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Objective: The objective of this study was to evaluate the microbiological profile of root canals indicated for endodontic retreatment due to secondary endodontic infections evidenced by the presence of chronic apical periodontitis (G1) or for prosthetic reasons, without clinical and radiographic signs of endodontic reinfection (G2). Methods: Microbiological samples were collected from thirty teeth (N=30) out of which 15 were indicated for retreatment due to the presence of chronic apical periodontitis (G1) and 15 were indicated exclusively for prosthetic reasons (G2). Samples were collected from root canals before (S1), after chemomechanical preparation (S2), and after 30 days of intracanal medication composed of calcium hydroxide and 2% chlorhexidine gel (S3). The molecular analysis was performed using Nested-PCR for the detection of 17 bacterial species. The efficacy of each stage of the retreatment in reducing the microbial load was verified by counting colony-forming units (CFU). The statistical analysis considered a significance level of 5%. Results: The results showed that bacteria were detected in 100% of the cases in S1, in both groups, by Nested PCR. The most frequently found species in S1 in both groups were Enterococcus faecalis, Fusobacterium nucleatum, Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Parvimonas micra. The microbial load of G1 was higher than G2 in the initial samples (S1). Endodontic retreatment was effective in reducing the microbial load in G1 and G2. Statistically significant associations were found between specific bacteria and clinical signs and symptoms. Conclusion: It was concluded that the microbial community present in the root canal of teeth indicated for endodontic retreatment is mixed and heterogeneous. G1 and G2 differ in the number of species per case and microbial load. Clinical relevance: Endodontic retreatment was effective in reducing the microbial load. Statistically significant associations were found between specific bacteria and clinical signs and symptoms. [ABSTRACT FROM AUTHOR]

Objective: To characterize the microbiota of teeth with endodontic treatment failure by 16S ribosomal RNA genetic sequencing (GS) and PCR at the different phases of the endodontic retreatment and to associate the presence of specific bacteria with clinical and radiographic features in teeth with apical periodontitis. Materials and methods: Twenty infected root canals of single-rooted teeth were selected. Samples were collected with sterile paper points before chemo-mechanical preparation (CMP) (S1), after CMP (S2) and after 30 days of intracanal medication (ICM) (S3). Microbial identification was performed using GS and PCR. Tukey-Kramer post hoc test and post hoc ANOVA were used for intergroup analysis. Paired t test and repeated-measures ANOVA were applied for intragroup analysis, at a significance level of 5%. Results: A total of 89 strains were identified using GS. Sixty-five strains were recovered in S1 and 15 strains in S2, and 9 strains remained in S3. Enterococcus faecalis was the most predominant bacteria. Gram-positive cocci bacteria predominated. Gram-negative species were also detected. Using species-specific PCR primers to detect seven species, the most prevalent ones at all the phases of the endodontic retreatment were E. faecalis and Porphyromonas gingivalis. However, Parvimonas micra and P. gingivalis were associated with previous pain, P. gingivalis was associated with tenderness to percussion and E. faecalis, Fusobacterium nucleatum and P. gingivalis were associated with periapical lesion > 3 mm. Conclusions: In conclusion, the microbiota of persistent infection is polymicrobial with predominance of E. faecalis and P. gingivalis in all phases of the endodontic retreatment, regardless of the method used for microbial identification. Associations were found between specific bacteria and clinical/radiographic features. Clinical relevance: The characterization of the bacteria present at all phases of the endodontic retreatment is important for the monitoring of the effectiveness of the techniques used and to better understand the susceptibility of these species to the disinfection agent used during the procedures. [ABSTRACT FROM AUTHOR]

