A systematic review and meta-analysis on the effects of phototherapy on postoperative pain in conventional endodontic reintervention.

OBJECTIVES: This systematic review and meta-analysis (SRM) aimed to evaluate the efficacy of laser phototherapy (LPT) on the reduction in postoperative pain (PP) of endodontic origin after conventional/non-surgical reintervention of root canals. METHODS: This SRM was registered with PROSPERO (CRD42021243500) and followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis. Meta-analysis was conducted using R software with the "META" package, the mean difference (MD) measure of effect was calculated, and the fixed effect model was applied with a 95% confidence interval (CI). The Cochrane collaboration scale was used to assess the risk of bias and the GRADE tool to assess the quality of evidence. RESULTS: Initially, 1028 articles were found, and five articles were included. Most studies were classified as "low" risk of bias. Of the five clinical studies, four showed a significant decrease in PP after endodontic reintervention in the LPT groups compared to the control group, especially in the first four days after the intervention. In symptomatic teeth with multiple roots, LPT led to less PP at 24 h (MD -0.52 [-1.03; -0.02] p = .04). However, no significant difference between the groups was found at 48 and 72 h (p > .05). The certainty of the evidence was classified as low. CONCLUSION: Despite the limitations of this SRM, LPT was shown to be a promising alternative for reducing and controlling PP in conventional endodontic reintervention. CLINICAL SIGNIFICANCE: The use of LPT in endodontic reintervention may be a safe and promising alternative to clinically efficacious agent for use in the management of PP in this procedure.

Effects of cigarette smoke inhalation on the immune-inflammatory profile of experimental apical periodontitis in rats.

OBJECTIVE: To evaluate the effects of cigarette smoke inhalation on the immune-inflammatory profile of experimental apical periodontitis in rats. METHODOLOGY: In total, 32 male Wistar rats were divided into four groups (n = 8): AP-induced apical periodontitis; S-cigarette smoke inhalation; APS-induced AP and cigarette smoke inhalation; and C (control)-neither AP nor cigarette smoke inhalation. To induce cigarette smoke inhalation, the animals were kept in a chamber filled with tobacco smoke for 8 min thrice a day for 50 days. AP was induced 20 days after inhalation initiation by exposing their coronary pulp to their oral environment for 30 days. After animals were euthanized, their right hemimaxillae were removed for histopathological, semi-quantitative and immunohistochemical (F4/80, CD206 and iNOS) analyses. RESULTS: Quantitative data showed a moderate number of inflammatory infiltrates in AP and an intense number in APS (p < .05). Comparing F4/80+ cells showed no statistically significant differences among groups, but we found more CD206+ cells in AP than in C and S (p > .05). INOS+ immunostaining showed a significant increase in AP and APS, when compared with C and S (p < .05). APS had more iNOS+ cells than AP (p < .05). CONCLUSION: Cigarette smoke inhalation worsened AP, leading to a predominantly pro- inflammatory profile in our experimental model.

Inflammatory profile of apical periodontitis exacerbated by cigarette smoke inhalation: Histological and immunohistochemical analysis in rats.

AIM: The aim of this study was to evaluate the effects of cigarette smoke inhalation (CSI) on inflammation, pro-inflammatory mediators and haematological parameters in rats with induced apical periodontitis (AP). METHODOLOGY: Thirty-two 3-month-old male Wistar rats were divided into four experimental groups (n = 8): C-Control; S-rats with CSI; AP-rats with AP; and SAP-rats with CSI + AP. Animals in groups S and SAP inhaled cigarette smoke by remaining inside a smoking chamber for 8 min, three times daily, for 50 days. After 20 days of smoke inhalation, animals in AP and SAP groups had the pulps of the lower right first molar exposed to oral environment for 30 days to induce AP. In these subsequent 30 days, animals in group S and SAP continued with CSI. On Day 50, animals were euthanized and mandibles were histologically processed to assess inflammatory infiltrate, immunohistochemical interleukins (IL-1ß, IL-6 and TNF-α), and blood samples collected for laboratory analysis. The Mann-Whitney test was performed for non-parametric data and the pairwise analyses of Student's t-test for parametric data, with a significance level of p < .050. RESULTS: Inflammatory infiltrate was moderate in AP group and more severe in the SAP (p = .010). The interleukins IL-6, IL-1ß and TNF-α were higher in SAP group (p < .001) when compared to the AP group. A greater number of red blood cells (p = .010), haemoglobin (p = .007) and neutrophils (p = .014) were observed in the SAP group in comparison with the AP group. CONCLUSION: Cigarette smoke inhalation induced a more severe inflammatory infiltrate, with increased levels of pro-inflammatory cytokines and changes in haematological parameters in rats with induced AP. Thus, CSI aggravated AP, exacerbating the inflammatory response.

