Influence of Passive Ultrasonic Irrigation of the Photosensitizer Used in Photodynamic Therapy on Microbial Reduction in the Root Canal System: An in Vitro Study.

Introduction: The success of endodontic treatment is based on microbial reduction promoted by the interaction of chemical and mechanical procedures. Photodynamic therapy (PDT) is used as an adjunct to conventional treatment, with significant microbial reduction. This study aimed to evaluate the influence of passive ultrasonic irrigation (PUI) of the photosensitizer (PS) used in PDT on microbial reduction in the root canal system. Materials and Methods: Forty-five mesiobuccal root canals from extracted human mandibular molars that were inoculated with standard strains of Enterococcus faecalis, Candida albicans, and Streptococcus mutans for 21 days were selected. The root canals were prepared using the ProTaper Next system and randomly divided into 3 groups (n=15): 1) PDT: PDT alone; 2) PUI+PDT: PUI followed by PDT; and 3) PUI/PS+PDT: PUI of the PS followed by PDT. Microbiological samples were collected from the canals before and after using the protocols described above. The data were analyzed by analysis of variance (Tukey's test) at a significance level of 5%. Results: Microbial counts before PDT, PUI+PDT, and PUI/PS+PDT did not differ significantly (P>0.05), showing methodological standardization in the microbial contamination of the root canal system. There was a significant reduction in microbial counts after PDT (61.05%), PUI+PDT (65.04%), and PUI/PS+PDT (68.58%) (P<0.01), but with no statistically significant difference between the three groups (P>0.05). Conclusion: Based on the present findings, it was concluded that the combination of PUI with PDT or PS activation did not influence microbial reduction achieved by PDT alone.

Photobiomodulation in the Treatment of Dysgeusia in Patients with Long COVID: A Single-Blind, Randomized Controlled Trial.

Objective: The aim of this study is to evaluate local and systemic photobiomodulation (PBM) in patients with COVID-19-related dysgeusia, with the expectation of improving taste dysfunction. Background: PBM has garnered attention as a potential therapy in long COVID, a condition characterized by many persistent symptoms following the acute phase of COVID-19. Among these symptoms, dysgeusia, or altered taste perception, can significantly affect patients' quality of life. Emerging research suggests that PBM may hold promise in ameliorating dysgeusia by modulating cellular processes and reducing inflammation. Further clinical studies and randomized controlled trials are essential to establish the efficacy and safety of PBM for the treatment of dysgeusia in long COVID, but initial evidence suggests that this noninvasive modality may offer a novel avenue for symptom management. Methods: Seventy patients experiencing dysgeusia were randomly assigned to receive active local and systemic PBM (n = 34) or simulated PBM (n = 36). Low-power laser (red wavelength) was used at 18 spots on the lateral borders of the tongue (3 J per spot), salivary glands (parotid, sublingual, and submandibular glands-3 J per spot), and over the carotid artery for 10 min (60 J). Alongside laser therapy, all patients in both groups received weekly olfactory therapy for up to 8 weeks. Results: Dysgeusia improved in both groups. At weeks 7 and 8, improvement scores were significantly higher in the PBM group than in the sham group (p = 0.048). Conclusions: Combined local and systemic PBM, as applied in this study, proved effective and could serve as a viable treatment option for alleviating dysgeusia in long-COVID patients. Clinical Trial Registration: RBR-2mfbkkk.

Evaluation of the Ability of 3 Reciprocating Instruments to Remove Obturation Material: A Micro-Computed Tomography Study.

INTRODUCTION: The purpose of this study was to evaluate the ability of the Reciproc, Reciproc Blue, and WaveOne Gold systems to remove filling material during endodontic retreatment of extracted human mandibular premolars. METHODS: Thirty-nine teeth were instrumented with the Protaper Universal System to the F3 file and filled with the Tagger hybrid technique using an F3 gutta-percha cone and AH Plus cement. At the end of this period, the teeth were scanned with micro-computed tomography before and after removal of the filling material from the root canals. The teeth were divided into 3 groups (n = 13) based on the apical volume, depending on the systems used to remove the filling material. Group GR: Reciproc 40/.06; Group GRB: Reciproc Blue 40/.06; and Group GWG: WaveOne Gold 35/.06. The results were statistically analyzed using the tests of Kruskal-Wallis, Duncan, and analysis of variance at a significance level of 5%. RESULTS: The results showed that there were no significant differences between the amounts of filling material removed, either for the apical and middle regions alone or in the overall evaluation for the 3 groups (P = .97). The time evaluation statistically showed that the GR and GWG groups required less time to clean the root canals than the GRB group. CONCLUSIONS: Reciproc R40 files and WaveOne Gold Medium files required less time for endodontic treatment than Reciproc Blue R40 files. There was no difference in the ability to remove obturation material between the 3 instruments. No instrument was able to completely remove the filling material from the root canals.

Evaluation of the apical sealing of an eggshell hydroxyapatite-based sealer.