The use of regenrative endodontics is restoring the health status of the root canals of retreated mature teeth is a novel approach. Therefore, the current trial aimed to compare the effectiveness of regenerative endodontic procedures (REPs) to non-surgical root canal retreatment (NS-RCR) in reducing periapical radiolucency over one year for the retreatment of mature incisors with periapical periodontitis. The secondary purpose was to assess clinical success and regain pulp sensibility. A parallel randomized controlled trial, 66 mature incisors with periapical radiolucencies were randomly divided into two equal groups and retreated with either REPs or NS-RCR. At baseline and after 6 and 12 months, teeth were assessed clinically and radiographically using a periapical index (PAI). The Mann–Whitney test was used to analyze nonparametric PAI scores. The Electric pulp test readings were analyzed using the repeated measure analysis of variance (ANOVA). Over the follow-up intervals, there was no significant intergroup difference in the PAI medians, the majority of the teeth displayed a reduction in periapical radiolucency. At the end of the follow-up period, the clinical successes for the REP and NS-RCR groups were 93.9% and 97%, respectively (p = 0.555). Positive pulp sensibility was recorded in 54.54% of cases in the REPs after 12 months. Both approaches showed a comparable diminishing of periapical radiolucencies and equivalent clinical results. A conventional, non-surgical endodontic retreatment may not always be necessary. [ABSTRACT FROM AUTHOR]

Aim: The objective of this study was to evaluate the presence of microorganisms in the root canals (RC) of teeth submitted to endodontic retreatment due to prosthetic reasons and without evidence of apical periodontitis. Material and methods: Twenty teeth referred to endodontic retreatment due to prosthetic reasons and without evidence of apical periodontitis were included in this study. Gutta-percha (GP) was collected from each third of the RC. After GP removal, microbial samples were also collected from the full extension of RC using paper points and files. The samples were cultivated in Fastidious Anaerobe Agar and the colony-forming units (CFU/mL) were counted. They were also semi-quantitatively analyzed by checkerboard DNA–DNA hybridization using 40 DNA bacterial probes. Results: Microorganisms were found in all samples. The coronal third of GP was more contaminated than the apical third (p ≤ 0.05). There was prevalence of Enterococcus hirae and Enterococcus faecalis in all RC thirds and also in the samples collected from the full extension of RCs. Conclusion: Microorganisms were found in all cases referred to endodontic retreatment due to prosthetic reasons and without evidence of apical periodontitis. Enterococcus was the genus most frequently detected. Clinical significance: An endodontic retreatment should be considered before replacing a prosthesis. [ABSTRACT FROM AUTHOR]

Data sources: The systematic review utilised multiple electronic databases to gather relevant literature, including PubMed, Scopus, EMBASE, Web of Science, and Medline. The search was conducted focusing on clinical studies where Enterococcus strains were isolated to assess their antimicrobial resistance. The search strategy was designed based on the PICO model, targeting patients with secondary/persistent endodontic infections (SPEI) and evaluating the resistance profiles of Enterococci to systemic antibiotics. Study selection: A total of 584 studies were initially identified through database searches. After removing duplicates, 517 studies were excluded based on title and abstract screening, leading to the final inclusion of 11 clinical trials that met the eligibility criteria. The studies were conducted in various countries, including Brazil, Lithuania, Poland, Germany, Sweden, the United States, and Japan. The focus was on permanent teeth with post-treatment apical periodontitis undergoing endodontic retreatment. Data extraction and synthesis: Data extraction was performed independently by two reviewers, who compiled details such as authorship, year of publication, country of study, sample groups, bacterial strains tested, antibiotics used, and resistance outcomes. The risk of bias was assessed using the ROB-2 platform, and all studies were considered to have a low risk of bias, with occasional minor deficiencies noted. The analysis revealed fluctuating resistance profiles of Enterococcus faecalis (E. faecalis) and Enterococcus faecium (E. faecium) to various antibiotics over time. Results: E. faecalis isolated from teeth with SPEI showed intermediate resistance to 16 antibiotics. The most effective antibiotics identified were the combination of amoxicillin and clavulanate, followed by amoxicillin and benzylpenicillin. In patients with penicillin allergies, moxifloxacin and azithromycin were suggested as alternatives, albeit with caution due to their varying resistance levels. The antibiotics demonstrating the highest resistance patterns against E. faecalis included clindamycin, gentamicin, metronidazole, and rifampicin, which are contraindicated in SPEI cases. Conclusions: Ongoing monitoring of antibiotic resistance patterns is crucial for effective endodontic treatment protocols. The emergence of resistance among Enterococci, particularly E. faecalis, necessitates regular susceptibility testing to inform clinical decisions and improve treatment outcomes. The findings underscore the need for health professionals to stay informed about the evolving resistance landscape to ensure safe and effective therapeutic regimens in endodontics. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the study is to evaluate the results of apical surgery (AS) in patients receiving high-dose antiresorptive medication (HDAR). Methods: Retrospective descriptive quality control study conducted in an Oral and Maxillofacial Department at a University Hospital. Fourteen patients on HDAR met the inclusion criteria. Only descriptive statistics were applied. Results: Fourteen patients had operation on seventeen teeth. Mean HDAR treatment period before apical surgery: 25 months (SD, ± 24.27; range, 1–78 months). Drug holiday during surgery and initial healing: mean, 8 months (SD, ± 5.96; range, 0.4–22 months). Sixteen out of seventeen teeth healed clinically and showed complete or ongoing radiographic healing. All patients except one became free of symptoms. Mean follow-up: 13 months (SD, ± 9.05; range, 2–31 months). Radiographic healing according to Molven and Rud: 7, complete; 6, uncertain; 1, unsatisfactory. Three patients died during follow-up and were considered drop-outs. Conclusions: The present case series suggest that apical surgery is a valid treatment option for apical periodontitis in patients on HDAR, where orthograde endodontic retreatment is not possible. None of the patients developed medication-related osteonecrosis of the jaw. Further studies in larger study groups and with longer follow-up periods are needed. The regional scientific ethical committee provided a document exemption, registration date 20 November 2013, and the local data protection agency approved handling of the recorded data (No. 2012-41-0045), registration date 11 January 2012. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the clinical relevance of using the XP-endo Finisher as a supplementary tool to improve the success of root canal treatment of posterior teeth with apical periodontitis, as assessed by 1-year follow-up. Methods: A randomized clinical trial was conducted with 92 posterior teeth with apical periodontitis. Root canal treatment was performed using a single reciprocating file, with or without the supplementary use of the XP-endo Finisher. The status of apical periodontitis was assessed using the periapical index (PAI) at baseline and 1 year follow-up. Changes on PAI indicated that the lesions were healed, healing, or not healed. Successful treatments were defined as healed or healing lesions without clinical symptoms. Chi-square analysis and logistic regression were used for data analysis (α = 0.05). Results: There was no significant difference in the distribution of healing status between the XP-endo Finisher group and the control group (p = 0.690). The success rates were also similar, with 81% in the XP-endo Finisher group and 78% in the control group. However, gender had a significant impact on success rates, with higher rates observed in females. Conclusions: The use of the XP-endo Finisher file as a supplementary tool did not affect the success rate of root canal treatment in posterior teeth with apical periodontitis. The findings indicate that the XP-endo Finisher file has limited clinical relevance in improving treatment outcomes for root canal treatment in posterior teeth with apical periodontitis. Clinical trial registration: The study protocol was registered in the Brazilian Clinical Trials Registry under identification number RBR-76w7cj (June 19, 2018). [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to identify disease-related markers in persistent apical periodontitis (PAP) biopsies and examine whether these were associated with comorbidities like rheumatoid arthritis (RA) and cardiovascular diseases (CVD). Materials and method: The levels of the cytokines/chemokines GM-CSF, IFN-γ, IL-2, IL-6, IL-9, IL-10, IL-13, IL-15, IL-17E/IL-25, IL-21, IL-23, IL-27, IL-28A/IFN -λ2, IL-33, MIP-3α/CCL20, and TNF-α were determined in lesions from patients with PAP (n = 20) and compared to healthy bone samples (n = 20). Results: We identified eleven cytokines to be differently expressed, and among them, IL-2, IL-6, IL-17E, IL-21, and IL-27 appeared to drive the discrepancy between the disease and healthy groups. The levels of T follicular helper (Tfh) cell promoting cytokines (IL-21, IL-6, IL-27) were enhanced while T helper (Th) 1 cell promoting cytokine (IL-2), Th2 cell promoting cytokine (IL-13), and Th17 cell promoting cytokine (IL-17E) were reduced in the PAP group. The data also indicate that Tfh cell differentiation (IL-21), along with Th1 (GM-CSF, IFNγ), Th2 (IL-13), and Th17 (GM-CSF) cell differentiation, might be increased in the subpopulation of patients suffering from RA, whereas no differences were found in patients with CVD. Conclusions: Levels of cytokines/chemokines in PAP were identified, and cluster analyzes indicated that these markers may be associated with the differentiation of different T cell populations. Patients with PAP and RA comorbidities showed elevated levels of markers reinforcing this association. Clinical relevance: Molecular analyses of PAP may result in identification of prognostic markers. [ABSTRACT FROM AUTHOR]