Biocompatibility and biomineralization assessment of mineral trioxide aggregate flow.

OBJECTIVE: Evaluate, in vivo, the biocompatibility via subcutaneous inflammatory tissue response and mineralization ability of the new MTA Flow compared to MTA Angelus and ProRoot MTA. MATERIALS AND METHODS: Forty male Wistar rats were assigned and received subcutaneous polyethylene tube implants containing the test materials and a control group with empty tube (n = 10 animals/group). After days 7, 15, 30, and 60, the animals were euthanized and the polyethylene tubes were removed with the surrounding tissues. Inflammatory infiltrate and thickness of the fibrous capsule were histologically evaluated. Mineralization was analyzed by Von Kossa staining and under polarized light. Data were analyzed via Kruskal-Wallis and Dunn's test with a significance level of 5%. RESULTS: MTA Angelus induced the mildest reaction after 7 (P > .05) and 15 days (P < .05) followed by MTA Flow, both cements achieving mild inflammatory reaction after 15 days. ProRoot MTA induced a severe inflammation on day 7 and was reducing after day 15 (P > .05). No difference was observed after days 30 or 60 (P > .05). Von Kossa staining and birefringent structures were positive to all materials. CONCLUSIONS: At the end of the experiment, the novel MTA Flow showed biocompatibility and induced biomineralization in all time periods. CLINICAL RELEVANCE: The final consistence obtained in MTA Flow may facilitate several procedures, indicating that the MTA Flow has a promising application in endodontics.

Evaluation of the relationship between obturation length and presence of apical periodontitis by CBCT: an observational cross-sectional study.

OBJECTIVE: The aim of this study was to evaluate the relationship between length of root canal obturation (RCO) and the presence of apical periodontitis (AP) in different dental groups using cone-beam computed tomography (CBCT) analysis. MATERIALS AND METHODS: A total of 392 roots with canal treatment performed for more than 4 years were evaluated using CBCT. Distances from the apex to the tip of filling material were measured and classified as more than 2 mm short of the apex, approximately 1-2 mm short of the apex, at the apex, and beyond the apex. Odds ratio, confidence interval, and the χ2 test were used for statistical analyses. RESULTS: The frequency of AP was significantly greater in molars than in the other tooth groups (p < 0.05). Moreover, RCO that ended 1-2 mm short of the apex was associated with a lower prevalence of AP in molars and premolars (p < 0.05) and in anterior teeth (p < 0.1) when compared with RCO at the apex, more than 2 mm short of the apex, or beyond the apex. When the RCO reached the apex, there was no difference in the presence of AP among dental groups (p > 0.05). CONCLUSION: The length of RCOs can influence the presence of AP, with molars showing a higher prevalence. RCOs ending 1-2 mm short of the apex are associated with an absence of AP. CLINICAL RELEVANCE: The length of obturation is related to the presence of apical peridontitis and consequently to the success of endodontic treatment.

Apical periodontitis and periodontal disease increase serum IL-17 levels in normoglycemic and diabetic rats.

