Auxiliary Chemical Substances Research Articles

Outcome of Root Canal Treatment of Teeth with Asymptomatic Apical Periodontitis Treated with Foraminal Enlargement and 2% Chlorhexidine Gel: A Retrospective Cohort Study

IntroductionThis retrospective cohort study aimed to estimate the success rate (SR) of primary root canal treatment on teeth with a diagnosis of pulp necrosis (PN) and asymptomatic apical periodontitis (AAP) when using 2% chlorhexidine gel as an auxiliary chemical substance and foraminal enlargement instrumentation technique. MethodsThis study evaluated 178 patients with 206 teeth submitted to primary root canal treatment performed by graduate residents in endodontics. The inclusion criteria were patients who underwent treatment over a period of 1–7 years on teeth with a diagnosis of PN and AAP. The SR was evaluated clinically and radiographically and categorized considering strict (complete resolution of the periradicular lesion) or loose (reduction in the size of the existing periradicular lesion) criteria. Cases of clinical and/or radiographic absence of repair were classified as a failure. Two calibrated examiners independently assessed treatment outcomes using ImageJ software (National Institutes of Health, Bethesda, MD). ResultsThe SRs were 81.1% (95% confidence interval, 75.7%–86.4%) and 87.4% (95% confidence interval, 82.8%–91.9%) when considering the strict or loose criteria, respectively. Females had a higher SR when strict criteria were applied. Also, the SR was significantly reduced when there was an increase in the patient’s age. ConclusionsTeeth with a diagnosis of PN and AAP and treated with 2% chlorhexidine gel and foraminal enlargement achieved substantial SR. Sex and age were prognostic factors that played a significant role in the SR. Future randomized controlled trials should further investigate the effects of foraminal enlargement and 2% chlorhexidine gel as an auxiliary chemical substance.

Periradicular repair after single- and two-visit root canal treatments using ultrasonic irrigant activation and calcium hydroxide dressing of teeth with apical periodontitis: study protocol for randomized controlled trials

BackgroundIn certain clinical situations, root canal treatment in teeth with apical periodontitis is performed in multiple visits, with the use of intracanal dressing between visits, aiming to reduce microorganisms and their by-products of the root canal system prior to filling. However, in recent years, discussions have been growing about the real need for the use of intracanal dressing in these cases. The use of ultrasonic activation of the auxiliary chemical substance has increased the potential for decontamination promoted during the chemomechanical preparation of the root canal. Thus, this study is designed to explore whether the use of intracanal dressing between visits during endodontic treatment favors periradicular repair in teeth with apical periodontitis.MethodsThis is a randomized, prospective, double-blinded, controlled clinical trial designed to evaluate 3 distinct clinical approaches used during endodontic therapy: group 1—root canal treatment in a single visit (RCT-SV); group 2—root canal treatment in two visits with intracanal dressing (RCT-TVWD); and group 3—root canal treatment in two visits without intracanal dressing (RCT-TVWOD). A total of 150 adult patients aged 18 to 60, with at least one tooth diagnosed with asymptomatic apical periodontitis and periradicular lesion (confirmed with a cone beam computed tomography (CBCT)), will be randomized and will undergo one of the types of clinical approaches during endodontic therapy. Patients’ postoperative pain levels will also be recorded in periods of 24, 48, and 72 h and 7 days. Subsequently, clinical findings and long-term follow-up evaluations, with periradicular repair, will be performed at 6 and 12 months by intraoral periapical radiograph (IOPAR) and CBCT at the 24-month follow-up.DiscussionThis study will evaluate the periradicular repair of mandibular molar teeth with apical periodontitis, providing information about the efficacy, benefits, and safety of performing the endodontic treatment in a single and two visits, with and without the use of calcium hydroxide dressing. All endodontic therapy procedures will be performed under a dental operating microscope and using ultrasonic activation of auxiliary chemical substances. These results may contribute to changes in the clinical approaches adopted during endodontic therapy of teeth with apical periodontitis and reveal the potential of complementary approaches that aim to enhance the decontamination of the root canal system during the preparation stage.Trial registrationClinicalTrials.gov NCT05256667. Registered on 24 February 2022

The effect of photodynamic therapy on postoperative pain in teeth with primary endodontic infection