Objective: This study evaluated the effect of the supplementary use of the XP-endo Finisher on postoperative endodontic pain. Methods: This study was a randomized clinical trial with a parallel design. Ninety-two posterior teeth with necrotic pulps and apical periodontitis were instrumented with a single file (Reciproc) in a reciprocating movement followed or not (control) by additional instrumentation with XP-endo Finisher. Postoperative pain was assessed 24 h, 48 h, 72 h, and 7 days after the endodontic treatment (single session) using a universal pain assessment tool. The pain level was scored as absent, mild, moderate, or severe. The occurrence of sealer extrusion and flare-up was also recorded. Data on postoperative pain were analyzed through chi-square analysis, and the odds ratio was adjusted using a logistic regression model (α = 0.05). Results: Similar levels and risks of postoperative pain were observed for both interventions, regardless of the assessment time. Approximately half of the participants presented any postoperative pain in the first 24 h after the endodontic treatment, and this occurrence reduced by less than 20% after 72 h. The extrusion of root filling material was observed in 36% of cases, and no participant presented flared-up. Conclusions: The supplementary use of the XP-endo Finisher file did not affect the incidence or level of postoperative pain reported after the endodontic treatment of posterior teeth with periapical lesions. Clinical relevance: The supplementary use of the XP-endo Finisher did not affect postoperative pain following the endodontic treatment of posterior teeth using a single-file reciprocating system. Clinical trial registration: The study protocol was registered in the Brazilian Clinical Trials Registry under identification number RBR-76w7cj (June 19, 2018). [ABSTRACT FROM AUTHOR]

Background: Apical periodontitis as an endodontic diagnosis has attracted attention for the close relationship between the periodontal nature and the endodontic nature that this pathology represents. The appearance of pathology in periodontal tissues, but originating from the infected canal of the affected tooth, is caused by the passage of pulpal infection–inflammation products only between the apical foramen toward the periodontal tissues positioned at the exit of the tooth canal. Depending on the morphology of the canal, it can be one inflamed area, or several that form a whole, if the pulp has terminal branches, like "river delta," in its apical exit. The study aims to evaluate the clinical significance whether to treat or not with antibiotics of apical periodontitis. This study aims to look at this pathology from the perspective of the articles already published in the literature and after processing the conclusions of all the articles, come up with current recommendations on the treatment or not with antibiotics of the clinical cases presented with the pathology of the apical periodontium. Results: The classification of apical periodontitis occurs depending on the clinical signs visible with radiographs and the objective and subjective complaints of the patient. Regardless of subclassifications of apical periodontitis, the cause is bacteria or symbiosis of bacteria causing pulpitis, so as in any bacterial infection there is a tendency to treat them with antibiotics locally rather than in a systemic way, as long as the infection does not cause systemic symptoms such as fever, or massive swelling of the affected area. Short conclusion: From the analysis of the collected information, it is clear that the trend for treatment of apical periodontitis in the future does not lie in the application of antibiotics, but rather in irrigation solutions or the use of devices for the purpose of disinfecting the canal affected by the pathology. However, in no case is it indicated to eliminate the mechanochemical canal cleaning protocol before applying any type of treatment methodology. [ABSTRACT FROM AUTHOR]

