Functionalization of gutta-percha surfaces with argon and oxygen plasma treatments to enhance adhesiveness.

Gutta-percha's lack of adhesion has been presented as a drawback to avoid gaps at sealer/gutta-percha interface. Plasma treatments have been scarcely assessed on gutta-percha surfaces as a method of enhancing adhesiveness. This study aimed to evaluate the effect of low-pressure Argon and Oxygen plasma atmospheres on conventional and bioceramic gutta-percha standardized smooth discs, assessing their roughness, surface free energy, chemical structure, and sealer wettability. A Low-Pressure Plasma Cleaner by Diener Electronic (Zepto Model) was used. Different gases (Argon or Oxygen), powers (25 W, or 50 W), and exposure times (30 s, 60 s, 120 s, or 180 s) were tested in control and experimental groups. Kruskal-Wallis and Student's t-test were used in data analysis. Statistically significant differences were detected when P < 0.05. Both gases showed different behaviors according to the parameters selected. Even though chemical changes were detected, the basic molecular structure was maintained. Argon or Oxygen plasma treatments favoured the wetting of conventional and bioceramic gutta-perchas by Endoresin and AH Plus Bioceramic sealers (P < 0.001). Overall, the functionalization of gutta-percha surfaces with Argon or Oxygen plasma treatments can increase roughness, surface free energy and wettability, which might improve its adhesive properties when compared to non-treated gutta-percha.

Supplementary solvent irrigation efficacy on filling remnants removal comparing XP-endo Finisher R vs IrriSafe.

This study aimed to compare the efficacy of XP-endo Finisher R and IrriSafe, with a solvent mixture of Methyl ethyl ketone/Tetrachloroethylene (MEK/TCE), in the removal of root filling residues. Twenty-four human mandibular incisors were pair-matched by micro-computed tomography according to volume and aspect ratio. After retreatment, specimens were allocated to two experimental groups (n = 12), according to the supplementary instrument used. The volume of residual filling material after each irrigating step and the time for retreatment was calculated. Statistical analyses were carried out using Mann-Whitney test, with a significance level of 5%. The volume of initial root canal filling material between the groups was similar (p > 0.05). With the final irrigation protocol (NaOCl and EDTA) the volume of the filling remnants decreased significantly (p < 0.05) with no differences between IrriSafe or XP-endo Finisher R (p > 0.05). The additional solvent mixture MEK/TCE increased the efficiency of filling materials reduction, regardless of the agitating instruments employed, IrriSafe or XP-endo Finisher R (p < 0.05). There was no difference between the two groups regarding the time (p = 0.149). Both supplementary instruments were effective in the reduction of filling remnants. The additional step with a solvent mixture of MEK/TCE enabled a total recovery of patency and the achievement of cleaner canals, independently of the agitation instrument.

Adjunctive procedure with solvent mixtures in non-surgical endodontic retreatment: does it affect root dentin hardness?

The aim of this study was to compare the effects of new irrigation solvent mixtures with Methyl ethyl ketone (MEK)/Tetrachloroethylene (TCE) and MEK/Orange oil (OOil), and different agitation techniques on dentin hardness. One hundred forty-four mandibular teeth were prepared and standardized, with each root's middle part transversely sectioned. Initial hardness was measured using a Vickers microhardness tester. Specimens were divided into four groups of agitation techniques (n = 36): no agitation; EndoActivator; IrriSafe; and XP-endo Finisher R. Each group was subdivided into six subgroups of irrigation protocols (n = 6): saline solution; NaOCl + EDTA; NaOCl + EDTA + MEK/TCE; MEK/TCE; NaOCl + EDTA + MEK/OOil; MEK/OOil. Final hardness was measured. The irrigation protocols NaOCl + EDTA, NaOCl + EDTA + MEK/TCE, and NaOCl + EDTA + MEK/OOil significantly decreased dentin hardness, while MEK/OOil increased it (p < 0.05). Comparing to NaOCl + EDTA sequence, dentin hardness increased significantly with the additional exposure to MEK/TCE (3%NaOCl + 17%EDTA + MEK/TCE) or MEK/OOil (3%NaOCl + 17%EDTA + MEK/OOil) (p < 0.05). There were no significant differences regarding agitation effects on dentin hardness decrease. The irrigation protocols affected dentin hardness significantly. However, the additional solvent proposals do not seem to address further concerns on dentin's mechanical properties. Agitation did not show any influence on dentin's hardness reduction.