Introduction: The objective of this study was to investigate the action of photodynamic therapy on pain control after endodontic treatment in asymptomatic teeth with a primary infection, within a single visit. Methods: Sixty (60) single-rooted teeth with pulp necrosis and periapical lesions were selected and randomly divided into two (2) groups (n = 30), according to the protocol; a control group (CG) and a group using photodynamic therapy (aPDT). The canals were instrumented with Reciproc files # 25 up to 40 along the entire length of the canal, using 2% chlorhexidine gel as the auxiliary chemical substance, followed by irrigation with sterile saline. aPDT consited of 0.005% methylene blue as photosensitizer, using AsGaAl diode laser, 660 nm wavelength, 100 mW of power and 9 J of energy, using optical fibers with 365 μm in diameter. The canals were filled with Endomethasone N cement. Results: Pain intensity was assessed at 8, 12, 24, 48, 72 h and 1 week after endodontic treatment using a visual analogue scale. The level of pain was classified as none (0), mild (1–3), moderate (4–7) or severe (8–10). The data were at a significance level of 5%. There was a statistically significant difference (p<0.05) in the periods of 8, 12, 24, 48 and 72 h between the control group and the aPDT group. After 1 week, there was no statistically significant difference. Conclusions: It is concluded that photodynamic therapy had a significant effect on decreasing post-endodontic treatment pain in teeth with necrotic pulp and asymptomatic periapical lesions.

The Influence of Sodium Hypochlorite and Chlorhexidine on Postoperative Pain in Necrotic Teeth: A Systematic Review.

Objective:The purpose of this systematic review was to provide the answer to the question: Can sodium hypochlorite and chlorhexidine influence postoperative pain after the endodontic treatment in necrotic teeth?Methods:The PROSPERO registration number is CRD42018096433 and was conducted following the PRISMA statements. The MeSH and free terms were used to search for articles published in the electronic databases (PubMed, Web of Science, Scopus, Cochrane Library, and Virtual Health Library), in the gray literature, and by a manual search. The reviewers selected the studies considering predetermined eligibility criteria, performed data extraction, and evaluated the risk of bias. Only clinical trials comparing the effect of sodium hypochlorite and chlorhexidine on postoperative pain in teeth of adult patients with necrotic pulps were included.Results:Five studies were qualified for the systematic review. Two studies were considered a low risk of bias. The results showed no statistically significant difference regarding postoperative pain in the groups. Only 1 study reported a statistically significant difference in the sixth postoperative hour, and the pain was associated with the sodium hypochlorite group.Conclusion:There was no influence of auxiliary chemical substance (NaOCl and CHX) on postoperative pain used in endodontic treatment in the teeth with pulp necrosis. However, one study observed a significant difference in the sixth postoperative hour, associated with the sodium hypochlorite group.

Effectiveness of calcium hydroxide-based intracanal medication on infectious/inflammatory contents in teeth with post-treatment apical periodontitis

The objective of this work was to investigate in vivo the effects of calcium hydroxide-based intracanal medication (ICM) on the levels of bacteria, pro-inflammatory cytokines (PICs), and matrix metalloproteinases (MMPs) in root canals and periradicular tissues of teeth with failure of the root canal treatment and apical periodontitis. Twenty infected root canals of single-rooted teeth were randomly assigned into two groups according to the irrigant used for chemomechanical preparation (CMP) (n= 10 per group): G1-2% chlorhexidine (CHX) gel and G2-6% sodium hypochlorite (NaOCl). Root canal contents were taken by using paper points before CMP (S1) and after 30days of calcium hydroxide-based ICM (S2). Microbial reduction was calculated by means of colony-forming unit count (CFU/mL), with PICs and MMPs (pg/mL) being measured by using enzyme-linked immunosorbent assay (ELISA). Culturable bacteria (101.2 ± 79.2), PICs (IL-1β 1.2 ± 0.4 and TNF-α 8.8 ± 4.7), MMP-2 (803.7 ± 96.4), MMP-3 (453.9 ± 229.3), MMP-8 (245.9 ± 122.4), MMP-9 (129.4 ± 29.6), and MMP-13 (70.8 ± 12.8) were present in all S1 samples. After 30days of ICM (S2), a 99.5% microbial reduction was observed, together with a significant reduction of PICs in all groups. Overall, it was observed a decrease in the levels of MMPs (S2), except MMP-13, which was found in increased levels after ICM (P< .05), independently of the groups. Calcium hydroxide-based intracanal medications have had a positive effect on the microbial reduction by decreasing the levels of PICs and MMPs. Both auxiliary chemical substances (i.e., 2% CHX and 6% NaOCl) presented similar effects when calcium hydroxide was used as intracanal medication. Teeth with failure of the root canal treatment and apical periodontitis, and consequently with high levels of bacteria, PIC, and MMP, may present a better prognosis after a 30days of a calcium hydroxide-based ICM.