OBJECTIVES: This study aimed to evaluate the influence of apical periodontitis (AP) and/or periodontal disease (PD) on serum interleukin-17 (IL-17) levels in a rat model of diabetes mellitus (DM). METHODS: Eighty male Wistar rats were divided into eight groups of ten animals each: normoglycemic, AP, PD, AP+PD, DM, DM+AP, DM+PD, and DM+AP+PD. DM was induced using streptozotocin, AP by dental pulp exposure to the oral environment, and PD by periodontal ligature. The animals were sacrificed after 30 days, and venous blood samples were collected via cardiac puncture to determine the serum IL-17 and neutrophil levels. The maxillae were dissected and processed for radiographic analysis. The periapical lesion areas were quantified in pixels. The total assessed values were tabulated according to each experimental group and were statistically analyzed using Spearman's correlation and Kruskal-Wallis test (p < 0.05). RESULTS: A significant difference in the serum IL-17 levels was observed between the groups without oral infections and the groups with AP+PD-associated lesions, regardless of the presence of DM (p < 0.05). Diabetes increased the neutrophil levels, regardless of the presence of oral infection. However, a combination of two oral infections increased the neutrophil levels in DM rats (p < 0.05). The level of bone resorption lesions was greater in DM rats than in normoglycemic rats (p < 0.05). CONCLUSION: The combination of AP and PD increased the serum IL-17 levels in DM and normoglycemic rats and increased the neutrophil levels in DM rats. Diabetes increased the neutrophil levels and bone resorption in rats. CLINICAL SIGNIFICANCE: AP is capable of potentiating systemic inflammatory changes when associated with PD, and increases in blood glucose can accelerate the pathogenesis of oral infections.

The use of NaOCl in combination with CHX produces cytotoxic product.

OBJECTIVES: The combination of sodium hypochlorite (NaOCl) and chlorhexidine (CHX) yields a "precipitate potentially toxic" (PPT). The aim of this study was to evaluate the tissue response to implanted polyethylene tubes filled with PPT-soaked fibrin sponge. METHODS: Forty rats received four polyethylene tubes each; each tube was filled with fibrin sponge soaked by 2.5 % NaOCl, 2.0 % CHX, PPT (2.5 % NaOCl plus 2.0 % CHX), or not soaked (control). The observation time points were 7, 15, 30, 60, and 90 days. At each time point, eight animals were killed, and the tubes and surrounding tissues were removed, fixed, and prepared for light microscopic analysis by performing glycol methacrylate embedding, serial cutting into 3-µm sections, and hematoxylin-eosin staining. Qualitative and quantitative evaluations of the reactions were performed. Results were statistically analyzed by Kruskal-Wallis test (p < 0.05). RESULTS: All chemical solutions caused moderate reactions at 7 days. On day 30, PPT group was more cytotoxic than the control group and the CHX group (p < 0.05). On days 15 and 60, PPT group was more cytotoxic than the control group (p < 0.05). On day 90, there was no statistically significant difference between the different groups. CONCLUSION: PPT is more cytotoxic than NaOCl and CHX alone, particularly in the short term. CLINICAL SIGNIFICANCE: Protocols which suggest the use of CHX and NaOCl must be revised because this mixture produces cytotoxic product.

Bone Resorption in Apical Periodontitis Enhanced by Cigarette Smoke Inhalation: Histometric, Immunohistochemical, and Microtomographic Analysis in Rats.

INTRODUCTION: This study evaluated the effects of cigarette smoke inhalation (CSI) on apical periodontitis (AP) induced in rats by histometric, immunohistochemical, and microtomographic analysis. METHODS: A total of 32 male Wistar rats were divided into 4 experimental groups (n = 8): control, CSI, AP, and CSI + AP. Rats in the CSI and CSI + AP groups inhaled cigarette smoke by remaining inside a smoking chamber for 8 minutes 3 times a day for 50 days. After 20 days of smoke inhalation, rats in the AP and CSI + AP groups had the pulp of their first right lower molar exposed to induce AP. Blood was collected on day 50 to evaluate nicotine and serum cotinine levels. The animals' mandibles were removed for histologic processing to evaluate bone resorption by histometric, immunohistochemical (receptor activator of nuclear factor kappa B ligand/osteoprotegerin), and microtomographic analysis. The Student t test was applied. RESULTS: Histometric analysis showed a larger area of bone resorption (P < .05) and microtomographic analysis found greater resorption volume (P < .001) for the CSI + AP group compared with the AP group. The CSI + AP group presented a high RANKL immunostaining pattern compared with the AP group (P < .001). CONCLUSIONS: CSI increased bone resorption caused by AP.