Effect of Gutta-percha Solvents on the Bond Strength of Sealers to Intraradicular Dentin: A Systematic Review.

Introduction: The aim of our systematic review was to assess the impact of gutta-percha solvents on the bond strength of endodontic sealers to intraradicular dentin using the push-out bond test. Methods and Materials: The literature was searched in databases (PubMed, Web of Science and Scopus) up to September 2020, using the following search terms: (bond strength AND solvent* AND sealer* AND (tooth root OR dentin OR retreatment OR root canal). No date limits were implemented, and English languages were included. The question research was constructed based on the PICO (Population, Intervention, Comparison, and Outcome) strategy: "Does gutta-percha solvents effect the bond strength of sealers to intraradicular dentin?". The studies were analyzed by two reviewers and were included if they utilized extracted permanent human teeth with completely formed apices, as well as assessed the influence of gutta-percha solvents on the bond strength of sealers to intraradicular dentin using push-out bond test. Review articles, case reports and studies that included immature, bovine or artificial teeth were excluded. The risk of bias was evaluated based on the Cochrane criteria adopted to in vitro studies. Results: Thirty-two papers were analyzed, seven accomplished the eligibility criteria and were selected for our systematic review. The global risk of bias was high. Due to variations in the methodological variables, a meta-analysis could not be performed. Conclusion: Our systematic review highlighted the adverse effect of chloroform, which decreased the bond strength of different sealers, and the generally higher bond strength of epoxy resin-based sealers, detected with the push-out bond test. We recommend the standardization of methods in future studies to obtain a more definitive conclusion about the influence of solvents on the bond strength of sealers to intraradicular dentin.

Simulated root canals preparation time, comparing ProTaper Next and WaveOne Gold systems, performed by an undergraduate student.

BACKGROUND: The aim of this study was to compare the WaveOne Gold and ProTaper Next systems regarding the time spent preparing simulated canals performed by an inexperienced student. MATERIAL AND METHODS: 0 simulated L-shaped canals were randomly divided into two groups (n = 40) and numbered in order of instrumentation. Canals were instrumented with WaveOne Gold (group 1) and ProTaper Next (group 2) systems. The effective instrumentation time and the number of instrumentation cycles were recorded. All procedures were performed by the same operator. Statistical analysis was obtained by the Mann - Whitney, Kruskal - Wallis test with significance of p<0.05. RESULTS: There were no statistically significant differences regarding the mean instrumentation time between the two instrumentation systems. The instrumentation time decreased over the experimental period, regardless of the technique used. CONCLUSIONS: Through a short learning curve, an inexperienced operator can prepare simulated canals in a very predictable time. Time spent was similar in a multi-file instrument system (ProTaper Next) and a single-file system (WaveOne Gold). Key words:Dental education, endodontics, preclinical, root canal preparation, undergraduate.

Effect of Sonic Agitation of a Binary Mixture of Solvents on Filling Remnants Removal as an Alternative to Apical Enlargement-A Micro-CT Study.

BACKGROUND: This work aimed to evaluate the efficacy of sonic agitation of a binary mixture of solvents (methyl ethyl ketone/tetrachloroethylene) on filling remnants removal and compare the effects of solvent agitation with the enlargement to the next instrument size. METHODS: Twenty-four mandibular incisors were prepared with ProTaper Next (X1, X2) and obturated with the single-cone technique and AH Plus sealer. The teeth were retreated with ProTaper Universal Retreatment and ProTaper Next and divided into two groups (n = 12) according to the final instrument (X3 or X4). All canals were submitted to a supplementary procedure consisting of a mixture of solvents-methyl ethyl ketone/tetrachloroethylene, agitated with EndoActivator. The volume of filling remnants was assessed through micro-computed tomography in the apical 5 mm. Statistical analysis was performed with a significance level of 5%. RESULTS: The supplementary procedure of agitation of the solvent mixture was beneficial in both groups (p < 0.05). There were no statistically significant differences between canals re-prepared until X4 and canals re-prepared until X3 plus solvent (p > 0.05). CONCLUSIONS: An additional step with a two-solvent solution potentiated by EndoActivator showed to be very effective for the removal of gutta-percha and resinous sealer remnants from apical root canals of mandibular incisors, avoiding further enlargement.