Detection and function of lipopolysaccharide and its purified lipid A after treatment with auxiliary chemical substances and calcium hydroxide dressings used in root canal treatment.

To investigate the influence of auxiliary chemical substances (ACSs) and calcium hydroxide [Ca(OH)2 ] dressings on lipopolysaccharides (LPS)/lipid A detection and its functional ability in activating Toll-like receptor 4 (TLR4). Fusobacterium nucleatum pellets were exposed to antimicrobial agents as following: (i) ACS: 5.25%, 2.5% and 1% sodium hypochlorite solutions (NaOCl), 2% chlorhexidine (CHX) (gel and solution) and 17% ethylenediaminetetraacetic acid (EDTA); (ii) intracanal medicament: Ca(OH)2 paste for various periods (1h, 24h, 7days, 14days and 30days); (iii) combination of substances: (a) 2.5% NaOCl (1h), followed by 17% EDTA (3min) and Ca(OH)2 (7days); (b) 2% CHX (1h), afterwards, 17% EDTA (3min) followed by Ca(OH)2 (7days). Saline solution was the control. Samples were submitted to LPS isolation and lipid A purification. Lipid A peaks were assessed by matrix-assisted laser desorption ionization time-of-flight mass spectrom (MALDI-TOF MS) whilst LPS bands by SDS-PAGE separation and silver staining. TLR4 activation determined LPS function activities. Statistical comparisons were carried out using one-way anova with Tukey-Kramer post-hoc tests at the 5% significance level. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry analysis of control lipid A demonstrated the ion cluster at mass/charge (m/z) 1882 and an intense band in SDS-PAGE followed by silver staining of control LPS. In parallel, LPS control induced a robust TLR4 activation when compared to ACS (P≤.001). 5.25% NaOCl treatment led to the absence of lipid A peaks and LPS bands, whilst no changes occurred to lipid A/LPS after treatment with others ACS. Concomitantly, 5.25% NaOCl-treated LPS did not activate TLR4 (P<.0001). As for Ca(OH)2 , lipid A was not detected by MALDI-TOF nor by gel electrophoresis within 24h. LPS treated with Ca(OH)2 was a weak TLR4 activator (P<.0001). From 24h onwards, no significant differences were found amongst the time periods tested (P>0.05). The addition of Ca(OH)2 for 7days to cells treated either with 2.5% NaOCl or 2% CHX led to the absence of lipid A peaks and LPS bands, leading to a lower activation of TLR4. 5.25% NaOCl and Ca(OH)2 dressings from 24h onwards were able to induce both, loss of lipid A peaks and no detection of LPS bands, rendering a diminished immunostimulatory activity through TLR4.

Effect of root canal preparation techniques on chlorhexidine substantivity on human dentin: a chemical analysis

Chlorhexidine binds to dentine to provide sustained action. The aim of the present study was to evaluate and compare the substantivity of chlorhexidine using manual, rotary, and reciprocating systems for root canal preparation. Forty-five extracted human single-rooted teeth were used for this study. The samples were divided into three groups (n=15) according to the instrumentation technique used: manual instrumentation (K-File), rotary instrumentation (ProTaper), and reciprocating instrumentation (Reciproc R25). Chlorhexidine gel (2%) was used as auxiliary chemical substance during root canal preparation. Longitudinal grooves were carved on the free surfaces of the roots, providing two halves of each root and resulting in 30 samples per group. Each group was randomly divided into three subgroups (n=10), and substantivity was evaluated after 48h, 7days, and 30days of incubation. The amount of CHX (in mg/mL) was measured through reverse-phase high-performance liquid chromatography. Statistical analysis was performed by analysis of variance and the Tukey test for post hoc comparisons (α=0.05). The manual did not show a statistical significant difference with rotary instrumentation (P>0.05), but higher CHX substantivity was recorded in all periods of observation when compared to reciprocating instrumentation (P<0.05). The CHX substantivity on human dentine is lowest when using reciprocating compared to manual and rotary instrumentation. Using chemical analysis, this study showed that a manual and rotary multi-instrument system results in greater chlorhexidine substantivity on human dentin than a reciprocating single-instrument system.