Background: The success of endodontic treatment can be influenced by the type of endodontic sealer used, as certain sealers may be prone to apical microleakage, leading to treatment failure. The limitations of currently available sealers necessitate the development of new materials to improve the success rate of endodontic treatment. Therefore, the objective of this study was to assess the apical microleakage of newly developed hydroxyapatite-based endodontic sealers, including one derived from eggshells, and compare them with other commercially available sealers. Material and Methods: Eighty-five extracted human upper anterior teeth were selected for this study. The teeth were divided into 5 experimental groups and 2 control groups. The experimental groups were designated as follows: (1) HPSINT - obturated with gutta-percha cone and synthetic hydroxyapatite-based sealer, (2) BIOC - obturated with gutta-percha cone and Bio C-Sealer sealer, (3) AHPLUS-BC - obturated with gutta-percha cone and AHPLUS Bioceramic sealer, (4) AHP - obturated with gutta-percha cone and AHPLUS sealer, and (5) HPO - obturated with gutta-percha cone and sealer based on hydroxyapatite extracted from eggshells. Additionally, there were positive and negative control groups consisting of instrumented teeth filled with gutta-percha cones without any sealer and instrumented teeth without any filling, respectively. Methylene blue dye penetration was used to assess apical microleakage. Descriptive statistical analysis and Shapiro-Wilk normality test were applied to the observed results. As the samples followed a normal distribution, the ANOVA test was applied. Results: The control groups confirmed the validity of the experimental method, while the experimental groups showed varying degrees of dye penetration. The group obturated with Bio C-Sealer exhibited the highest mean apical microleakage, while AHPLUS Bioceramic sealer demonstrated lower mean than AHPLUS sealer and sealer based on hydroxyapatite extracted from eggshells (p<0.05). Finally, there was no difference between the synthetic hydroxyapatite-based sealer and AHPLUS Bioceramic sealer, AHPLUS sealer and sealer based on hydroxyapatite extracted from eggshells (p>0.05). No significant difference was observed between the hydroxyapatite-based sealers and the AHPLUS-BC sealer. Conclusions: The results of this study suggest that the newly developed hydroxyapatite-based endodontic sealers, including the one derived from eggshells, may have a lower risk of apical microleakage compared to other commercially available sealers. These findings highlight the potential of hydroxyapatite-based sealers to improve the success rate of endodontic treatment. Further research and clinical studies are warranted to validate these results and explore the long-term effects of these novel sealers. Key words:Endodontic treatment, apical microleakage, endodontic sealer, hydroxyapatite, eggshell-derived sealer.

Analysis of antimicrobial efficacy of sodium hypochlorite and ozonated water against biofilm in oval canals.

This in vitro study compared the antimicrobial efficacy of 2.5% sodium hypochlorite (NaOCl) and 8 µg/mL ozonated water agitated by passive ultrasonic irrigation (PUI) or PUI combined with EndoActivator (EA) against mature multispecies biofilm. One hundred and five oval-shaped mandibular premolars were instrumented, sterilized, and inoculated with Enterococcus faecalis, Candida albicans, and Staphylococcus aureus, divided into: control group - saline; O3 group - ozonated water; O3 PUI group - ozonated water with PUI agitation; O3 PUI+EA group - ozonated water with PUI+EA agitation; NaOCl group - NaOCl; NaOCl PUI group - NaOCl with PUI agitation; and NaOCl PUI+EA group - NaOCl with PUI+EA agitation. Microbiological samples were collected before (S1) and after (S2) the disinfection procedures and the data were statistically analyzed using the Kruskal-Wallis test. In the culture method, there was significant disinfection in the O3 PUI+EA, NaOCl, NaOCl PUI, and NaOCl PUI+EA groups (p˂0.05). The combination of NaOCl with PUI+EA reduced microbial counts to zero (p˂0.05). In the qPCR method, there was a significant reduction in the total count of viable microorganisms in the O3 PUI, O3 PUI+EA, NaOCl, NaOCl PUI, and NaOCl PUI+EA groups (p˂0.05). It can be concluded that 2.5% NaOCl with and without agitation, as well as 8 µg/mL ozonated water with its action enhanced by the agitation techniques, were effective in root canal disinfection, and their antimicrobial efficacy is related to the microorganisms present in the biofilm.

Analysis of antimicrobial efficacy of sodium hypochlorite and ozonated water against biofilm in oval canals

Abstract This in vitro study compared the antimicrobial efficacy of 2.5% sodium hypochlorite (NaOCl) and 8 µg/mL ozonated water agitated by passive ultrasonic irrigation (PUI) or PUI combined with EndoActivator (EA) against mature multispecies biofilm. One hundred and five oval-shaped mandibular premolars were instrumented, sterilized, and inoculated with Enterococcus faecalis, Candida albicans, and Staphylococcus aureus, divided into: control group - saline; O3 group - ozonated water; O3 PUI group - ozonated water with PUI agitation; O3 PUI+EA group - ozonated water with PUI+EA agitation; NaOCl group - NaOCl; NaOCl PUI group - NaOCl with PUI agitation; and NaOCl PUI+EA group - NaOCl with PUI+EA agitation. Microbiological samples were collected before (S1) and after (S2) the disinfection procedures and the data were statistically analyzed using the Kruskal-Wallis test. In the culture method, there was significant disinfection in the O3 PUI+EA, NaOCl, NaOCl PUI, and NaOCl PUI+EA groups (p˂0.05). The combination of NaOCl with PUI+EA reduced microbial counts to zero (p˂0.05). In the qPCR method, there was a significant reduction in the total count of viable microorganisms in the O3 PUI, O3 PUI+EA, NaOCl, NaOCl PUI, and NaOCl PUI+EA groups (p˂0.05). It can be concluded that 2.5% NaOCl with and without agitation, as well as 8 µg/mL ozonated water with its action enhanced by the agitation techniques, were effective in root canal disinfection, and their antimicrobial efficacy is related to the microorganisms present in the biofilm.