Efficacy and Cytotoxicity of Binary Mixtures as Root Canal Filling Solvents.

OBJECTIVES: This study reports the efficacy of two solvent mixtures on the dissolution of gutta-percha and AH Plus sealer, together with the cytotoxicity. METHODS: Methyl ethyl ketone (MEK), orange oil, tetrachloroethylene, MEK/tetrachloroethylene (1:1), MEK/orange oil (1:1), and chloroform (control) were tested. Twelve groups (n = 15) of standardized stainless-steel molds filled with softened gutta-percha cones and twelve (n = 15) filled with AH Plus were immersed in the corresponding mixture or individual solvent, in an ultrasonic bath, for either 2 or 5 min. The effect of the solvents was assessed qualitatively by a topographical analysis (scanning electron microscopy) and chemical analysis (Fourier transform infrared spectroscopy), and quantitatively by a weight loss and viscoelastic property (dynamic mechanical analysis) evaluation. The cytotoxicity was assessed on MG63 human osteoblastic cells. RESULTS: The mixtures did not show the formation of new compounds. Both presented significantly higher efficacies compared to their individual solvents, suggesting a synergistic effect. Their dissolution efficacy was similar to that of chloroform, showing high cytocompatibility. CONCLUSIONS: The proposed strategy, incorporating ultrasound agitation and profiting from the synergy of adequate solvents, might enhance root canal cleanliness allowing a single-step procedure to dissolve gutta-percha and the sealer remnants, while assuring cytocompatibility with the periapical tissues.

The Precision of Propex Pixi with Different Instruments and Coronal Preflaring Procedures.

OBJECTIVE: This study aimed to evaluate the influence of the instrument regarding the apical fit and type of the alloy and coronal preflaring procedures in the accuracy of Propex Pixi. METHODS: A total of 40 extracted human single-rooted permanent teeth with apical diameters of 200 µm were selected. A #10 K-file was inserted in the root canal until its end could be observed by a dental microscope to obtain the actual working length (WL). Electronic measurements were performed using Propex Pixi to the root apex ("0.0"). Different file alloys (stainless steel [SS] and nickel titanium [NiTi]) and sizes (#10, #15, and #20) were used before and after coronal flaring. Statistical analysis was performed by a factorial analysis of variance (P≤0.05). RESULTS: Results showed that the measurements of electronic length (EL) were closer to the actual working length (WL) after coronal flaring (P<0.05). A significant intraclass correlation was observed between EL and WL. In addition, results showed no significant differences between files with different sizes or alloys. CONCLUSION: Under the conditions of this study, Propex Pixi demonstrated adequate precision. Its accuracy was enhanced by coronal preflaring procedures regardless of the instrument type used (SS or NiTi) and the apical fit.

New Insight into the Dissolution of Epoxy Resin-based Sealers.

INTRODUCTION: The purpose of this study was to evaluate the use of solvents that are not traditionally used in dentistry for the dissolution of an epoxy resin-based sealer and the effect of ultrasonic agitation (UA). METHODS: The dissolution of the AH Plus sealer (Dentsply DeTrey, Konstanz, Germany) and the effect of UA in various solvents (eucalyptol, xylene, chloroform, EndoSolv R [Septodont, Cedex, France], EndoSolv E [Septodont], methyl ethyl ketone [MEK], and ethyl acetate) were quantified. The dissolving capacity was assessed by weight loss, Vicker microhardness, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results were compared with factorial analysis of variance using IBM SPSS Statistics 23.0 software (IBM, Armonk, NY), considering a 0.05 significance level. A preliminary ex vivo study was performed in extracted teeth, with MEK activated by UA as the final irrigation after mechanical removal of the filling material. SEM was used for assessing the cleanliness of the root canal walls. RESULTS: The new solvent proposals, ethyl acetate and MEK, exhibited high dissolution ability, almost reaching chloroform. UA increased dissolution. Vicker values corroborated the dissolution assays. SEM and XRD revealed that solvents affected mainly the organic component of the sealer. Ex vivo results confirmed the immersion model findings. CONCLUSIONS: MEK and ethyl acetate proved to be excellent alternatives to chloroform or xylene solvents. MEK presented a high sealer dissolving ability in a short period, especially with UA, without the potential hazards of chloroform, suggesting it is a good approach to AH Plus sealer's dissolution empowered by UA. These results should encourage further studies in order to confirm their clinical relevance.