Biocompatibility and biomineralization assessment of a new root canal sealer and root-end filling material.

OBJECTIVE: This study investigated the short-term subcutaneous tissue reaction and biomineralization ability of two epoxy-based root canal sealers containing calcium hydroxide (MBP and MBPc) and ProRoot MTA. MATERIALS AND METHODS: Polyethylene tubes containing the materials were implanted into the dorsal connective tissue of Wistar rats (n = 52) for 7 or 30 days; empty implanted tubes served as controls. Specimens were stained with hematoxylin-eosin and von Kossa stain or left unstained for observation under polarized light. Qualitative and quantitative evaluations of all tissue reactions were performed. One-way anova and the Kruskal-Wallis test were used for statistical analysis (P < 0.05). RESULTS: No significant differences were observed among the groups. All three materials induced mild-to-moderate tissue reactions at 7 days, which decreased over time. Dystrophic mineralization and birefringent structures were observed only in the ProRoot MTA (®) group. CONCLUSION: Both MBP and MBPc appear to be biocompatible but do not stimulate biomineralization.

Biocompatibility, Biomineralization and Induction of Collagen Maturation with the Use of Calcium Hydroxide and Iodoform Intracanal Dressing.

Biocompatibility and biomineralization of root canal dressings are important requirements for periapical healing. This study evaluated the inflammatory response, biomineralization and tissue repair by collagen fiber maturation in the subcutaneous tissue of rats. Eighteen Wistar rats (n = 6) received subcutaneous implants: calcium hydroxide + propylene glycol [CH+P], calcium hydroxide + propylene glycol + iodoform [CH+P+I], iodoform + carbowax [I+Cwax] and carbowax [Cwax]. Extra empty tubes were used as a control [C]. After 7, 15 and 30 days, the implants were removed with surrounding tissue for staining of hematoxylin-eosin, Von Kossa, picrosirius red and without staining for analysis under polarized light. Results were analyzed via Kruskal-Wallis followed by Dunn testing for nonparametric data and ANOVA followed by a Tukey post hoc test for parametric data (p < 5%). At 7 days, all groups showed a moderate inflammatory reaction and thick fibrous capsule, except the [Cwax] group, with a severe inflammatory infiltrate (p < 0.05). After 15 days, all groups but control had a decrease in inflammatory response. At 30 days, all groups presented a mild reaction and thin fibrous capsule (p > 0.05). Only groups containing calcium hydroxide were found to be positive using Von Kossa staining and polarized light in all periods. At 7 days, all groups showed a higher proportion of immature fibers. At 15 days, the [CH+P] and [Cwax] groups increased their proportion of mature/immature fibers. At 30 days, only the [CH+P] group presented a significant prevalence of mature collagen fibers (p < 0.05). All groups showed biocompatibility, but only groups containing calcium hydroxide induced biomineralization. The addition of iodoform delayed tissue healing.

Biological investigation of resinous endodontic sealers containing calcium hydroxide.

