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Objectives: The aim of this study was to compare the efficacy of apical negative pressure irrigation (ANP) and passive ultrasonic irrigation (PUI) with apical positive pressure irrigation (PP-conventional irrigation) in the periapical repair of dogs' teeth with apical periodontitis., Methods: Forty-nine mesial and distal root canals of premolars of three dogs with experimentally induced periapical lesions were subjected to a single-session root canal treatment. The teeth were randomly assigned to three groups: ANP, PUI, and PP (control). After 180 days, the animals were euthanized, and the anatomic pieces were removed and subjected to histotechnical processing for morphological and morphometric histological analyses of hematoxylin and eosin (HE)-stained sections under conventional and fluorescence microscopy. Periapical lesion size before and 180 days after root canal treatment was measured by periapical radiographic examination. Tartrate-resistant acid phosphatase (TRAP) histoenzymology was performed for osteoclast counting and Brown and Brenn staining to assess bacteria. Data were analyzed statistically by the Kruskal-Wallis test (α = 5 %)., Result: There were no statistically significant differences among the groups regarding periapical lesion size in the radiographic evaluation (p = 0.91). In the comparison of histopathological parameters, group ANP presented more homogeneous results. There was a statistically significant difference (p = 0.02) between groups ANP and PP, with better results for group ANP in which milder infiltrate inflammatory was observed. No statistically significant difference (p > 0.05) was found among the groups with respect to periodontal ligament space, presence of mineralized tissue resorption, size of the periapical lesions, and number of osteoclasts., Conclusion: Although the three irrigation systems elicited similar periapical tissue response with respect to almost all evaluated parameters, ANP presented the mildest inflammatory infiltrate, suggesting an advantage over PP in the indication for clinical use., Clinical Relevance: Irrigation of the root canal systems is an extremely important step in root canal treatment. Therefore, it is of relevance to evaluate the efficacy of these systems by in vivo experimental models to provide scientific background for the clinical practice.

Introduction: The aim of this study was to characterize the response of mouse subcutaneous tissue to triple antibiotic paste (TAP) using conventional light microscopy and real-time PCR (qRT-PCR)., Methods: Polyethylene tubes containing TAP or calcium hydroxide (CH) (ie, the control group) were implanted in mouse subcutaneous tissue. Animals that received empty tubes or no tubes were used as additional controls. After periods of 7, 21, and 63 days postimplantation, the specimens were removed and subjected to histologic processing. The number of inflammatory cells and vessels, vessel areas, vascular density, and relative percentage of collagen were evaluated. Gene expression of proinflammatory (interleukin-1 beta, tumor necrosis factor alpha, and interleukin 17) and anti-inflammatory (transforming growth factor beta) cytokines and angiogenic factors (vascular endothelial growth factor and hypoxia-inducible factor-1 alpha) was quantified by 7 and 21 days postimplantation. Results were analyzed using the Student t test, analysis of variance, and the Tukey test (α = 0.05)., Results: TAP induced an exuberant inflammatory and angiogenic response, with higher numbers of inflammatory cells, higher vascular area and density, and lower relative percentage of collagen compared with CH. In general, the expression of genes involved in inflammation and angiogenesis was higher in the TAP group compared with animals that received CH or empty tubes., Conclusions: The response of mouse subcutaneous tissue to TAP was characterized by exuberant and persistent inflammatory and angiogenic responses with no repair and high gene expression of biomarkers associated with inflammation and angiogenesis., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Substances containing chlorhexidine (CHX) have been studied as intracanal medicaments. The aim of the present study was to characterize the response of mouse subcutaneous connective tissue to CHX-containing medications by conventional optical microscopy. The tissue response was evaluated by implanting polyethylene tubes containing one of the substances evaluated: Calen paste + 0.5% CHX, Calen + 2% CHX, 2% CHX gel, and Calen paste (control). After experimental periods of 7, 21, and 63 days, the implants (n = 10) were removed along with the subcutaneous connective tissue. Tissue samples were subjected to histological processing, and sections were stained with hematoxylin and eosin. Qualitative and quantitative analyses of the number of inflammatory cells, blood vessels, and vascularized areas were performed. Results were analyzed by ANOVA and Tukey tests with the significance level set at 5%. We concluded that Calen + 0.5% CHX led to reparative tissue response in contrast with Calen + 2% CHX and 2% CHX gel, which induced persistent inflammatory response, pointing to the aggressive nature of this mixture. When Calen + 2% CHX and 2% CHX gel were compared, the latter induced more intense inflammatory response., (Copyright © 2012 Wiley Periodicals, Inc.)