Periodontitis apical y estado de salud oral en individuos con diferentes condiciones sistémicas y hábitos de tabaquismo en una población portuguesa / Apical periodontitis and oral status in patients with different systemic conditions and smoking habits in Portuguese population

Objetivo: Determinar la prevalencia de periodontitis apical (PA), tratamiento endodóncico (TE) y estado de salud oral en individuos con diferentes condiciones sistémicas y hábitos de tabaquismo. Métodos: se evaluaron las radiografías panorámicas y procesos clínicos de la primera consulta de 199 pacientes en la Facultad de Medicina Dentaria de la Universidad de Porto. Se registraron el número y presencia de PA y TE, el estado de salud oral (número de dientes ausentes, caries y raíces) y la presencia de diabetes mellitus (DM), enfermedades cardiovasculares (ECV), alergias y hábitos de tabaquismo en cada individuo. Los dientes fueron evaluados de acuerdo con el Índice Periapical de Ørstavik. Los datos fueron analizados por medio de estadística inferencial, considerando un nivel de significancia de 5%. Resultados: La prevalencia de PA y TE por individuo fue de 44,2% (IC 95%, 37,3%-51,4%) y 47,2% (IC 95%, 40,2%-54,4%), respectivamente. Se verificó una asociación entre el número de PA (≥3) e individuos fumadores (p = 0,025). Se detectó que el número de dientes ausentes aumentaba con la edad (r = 0,723; p < 0,005) y era mayor en individuos diabéticos (p = 0,000). Un mayor número de dientes perdidos, caries y raíces fue detectado en los individuos con AP (p = 0,02, p = 0,000, p = 0,000, respectivamente) y con ECV (p = 0,000, p = 0,001, p = 0,040, respectivamente). Conclusiones: La PA y el TE eran altamente prevalentes en la populación estudiada, independientemente de la condición sistémica o hábitos de tabaquismo del paciente. Se verificó que una mayor prevalencia del número de dientes ausentes, caries y raíces estaba asociada a ciertas condiciones sistémicas, lo que sugiere una mayor susceptibilidad de estos individuos a desarrollar lesión endodóncica primaria

Objective: To determine the prevalence of apical periodontitis (AP), endodontic treatment (ET), and oral status in patients with different systemic conditions and smoking habits. Methods: Panoramic radiographs and clinical processes of 199 patients from their first visit to the clinic of the Faculty of Dentistry of the University of Porto were assessed. The number and presence of AP and ET, the oral status (number of missing teeth, caries, and roots), and the presence of diabetes mellitus (DM), cardiovascular diseases (CVD), allergies, and smoking habits were registered. Teeth were assessed according to Ørstavik’s periapical index. Data were analyzed using inferential statistics, based on a significance level of 5%. Results: The prevalence of AP and ET per patient was 44.2% (95% CI, 37.3%-51.4%) and 47.2% (95% CI, 40.2%-54.4%), respectively. An AP ≥ 3 was associated with smokers (p = 0.025). The number of missing teeth increased with age (r = 0.723; p = 0.005) and was higher in patients with DM (p = 0.000). A higher number of missing teeth, caries, and roots was detected in patients with AP (p = 0.002, p = 0.000, p = 0.000, respectively) and patients with CVD (p = 0,000, p = 0,001, p = 0.040, respectively). Conclusions: AP and ET were highly prevalent in the studied population, regardless of the patient’s systemic condition and smoking habit. A higher prevalence of missing teeth, caries, and roots was associated with certain systemic conditions, thus suggesting a higher susceptibility of these patients to develop primary endodontic disease

Endodontic Treatment of an Autogenous Transplanted Tooth Using an Er,Cr:YSGG Laser and Radial Firing Tips: Case Report.