The purpose of this study was to evaluate, in vivo, the biocompatibility, biomineralization, collagen maturation and the in vitro antibacterial and cytotoxicity of resinous endodontic sealers containing calcium hydroxide. Forty rats were implanted with polyethylene tubes containing Sealer 26, Sealer Plus, Dia-ProSeal and an empty tube, examined after 7, 15, 30 and 60 days. Antimicrobial activity was evaluated against Enterococcus faecalis by Agar Diffusion Test (ADT) through inhibition zones. For cytotoxicity, undifferentiated pulp cells (OD-21) were cultured and assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, exposed to dilution of serial extracts at 6, 24, 48h. Cytotoxicity was analyzed by two-way ANOVA and Bonferroni correction. Kruskal-Wallis test followed by Dunn test was performed for nonparametric data (p<0.05). MTT assay revealed cell proliferation affected by sealers extract in all periods (p<0.0001), except for Dia-Proseal and Sealer Plus ⅛ dilution. Subcutaneous analysis showed at day 7th moderate inflammatory infiltration. After 30 days, Sealer 26 still showed moderate inflammatory infiltrate compared to mild inflammation from control and Dia-ProSeal (p = 0.006). At day 60th, all groups showed similar mild inflammatory infiltrate (p>0.05). Sealer 26 induced more biomineralization than other sealers in all periods. At 7 and 15 days, all sealers had significant percentage of immature collagen fibers. After 60 days Sealer 26 showed more mature fibers compared to other sealers (p<0.001). All sealers had a smaller zone of inhibition than chlorhexidine, but with no significant difference among any group (p>0.05). All sealers showed satisfactory biological responses with in vitro/in vivo biocompatibility and antimicrobial activity against planktonic bacteria. Sealer 26 induced more biomineralization than Sealer Plus and Dia-ProSeal.

Biocompatibility and immunolabeling of fibronectin and tenascin of resinous root canal sealers.

Aims: The aim of this study was to evaluate the biocompatibility of resinous root canal sealers: Sealer 26, AH plus, and SK Seal Root Canal Sealer in the subcutaneous tissue of rats. Subjects and Methods: Twenty-four Wistar rats received polyethylene tubes containing the sealers and empty tubes as control (n = 6). After 7, 15, 30, and 60 days, animals were killed and polyethylene tubes were removed with the surrounding tissues. The specimens were embedded in paraffin, processed for hematoxylin-eosin and immunohistochemistry assessed for fibronectin (FN) and tenascin (TN). Statistical Analysis Used: Data were tabulated and analyzed via Kruskal-Wallis and Dunn's test (P < 0.05). Results: All groups induced a moderate inflammatory reaction after 7 and 15 days (P > 0.05); after 30 days, a mild inflammatory infiltrate was observed in control groups, and moderate in sealers groups (P > 0.05); all groups showed mild inflammatory infiltrate at 60 days (P > 0.05). Overall, the fibrous capsule was considered thick only on the 7th day and became thin over time. All groups had expression for FN and TN in all analyzed periods, with high immunolabeling in sealers groups when comparing with the control group (P < 0.05). Conclusion: All sealers demonstrated biocompatibility and induced FN and TN expression.

Accuracy of Root ZXII, E-PEX and FIND apex locators in teeth with vital pulp: an in vivo study.

This research evaluated, in vivo, the accuracy of three electronic apex locators - EALs (Root ZXII, E-PEX and FIND) in teeth with vital pulp submitted to biopulpectomy, preserving the periodontal stump. For this study, 90 single-rooted teeth with extraction indication were selected. After positive pulpal cold sensitivity test, pulp chamber access was performed. The cervical and middle thirds of root canals were instrumented with Reciproc R25, and the K#15 file was used as a standard instrument to determine working length, forming 2 groups: Constriction (insertion of the instrument until the apical constriction limit) and Foramen (insertion of the instrument until the foramen and then repositioning at constriction, without removing the file from the canal). The hand file was stabilized with a light-cured flow resin. After extraction, the samples were analyzed through microCT SkyScan 1272, with CTAN software, which evaluated the proximity between the tip of the file to the apical constriction, providing data for comparative analysis using Kruskal-Wallis and Dunn tests (p<0.05). There was a statistically significant difference in the abilities of the EALs to detect the apical constriction after reaching the foramen with Root ZX II showing higher accuracy (89%). However, there was no difference in the accuracy of the three EALs in detecting the apical constriction without reaching the foramen. Based on the present results, we conclude that EALs may show accurate measures in detecting apical constriction and foramen, even without damaging the periodontal stump in biopulpectomy.