Aim: To investigate the root canal microbiota of primary teeth with apical periodontitis and the in vivo antimicrobial effects of a calcium hydroxide/chlorhexidine paste used as root canal dressing., Design: Baseline samples were collected from 30 root canals of primary teeth with apical periodontitis. Then, the root canals were filled with a calcium hydroxide paste containing 1% chlorhexidine for 14 days and the second bacteriologic samples were taken prior to root canal filling. Samples were submitted to microbiologic culture procedure to detect root canal bacteria and processed for checkerboard DNA-DNA hybridization., Results: Baseline microbial culture revealed high prevalence and cfu number of anaerobic, black-pigmented bacteroides, Streptococcus, and aerobic microorganisms. Following root canal dressing, the overall number of cfu was dramatically diminished compared to initial contamination (P <0.05), although prevalence did not change (P > 0.05). Of 35 probes used for checkerboard DNA-DNA hybridization, 31 (88.57%) were present at baseline, and following root canal dressing, the number of positive probes reduced to 13 (37.14%). Similarly, the number of bacterial cells diminished folowing application of calcium hydroxide/chlorhexidine root canal dressing (P = 0.006)., Conclusion: Apical periodontitis is caused by a polymicrobial infection, and a calcium hydroxide/chlorhexidine paste is effective in reducing the number of bacteria inside root canals when applied as a root canal dressing., (2011 The Authors. International Journal of Paediatric Dentistry © 2011 BSPD, IAPD and Blackwell Publishing Ltd.)

Objective: The objective of this study was to evaluate in vivo the revascularization and the apical and periapical repair after endodontic treatment using 2 techniques for root canal disinfection (apical negative pressure irrigation versus apical positive pressure irrigation plus triantibiotic intracanal dressing) in immature dogs' teeth with apical periodontitis., Study Design: Two test groups of canals with experimentally induced apical periodontitis were evaluated according to the disinfection technique: Group 1, apical negative pressure irrigation (EndoVac system), and Group 2, apical positive pressure irrigation (conventional irrigation) plus triantibiotic intracanal dressing. In Group 3 (positive control), periapical lesions were induced, but no endodontic treatment was done. Group 4 (negative control) was composed of sound teeth. The animals were killed after 90 days and the maxillas and mandibles were subjected to histological processing. The sections were stained with hematoxylin and eosin and Mallory Trichrome and examined under light microscopy. A description of the apical and periapical features was done and scores were attributed to the following histopathological parameters: newly formed mineralized apical tissue, periapical inflammatory infiltrate, apical periodontal ligament thickness, dentin resorption, and bone tissue resorption. Intergroup comparisons were done by the Kruskal-Wallis and Dunn's tests (alpha = 0.05)., Results: Although statistically significant difference was found only for the inflammatory infiltrate (P < .05), Group 1 presented more exuberant mineralized formations, more structured apical and periapical connective tissue, and a more advanced repair process than Group 2., Conclusion: From the histological observations, sodium hypochlorite irrigation with the EndoVac system can be considered as a promising disinfection protocol in immature teeth with apical periodontitis, suggesting that the use of intracanal antibiotics might not be necessary., (Copyright (c) 2010 Mosby, Inc. All rights reserved.)