The purpose of this study is to assess the laser effect in root canal disinfection and periapical healing of endodontically treated teeth from patients with asymptomatic apical periodontitis. This study was performed as a randomized clinical trial. Thirty patients were selected according to the inclusion/exclusion criteria. Fifteen patients received the root canal retreatment (RCR) combined with 980-nm diode laser irradiation (LI). The canals were irrigated with saline solution and gently dried with paper points, keeping the dentin partially moist. The irradiation was performed using a 320-µm-diameter fiber in helicoidal movements (pulsed mode, power output of 1.5 W, 100 Hz for 20 s). The other 15 patients received the RCR with placebo irradiation (PI). Microbiological samples were taken in three periods: S1, after the filling material removal (baseline); S2, after laser or placebo irradiation (LI or PI); and S3, after the RCR followed by laser or placebo. The samples were submitted to the total microbial and E. faecalis counting. The periapical radiographic healing was analyzed after 3, 6, 9, and 12 months. Microbiological data (CFU/mg) were analyzed by ANOVA and Tukey’s test (P < 0.05), and the repair by Mann–Whitney test (P < 0.05). In S2, the laser provided 42.44% microbial reduction and 53.14% of E. faecalis, different from the placebo that had no reduction, and 4.85% for Enterococcus (P < 0.05). In S3, the bacterial counts decreased without differences between groups. No differences in healing were found at 3 months. However, diode laser facilitated the repair from 3- to 12-month follow-up (P < 0.05) and had 45% more healed cases than placebo. Diode laser provided an antimicrobial effect before the biomechanical preparation but was not synergistic in RCR. It improved the periapical healing during follow-up. [ABSTRACT FROM AUTHOR]

Objective: Porphyromonas (P.) species (spp.) are a major etiological agent of apical periodontitis (AP), which in turn represents a risk factor for cardiovascular diseases. This study explored the associations between endodontic infection with Porphyromonas species, the systemic bacterial burden, and cardiovascular risk, based on high-sensitivity C-reactive protein (hsCRP), in young adults with AP. Materials and methods: Cross-sectional study. Otherwise, healthy individuals with AP and controls (n = 80, ≤ 40 years) were recruited at the University Dental Clinic. Oral parameters and classic cardiovascular risk factors were registered. Endodontic Porphyromonas endodontalis and Porphyromonas gingivalis were identified using conventional PCR. Serum concentrations of anti-P. endodontalis and anti-P. gingivalis antibodies, and endotoxins were determined through ELISA and Limulus-amebocyte assays. Serum hsCRP was determined for cardiovascular risk stratification. Results: Intracanal detection of P. endodontalis and P. gingivalis in AP were 33.3% and 22.9%, respectively. Serum anti-P. endodontalis and anti-P. gingivalis IgG was higher in AP than controls (p < 0.05 and p = 0.057, respectively). Intracanal P. endodontalis associated with higher endotoxemia (p < 0.05). Among endodontic factors, the presence (OR 4.2–5.5, p < 0.05) and the number of apical lesions (OR 2.3, p < 0.05) associated with moderate-severe cardiovascular risk, whereas anti-P. endodontalis IgG were protective (OR 0.3, p > 0.05). Conclusions: AP and infection with P. endodontalis positively associated with cardiovascular risk based on hsCRP levels and endotoxemia, respectively, whereas anti-P. endodontalis IgG response seems to be protective against low-grade systemic inflammation. Clinical relevance: Apical periodontitis and endodontic P. endodontalis can influence the systemic burden with impact on the surrogate cardiovascular risk marker hsCRP, providing mechanistic links. [ABSTRACT FROM AUTHOR]

Objectives: This randomized, controlled, pilot study assessed the outcome of non-surgical primary/secondary root canal treatments either with a novel bioactive sealer and the single-cone technique or with gutta-percha, zinc oxide-eugenol sealer (ZOE), and warm vertical compaction. Materials and methods: Sixty-nine patients were randomly divided into two groups that were treated using the single-cone technique with BioRootTM RCS (Septodont) (BIO group) or warm vertical compaction with gutta-percha and ZOE sealer (PCS group). Two subsamples (BIOAP and PCSAP) comprised the cases with apical periodontitis. Treatment was undertaken by four residents using a standardized instrumentation and disinfection protocol. The periapical index (PAI) was recorded, and clinical and radiographic follow-up performed at 1, 3, 6, and 12 months. Treatment success was assessed according to "periapical healing" and "tooth survival". The test for the equality of proportions, t tests for the equality of means, and non-parametric K-sample tests for the equality of medians were applied when appropriate. Results: The survival rate was similar in the BIO and PCS (p = 0.4074) and the BIOAP and PCSAP groups (p = 0.9114). The success rate was higher in the BIO groups, but not statistically significant (p = 0.0735). In both BIOAP and PCSAP