 CFU/mL with and without surfactant or ultrasonic activation [PUI]). Even with PUI, Reciproc (median of 2.5 CFU/mL with PUI and 5 without it) could not reduce as many colonies as ProTaper Universal without US. The BioRaCe system had greater bacterial reduction when using US (median of 0 CFU/mL with PUI and 30 without it). Conclusions: US promoted greater reduction in the number of bacteria in the flattened root canals prepared with nickel-titanium mechanized systems. Regarding the instruments used, the ProTaper Universal system was the most effective in reducing the bacterial number.

Avaliação através de microtomografia da influência do comprimento do glide path no volume e no limite apical das obturações de canais / Microtomography evaluation of glide path length influence on volume and apical limit of root canal fillings

Objetivo: o objetivo desse estudo foi avaliar, por meio de microtomografia, a influência do glide path no volume e no limite apical das obturações de canais radiculares, utilizando instrumentos PathFile. Métodos: trinta e quatro canais de dezessete raízes mesiais de molares inferiores foram divididos em dois grupos, de acordo com o comprimento do glide path criado, usando instrumentos PathFile de números 13, 16 e 19: Grupo 1 (G1) ­ toda a extensão do canal radicular, até o forame apical; e Grupo 2 (G2) ­ 1 mm aquém do forame apical. Os canais radiculares foram instrumentados com instrumentos Reciproc R25 até 1 mm aquém do forame apical nos dois grupos e obturados com cimento AHPlus e cone único. O volume do material de obturação na região dos 3 mm apicais dos canais e a distância do material obturador até o forame apical foram determinados por meio de microtomografia computadorizada. Os dados foram avaliados estatisticamente com o teste de Mann-Whitney para a comparação entre os grupos. Resultados: não foi observada diferença estatística quanto ao volume de material obturador presente na região apical dos dois grupos (p > 0,05). Entretanto, a distância entre o limite apical da obturação e o forame apical variou de forma estatisticamente significativa entre os grupos G1 (0,4335 mm) e G2 (1,241 mm) (p < 0,05). Conclusões: a confecção do glide path nos canais radiculares em toda a sua extensão favoreceu um limite apical das obturações endodônticas mais próximo ao ápice radicular, mas não teve influência significativa no seu volume.

Effect of ultrasonic streaming on intra-dentinal disinfection and penetration of calcium hydroxide paste in endodontic treatment

ABSTRACT Objective The antimicrobial effect of ultrasonic agitation of calcium hydroxide (CH) pastes in infected bovine dentin and their penetrability were evaluated using confocal laser scanning microscopy (CLSM) and microbiological culture. Material and Methods Fifty-two bovine teeth were infected with Enterococcus faecalis using a new contamination protocol; then they received CH paste and were divided into groups with or without ultrasound. Ultrasonic agitation was conducted for 1 min with a plain point insert. After 15 d, the CLSM analyzed the viable and dead bacteria with Live and Dead assay. The dentinal wall debris was collected by burs, and the colony forming units (CFU/mL) were counted. The penetrability of the paste inside dentinal tubules was tested using the B-rodamine dye. Results The calcium hydroxide paste showed better results with the use of ultrasonic agitation (p<0.05). Conclusion The ultrasonic agitation of CH paste increased its antimicrobial action and was responsible for intradentinal penetration with the fulfilment of the tubules.