Biological assessment of a new ready-to-use hydraulic sealer.

OBJECTIVES: This study compared the cytotoxicity, biocompatibility, and tenascin immunolabeling of a new ready-to-use hydraulic sealer (Bio-C Sealer) with MTA-Fillapex and white MTA-Angelus. MATERIALS AND METHODS: L929 fibroblasts were cultivated and exposed to undiluted and diluted material extracts. Polyethylene tubes with or without (the control) the materials were implanted into the dorsa of rats. At 7 days and 30 days, the rats were euthanized, and the specimens were prepared for analysis; inflammation and immunolabeling were measured, and statistical analysis was performed (p < 0.05). RESULTS: MTA-Fillapex exhibited greater cytotoxicity than the other materials at all time points (p < 0.05). The undiluted Bio-C Sealer exhibited greater cytocompatibility at 6 and 48 hours than white MTA-Angelus, with higher cell viability than in the control (p < 0.05). White MTA-Angelus displayed higher cell viability than the control at 24 hours, and the one-half dilution displayed similar results at both 6 and 48 hours (p < 0.05). At 7 days and 30 days, the groups exhibited moderate inflammation with thick fibrous capsules and mild inflammation with thin fibrous capsules, respectively (p > 0.05). At 7 days, moderate to strong immunolabeling was observed (p > 0.05). After 30 days, the control and MTA-Fillapex groups exhibited strong immunolabeling, the white MTA-Angelus group exhibited moderate immunolabeling (p > 0.05), and the Bio-C Sealer group exhibited low-to-moderate immunolabeling, differing significantly from the control (p < 0.05). CONCLUSIONS: Bio-C Sealer and white MTA-Angelus exhibited greater cytocompatibility than MTA-Fillapex; all materials displayed adequate biocompatibility and induced tenascin immunolabeling.

Biocompatibility, Biomineralization, and Maturation of Collagen by RTR®, Bioglass and DM Bone® Materials.

This study evaluated the biocompatibility, biomineralization, and collagen fiber maturation induced by Resorbable Tissue Replacement (RTR®; ß-tricalcium phosphate [TCP]), Bioglass (BIOG; bioactive glass), and DM Bone® (DMB; hydroxyapatite and ß-TCP) in vivo. Sixty-four polyethylene tubes with or without (control group; CG) materials (n=8/group/period) were randomly implanted in the subcutaneous tissue of 16 male Wistar rats (four per rat), weighting 250 to 280 g. The rats were killed after 7 and 30 days (n=8), and the specimens were removed for analysis of inflammation using hematoxylin-eosin; biomineralization assay using von Kossa (VK) staining and polarized light (PL); and collagen fiber maturation using picrosirius red (PSR). Nonparametric data were statistically analyzed by Kruskal-Wallis and Dunn tests, and parametric data by one-way ANOVA test (p<0.05). At 7 days, all groups induced moderate inflammation (p>0.05). At 30 days, there was mild inflammation in the BIOG and CG, and moderate inflammation in the RTR and DMB groups, with a significant difference between the CG and RTR (p<0.05). The fibrous capsule was thick at 7 days and predominantly thin at 30 days in all groups. All materials exhibited structures that stained positively for VK and PL. Immature collagen fibers were predominant at 7 and 30 days in all groups (p>0.05), although DMB exhibited more mature fibers than BIOG at 30 days (p<0.05). RTR, BIOG, and DMB were biocompatible, inducing inflammation that reduced over time and biomineralization in the subcutaneous tissue of rats. DMB exhibited more mature collagen fibers than BIOG over a longer period.

Does photodynamic therapy with methylene blue affect the mechanical properties and bond strength of glass-fiber posts in different thirds of intraradicular dentin?

