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This study evaluated changes in the root canal length (RCL) and the accuracy of the electronic apex locator (EAL) during the different stages of endodontic treatment and retreatment. Fifty-six mesial root canals of mandibular molars were selected. The actual root canal length (AL) of the canals was obtained by inserting a size 15 hand file up to the apical foramen, under magnification. The electronic lengths were obtained at the "APEX" mark of Root ZX II, using an alginate model. Both measurements were performed at three different stages of the initial root canal treatment—unflared, flared, and concluded—and at two stages of retreatment, after achieving patency and repreparation. Data were statistically analyzed and the significance level established was 5%. All stages produced a significant reduction in the AL (p < 0.05). The greatest variation was observed between the unflared–flared stages (0.2 mm) and between concluded–patency stages (0.09 mm), with no difference between them (p > 0.05). The accuracy of Root ZX II was negatively affected after achieving patency, presenting statistically significant difference compared to the other stages (p < 0.05). A significant reduction in the RCL was observed along the different stages of endodontic treatment and retreatment. The EAL was accurate to measure the root canals in most stages, except after achieving patency for endodontic retreatment. Determining and monitoring the RCL is an essential step towards a favorable prognosis, since it reduced along the different stages evaluated. Root ZX II was not accurate for endodontic retreatment. [ABSTRACT FROM AUTHOR]

Objectives: To compare the efficacy of fiber post removal using conventional (CONV) versus guided endodontics (GE) in terms of dentin loss, residual resin material, procedural errors, and working time in vitro. Material and methods: Ninety human central incisors were root-filled and scanned by micro-computed tomography (CT), then restored with fiber posts and composite. Twenty-four sets of teeth with up to four human maxillary central incisors were fabricated and divided into three groups: conventional post removal by a general dentist (CG) or endodontology specialist (CS) and guided endodontics (GE) by a general dentist, yielding 30 teeth per operator and group. After treatment, the prepared access cavities were volumetrically assessed by micro-CT. Statistical significance was evaluated by one-way analysis of variance followed by post hoc comparisons with Tukey's HSD test and Pearson's chi-squared test for independence. Results: Both CONV and GE resulted in dentin loss and residual resin material. CS resulted in more dentin loss and less residual resin material than CG and GE (p <.05). All groups had some deviations from the original root canal but no perforations. The shortest working time was observed in the GE group. Conclusions: Compared to the conventional freehand technique, GE resulted in significantly less radicular dentin loss, a few deviations but no perforations. Clinical relevance: Guided endodontics can improve the speed and safety of fiber post removal without root perforation. [ABSTRACT FROM AUTHOR]

Objective: To assess apical root canal transportation using Mtwo or Reciproc during retreatment of severely curved canals, using a multi-analytical approach. Methods: Forty mesial canals from mandibular molars (Vertucci type IV) were evaluated before and after endodontic retreatment to compare apical transportation with Mtwo retreatment or Reciproc. The systems were used on the same root but alternating the mesial canals. The analyses were performed by micro-computed tomography. Four evaluations were performed: (a) longitudinal transportation, (b) horizontal transportation, (c) variation in the angle of curvature of the canal, and (d) canal-root width ratio. Horizontal transportation and canal-root width ratio were evaluated in 1-, 3-, and 5-mm levels. Results: Longitudinal transportation occurred in all samples, with a mean of 0.13 mm for Mtwo and 0.17 mm for Reciproc. Horizontal transportation increased as distant from the apex was the evaluated level, in mean. However, the transport was not observed in all samples. The mean angle of curvature was 4.16 for Mtwo and 3.03 for Reciproc. Canal-root width decreased as distant from the apex was the evaluated level. No significant differences were observed considering all tested variables, independently of the retreatment system or evaluated level (p > 0.05). Conclusion: Mtwo retreatment and Reciproc presented similar apical transportation (horizontal or vertical). Clinical relevance: Both Mtwo retreatment and Reciproc systems could be considered safe regarding apical transportation. [ABSTRACT FROM AUTHOR]