Antimicrobial Effect and Surface Tension of Some Chelating Solutions with Added Surfactants

Abstract This study assessed the antimicrobial efficacy and surface tension of established irrigating solutions with a new experimental chelating solution in infected dentin tubes. Twenty-five specimens were randomly assigned to each of the irrigating solutions. Twenty specimens were used as negative and positive controls. After 21 days of contamination with E. faecalis, the irrigating solutions MTAD, QMiX and Tetraclean NA were delivered into each infected root canal. The solutions were removed and dentin samples were withdrawn from the root canals with sterile low-speed round burs with increasing ISO diameters. The dentin powder samples obtained with each bur were immediately collected in separate test tubes containing 3 mL of BHI broth. After that, 100 μL from each test tube was cultured on blood agar. The grown colonies were counted and recorded as colony-forming units (CFU). The surface tension of the irrigants was measured using a Cahn DCA-322 Dynamic Contact Angle Analyzer. A Kruskal Wallis nonparametric ANOVA and a Friedman test were used (p<0.05). Tetraclean NA showed lower surface tension and CFU values than MTAD and QMiX. Better antibacterial action and low surface tension were observed for Tetraclean NA, probably due to the improved penetration into the root canal and dentinal tubes

Resumo Este estudo avaliou a eficácia antimicrobiana e tensão superficial de soluções irrigadoras e uma nova solução quelante em tubos de dentina infectada. Vinte e cinco espécimes foram aleatoriamente distribuídos conforme as soluções irrigantes. Decorrifdos 21 dias de contaminação com E. faecalis, a soluções de irrigação MTAD, QMiX e Tetraclean NA foram distribuídas em cada canal radicular infectado. As soluções foram removidas e as amostras de dentina foram retiradas dos canais radiculares com brocas esféricas de baixa velocidade com diâmetros ISO sucessivamente maiores. As amostras do pó de dentina obtidas com cada broca foram imediatamente colocadas em tubos de ensaio separados contendo 3 mL de caldo BHI. A seguir, 100 μL de cada amostra do tubo de teste foi cultivada em agar de sangue. As colônias crescidas foram contadas e registadas como unidades formadoras de colônias (UFC). A tensão superficial das soluções irrigantes foi medida utilizando o método de Wilhelmy. A análise não paramétrica de Kruskal-Wallis e o teste de Friedman foram utilizados (p<0,05). Tetraclean NA apresentou menor tensão de superfície e menores valores de UFC do que MTAD e QMiX. A melhor ação antibacteriana e baixa tensão superficial foram observadas para Tetraclean NA, provavelmente devido à melhor penetração no canal radicular e túbulos dentinários.

Tissue dissolution and modifications in dentin composition by different sodium hypochlorite concentrations

ABSTRACT Sodium hypochlorite (NaOCl) remains the most used irrigation solution during root canal preparation because of characteristics such as wide-spectrum antimicrobial activity and organic tissue dissolution capacity. However, these solutions can alter dentin composition and there is no consensus on the optimal concentration of NaOCl to be used. Objectives To determine the organic matter dissolution and changes in dentin chemical composition promoted by different concentrations of NaOCl over time. Material and Methods: Fragments of bovine muscle tissue were weighed before and after 5, 10, and 15 min of immersion in the groups (n=10): G1- 0.9% saline solution; G2- 1% NaOCl; G3- 2.5% NaOCl; and G4- 5% NaOCl. Bovine dentin fragments were subjected to the same irrigants and absorption spectra were collected by Attenuated Total Reflectance of Fourier Transform Infrared Spectroscopy (ATR-FTIR) before and after 0,5, 1, 2, 3, 5, 8, and 10 min of immersion in the solutions. The ratios of the amide III/phosphate and carbonate/phosphate absorption bands were determined. The tissue dissolution and carbonate/phosphate ratios were submitted to the two-way analysis of variance (ANOVA) with Tukey’s multiple-comparison test (α<0.05) and to the one-way analysis of variance with Tukey’s (α<0.05). The amide III/phosphate ratio was analyzed by Friedman test (α<0.05) and the Kruskal-Wallis test with Dunn’s post-hoc (α<0.05). Results The increase in NaOCl concentration and contact time intensified the dissolution of organic matter and dentin collagen with reduction in the amide III/phosphate ratio. Significant differences between all groups (p<0.05) were observed in the dissolution of organic matter at 10 min and in the amide III/phosphate ratio between the saline solution and 5% NaOCl at 5 min. The carbonate/phosphate ratio decreased significantly in G2, G3, and G4 after 0,5 min of immersion (p<0.05), but more alterations did not occur in the subsequent periods (p>0.05). Intergroup differences were not observed in this ratio (p>0.05). Conclusions The increase in the exposure time and in the concentration of NaOCl solution lead to an increase in the tissue dissolution and dentin collagen deproteination. Furthermore, some carbonate ions are removed from the dentin inorganic phase by the NaOCl.