Objective: The aim of this study was to compare in vivo the efficacy of 2 root canal disinfection techniques (apical negative pressure irrigation versus apical positive pressure irrigation plus triantibiotic intracanal dressing) in immature dog teeth with apical periodontitis., Study Design: Two groups of root canals with pulp necrosis and apical periodontitis were evaluated according to the disinfection technique: group 1: apical negative pressure irrigation (EndoVac system); and group 2: apical positive pressure irrigation (conventional irrigation) plus triantibiotic intracanal dressing. The first sample (S1) was collected after lesions were radiographically visible, and the second sample (S2) was collected after apical negative pressure irrigation (group 1) or conventional irrigation/triantibiotic dressing (group 2). All samples were seeded in a culture medium for anaerobic bacteria. Colony-forming unit counts were analyzed statistically by the Mann-Whitney test (alpha = .05)., Results: Microorganisms were present in 100% of canals of both groups in S1. In S2, microorganisms were absent in 88.6% of group 1's canals and 78.28% of group 2's canals. There was no significant difference between the groups in either S1 (P = .0963) or S2 (P = .0566). There was significant (P < .05) bacterial reduction from S1 to S2 in both groups., Conclusion: In immature teeth with apical periodontitis, use of the EndoVac system can be considered to be a promising disinfection protocol, because it provided similar bacterial reduction to that of apical positive pressure irrigation (conventional irrigation) plus intracanal dressing with the triantibiotic paste, and the use of intracanal antibiotics might not be necessary., (Copyright 2010 Mosby, Inc. All rights reserved.)

Sodium hypochlorite solution is toxic to vital tissues, causing severe effects if extruded during endodontic treatment. This paper presents a report on the tissue damage related to inadvertent extrusion of concentrated sodium hypochlorite solution during root canal treatment. A 65-year-old woman was referred with moderate pain, ecchymosis, and severe swelling of the right side of the face. These symptoms appeared immediately after a root canal treatment of the maxillary right canine, which had been started 21 hours earlier. It was diagnosed as air emphysema related to sodium hypochlorite solution extravasation during the endodontic treatment. To avoid this, an initial radiograph should be taken to determine the correct canal working length and confirm root canal integrity.

The present study aimed to evaluate whether the association between a calcium hydroxide paste (Calen paste) and 0.4% chlorhexidine (CHX) affects the development of the osteogenic phenotype in vitro. With rat calvarial osteogenic cell cultures, the following parameters were assayed: cell morphology and viability, alkaline phosphatase activity, total protein content, bone sialoprotein immunolocalization, and mineralized nodule formation. Comparisons were carried out by using the nonparametric Kruskal-Wallis test (level of significance, 5%). The results showed that the association between Calen paste and 0.4% CHX did not affect the development of the osteogenic phenotype. No significant changes were observed in terms of cell shape, cell viability, alkaline phosphatase activity, and the total amount of bone-like nodule formation among control, Calen, or Calen + CHX groups. The strategy to combine Ca(OH)(2) and CHX to promote a desirable synergistic antibacterial effect during endodontic treatment in vivo might not significantly affect osteoblastic cell biology.

This study aimed to evaluate the efficacy of SmearClear (SybronEndo, Orange, CA) and EDTA for smear layer removal from root canals of permanent teeth after instrumentation. Thirty extracted human permanent teeth (n = 10) were randomly assigned to the following groups: group 1 = 14.3% EDTA, group 2 = SmearClear, and group 3 = no smear layer removal procedure was undertaken (control). The specimens were submitted to scanning electron microscopy analysis. Magnifications of 200x and 750x were used to evaluate cleaning at the apical, middle, and cervical thirds according to a three-point scoring system. Data were analyzed statistically by the Mann-Whitney U test (5% significance level). Groups 1 and 2 differed significantly from group 3 (p < 0.01). However, there was no statistically significant difference (p > 0.05) between groups 1 and 2. In conclusion, SmearClear was able to remove the smear layer from the root canals of permanent teeth similarly as 14.3% EDTA, suggesting that both solutions may be indicated for such purpose.