Action of Chlorhexidine, Zingiber officinale, and Calcium Hydroxide on Candida albicans, Enterococcus faecalis, Escherichia coli, and Endotoxin in the Root Canals.

The purpose of this in vitro study was to evaluate the antimicrobial activity of 2% chlorhexidine gel (CHX) as auxiliary chemical substance and intracanal medications on Candida albicans, Enterococcus faecalis, Escherichia coli, and their endotoxins in the root canals. The study was conducted on 48 single-rooted human teeth divided into four groups (n = 12), according to intracanal medications used: (1) Calcium hydroxide + apyrogenic saline solution (Ca(OH)2 + SS), (2) 20% ginger glycolic extract (GEN), (3) calcium hydroxide + 20% ginger glycolic extract (Ca(OH)2 + GEN), (4) apyrogenic SS (control). Collections were made from the root canal content before preparation (baseline-S1), immediately after instrumentation (S2), 7 days after instrumentation (S3), after 14 days the action of intracanal medication (S4), and 7 days after removal of the intracanal medication (S5). The antimicrobial activity and endotoxin content were analyzed for all collections. The results were statistically analyzed by the Kruskal-Wallis and Dunn tests at a significance level of 5%. After instrumentation with CHX, there was complete elimination of E. coli and C. albicans, except for E. faecalis, which was significantly reduced and then completely eliminated after intracanal medication. There was significant reduction of endotoxin after instrumentation. Comparison of collection after instrumentation and intracanal medication revealed reduction of endotoxins in all groups; this reduction was greater in group Ca(OH)2 followed by the group GEN. It was concluded that the instrumentation using CHX and intracanal medication used were able to eliminate the microorganisms from the root canal; the endotoxins were reduced, yet not completely eliminated. This study is important and relevant for searching alternatives during endodontic therapy, since it aims to study the effect of Zingiber officinale on microorganisms and endotoxins present in root canals.

Avaliação da capacidade de dissolução de tecido pulpar bovino pelo hipoclorito de sódio em diferentes concentrações

ResumoIntroduçãoO hipoclorito de sódio é a substância química auxiliar do tratamento endodôntico mais utilizada devido à sua ação antimicrobiana e à sua capacidade de dissolver matéria orgânica.ObjetivoO objetivo do presente estudo foi comparar a velocidade de dissolução de fragmentos de tecido pulpar bovino em diferentes concentrações de hipoclorito de sódio.Material e métodoFragmentos de tecido pulpar bovino, com peso determinado, foram imersos em 20 mL de hipoclorito de sódio, em frascos de Becker colocados em uma incubadora/agitadora. Foram testadas as concentrações de 1%, 2,5% e 5%, com pH 11, a 36°C. As amostras foram avaliadas visualmente durante a agitação, com auxílio de lupa, até sua completa dissolução. A velocidade de dissolução de cada fragmento foi determinada em miligramas por minuto e a velocidade média de cada grupo, analisada pelos métodos estatísticos de Kruskal-Wallis e Dunn's Multiple.ResultadoHouve diferença estatisticamente significante entre a concentração de 1%, que apresentou a menor velocidade, e as demais.ConclusãoA velocidade de dissolução do hipoclorito de sódio, nas concentrações testadas, se torna mais rápida com o aumento da concentração.

Accuracy of Turbidimetric Limulus Amebocyte Lysate Assay for the Recovery of Endotoxin Interacted with Commonly Used Antimicrobial Agents of Endodontic Therapy