BACKGROUND: There are few studies on the influence of methylene blue as a photosensitiser on the mechanical properties and adhesion of glass-fiber posts to intraradicular dentin. Thus, this in vitro study aimed to evaluate the influence of photodynamic therapy with a methylene blue photosensitizer on the Martens hardness, elastic modulus, and bond strength of glass-fiber posts in different thirds of intraradicular dentin. METHODS: Eighty bovine teeth were divided into the following five groups: a control using deionized water, and four other groups according to the methylene blue concentration (50 mg/L or 100 mg/L) and substrate treatment (with or without red laser action). Ultramicrohardness test was used to evaluate the mechanical properties in different regions of the root dentin (n = 8). Push-out analysis was evaluated using a universal testing machine (n = 8). Data were subjected to the Kruskal-Wallis test, followed by Dunn's test for comparing groups, and the Friedman test for comparing thirds (α = 0.05). Representative scanning electron microscopy images were obtained. RESULTS: In general, methylene blue in distinct concentrations, with or without laser action, did not cause differences in the mechanical properties or bond strength in different regions of root dentin (P > 0.05). Methylene blue at a higher concentration, activated with laser, produced lower bond strength values in the middle third of the root canal (P < 0.05). CONCLUSIONS: Methylene blue at 50 mg/L had no influence on the mechanical properties of the bovine tooth and the bond strength of the glass-fiber posts to intraradicular dentin.

Cyclic fatigue resistance of novel Genius and Edgefile nickel-titanium reciprocating instruments.

This study aimed to assess the cyclic fatigue resistance of Genius and EdgeFile X1 reciprocating instruments compared with WaveOne Gold Primary. Twenty Genius (Ultradent) 25.04, 20 Genius 30.04, 20 EdgeFile X1 (EdgeEndo) and 20 WaveOne Gold Primary (Dentsply Maillefer) instruments were included in this study and tested in a static cyclic fatigue testing device, which has an artificial stainless steel canal with a 60° angle of curvature and a 5-mm radius of curvature. All instruments were operated in reciprocation mode until fracture occurred. The number of cycles to failure (NCF) was calculated and time to fracture (TF) was recorded in seconds using a digital chronometer. The mean and standard deviations of NCF and TF were calculated for each reciprocating system and the data were subjected to Kruskal-Wallis one-way analysis of variance and to Dunn's test (p < .05) using SigmaPlot software (Systat software, CA, USA). The fractured surfaces of five instruments from each brand were randomly examined and microphotographed by a low-vacuum environmental scanning electron microscopy - SEM (Tabletop Microscope TM3030, Hitachi, Japan) to confirm the cyclic fatigue fracture. EdgeFile exhibited the highest cyclic fatigue resistance, followed by both Genius files (p < .05). Within the limitations of this in vitro study, EdgeFile X1 instruments had significantly higher cyclic fatigue resistance than did Genius and WaveOne Gold Primary instruments. The cyclic fatigue resistance of both Genius files was higher than that of WaveOne Gold Primary.

Anti-inflammatory potential of a carvedilol gel in the pulpal tissue of rats after dental bleaching: A histopathological evaluation.

AIM: Carvedilol is an antioxidant that decreases inflammation in periodontitis. The hydrogen peroxide (H2 O2 ) of bleaching gel causes inflammation and necrosis of the dental pulp. In the present study, we evaluated the anti-inflammatory potential of carvedilol in the pulp of rats after bleaching. METHODS: The right upper molars of rats received 35% H2 O2 (1× 30 minutes), and the left upper molars were used as the control. Half of the rats received carvedilol gel (1× 10 minutes), forming the following groups: bleached, bleached followed by carvedilol (bleached+carvedilol), and control. After 2 and 30 days (N = 7 hemi-maxillae/group), the rats were killed for histological evaluation, and statistical tests were performed (P < 0.05). RESULTS: After 2 days, the bleached group showed necrosis in the occlusal third of the coronal pulp, and in the bleached+carvedilol group, severe inflammation (P > 0.05), both different from the control (P < 0.05). In the middle third, the bleached group showed severe inflammation, and the bleached+carvedilol group showed moderate inflammation (P > 0.05), with the only difference between the bleached and control groups (P < 0.05). In the cervical third, the bleached group showed moderate inflammation, and the bleached+carvedilol group showed mild inflammation (P > 0.05). The difference again was only between the bleached and control groups (P < 0.05). At 30 days, there was no inflammation and a marked amount of tertiary dentin in bleached teeth (P > 0.05). CONCLUSION: Carvedilol gel has the potential of minimizing H2 O2 damage, especially in deep regions of the dental pulp of rats after bleaching.