Objective: The objective of this study was to evaluate the effect of a calcium hydroxide Ca(OH)(2)-based paste (Calen) associated or not to 0.4% chlorhexidine digluconate (CHX) on RAW 264.7 macrophage cell line culture., Study Design: The cell viability (MTT assay), immunostimulating properties (NO dosage), and anti-inflammatory properties (NO, TNF-alpha, and IL-1alpha dosage) were evaluated after cell exposure to the materials. Data were analyzed statistically by Kruskal-Wallis test at 5% significance level., Results: There was low immunostimulating activity of the Calen paste associated or not to 0.4% CHX in the different materials' concentrations evaluated (P > .05). Anti-inflammatory activity with inhibition of NO and cytokine (TNF-alpha and IL1-alpha) release was observed only with Ca(OH)(2) + CHX at the highest concentration (25 microg/mL)., Conclusion: As the Calen paste associated to 0.4% CHX did not alter cell viability or the immunostimulating and anti-inflammatory properties, the addition of CHX brought no benefits to the Ca(OH)(2)-based paste with regard to the tested parameters.

The objective of this study was to evaluate the apical and periapical repair after endodontic treatment of teeth with pulp necrosis and a chronic periapical lesion in dogs. Seventy-two root canals from four mongrel dogs were submitted to biomechanical preparation, using 5.25% sodium hypochlorite or 2% chlorhexidine digluconate as the irrigating solution. The root canals were subsequently either filled immediately with Sealapex, using active lateral gutta-percha condensation, or a calcium hydroxide root canal dressing was applied for 15 days before filling with Sealapex. After 210 days, the animals were killed by anesthetic overdose, and the obtained histological sections were stained with hematoxylin and eosin for optical microscopic analysis of apical and periapical repair. There was better histological repair in the groups with the root canal dressing (p < 0.05) than the groups with immediate obturation. Comparing the immediate obturation groups, irrigation with chlorhexidine solution resulted in better repair than sodium hypochlorite.

The antimicrobial activity of irrigating solutions--Endoquil (castor oil detergent), 2% chlorhexidine gluconate solution, and 0.5% NaOCl solution-was evaluated against gram-positive cocci (Micrococcus luteus, Staphylococcus aureus, Enterococcus faecalis, Staphylococcus epidermidis, Streptococcus mutans, and Streptococcus sobrinus), gram-negative rods (Escherichia coli and Pseudomonas aeruginosa), and the yeast Candida albicans. Activity was evaluated using the two-layer agar diffusion technique. The base layer was obtained by pouring 10.0 ml of Muller Hinton Medium or 10.0 ml of Brain Heart Infusion agar in a Petri dish. After solidification a 5.0 ml seed layer of Muller Hinton Medium or Brain Heart Infusion agar with inoculum (106/ml) was added. Absorbent paper disks (6.0 mm in diameter) immersed in the solutions were placed at equidistant points. Plates were maintained at room temperature for 2 h for prediffusion of the solutions and incubated at 37 degrees C for 24 h. The candle jar system was used for the Brain Heart Infusion agar plates. All tests were performed in duplicate. After incubation the medium was optimized with 0.05 g% triphenyltetrazolium chlorate gel and inhibition halos were measured. All bacterial strains were inhibited by 2.0% chlorhexidine gluconate. Endoquil was effective against gram-positive microorganisms, and 0.5% NaOCl was effective only against S. aureus.

Eighty-four root canals of premolars from six dogs were left open for 7 days, and then sealed and followed for 45 days until periradicular periodontitis developed. The root canals were then treated endodontically using 5.25% sodium hypochlorite as the irrigating solution. After instrumentation, all root canals were filled with a calcium hydroxide-based antibacterial dressing (Calen PMCC or Calasept) that was left in place for 30 days. After this period the root canals were filled with gutta-percha cones and a root canal sealer (Sealapex or AH Plus)--group I: Calen PMCC + Sealapex; group II: Calasept + Sealapex; group III: Calen PMCC + AH Plus; and group IV: Calasept + AH Plus. Periapical radiographs of the teeth were made after root canal filling and after 90, 180, 270, and 360 days. Radiographic images were digitalized by scanning, and the Mocha program was used to measure the periapical lesions. Analysis showed that the lesions of groups I to III were statistically similar reduction in size, whereas group IV had a smaller reduction in lesion size (p < 0.05).