Objective: Confocal laser scanning microscopy (CLSM) was used to investigate the penetration of endodontic sealers into the dentinal tubules after retreatment using two different obturation techniques. Materials and methods: Thirty mandibular premolars were prepared up to instrument F3 (ProTaper Universal, Dentsply) and filled with Endofill using the single cone technique. The canals were retreated using Mtwo instruments. Reobturation was performed with the Bio-C sealer mixed with a fluorophore dye (Fluo-3) using either the lateral condensation technique (group LC) or the single cone technique (group SC) (n = 15). Teeth were sectioned 2, 4, and 6 mm from the apex and analyzed with CLSM to assess the penetration of the sealer into the canal perimeter and the maximum depth of penetration of the sealer into the dentinal tubules. Data were analyzed using ANOVA and the Student-t and Holm-Sidak tests. Results: In the apical segment, the penetrated perimeter was significantly higher in the LC group than in the SC group (p < 0.05); no significant difference was found in the middle and cervical segments (p > 0.05). In terms of penetration depth, no significant differences were found for any of the segments studied (p > 0.05). Conclusion: The LC technique promoted a higher percentage of canal circumference penetrated by the sealer than the SC technique in the apical segment after endodontic retreatment. Clinical relevance: CLSM demonstrated that the LC technique promoted a higher percentage of canal perimeter penetrated by the Bio-C sealer than the SC technique in the apical segment of mandibular premolars after retreatment. [ABSTRACT FROM AUTHOR]

Objective: The persistence of pathogenic microorganisms in root canals is the most common reason for the failure of root canal treatment and the necessity of a root filling treatment, which results in an uncertain prognosis due to technical complexity and the variety of highly adaptable microorganisms. This study evaluated the effect of passive ultrasonic irrigation (PUI) on the outcome of the microbial analysis of root canal-treated teeth with persistent or recurrent apical inflammation in vivo. Materials and methods: Sample collection was performed after root filling removal (sample S1, control group) and after PUI with NaCl (sample S2) using sterile paper points. In total, 19 samples were obtained. Quantification was performed by means of serial dilution of the samples. Subcultivated pure cultures were identified using MALDI-TOF MS complemented by the Vitek-2-System or PCR, followed by sequencing of the 16S rRNA gene. The results of the samples (S1 and S2) were evaluated regarding their bacterial count and composition. Results: The total count of bacteria and the number of aerobic/facultative anaerobic microorganisms significantly increased in the S2-samples after application of PUI. The number of obligate anaerobic microorganisms showed an increase after PUI, although it was not significant. We detected 12 different aerobic/facultative anaerobic microorganisms before PUI, and in 21 cases after PUI. Two different obligate anaerobic microorganisms were found in S1 samples compared to nine different species in S2 samples. Conclusions: PUI is a powerful method for detaching bacteria in infected root canals and enables a more precise analysis of the etiology of persistent endodontic infections. Clinical relevance: This study indicates that PUI exerts a positive cleansing effect and adds to the accessibility of microorganisms during the application of bactericidal rinsing solution in root canal treatments. [ABSTRACT FROM AUTHOR]

Objective: This clinical trial aimed to evaluate the effect of nano-silver and nano-calcium hydroxide intracanal medicaments (ICM) during retreatment regarding their antibacterial effect and their effect on post-operative pain and flare-ups. Materials and methods: Sixty-nine patients scheduled for endodontic retreatment were included in this randomized clinical trial and randomly allocated to 3 equal groups (n = 23) according to the type of ICM used. The first microbial sampling (S1) representing the original microbiota was obtained after the removal of the old canal filling. After chemo-mechanical debridement, another sample (S2) was obtained representing the microbial state before ICM application. Patients were randomly allocated to receive either nano-silver (nano-Ag), nano-calcium hydroxide (nano-CH), or calcium hydroxide (CH) as ICM. Patients rated their pain pre-operatively and then after 6, 12, 24, 48, and 72 h. During the second visit (7 days later), the last microbial sample (S3) was obtained after removal of the ICM. Reduction of total bacterial and total E. faecalis counts and the biofilm-forming capability of the existing microbiota were determined. Results: Results showed reduction in total bacterial count, total E. faecalis count and the biofilm-forming,capability of the existing microbiota after chemo-mechanical debridement (S1-S2) and after the application of ICM (S3-S2). However, the reduction after cleaning and shaping was significantly more pronounced (p < 0.001) compared to the effect of ICM application, with no difference between the 3 ICM (p > 0.05). Post-operative pain was significantly reduced at the 48- and 72-h intervals after the application of nano-Ag and nano-CH only (p < 0.001), with no significant difference between these two ICM (p > 0.05). The incidence of flare-ups in all groups was similar (p > 0.05). Conclusions: The antibacterial effect of the nano-Ag and nano-CH was equivalent to that of CH, but they contributed to better pain control. Clinical relevance. Nanoparticles may have a positive impact on post-endodontic pain. [ABSTRACT FROM AUTHOR]