OBJECTIVE AND BACKGROUND: Although several surgical techniques have been reported, no study has yet reported alternative strategies for endodontic treatment of autogenous transplanted teeth. Therefore, the aim of this clinical report is to present the long-term endodontic outcome of a nonvital autogenously transplanted third molar treated with an Er,Cr:YSGG laser and radial firing tips (RFTs). CASE REPORT: Autogenous tooth transplantation can be considered an alternative to restore edentulous areas and, in donor's teeth with complete root formation, root canal treatment should be performed up to 14 days following transplantation. In the present case report, the patient returned only after 6 months, with clinical and radiological signs of apical periodontitis (AP) associated with the transplanted tooth. METHODS: Instead of traditional endodontic chemical irrigants or medications, the protocol for smear-layer removal and root canal disinfection was based on intracanal irradiation with an Er,Cr:YSGG laser and RFTs. RESULTS: After 3-years' follow-up, the complete reestablishment of the periodontal ligament and the arrest of the resorptive process could be noticed. CONCLUSIONS: This protocol has shown to be effective for the endodontic treatment of a transplanted multi-rooted tooth with AP. Further randomized clinical trials should be conducted to clearly demonstrate the effectiveness of this laser-assisted endodontic protocol.

Antibiofilm and Antimicrobial Activity of Polyethylenimine: An Interesting Compound for Endodontic Treatment.

AIM: Bacteria levels of necrotic teeth are greatly reduced after endodontic treatment procedures but the presence of persisting microorganisms leads to continuous efforts to develop materials with antimicrobial properties. The purpose of the study was to determine the antimicrobial activity of polyethylenimine (PEI) against common bacteria and yeasts, regarding planktonic cells and biofilm, and to clarify its antimicrobial mechanism of action through flow cytometry. MATERIALS AND METHODS: The antibiofilm and antimicrobial effect of PEI was determined against Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Candida albicans strains using reference protocols. The effect of PEI was evaluated regarding adhesion, biofilm formation and biofilm disaggregation. In order to understand PEI cellular effects flow cytometric analysis was performed with different fluorescent markers. RESULTS: It was verified that minimal inhibitory concentrations (MIC) values and minimal lethal concentrations (MLC) obtained for PEI were similar and ranged between 50 and 400 mg/l, proving the microbicidal and fungicidal activity of this compound. Antibiofilm activity was also proved for all the microorganisms. Severe lesion of the membrane and cell depolarization was demonstrated. CONCLUSION: Polyethylenimine showed antimicrobial and antibiofilm activity against microorganisms often associated with apical periodontitis. CLINICAL SIGNIFICANCE: Theoretically, prolonging the antibacterial effects of materials used in endodontics may be interesting to help prevent reinfection and possibly to affect residual bacteria that survived the treatment procedures.

Response of human osteoblastic and osteoclastic cells to AH plus and pulp canal sealer containing quaternary ammonium polyethylenimine nanoparticles.

INTRODUCTION: The incorporation of quaternary ammonium polyethylenimine (QPEI) nanoparticles into endodontic sealers induces alterations in their structure and surface properties, which may affect the compatibility with the periapical tissues. This work addressed the behavior of human bone cells exposed to extracts from commercial and QPEI containing AH Plus (DeTrey, Konstanz, Germany) and Pulp Canal Sealer EWT (PCS; Kerr Italia Srl, Salerno, Italy). METHODS: Freshly mixed AH Plus and PCS or containing 2% QPEI (0.3 mL spread over the well bottom of a 24-well plate) were extracted with culture medium (1.5 mL for 24 hours at 37°C) and diluted (1:20-1:5000). Osteoblastic or osteoclastic cells were cultured in the presence of QPEI particles (1%-10%) and were exposed to the extracts from unmodified and QPEI containing sealers. RESULTS: QPEI nanoparticles, at 1% and 2%, did not affect cell behavior. On osteoblastic cells, AH Plus and PCS increased DNA at 1:2500 dilution (levels ≤1:100 were cytotoxic). Alkaline phosphatase activity decreased at dilutions ≤1:500. Comparatively, QPEI containing AH Plus increased DNA at 1:2500 and 1:500 dilutions, and QPEI containing PCS induced ALP activity at 1:2500 and 1:500 dilutions. Regarding osteoclastic cells, DNA increased (AH Plus) or was not affected (PCS) at dilutions up to 1:500 and decreased with more concentrated extracts. Tartrate-resistant acid phosphatase activity decreased with dilutions ≤1:500 for both sealers. QPEI containing sealers presented a similar behavior. The sealers affected some intracellular signaling pathways, and QPEI containing sealers further modulate these mechanisms. CONCLUSIONS: QPEI nanoparticles, at 2%, did not affect cell behavior. However, the incorporation of 2% QPEI particles into AH Plus and PCS modulates the proliferation and differentiation of bone cells, depending on the sealer and the cell type, without increasing the sealers' cytotoxicity.