Dogs' teeth with induced chronic periapical periodontitis were treated endodontically by two different methods, and the results were compared. A total of 40 root canals from the upper and lower premolars of two dogs were prepared chemomechanically. In method 1, a high-concentration (5.25%) hypochlorite solution was used during the instrumentation of the root canal, and an antibacterial dressing was applied between sessions, followed by filling of the root canal. In method 2, a low-concentration (0.5%) sodium hypochlorite solution was used as an adjunct to mechanical debridement, and the root canal was filled during the same session. The histopathological results showed that method 1 led to better periapical repair than method 2.

The objective of the present study was to evaluate radiographically and bacteriologically apical and periapical repair in dogs' teeth with induced chronic periapical lesions with the use of two different operative techniques (techniques 1 and 2). The study was conducted on 40 root canals of upper and lower premolars from two dogs aged approximately 12 months. Periapical lesions were induced by leaving the root canals exposed to the oral environment for 5 days and then sealing them with zinc oxide-eugenol for 45 days. After this period, radiographic examination revealed the occurrence of a radiolucent lesion and endodontic treatment was started. The two techniques did not differ in terms of chemomechanical preparation, final filling, or type of cement, but differed in terms of irrigating solution and the presence of an antibacterial dressing. Thus 4% to 6% hypochlorite and hydrogen peroxide (10 volumes) were used in technique 1 during chemomechanical preparation and an antibacterial dressing based on calcium hydroxide was applied between sessions, whereas Dakin's fluid (0.5% sodium hypochlorite solution) and a final filling with no antibacterial dressing were used in technique 2. After chemomechanical preparation, the root canals were filled with gutta-percha cones and Sealapex (Sealapex-Sybron, Kerr, Sao Paulo, Brazil), and the animals were killed 270 days after the final filling. Blocks were cut into 6-microns sections and stained by the Brown and Brenn method.(ABSTRACT TRUNCATED AT 250 WORDS)

Periapical tissue response was evaluated histologically in teeth of 6-month-old dogs with incomplete root formation and periapical lesions in order to compare the effects of two calcium hydroxide-containing pastes prepared with different vehicles on induced root apex formation and repair of the periapical region. A group of teeth with no root canal dressing was used as control. After induction of the periapical lesion, the root canals were instrumented and filled with one of the two pastes (Calen and Calasept), which were renewed monthly for 90 days. At the end of the follow-up period (3 months), the animals were killed. Block sections from the actual areas were dissected free and prepared for histopathological analysis. Both calcium hydroxide pastes helped induce apical sealing and repair of the region, but the Calen paste yielded better results than Calasept. The induced mineralized tissue was predominantly of the cementoid type after the use of both pastes, but the inflammatory infiltrate was significantly less intense with the use of the Calen paste. In the control group, the absence of a root canal dressing impaired the process of periapical repair and yielded no apical root closure in any of the cases analyzed.

Periapical repair and apical bridging were studied in dog's teeth with incomplete root formation and induced chronic periapical lesions treated with different dressings. A total of 75 root canals from the upper and lower premolars of 4 dogs approximately 6 months of age were chemo-mechanically prepared and filled with the following dressings: antibacterial dressing consisting of a calcium hydroxide+camphorated p-monochlorophenol paste applied for 7 days and followed by monthly renewed calcium hydroxide paste as temporary dressing at 30, 60 and 90 days (Group A); antibacterial dressing consisting of camphorated p-monochlorophenol alone for 7 days, followed by temporary dressing with calcium hydroxide paste renewed at 30, 60 and 90 days (Group B). A control group (Group C) received no dressings. Ninety days after the last calcium hydroxide paste (Groups A, B) and after the last irrigation/aspiration (Group C), the animals were killed, the maxillae and mandibles were removed, and the material submitted to routine histological processing and examination. Both root canal dressings, were of fundamental importance for apical repair and bridging. The apical bridging was predominantly complete in Group A, incomplete in Group B, and absent in Group C. The calcium hydroxide+camphorated p-monochlorophenol combination gave better results than camphorated p-monochlorophenol alone.