IntroductionThis study was conducted to investigate whether the interaction between the turbidimetric limulus amebocyte lysate (LAL) substrate for endotoxin measurement and the substances/antimicrobial agents used in endodontic therapy can lead to the inhibition/enhancement of endotoxin recovery. MethodsTen microliters of a suspension of Escherichia coli endotoxin (O55:B55) was inoculated and kept in contact for 1 hour with different substances categorized as follows: group 1: auxiliary chemical substances: 5.25% and 2.5% sodium hypochlorite solutions, 2% chlorhexidine (CHX) (gel and solution), 1% Natrosol gel (Drogal Chemicals and Pharmaceuticals Ltd, Piracicaba, SP, Brazil), 17% EDTA, 10% citric acid, 3% hydrogen peroxide, 5% sodium thiosulfate, and 0.5% Tween 80 associated with 0.07% soy lecithin (Drogal Chemicals and Pharmaceuticals Ltd) and group 2: intracanal medications: neomycin/polymyxin B/hydrocortisone (Otosporin; Glaxo Wellcome, Rio de Janeiro, RJ, Brazil); calcium hydroxide (Ca[OH]2); Ca(OH)2 + 2% CHX gel; Ca(OH)2 + 2% CHX gel + zinc oxide eugenol; Ca(OH)2 + camphorated paramonochlorophenol (Calen; S.S. White, Rio de Janeiro, RJ, Brazil); triple antibiotic paste; mineral trioxide aggregate (MTA); and iodoform. Positive and negative controls consisted of root canal hemorrhagic exudate and pyrogen-free sterile water, respectively. All samples were diluted up to a 10:4 dilution. Each dilution was individually examined by the turbidimetric LAL assay. Collected data were analyzed through performance characteristics of the LAL assay such as linearity, coefficient of variation percentage, and product positive control (PPC) values. ResultsCorrelation coefficient (≥0.980) and coefficient of variation percentage (<10%) of the standard curve in triplicate showed the tests' linearity. Spike recovery of auxiliary chemical substances achieved PPC values ranging from 50%–197%, showing no interferences with LAL substrate. Conversely, 3% hydrogen peroxide achieved product inhibition in which endotoxin values were underestimated even after the 10:4 dilutions. Regarding intracanal medicaments, neomycin/polymyxin B/hydrocortisone also inhibited endotoxin detection in all dilutions investigated (PPC values <50%). In contrast, Ca(OH)2 + 2% CHX gel + ZOE as well as triple antibiotic paste led to the enhancement of endotoxin detection in which endotoxin values could not be validated by the turbidimetric kinetic LAL assay (PPC value >200%). ConclusionsThe performance characteristics of the kinetic turbidimetric assay for endotoxin measurement, such as precision and reproducibility, are modulated by the interaction of the LAL substrate with the substances/antimicrobial agents used in endodontic therapy.

Effectiveness of different auxiliary chemical substances in the rapid disinfection of gutta-percha points - an in vitro study

Aim: to evaluate in vitro the effectiveness of different chemical auxiliary substances used to promote decontamination of gutta-percha cones contaminated with different microorganisms. Material and methods: The microorganisms tested were strains of Enterococcus faecalis, Candida albicans, and Staphylococcus aureus. The 72 gutta-percha points were divided into three groups of 24 points, which were individually transferred into three tubes containing 5 ml of each bacterial suspension for 1 hour. The 24 gutta-percha points of each bacterial strain were randomly distributed into six groups (n=4) based on chemical auxiliary substance and period of decontamination, as follow: G1 (distilled water; DW); G2 (2.5% sodium hypochlorite; NaOCl); G3 (2.5% calcium hypochlorite; Ca(OCl)2); G4 (2% chlorhexidine gel; CHX); G5 (QMix); and G6 (6.5% grape seed extract; GSE). There were four evaluation periods (30, 60, 90, and 120 seconds). After disinfecting, the gutta-percha points were transferred to tubes containing 450 µL of sterile saline solution, homogenised, and diluted. Aliquots of 100 µL of the solution and the dilutions were cultivated in duplicate on plates containing blood agar. This material was incubated for 48 hours at 37 oC. Next, the number of colony-forming units (CFU/mL) were counted. Results: Groups G2 (NaOCl), G3 (Ca(OCl)2), G4 (CHX), and G5 (QMix) showed no bacterial growth of tested microorganisms at all periods of observation, and were statistically different from all other groups (p<0.05). G6 (GSE) showed better antimicrobial activity (p<0.05) against Enterococcus faecalis, Candida albicansi, and Staphylococcus aureus when compared to G1 (DW). Conclusion: We determined that 2.5% sodium hypochlorite, 2.5% calcium hypochlorite, 2% chlorhexidine gel, and QMix can be used as effective agents to rapidly disinfect contaminated gutta-percha points after 30 seconds of use. Key-words: calcium hypochlorite, QMix, grape seed extract, Enterococcus faecalis, Candida albicans, Staphylococcus aureus.