Influence of curcumin photosensitizer in photodynamic therapy on the mechanical properties and push-out bond strength of glass-fiber posts to intraradicular dentin.

BACKGROUND: The effects of using curcumin as photosensitizer on the mechanical properties of intraradicular dentin and on the bond strength of glass-fiber posts are unknown. Thus, this in vitro study evaluated the influence of using curcumin as photosensitizer during photodynamic therapy on the Martens hardness, elastic modulus, and bond strength of glass-fiber posts luted to intraradicular dentin, in different tooth root thirds. METHODS: Eighty bovine teeth were divided into 5 groups according to the concentration of curcumin applied, with or without blue LED light activation: Control-deionized water; Curcumin 500 mg/L; Curcumin 500 mg/L + blue LED; Curcumin 1000 mg/L; and Curcumin 1000 mg/L + blue LED. Mechanical properties were measured in different thirds of the radicular dentin using an ultramicrohardness tester (n = 8). A universal testing machine was used to evaluate the push-out bond strength (n = 8). Mechanical properties were compared across groups with the Kruskal-Wallis test, and across regions with the Friedman test. Bond strength data were subjected to ANOVA, followed by Tukey's test (α = 0.05). Scanning electron microscopy was used to analyze the failure mode of the specimens. RESULTS: The use of curcumin photosensitizer, with or without blue LED light, improved mechanical properties compared to those of the control group (P < 0.05), and promote no statistically significant difference in bond strength values (P > 0.05). Overall, there was no difference among the intraradicular thirds for Martens hardness and push-out bond strength values (P > 0.05). CONCLUSIONS: Curcumin photosensitizer, with or without photodynamic therapy, changed the mechanical properties of intraradicular dentin; however, the Martens hardness and bond strength values did not differ with the depth of the dentin.

Comparison of two rotary systems in bacteria/lps removal from endodontic infections: randomized clinical trial.

This clinical study compared the effectiveness of two rotary systems: HyFlex CM (Coltene-Whaledent, Altstetten, Switzerland) and ProTaper Next (Dentsply Sirona, Ballaigues, Switzerland) on the removal of cultivable bacteria and endotoxins from primarily infected root canals. This study was designed as a randomized single-blinded, 2-arm, clinical trial. Twenty-four primarily infected root canals were selected and randomly divided into 2 groups: HyFlex CM (n = 12); and ProTaper Next (n = 12). Samples were collected before and after the biomechanical preparation and inoculated in specific flasks. Irrigation was performed using 2.5% sodium hypochlorite. A kinetic turbidimetric lysate assay of limulus amoebocytes was used to quantify endotoxins. Microbiological culture technique was used to determine the count of bacterial colony forming units (CFU/mL). Data collected were statistically analyzed using SigmaPlot 12.0 for Windows. The Two-Way ANOVA statistical test was performed and the level of significance was 5%. In the samples before the biomechanical preparation, cultivable bacteria and endotoxins were evidenced in 100% of the cases. The culture analysis revealed that there was no statistically significant difference in the bacterial reduction between the two instrumentation systems. Endotoxins were present in 100% of the canals after instrumentation and there was no statistical difference between the two systems in endotoxin reduction. Thus, it was concluded that both instrumentation systems were effective in reducing root canal bacteria and endotoxins with primary endodontic infection and that there was no statistical difference between them. However, no system was able to eliminate 100% of the bacteria and their by-products.