Resumo Este estudo in vitro comparou a desinfecção do hipoclorito de sódio 2,5% (NaOCl) e da água ozonizada 8 µg/mL agitados pela irrigação ultrassônica passiva (PUI) e por associação da PUI com EndoActivator (EA) na redução de biofilme misto maduro. Cento e cinco pré-molares inferiores ovalados foram instrumentados, esterilizados e inoculados com Enterococcus faecalis, Candida albicans e Staphylococcus aureus, divididos em: Grupo controle: soro; Grupo O3: água ozonizada; Grupo O3 PUI: água ozonizada agitada por PUI; Grupo O3 PUI + EA: água ozonizada agitada por PUI e EA: Grupo NaOCl: hipoclorito de sódio; Grupo NaOCl PUI: hipoclorito de sódio agitado por PUI; Grupo NaOCl PUI + EA: hipoclorito de sódio agitado por PUI e EA. Amostras microbiológicas foram coletadas antes (S1) e após (S2) os procedimentos de desinfecção e os dados foram analisados estatisticamente pelo teste de Kruskal-Wallis. No método de cultura, houve desinfecção significativa nos grupos O3 PUI + EA, NaOCl, NaOCl PUI e NaOCl PUI + EA (p˂0.05), sendo que no grupo NaOCl PUI + EA não houve crescimento de microrganismo (p˂0.05). No método de qPCR, nas contagens dos microrganismos antes e após os protocolos de desinfecção, houve redução microbiana nos grupos O3 PUI, O3 PUI + EA, NaOCl, NaOCl PUI, NaOCl PUI + EA (p˂0.05). Concluiu-se que o NaOCl 2,5% com e sem agitação foi eficiente, assim como a água ozonizada 8 µg/mL potencializada pelos métodos de agitação na desinfecção e que a mesma está relacionada com os microrganismos presentes no biofilme.

Ex Vivo Evaluation of the Efficacy of Photodynamic Therapy in Eliminating Enterococcus faecalis from Dentinal Tubules by Confocal Laser Scanning Microscopy.

INTRODUCTION: The aim of the present study was to investigate ex vivo by confocal laser scanning microscopy the antibacterial effect of photodynamic therapy (PDT) on dentinal tubules in the apical 5 mm of human mandibular premolars contaminated with Enterococcus faecalis. METHODS: Thirty-four teeth were standardized to 20 mm and foraminal anatomic diameters using a #20 K-file (Dentsply Maillefer). Samples were contaminated for 21 days and divided into the following 3 experimental groups (n = 10): the PDT group (instrumented canals and PDT), the passive ultrasonic irrigation (PUI) group (instrumented canals and PUI), and the PUI-PDT group (instrumented canals, PUI, and PDT), along with a control group (n = 4) (noninstrumented canals). The canals in the experimental groups were instrumented with ProTaper Next (Dentsply Maillefer) up to X3 and rinsed with EDTA and sodium hypochlorite. The photosensitizer used was 0.01% methylene blue with a preirradiation time of 5 minutes and a diode laser with 4 J energy and a 660-nm wavelength. Cross sections were made 5 mm from the apex of all samples, which were analyzed using confocal laser scanning microscopy. The results were analyzed using the Shapiro-Wilk and Kruskal-Wallis (Dunn) tests. RESULTS: There was a lower percentage of live bacteria in the PUI-PDT group, with a statistical difference compared with the control and PDT groups (P < .05). There was no statistical difference in the percentage of live bacteria between PUI-PDT and PUI (P > .05). CONCLUSIONS: It was concluded that the PUI-PDT association was most effective in disinfecting root canals compared with the control group and PDT.

Effect of cone-beam computed tomography metal artefact reduction on incomplete subtle vertical root fractures.