Antibiofilm effects of endodontic sealers containing quaternary ammonium polyethylenimine nanoparticles.

INTRODUCTION: This study evaluated the antibiofilm effects of 2 endodontic sealers incorporated with quaternary ammonium polyethylenimine (QPEI) nanoparticles at a 2% concentration (w/w). METHODS: The materials tested were AH Plus and Pulp Canal Sealer EWT (PCS) in the commercial unmodified form or containing 2% QPEI. Antibiofilm assays were conducted by using direct-contact and membrane-restricted tests for evaluation of bacterial viability in biofilms grown onto membranes or paper disks and the crystal violet microtiter-plate assay to evaluate the effects of sealer extracts on the biofilm biomass. Two Enterococcus faecalis strains (ATCC and an endodontic isolate) were used. RESULTS: Direct contact and membrane-restricted antibiofilm tests revealed that PCS 2% was the only material to promote total killing of E. faecalis ATCC biofilms. All the materials significantly reduced bacterial counts in E. faecalis ATCC biofilms when compared with the positive control in both tests (P < .05). In the direct test against E. faecalis RW35, PCS 2% was significantly more effective than the other materials and was the only one that showed significantly lower counts than the positive control (P < .05). In the crystal violet assay, only AH Plus 2% presented optical density readings significantly lower than the positive control of the ATCC strain (P < .05). No other significant effects on the biofilm biomass of the 2 E. faecalis strains were observed for any of the sealers tested (P > .05). CONCLUSIONS: Addition of QPEI nanoparticles improved the killing ability of PCS against biofilms of both E. faecalis strains and the effects of AH Plus on the biomass of biofilms from the ATCC strain.

Synergistic antimicrobial action of chlorhexidine and ozone in endodontic treatment.

OBJECTIVES: The aim of this study was to determine whether irrigation with sodium hypochlorite, chlorhexidine, and ozone gas, alone or in combination, were effective against Enterococcus faecalis and Candida albicans; these are microorganisms frequently isolated from teeth with periapical lesions resistant to endodontic treatment. MATERIAL AND METHODS: 220 single root teeth, recently extracted, were inoculated with Candida albicans and Enterococcus faecalis. The formulations tested were sodium hypochlorite at 1, 3, and 5% chlorhexidine at 0.2% and 2% and ozone gas applied for different periods of time. The combination of sodium hypochlorite at 5% and chlorhexidine at 2%, with gaseous ozone, were also assessed. For the most active treatments the mechanism of action was assessed through flow cytometry. RESULTS: Sodium hypochlorite, chlorhexidine, and gaseous ozone alone were ineffective in completely eliminating the microorganisms. The association of chlorhexidine at 2% followed by ozone gas for 24 seconds promoted the complete elimination of Candida albicans and Enterococcus faecalis. Flow cytometry shows that ozone and chlorhexidine act differently, which could explain its synergic activity. CONCLUSIONS: This new disinfection protocol, combining irrigation with chlorhexidine at 2% and ozone gas for 24 seconds, may be advantageous when treating infected root canals.

New intracanal formulations containing doxycycline or chlorhexidine against Enterococcus faecalis.

The present study aims to evaluate the antimicrobial effect of two new intracanal preparations against E. faecalis. Thirty single-rooted human canine teeth were used. The crowns were removed and the roots were instrumented using a conventional technique. Three groups of ten teeth each were infected with 108 CFU/ ml of E. faecalis for 21 days. The root canals were flled with new intracanal medications containing 3% doxycycline hydrochloride (DX) or 2% chlorhexidine digluconate (CHX). Ten teeth received no medication (NM)-negative control. Microbial samples were obtained 21 days after contamination: 14 days under the effect of the intracanal medications and 7 days after replacing the medications by BHI broth. The samples were homogenized, diluted, seeded on BHI agar and incubated for 48h/36°C. The number of colony forming units (CFU/ml) was obtained and analyzed statistically. All intracanal dressings significantly reduced the number of bacterial cells in the root canal after 14 days with medication. After the period with 7 days with BHI broth, the CFU counts of E. faecalis remained at low values. However, the NM group showed a significant increase of CFU in this period to similar values of the initial contamination. 3% doxycycline hydrochloride gel and 2% CHX gel were effective to eliminate E. faecalis from the root canal system.