Evaluation of postoperative pain after endodontic treatment with foraminal enlargement and obturation using two auxiliary chemical protocols

Aim This prospective randomized clinical study examined the influence of two different auxiliary chemical substances on postoperative pain in 301 single-visit endodontic treatments, with enlargement of the apical foramen and extrusion of cement into the periapical region. Material and method The two auxiliary chemicals used were 2% chlorhexidine (2% CHX gel; n = 145) and 5.25% sodium hypochlorite (5.25% NaOCl; n = 156). The incidence of postoperative pain and discomfort was assessed at 24 hours and expressed as percentages. The Fisher exact test and the Chi-square test were used to compare variation in postoperative pain. The variables analyzed were previous pain, pulp status, age, and number of root canals. Result In teeth with previous pain instrumented with 2% CHX gel, the incidence of postoperative pain was 22.22% (6/27) versus 11.11% (3/22) in teeth instrumented with 5.25% NaOCl. In teeth without previous pain instrumented with 2% CHX gel, the incidence of postoperative pain was 8.5% (6/118) versus 2.33% (3/129) in teeth instrumented with 5.25% NaOCl, with no statistically significant difference between the groups. Results showed that previous pain had a significant influence on postoperative status (p &lt; 0.001). After 24 hours postoperatively, 93.7% (282/301) of the teeth had no pain and 6.3% (19/301) had some level of pain, and used one or two doses of medication. Conclusion Based on the results, it can be concluded that the auxiliary chemical substances had no influence on postoperative pain.

In vitro antimicrobial and anti-endotoxin action of Zingiber Officinale as auxiliary chemical and medicament combined to calcium hydroxide and chlorhexidine

Objective. This study was conducted in vitro to compare the effectiveness of Zingiber Officinale as an auxiliary chemical substance followed by placement of different intra-canal medication in removing endotoxins and cultivable micro-organisms from infected root canals. Materials and methods. Seventy-two root canals were contaminated with Enterococcus faecalis, Candida albicans and Escherichia coli for 28 days. After, the teeth were instrumented using Zingiber Officinale and divided into six groups according to the intra-canal medication: chlorhexidine gel; calcium hydroxide + chlorhexidine gel; glycolic ginger extract; calcium hydroxide + glycolic ginger extract; calcium hydroxide + saline solution and saline solution (control). Sample collections were performed after root canal contamination (Baseline; S1), after instrumentation (S2), 7 days after instrumentation (S3), after 14 days with intra-canal medication (S4) and 7 days after removal of intra-canal medication (S5). The results were analyzed by the Kruskal-Wallis and Dunn tests. Results. It was observed that in S2 and S3 there was significant reduction of the micro-organisms and the quantity of endotoxins after instrumentation. In samples S4 and S5 there was complete elimination of micro-organisms and significant reduction of endotoxins. Conclusion. It was concluded that Zingiber Officinale as an auxiliary chemical substance was effective on the micro-organisms tested, yet was unable to eliminate the endotoxins. Similarly, the intra-canal medication were effective on micro-organisms, yet did not completely eliminate the endotoxins.

Response of E. faecalis biofilms to different associations of auxiliary substances during root canal preparation: A confocal laser microscopy analysis

This in vitro study evaluated the effect of different endodontic auxiliary chemical substances over Enterococcus faecalis (Ef) biofilm through confocal laser scanning microscopy (CLSM). Forty-five bovine incisors were infected with Ef for 21 days. Teeth were divided into five groups: group 1: 2.5% NaOCl + EDTA, group 2: 2% CHX gel + EDTA, group 3: 2% CHX liquid + EDTA, group 4: 2.5% NaOCl + 2% CHX gel + EDTA, group 5: 2.5% NaOCl + 2% CHX liquid + EDTA and a negative and a positive control group (NCG; PCG). The samples were stained with SYTO9 and propidium iodide and analyzed by CLSM. Bacterial viability was quantitatively analyzed by the proportions of dead and live bacteria in the biofilm remnants. Scores were standardized according to the total bacterial load (TBL)-1: ≤ 25%, 2: >25 ≤ 50%, 3: >50 ≤ 75%, 4: >75% and debris-1: absence of debris; 2: presence of debris. Statistical analysis was carried out through the Kruskal-Wallis and the Fischer exact tests (P = 0.05). No statistical differences were observed to CFU, debris and bacterial viability. None of the tested substances could completely eliminate Ef from the root canal space.