Purpose: This study compared the accuracy of detection of incomplete vertical root fractures (VRFs) in filled and unfilled teeth on cone-beam computed tomography images with and without a metal artefact reduction (MAR) algorithm. Materials and Methods: Forty single-rooted maxillary premolars were selected and, after endodontic instrumentation, were categorized as unfilled teeth without fractures, filled teeth without fractures, unfilled teeth with fractures, or filled teeth with fractures. Each VRF was artificially created and confirmed by operative microscopy. The teeth were randomly arranged, and images were acquired with and without the MAR algorithm. The images were evaluated with OnDemand software (Cybermed Inc., Seoul, Korea). After training, 2 blinded observers each assessed the images for the presence and absence of VRFs 2 times separated by a 1-week interval. P-values<0.05 were considered to indicate significance. Results: Of the 4 protocols, unfilled teeth analysed with the MAR algorithm had the highest accuracy of incomplete VRF diagnosis (0.65), while unfilled teeth reviewed without MAR were associated with the least accurate diagnosis (0.55). With MAR, an unfilled tooth with an incomplete VRF was 4 times more likely to be identified as having an incomplete VRF than an unfilled tooth without this condition, while without MAR, an unfilled tooth with an incomplete VRF was 2.28 times more likely to be identified as having an incomplete VRF than an unfilled tooth without this condition. Conclusion: The use of the MAR algorithm increased the diagnostic accuracy in the detection of incomplete VRF on images of unfilled teeth.

Micro- CT evaluation of sealers removal by reciprocal instrumentation followed by continuous ultrasonic irrigation in teeth with oval root canals.

Background: The ability of the Reciproc system (R40) followed by continuous ultrasonic irrigation (CUI) to remove filling material from oval root canals of mandibular premolars filled with gutta-percha and AH Plus or Bio-C Sealer was evaluated by microtomography (micro-CT). Material and Methods: The straight and oval root canals of 42 mandibular premolars were prepared with the ProDesign R 35.05 reciprocal file and randomly divided into two groups according to the material used to fill the canals (n=21): Group AH - Master Cone and AH Plus; Group BC - Master Cone and Bio-C Sealer. After filling and provisional sealing, the teeth were stored at 100% relative humidity and a temperature of 37°C for 30 days. The filling material was then removed with an R40 file. The material was considered completely removed when the R40 file reached the working length (WL), and no remaining filling material was visible on the canal walls. CUI was then performed. The teeth were scanned by micro- CT before and after removal of the filling material. The remaining filling material was measured in mm in the last apical 5 mm. The data were analyzed with the nonparametric Friedman test and subsequently with the Dunn test. The Mann-Whitney U test was also performed. Statistical significance was accepted at the 5% level. Results: After instrumentation with the Reciproc R40, the volume of residual filling material was significantly greater in the BC group than in the AH group (P = 0.035). After CUI, there was no difference in the volume of residual material between the two groups (P = 0.705). Conclusions: Bio-C sealer was more difficult to remove with the Reciproc file than AH Plus. CUI improved the removal of residual filling material regardless of sealer type. However, no technique was able to completely clear the canals of filling material. Key words:Bioceramic cement, CUI, micro-CT, reciproc, retreatment.

Influence of Heat Treatment of Nickel-Titanium Instruments on Cyclic Fatigue Resistance in Simulated Curved Canals.

OBJECTIVE: The aim of this study was to compare the cyclic fatigue of heat-treated and non-treated instruments. MATERIALS AND METHODS: Twenty instruments with and without heat treatment from Bassi Logic were evaluated (n = 10). All instruments were subjected to dynamic cyclic fatigue through continuous rotations inside a stainless-steel tube (1.4-mm diameter, 9-mm curvature with 6-mm radius, and 90° angle) using a custom-made device, which performed 1 axial oscillation every 2 seconds with an amplitude of 3 mm, powered by a torque-controlled motor (Silver Reciproc, VDW, Germany), with speed adjusting to 950 rpm and torque to 4 N, according to manufacturer's guidance. The groups were compared using the Mann-Whitney test. RESULT: The fracture time of the heat-treated instruments (97.20 ± 39.94 second and non-treated instruments (14.30 ± 6.78 seconds had statistical differences [p < 0.05]). Heat-treated instruments were 6.8 times more resistant to fatigue than non-treated instruments (p < 0.05). CONCLUSION: Heat treatment provides increased fatigue resistance of NiTi alloy with the same design.

In vitro evaluation of EDTA combined with photodynamic therapy to reduce Streptococcus mutans in carious dentin.

BACKGROUND: This in vitro study aimed to evaluate the use of EDTA combined with photodynamic therapy to reduce Streptococcus mutans in carious dentin. METHODS: Sixty third molars were sectioned to obtain flat dentin surfaces. All specimens were waterproofed, except for the coronal dentin, and subjected to cariogenic challenge in brain-heart infusion (BHI) broth supplemented with 0.5% yeast extract, 1% glucose, 1% sucrose, and standard strain of S. mutans (ATCC 25175). The specimens were divided into 6 groups (n = 10 each): (1) control - caries collection; (2) EDTA - 17% EDTA was actively applied with a microbrush for 1 min; (3) aPDT - antimicrobial photodynamic therapy with 0.01% methylene blue photosensitizer (wavelength of 660 nm, energy of 4 J, power of 100 mW, spot size of 0.028 cm2, energy density of 142 J/cm2 for 40 s); (4) EDTA+aPDT - 17% EDTA actively applied for 1 min plus aPDT; (5) (EDTA+PT) + L - application of EDTA compounded with photosensitizer plus laser irradiation; and (6) PT - photosensitizer alone. Collection of caries was performed after the different cavity disinfection protocols. Aliquots from each dilution were seeded for colony-forming unit (CFU) counts. The results were log10-transformed and analyzed by the Kruskal-Wallis test (Student-Newman-Keuls). RESULTS: There was a significant reduction in S. mutans after aPDT (p<0.05), EDTA+aPDT (p<0.001), and (EDTA+PT) + L (p<0.001). The percentage of microbial reduction in ascending order was as follows: EDTA: 1.65%; PT: 15.51%; aPDT: 38.28%; EDTA+aPDT: 75.24%; and (EDTA+PT) + L: 97.35%. CONCLUSION: Application of 17% EDTA prior to photosensitization or compounded with a photosensitizer increased the antimicrobial effect of aPDT on S. mutans in carious dentin.