Outcome of Er,Cr:YSGG laser-assisted treatment of teeth with apical periodontitis: a blind randomized clinical trial.

OBJECTIVE: As clinical studies conducted to explore the safety and efficacy of new procedures are considered an important focus in endodontic research, the aim of this controlled clinical study was to compare a laser-assisted endodontic treatment using an erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser and radial firing tips (RFT) versus the conventional use of 3% sodium hypochlorite and interim calcium hydroxide paste, in teeth with chronic apical periodontitis. METHODS: Forty-three single-rooted and premolar teeth were randomly assigned. In group 1, teeth were prepared and irrigated with 3% sodium hypochlorite and calcium hydroxide inter-appointment dressing was applied; in group 2 teeth were prepared with saline solution and irradiated with Er,Cr:YSGG laser using RFT2 (140 µs, 37.5 mJ, 20 Hz) and RFT3 (140 µs, 62.5 mJ, 20 Hz) at the first and second appointments, respectively, four times each, moving at 2 mm/sec(-1) from apical to coronal. The primary outcome measure was change in apical bone density at 12 months, using the periapical index (PAI) for blind radiographic assessment. RESULTS: Thirty teeth were examined and subjected to statistical analysis, 12 in the control group and 18 in the test group. There were two treatment failures in the control group that were not included for analysis; both groups exhibited statistically significant decreases in PAI scores. CONCLUSIONS: The present findings suggest that for single-rooted and premolar teeth, this laser-assisted protocol can achieve predictable endodontic outcomes, comparable to conventional strategies in 1 year of follow-up.

Influence of the timing of post space preparation on apical sealing / Influência do timing da colocação de retentor intra-radicular no selamento apical

Objective: To evaluate the integrity of the apical seal in root filled teeth following immediate post space preparation and after eight days.Methods: Forty extracted single-rooted human teeth were instrumented and filled, using lateral condensation technique, with gutta-percha and Sealapex® sealer (Kerr-Sybron, Scafati, Italy). The teeth were randomly assigned to four groups: group I (GI) with seventeen teeth (immediate post space preparation), seventeen in group II (GII) (delayed post space preparation) and three teeth in each control group, group III (GIII) positivecontrol and group IV (GIV) negative control. In GI and GII, the post space was prepared with ProTaper Universal® retreatment files (Dentsply/Maillefer, Ballaigues, Switzerland). After the post space preparation, all specimens were coated, except for two apical millimeters, immersed inmethylene-blue dye for eight days, and then sectioned longitudinally. The extent of staining was examined under a stereomicroscope. Results: In GI there was an average apical leakage of 7,42 mm, while in GII it was 6,82 mm. There were no statistically significant differences between groups I and II (p>0.05). Conclusion: The timing of post space preparation, in teeth filled with Sealapex® sealer (Kerr-Sybron, Scafati, Italy), did not affect the apical sealing ability.

Objetivo: Avaliar o selamento apical em dentes desobturados imediatamente após a obturação radicular e desobturados oito dias depois, para a colocação de retentor intra-radicular. Métodos: Quarenta dentes unirradiculares, foram instrumentados manualmente e obturados pela técnica de condensação lateral com cones de gutaperchae cimento Sealapex® (Kerr-Sybron, Scafati, Italy). Foram aleatoriamente distribuídos em 4 grupos. Grupo I (GI) 17 dentes - desobturaçãoimediata; Grupo II (GII) 17 dentes - desobturação tardia; Grupo III (GIII) 3 dentes - controle positivo; Grupo IV (GIV) 3 dentes - controle negativo.Para a desobturação (GI e GII) foram utilizados instrumentos mecanizados de retratamento ProTaper Universal® (Dentsply/Maillefer, Ballaigues,Switzerland). Após desobturação, os dentes foram impermeabilizados com esmalte, exceto nos 2 milímetros apicais, foram imersos em soluçãode azul-de-metileno durante 8 dias e seccionados longitudinalmente. Com o auxílio de uma lupa ?Wild Makroskop M420? foi realizada a leitura da infiltração. Resultados: No GI, obteve-se infiltração apical média de 7,42 mm e no GII de 6,82 mm. Estas diferenças não foram estatisticamente significativas (p>0,05). Conclusão: O momento de desobturação para a colocação de retentores intra-radiculares, de dentes obturados com cimento Sealapex® (Kerr-Sybron, Scafati, Italy), não afetou o selamento apical.