Effects of Reducing Agents on Birefringence Dentin Collagen after Use of Different Endodontic Auxiliary Chemical Substances

Introduction The aim of this study was to evaluate the effect of 10% ascorbic acid or 10% sodium ascorbate on organic matrix collagen of bovine dentin root canal walls after irrigation with 5.25% sodium hypochlorite (NaOCl), 17% ethylenediaminetetraacetic acid (EDTA), or 0.9% sodium chloride. Methods Eighty bovine incisors were randomly divided into 8 groups (n = 10): group 1, 0.9% sodium chloride (control); group 2, 5.25% NaOCl + 17% EDTA (NaOCl + EDTA); group 3, 5.25% NaOCl + 17% EDTA + 10% ascorbic acid (NaOCl + EDTA + AA); group 4, 5.25% NaOCl + 17% EDTA + 10% sodium ascorbate (NaOCl + EDTA + SA); group 5, 5.25% NaOCl (NaOCl); group 6, 17% EDTA; group 7, 10% ascorbic acid (AA); and group 8, 10% sodium ascorbate (SA). Teeth were chemomechanically prepared, submitted to histologic processing, and stained with Sirius Red dye to be analyzed under polarized light microscopy. Absorbance assay was also performed to confirm the loss of collagen. Results NaOCl + EDTA and NaOCl groups presented a significantly different birefringence pattern compared with the control group ( P < .05). The measurement of the optical retardations of NaOCl + EDTA + SA indicated that this group was not statistically different from the control group. Although the measurement of the optical retardations of NaOCl + EDTA + AA was statistically different from the control group, the results were significantly higher than for NaOCl + EDTA. The birefringence of EDTA, AA, and SA groups was not statistically different from that of control group. The absorbance assay of NaOCl + EDTA and NaOCl groups confirmed the loss of collagen ( P < .05). Conclusions It is possible to conclude that 5.25% NaOCl, whether associated or not with 17% EDTA, causes birefringence alterations and loss of dentin collagen. These alterations reduced the ability of Sirius Red to bind with collagen fiber molecules. The reductions in the optical retardation values could be reversed by the application of either 10% ascorbic acid or 10% sodium ascorbate after 5.25% sodium hypochlorite and 17% EDTA irrigation.

In vitro evaluation of the action of irrigating solutions associated with intracanal medications on Escherichia coli and its endotoxin in root canals

ObjectiveThe purpose of this study was to evaluate the efficacy of auxiliary chemical substances and intracanal medications on Escherichia coli and its endotoxin in root canals.Material and MethodsTeeth were contaminated with a suspension of E. coli for 14 days and divided into 3 groups according to the auxiliary chemical substance used: G1) 2.5% sodium hypochlorite (NaOCl); G2) 2% chlorhexidine gel (CLX); G3) pyrogen-free solution. After, these groups were subdivided according to the intracanal medication (ICM): A) Calcium hydroxide paste (Calen®), B) polymyxin B, and C) Calcium hydroxide paste+2% CLX gel. For the control group (G4), pyrogen-free saline solution was used without application of intracanal medication. Samples of the root canal content were collected immediately after biomechanical preparation (BMP), at 7 days after BMP, after 14 days of intracanal medication activity, and 7 days after removal of intracanal medication. The following aspects were evaluated for all collections: a) antimicrobial activity; b) quantification of endotoxin by the Limulus Amebocyte Lysate test (LAL). Results were analyzed by the Kruskal-Wallis and Dunn’s tests at 5% significance level.ResultsThe 2.5% NaOCl and CLX were able to eliminate E. coli from root canal lumen and reduced the amount of endotoxin compared to saline.ConclusionsIt was concluded that 2.5% NaOCl and CLX were effective in eliminating E. coli. Only the studied intracanal medications were to reduce the amount of endotoxin present in the root canals, regardless of the irrigant used.

Mineral trioxide aggregate as an apical plug in infected immature teeth: a case series

PURPOSE: The purpose of this article is to present three clinical cases of infected immature teeth that were treated by using mineral trioxide aggregate (MTA) as an apical plug. CASES DESCRIPTION: All cases underwent premature interruption of root development as consequence of pulp necrosis. Root canals were instrumented by using chlorhexidine gel 2% (CHX) as auxiliary chemical substance. A paste of calcium hydroxide and CHX was kept for one week as intracanal dressing. In a second appointment, the apical portion of the canals (3-4 mm) was filled with MTA. The remaining portions of the root canals were then obturated by the thermomechanical technique by utilizing gutta-percha condensers and a zinc oxide and eugenol-based root canal sealer. Follow-up periods at both 6 months and 1 year showed radiographic favorable response and absence of symptoms. CONCLUSION: MTA seems to be nowadays, an interesting option of treatment for cases of immature teeth with the advantage of shorter treatment approaches.