Impact of Sodium Hypochlorite on Organic Tissue Dissolution in the Periapical Region of Immature Permanent Teeth: An Ex Vivo Study.

INTRODUCTION: The purpose of this study was to evaluate the impact of different sodium hypochlorite (NaOCl) irrigation protocols on organic tissue dissolution in the periapical region of simulated immature permanent teeth. METHODS: Eight single-rooted premolars and 48 samples of porcine palatal mucosa were used. Acrylic resin prototypes were constructed, placing the tissue in close contact with the dental apices. Specimens were then divided into 6 groups (n = 8): 2 control groups of normal saline irrigation with (NS/WA) or without (NS/NA) ultrasonic activation and 4 experimental groups of 1.5% and 2.5% NaOCl irrigation with (NaOCl 1.5%/WA and NaOCl 2.5%/WA) or without (NaOCl 1.5%/NA and NaOCl 2.5%/NA) activation. Root canals were irrigated with 20 mL of the solution for 5 minutes distributed over 4 irrigation cycles. In each cycle, after irrigation, the solution was either kept stagnant or activated for 30 seconds and then replaced. Specimens were weighed on a precision balance before and after the irrigation protocols. Tissue dissolution was measured by the difference between the initial and final weights. One-way analysis of variance was applied followed by the Tukey honestly significant difference test (α = 0.05). RESULTS: The NS/NA and NS/WA groups had mean weight reductions similar to the 1.5% NaOCl/NA group (P > .05) and lower than the others (P < .05). The 2.5% NaOCl/NA and 2.5% NaOCl/WA groups had the highest mean weight loss (P < .05), whereas the 1.5% NaOCl/WA group had intermediate values (P < .05). CONCLUSIONS: Periapical tissue dissolution occurred in all groups, with a greater impact observed with 2.5% NaOCl with or without ultrasonic activation.

Ex Vivo Evaluation of Bacterial Leakage and Coronal Sealing Capacity of Six Materials in Endodontically Treated Teeth.

Introduction: Successful endodontic treatment requires an effective coronal sealing to prevent the penetration of saliva and microorganisms into the root canal system. We aimed to investigate the sealing capacity of Maxxion R, Intermediate Restorative Material (IRM), Mineral Trioxide Aggregate-like material (Biodentine), White Cimpat, Flow Resin and Z250 Resin against Enterococcus (E.) faecalis infiltrates, when used as coronal sealants after endodontic treatment. Materials and Methods: Sixty-six roots of adult lower premolars were randomly divided into 6 experimental groups with 10 roots each (n=10), and two control groups (positive and negative) with three roots each. The root canals were instrumented to ProTaper F3 file, irrigated with 2.5% NaOCl and 17% EDTA, and filled using Tagger's Hybrid technique with AH-Plus cement. After removing 2 mm of the coronal third filling with a Gates Glidden #6 drill, the cervical portion of each of the sixty roots was sealed with a 2 mm-thick plug, plus the respective material being tested in this study. All roots were fitted to silicone devices (Eppendorf) with cut extremities and sterilized with ethylene oxide; experimental procedures were performed in a laminar flow chamber for aseptic chain maintenance. All specimens were inoculated with E. faecalis, and the culture medium was renewed every 3 days for 60 days. Medium turbidity was evaluated daily. The obtained data were subsequently submitted to analysis of variance (ANOVA-R) complemented by Student's t-test at a significance level of 5%. Analyzes of variance were calculated using the SAS system GLIMMIX procedure. Results: Biodentine (56.90), Z250 Resin (54.90) and White Cimpat (53.30) resisted contamination for a longer time compared to Maxxion R (51.30), Flow Resin (50.70), and IRM (48.70) over a period of 60 days. Conclusion: Biodentine, Resin Z 250 and White Cimpat presented the lowest infiltration averages when compared to the other tested materials.