groups, a progressive decrease in the PAI was observed. Conclusion: At 12 months, both techniques showed reliable results. Further studies and longer follow-ups are needed. Clinical relevance: This study documents the feasibility of using a bioactive sealer in conjunction with the single-cone technique to obturate the root canal and obtaining a predictable outcome. Trial registration: ClinicalTrials.gov Identifie: NCT04249206 [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the prevalence of missed canals in endodontically treated maxillary molars through cone-beam computed tomography (CBCT) images and to verify their association with the presence of periapical lesions. Material and methods: Three oral radiologists evaluated 633 maxillary molars in CBCT exams regarding number of roots, number of root canals, number of missed canals, anatomic identification of missed canals, presence of periapical lesions, and root location of the periapical lesions. Data were statistically analyzed at a 5% significance level. Results: Descriptive statistical analysis showed that among 395 first molars, 218 had at least one missed canal, and 186 (46.5%) had a missed canal and periapical lesion simultaneously. Of these, 72.4% (134) of the missed canals were only mesiobuccal 2 (MB2). Among 238 s molars evaluated, 121 presented at least one missed canal, and 104 (43.6%) had a missed canal and periapical lesion simultaneously. Of these, 81.7% (85) of the missed canals were only MB2. The chi-squared test showed an association between the presence of missed canals and periapical lesions for 1st and 2nd maxillary molars. Teeth that presented a missed canal showed an odds ratio (OR) of 2.57 (p < 0.0001) of being associated with a periapical lesion. Missed canal occurrence was positively related to the number of root canals (z = 13.06, p < 0.0001), meaning when the number of root canals is higher, there is a higher probability of missed canal occurrence. According to the model calculated prediction, for a one-unit increase in the number of canals, the probability of missed canals increases by 4.22%. Conclusions: It was concluded that MB2 was the most frequently missed canal, associated with the presence of periapical lesions in endodontically treated maxillary molars. Clinical relevance: Professionals' negligence of anatomical root variations has been contributed to the high prevalence of missed canals, leading to failures in endodontic treatment. Their association with periapical lesion occurrence emphasizes the importance of correct detection and instrumentation of these canals. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of several clinical factors on the success and survival rates of multiple-visit non-surgical root canal (NSRC) retreatment. Failed endodontically treated 236 teeth in 161 patients (18–72 years, 48% males; and 52% females) were retreated between March 2014 and December 2015 and were enrolled in this study. Two calibrated examiners evaluated the preoperative, intraoperative, and postoperative outcomes using the periapical index (PAI) scores. The teeth were classified as healed (healthy apical tissues, PAI ≤ 2, no signs or symptoms), healing (no signs and symptoms, PAI > 2 but reduced from the initial PAI score), and not-healed (presence of apical periodontitis, signs and/or symptoms, PAI > 2). The teeth scored as healed and healing was considered to be successful, while the not-healed ones were considered as failures. Of the 236 teeth, 135 (57.3%) in 103 patients (63.9%) were lost to follow-up, yielding to follow-up of 101 teeth (42.7%) in 58 patients (36%). Three teeth were extracted yielding to an overall success rate of 85.1%, at a mean observation time of 33.8 months. The teeth with periapical lesions < 5 mm had an 88.6% success rate, while those ≥ 5 mm had an 80% success rate (P > 0.05). While, age, gender, preoperative, intraoperative, and postoperative factors did not significantly affect the outcomes (P > 0.05), tooth type significantly affected the success rate (P < 0.05). The most frequently failed teeth were the mandibular first molars (P < 0.05). Based on these results, the multiple-visit NSRC retreatment exhibited a favorable success rate and could be offered for the endodontically failed teeth. [ABSTRACT FROM AUTHOR]

Objective: 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. Materials and methods: 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 30 days 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). Results: 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 30 days 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. Conclusions: 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. Clinical relevance: 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 30 days of a calcium hydroxide-based ICM. [ABSTRACT FROM AUTHOR]