Structural Analysis of Bovine Root Dentin after Use of Different Endodontics Auxiliary Chemical Substances

Introduction The use of chemical substances in endodontics during chemical-mechanical preparation may alter the structure of dentin, mainly collagen, which contributes considerably to the mechanical properties of this structure. This study evaluated the effect of different auxiliary chemical substances during endodontic treatment in root canal walls by implementing polarized light microscopy (PLM) and scanning electron microscopy (SEM). Methods Sixty bovine incisors were randomly divided into six groups ( n = 10): G1, 5.25% NaOCl + 17% EDTA; G2, 2% chlorhexidine (CHX) gel; G3, 5.25% NaOCl; G4, 17% EDTA; G5, 2% CHX + 17% EDTA; and G6, 0.9% sodium chloride solution (control). Teeth were chemomechanically prepared and fractured into two fragments. One fragment was used for PLM, and the other was used for SEM analysis. Results Groups treated with 5.25% NaOCl, whether associated or not associated to 17% EDTA, presented a significantly different birefringence pattern compared with the control group. The results revealed that groups irrigated with 2% CHX and EDTA, independently or combined, did not present any significant differences compared with the control group. SEM analysis showed structural alterations of the root canal inorganic matrix for all groups that used 17% EDTA. Conclusions It is possible to conclude that 5.25% NaOCl, whether associated or not associated with 17% EDTA, causes alterations in the dentin collagen. The obtained SEM images revealed demineralization areas for groups that used 17% EDTA alone or associated with other substances.

Smear Layer Removal by Auxiliary Chemical Substances in Biomechanical Preparation: A Scanning Electron Microscope Study

The aim of this study was to assess, by scanning electron microscopy analysis, the cleaning ability of irrigants and auxiliary chemical substances in biomechanical preparation. Thirty-two single-rooted human teeth were subjected to standardized root canal instrumentation with different irrigants (n = 8): group 1, 2.5% NaOCl + 17% ethylenediaminetetraacetic acid (EDTA); group 2, 2% chlorhexidine gel + 17% EDTA; group 3, Canal Plus + 2.5% NaOCl; group 4, saline + 17% EDTA. After instrumentation, the teeth were prepared for scanning electron microscopy analysis (2000×) to evaluate the cleaning of cervical, middle, and apical thirds. The area analyzed was quantified according to the percentage of open tubules, and data were statistically analyzed by analysis of variance and Tukey tests (P = .05). The results showed statistically significant difference with higher quantity of open tubules in groups 1 and 3. In all groups, the cleaning obtained on the cervical third was better than that obtained on the middle and apical thirds, with statistically significant difference in the chlorhexidine group. Irrigation with Canal Plus in combination with NaOCl and NaOCl followed by EDTA produced greater cleaning of the root canal walls.

Comparative analysis of endodontic pathogens using checkerboard hybridization in relation to culture

The purpose of this study was to detect bacterial species and to quantify the total number of bacteria from samples of infected root canals before (S1) and after chemo-mechanical preparation using 2% chlorhexidine (CHX) gel as auxiliary chemical substance (S2) and after 7 days of intracanal dressing (S3) to compare microbial changes. Twenty-four teeth were selected for this study. Chemo-mechanical preparation was performed using 2% CHX gel, then three different intracanal medicaments [M1: Ca(OH)(2) paste; M2: 2% CHX gel; and M3: Ca(OH)(2) paste plus 2% CHX gel] were used for 7 days. Checkerboard DNA-DNA hybridization was performed to detect 40 bacterial species. Aerobic and anaerobic culture techniques were used to determine the bacterial community by counting the colony-forming units (CFU). The species most frequently identified by checkerboard in S1 were: Fusobacterium nucleatum ssp. polymorphum, Treponema socranskii ssp. socranskii, Parvimonas micra and Enterococcus faecalis. In S2 and S3 a total of eight different species were identified; and only one of them was gram-positive (E. faecalis). Microorganisms were not identified after use of M2 for 7 days. The quantification obtained on agar plates ranged from 4 x 10(5) to 2.6 x 10(6) CFU/ml in S1, mean CFU was reduced by 99.96% in S2, and there was no statistical difference between the CFU in S2 and S3. The antibacterial effect of the mechanical preparation supplemented by the use of an antibacterial auxiliary substance greatly reduced the microorganisms in the main root canal.