Evaluation of temporary cement to prevent bacterial contamination of the root canal after pulpectomy / Avaliação da capacidade do cemento temporário prevenir a contaminação bacteriana do canal após pulpectomia

ABSTRACT To evaluate the ability of temporary cement (TC) and gutta-percha sticks (GP) to prevent bacterial contamination of the root canal through the coronal seal after pulpectomy. Eighty artificial primary maxillary central incisors were selected and randomly divided into 2 groups: TC (n = 40) and GP (n = 40). Endodontic access, rotary instrumentation, root canal filling, and coronal sealing were performed according to group allocation. The root canal opening was seeded with S. mutans and E. faecalis. Both groups were subdivided into 5 experimental time points (24, 48, 72, 96, and 120 hours), with 8 specimens per time-point group: 5 in which both root canal filling and coronal sealing were performed (with either TC or GP) and 3 controls (coronal sealing alone, without root canal filling). All specimens were incubated in an anaerobic jar at 37°C, and bacterial contamination was assessed in a spectrophotometer. ANOVA (t-test) was used to compare contamination and the Kruskal-Wallis test to compare filling scores between the experimental groups. A significant difference was observed in sealing in the first 24 hours between GP and controls (p = 0.046). There was no significant difference in the filling pattern between canals sealed with TC versus GP. Specimens sealed with GP showed less contamination than controls in the first 24 hours. At later time points, neither GP nor TC were effective at controlling bacterial contamination; both failed to provide adequate coronal sealing.

RESUMO Avaliar a capacidade do obturador provisório (OP) e da gutapercha em bastão (GP) de prevenir a contaminação bacteriana dos condutos radiculares. Foram selecionados 80 incisivos centrais superiores decíduos artificiais que foram divididos aleatoriamente em 2 grupos: OP (n = 40) e GP (n = 40). Foi realizado acesso endodôntico, instrumentação rotatória, preenchimento do canal radicular e selamento coronário conforme os grupos. Foi feita a semeadura de S.mutans e E. faecalis na entrada do canal radicular. Ambos os grupos foram subdivididos em 5 tempos experimentais (24, 48, 72, 96 e 120 horas), com 8 espécimes por tempo experimental: 5 submetidos a preenchimento do canal radicular e selamento coronário (com OP ou GP) e 3 controles (apenas selamento coronário, sem preenchimento do canal). Todos os espécimes foram incubados em jarras de anaerobiose a 37°C e a contaminação bacteriana foi avaliada em espectrofotômetro. Utilizou-se ANOVA (teste t) para a comparação da contaminação e o teste de Kruskal-Wallis para a comparação dos escores da obturação entre os grupos experimentais. Foi observada diferença significativa no selamento nas primeiras 24 horas entre GP e controles (p = 0,046). Não houve diferença estatisticamente significativa no padrão de preenchimento entre os canais selados com OP versus GP. Os espécimes selados com GP apresentaram menor contaminação do que os controles nas primeiras 24 horas. Nos demais tempos experimentais, tanto GP quanto OP não foram eficientes no controle da contaminação bacteriana; ambos apresentaram falha no selamento coronário.

Influência do hipoclorito de sódio na resistência à fadiga cíclica em instrumentos rotatórios endodônticos de memória controlada de NiTi: uma avaliação experimental / Influence of sodium hypochlorite on cyclic fatigue resistance in niti controlled memory endodontics rotary instruments: an experimental evaluation

Introdução: É importante saber se o hipoclorito de sódio (NaOCl) influencia a resistência à fadiga cíclica das limas de níquel-titânio (NiTi). Objetivo: Avaliar a influência de NaOCl 2,5% na resistência à fadiga cíclica de dois sistemas de NiTi. Material e método: 40 instrumentos rotatórios - 20 TruNatomy® (TRU, Dentsply Sirona, Maillefer, Ballaigues, Suíça) e 20 Prodesing Logic2® (PDL2, Bassi, Belo Horizonte, Minas Gerais, Brasil) - foram aleatoriamente distribuídos em 4 grupos experimentais (n = 10) imersos em água destilada (H2O) e NaOCl 2,5% em temperatura a 37°C. Foram submetidos a testes de fadiga cíclica mensurando o número de ciclos para fratura (NCF) e análise dessas superfícies pós-teste em microscópio eletrônico por varredura. Para a análise estatística entre os grupos, foi aplicada a análise de variância (ANOVA), complementada com o pós-teste de Tukey. Resultado: Houve diferença estatística em todos os grupos (P<0.05). Os instrumentos PDL2 obtiveram maior resistência à fratura nas condições em H2O e em NaOCl 2,5% comparados aos instrumentos TRU. Na análise de grupos de instrumentos nas soluções de NaOCl e H2O, foi observado que o NaOCl 2,5% diminuiu o NCF. Conclusão: A resistência à fadiga cíclica dos instrumentos TRU e PDL2 diminuiu com NaOCl 2,5%. Os instrumentos PDL2 foram mais resistentes à fratura em relação aos instrumentos TRU.