Análise, com microscopia confocal de varredura a laser, da formação de biofilme de Bifidobacterium dentium e Fusobacterium nucleatum sobre diferentes substratos / Analysis of Bifidobacterium dentium and Fusobacterium nucleatum biofilm formation on different substrates by confocal laser scanning microscopy

Objetivo: o objetivo do presente estudo foi avaliar, por meio da microscopia confocal de varredura a laser (MCVL), a influência de diferentes substratos (dentina bovina em blocos, blocos de vidro) sobre o desenvolvimento de biofilmes de F. nucleatum e B. dentium. Métodos: placas para cultura de células com 24 poços foram usadas para induzir o biofilme sobre os substratos, com uma linhagem de F. nucleatum ATCC 25586 e uma de B. dentium ATCC 27534, durante 7 dias. Após o período de indução do crescimento, os espécimes foram corados com Live/Dead e analisados por MCVL. Os resultados obtidos pela MCVL foram analisados no software BioImage_L. Resultados: todos os resultados foram analisados pelo teste não paramétrico de Kruskal-Wallis, para comparação entre os grupos (p < 0,05). Houve formação de biofilme em todos os grupos experimentais. O biovolume total e a porcentagem de bactérias viáveis no biofilme de B. dentium nos blocos de dentina e nos blocos de vidro não mostraram diferenças estatísticas. O biovolume de bactérias viáveis não revelou diferença entre os substratos no biofilme de F. nucleatum nos blocos de dentina e nos blocos de vidro. Já o biovolume total mostrou-se maior no biofilme formado em blocos de dentina. B. dentium e F. nucleatum são capazes de formar biofilme em todos os substratos estudados. Conclusão: pela metodologia adotada, o tipo de substrato influencia as características do biofilme formado, sendo o bloco de dentina mais propício para a formação do biofilme dos microrganismos estudados.

A new improved protocol for in vitro intratubular dentinal bacterial contamination for antimicrobial endodontic tests: standardization and validation by confocal laser scanning microscopy

Objectives To compare three methods of intratubular contamination that simulate endodontic infections using confocal laser scanning microscopy (CLSM). Material and Methods Two pre-existing models of dentinal contamination were used to induce intratubular infection (groups A and B). These methods were modified in an attempt to improve the model (group C). Among the modifications it may be included: specimen contamination for five days, ultrasonic bath with BHI broth after specimen sterilization, use of E. faecalisduring the exponential growth phase, greater concentration of inoculum, and two cycles of centrifugation on alternate days with changes of culture media. All specimens were longitudinally sectioned and stained with of LIVE/DEAD® for 20 min. Specimens were assessed using CLSM, which provided images of the depth of viable bacterial proliferation inside the dentinal tubules. Additionally, three examiners used scores to classify the CLSM images according to the following parameters: homogeneity, density, and depth of the bacterial contamination inside the dentinal tubules. Kruskal-Wallis and Dunn’s tests were used to evaluate the live and dead cells rates, and the scores obtained. Results The contamination scores revealed higher contamination levels in group C when compared with groups A and B (p<0.05). No differences were observed between group A and B (p>0.05). The volume of live cells in group C was higher than in groups A and B (p<0.05). Conclusion The new protocol for intratubular infection resulted in high and uniform patterns of bacterial contamination and higher cell viability in all specimens when compared with the current methods.

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 fromCasearia 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.