Introduction: It is important to know whether sodium hypochlorite (NaOCl) influences the cyclic fatigue resistance of nickel-titanium (NiTi) files. Objective: To evaluate the influence of NaOCl 2.5% on the cyclic fatigue resistance of two NiTi systems. Material and method: Forty rotary instruments - 20 TruNatomy® (TRU, Dentsply Sirona, Maillefer, Ballaigues, Switzerland) and 20 Prodesign Logic2® (PDL2, Bassi, Belo Horizonte, Minas Gerais, Brazil) - were distributed randomly across four experimental groups (n=10) and submerged in distilled water (H2O) or 2.5% NaOCl at 37°C according to allocation. Cyclic fatigue testing was then performed, measuring the number of cycles to fracture (NCF), and post-test surfaces were analysed by scanning electron microscopy (SEM). Statistical Analysis: Analysis of variance (ANOVA) was applied for between-group analysis, followed by Tukey's post-hoc test. Result: A significant difference was observed in all groups (P<0.05). PDL2 instruments showed higher fracture resistance under H2O and 2.5% NaOCl conditions compared to TRU. Analysis of all instrument groups showed that exposure to 2.5% NaOCl decreased the NCF compared to H2O. Conclusion: Cyclic fatigue resistance of the TRU and PDL2 instruments was decreased by exposure to 2.5% NaOCl. PDL2 instruments were more resistant to fracture than TRU instruments.

Aspectos técnicos dos tratamentos endodônticos realizados por cirurgiões-dentistas da PMESP: avaliação por meio de questionário / Technical aspects of endodontic treatments performed by PMESP dentists: evaluation by means of a questionnaire

Introdução: De todas as especialidades na Odontologia, uma das mais favorecidas nos últimos anos com o desenvolvimento de novas tecnologias tem sido a Endodontia. Objetivo: O presente estudo visou obter informações sobre os aspectos técnicos dos tratamentos endodônticos realizados por cirurgiões-dentistas da Polícia Militar do Estado de São Paulo (PMESP), dando ênfase aos materiais, técnicas e equipamentos empregados. Métodos: Um questionário com 25 questões de múltipla escolha foi enviado aos 147 dentistas da PMESP, e o critério de inclusão foi que os profissionais realizassem tratamentos endodônticos. Resultados: A análise estatística foi feita por meio do teste qui-quadrado, com p<0,05. Entre os 42 profissionais avaliados, 59,5% eram do sexo masculino, o dique de borracha foi utilizado em 54,8% dos casos, o comprimento de trabalho foi obtido por meio de radiografias em 71,4%, o sensor digital foi utilizado em 28,6%, a magnificação visual foi utilizada em 23,8% e a técnica de condensação lateral foi a mais utilizada, com 90,2%. Outra análise foi realizada com 10 especialistas do Centro Odontológico da PMESP que efetuavam unicamente tratamento endodôntico, sendo que 50% eram do sexo masculino e tratavam mais de 15 casos/mês: o dique de borracha foi utilizado em 80% dos casos; o comprimento de trabalho foi obtido com localizador foraminal em 50% dos casos; o sensor digital foi utilizado em 90%, assim como o motor elétrico; a técnica de condensação lateral foi utilizada em 60% dos casos e o ultrassom, em 20%. Conclusões: Conclui-se que os especialistas utilizaram mais as novas tecnologias, e que o ultrassom e a magnificação visual foram pouco utilizados em ambos os grupos (AU).

Introduction: Of all the specialties in dentistry, one of the most favored in recent years with the development of new technologies has been endodontics. Objective: This study aimed to obtain information on the technical aspects of endodontic treatments performed by dentists from the Military Police of the State of São Paulo, emphasizing the materials, equipment, and techniques used. Methods: A questionnaire with 25 multiple choice questions was sent to 147 dentists from PMESP and the inclusion criterion was professionals who performed endodontic treatment. Results: The statistical analysis was done through the chi-square test, with p< 0.05. The professionals evaluated 59.5% were male, the rubber dam was used in 54.8% of the cases, the working length by means of radiographs was obtained in 71.4%, the digital sensor was used in 28.6%, the visual magnification was used in 23.8% and the lateral condensation technique was the most used with 90.2%. Another analysis was performed with 10 specialists of the Dental Center who performed only endodontic treatment, 50% were male, treated more than 15 cases/month, the rubber dike was used in 80% of the cases, the working length was performed in 50% of the cases by foraminal locator, the digital sensor was used in 90%, as well as the electric motor, the technique of lateral condensation was used in 60% of the cases and ultrasound 20%. Conclusion: It was concluded that the specialists used more new technologies and that the use of ultrasound and visual magnification was little used in both groups (AU).

Effect of cetrimide 2% with and without photodynamic therapy to reduce Streptococcus mutans burden in dentinal carious lesions.

To evaluate the use of cetrimide alone and combined with photodynamic therapy to reduce S. mutans burden in carious lesions. Sixty permanent third molars were sectioned and the coronal dentin exposed. A cariogenic challenge was performed using brain-heart infusion (BHI) medium supplemented and S. mutans ATCC 25175. Specimens were incubated in anaerobic jars at 37 °C for 15 days, with BHI renewed every 24 h. After 15 days, specimens were randomly divided into six groups (n = 10): C, control (no treatment); CHX, application of chlorhexidine 2%; CT, application of cetrimide 2%; CT+aPDT, application of cetrimide 2% followed by methylene blue dye and aPDT (antimicrobial photodynamic therapy: wavelength 660 nm, energy 4J, power 100 mW, spot size 0.0028 cm2, energy density 142 J/cm2 for 40 s); ES+aPDT, application of experimental solution (methylene blue dye with cetrimide) and aPDT; and aPDT alone. Carious tissue from each specimen was collected before and after the applications. Five decimal dilutions were performed, and the resulting solution was seeded in mitis-salivarius-bacitracin agar. Plates were incubated in anaerobic jars at 37 °C for 48 h. Analysis of variance (ANOVA) with post hoc Tukey's test was used to compare total S. mutans counts. Significant reductions in S. mutans were observed after application of CT+aPDT (0.30 (0.97), p < 0.0001) and ES+aPDT (0.52 (1.13), p < 0.0001). Cetrimide 2% with methylene blue dye, applied consecutively or as a mixture, can be used as a photosensitizing agent for aPDT to reduce S. mutans burden in dentinal caries.

The ability of reciprocating glide path instruments to reach the full root canal working length.

This study evaluated the ability of reciprocating glide path instruments to reach the full working length (RFWL). Thirty mesial roots of mandibular molars were matched into 2 groups (n = 15 teeth, 30 root canals), according to the system used for glide path: WaveOne Gold Glider (WOGG) and R-Pilot. The samples with fractured instruments or when it was not possible to RFWL were scanned using micro-computed tomography. Fractured instruments were also visualised through a scanning electron microscopy to verify the type of fracture. The parameters were compared statistically by Fisher's and chi-square tests (P < 0.05). No instrument fractures were observed in the R-pilot, while 2 fractures occurred in the WOGG group (P > 0.05). RFLW was achieved in 29 canals (96.66%) and 28 canals (93.33%) with R-pilot and WOGG instruments, respectively (P > 0.05). The instruments are able to RFWL in mesial canals of mandibular molars. WOGG showed two fractures while no R-Pilot instruments fractured.

Chitosan-Based Biomaterial, Calcium Hydroxide and Chlorhexidine for Potential Use as Intracanal Medication.

The objective of this study was to develop a chitosan-based biomaterial with calcium hydroxide and 2% chlorhexidine for intracanal treatment application and, consequently, to diminish the number of microorganisms in the root canal system. The chitosan solution was prepared by dissolving it in 2% and 4% acetic acid (v/v) for 1 h at room temperature (25 °C) with magnetic agitation (430 rpm). Calcium hydroxide was obtained in two stages: the first was the synthesis of the calcium oxide-CaO, and the second was that of the calcium hydroxide-Ca(OH)2. The samples were developed using different concentrations of chitosan, calcium hydroxide, and chlorhexidine 2%. They were codified as Ca(OH)2 + Q2% (M1), Ca(OH)2 + Q4% (M2), Ca(OH)2 + Q2% + CLX (M3), Ca(OH)2 + Q4% + CLX (M4), Ca(OH)2 + Q2% + PEG (M5), and Ca(OH)2 + Q4% + PEG (M6). They were characterized through Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and rheological measurement, and the antimicrobial activity was evaluated in vitro. Characteristic absorption bands of the source materials used in this research were observed in the FTIR spectra. The X-ray diffraction technique indicated that the material has a semi-crystalline structure and that the presence of calcium hydroxide made the biomaterial more crystalline. The viscosity measurement showed a pseudoplastic behavior of the studied samples. The microbiologic analysis was positive for all samples tested, with bigger inhibition zones for the samples M3 and M4. As a result, we conclude that the formulation developed based on chitosan is promising and has potential to be an intracanal medication.

Irrigant Agitation Techniques versus Passive Ultrasonic Irrigation for Removing Debris from Curved Root Canals: An Environmental Scanning Electron Microscopic Study.

Introduction: The aim of this study was to compare the efficacy of passive ultrasonic irrigation (PUI) versus mechanical agitation of the irrigant promoted by the EasyClean (EC) and XP-Endo Finisher (XP-F) systems in removing debris from root canal walls, using environmental scanning electron microscopy (ESEM). Methods and Materials: Twelve curved mesiobuccal canals of mandibular molars were prepared with the ProTaper Next system up to file X2 (25/0.06). The specimens were embedded in flasks containing silicone putty, sectioned lengthwise, and a 4-mm long groove was made on the canal wall of the buccal half of the specimen, extending from 2 mm up to 6 mm short of the apex. Five cross-sectional markings were made along this groove to establish standardized locations for imaging. The same specimens were used to prepare a negative control group (without debris), a positive control group (completely covered by debris), and 3 experimental groups according to the final irrigation protocol employed: PUI, EC or XP-F. ESEM images were obtained and evaluated by 3 examiners. The amount of debris observed on the images was classified according to a 4-category scoring system. The kappa test was used to assess inter-examiner agreement, and the Kruskal-Wallis and Dunn tests were used to compare the scores (P<0.05). Results: The scores attributed to the PUI, EC, and XP-F groups were statistically similar to those attributed to the negative control group (P>0.05). Conclusion: Based on this in-vitro study, the mechanical agitation of the irrigant promoted by EC and XP-F was as effective as using PUI to remove debris from the root canal walls.