Background: The aim of this systematic review and meta-analysis (SRM) was to assess the postoperative pain (PP) after non-surgical endodontic retreatment (NSER) in a one visit compared to multiple visits. The PICO question used was "Does NSER in patients with unsatisfactory endodontic treatment in a one-visit visit have a similar PP to that of NSER in multiple visits?" Materials and methods: This systematic review followed PRISMA and was registered in PROSPERO (CRD42019136700). Searches were performed in the PubMed/MEDLINE, Scopus, and the Cochrane Library databases for articles published until September 2020. The eligible criteria were randomized clinical trials (RCTs). The meta-analysis was based on the Mantel-Haenszel. The PP after the retreatment was analyzed using a dichotomous outcome, measured according to risk ratio (RR) when p < 0.05. The Cochrane scale was used to assess risk of bias, and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to assess the quality of evidence. Results: Four studies were included. In general analysis without considering intensity, one-visit NSER presented lower PP than the multiple visits only for 1 and 30 days [(RR = 0.67; CI: 0.48 to 0.93; p = 0.02), and (RR = 0.09; CI: 0.01 to 0.66; p = 0.02)], respectively. Regarding sub-analysis considering the intensity, one visit present lower mild PP when compared with multiple visits [(RR = 0.54; CI: 0.30, 0.96; p = 0.04); (RR = 0.33; CI: 0.12, 0.88; p = 0.03); and (RR = 0.12; CI: 0.02, 0.86; p = 0.03)], respectively. However, sub-analysis for moderate and severe PP showed no significant difference, independently of period evaluated (p > 0.05). Regarding the risk of bias analysis, a low risk was observed for most domains, except allocation that was considered unclear, while the certainty of evidence for each analysis was considered low. Conclusion: Within the limitations of study, the one and multiple visit can be considered adequate, because both present a similar occurrence of PP, except for mild pain. However, due to the low number of studies, further well conducted and standardized RCTs are needed to reassess these results. Clinical relevance: Both therapies of endodontic retreatment can be considered in clinical practice. Therefore, the endodontist must consider the patient's individual characteristics and experience to consider the best treatment approach. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this clinical study was to evaluate and compare the incidence and intensity of postoperative pain following removal of gutta-percha from root canals using rotary and reciprocating instruments.Materials and methods: One hundred and sixty patients scheduled for a non-surgical endodontic retreatment were included for evaluation. Preoperative pain was recorded with using a questionnaire with a 10-cm visual analogical scale (VAS). Endodontic filling material was removed with Reciproc (VDW, Munich, Germany) or ProFile (Dentsply Tulsa Dental Specialties, Tulsa, OK) instruments. Patients then recorded their postoperative pain in a VAS pain scale at 4, 8, 16, 24, 48, and 72 h post-treatment. Results were analyzed using the Mann-Whitney U, Kruskal-Wallis, and Chi-square tests. Multivariate logistic and a multiple regression analysis were used to detect the effect of confounding factors.Results: Results showed a direct relation between the intensity of pre-operative pain and that of postoperative pain (P < .05). No significant differences were observed between the two groups regarding postoperative pain (P > .05) as a qualitative variable. As numerical values, statistically significant differences were found regarding sex and the system used (P < .05).Conclusions: The method for pain evaluation was determinant in postoperative pain findings. Endodontic retreatment preparation with Reciproc results in lower values of postoperative pain compared with ProFile. Women are more susceptible to postoperative pain than are men.Clinical relevance: One of the most significant contributions of this research is the importance given to the method used for pain evaluation. The present study analyzed postoperative pain resulting from the use of reciprocating or continuous rotary instruments during removal of gutta-percha in retreatment procedures. [ABSTRACT FROM AUTHOR]

Introduction: This clinical study was conducted to compare the effectiveness of single-file reciprocating systems and rotary systems in removing endotoxins and cultivable bacteria in endodontic retreatment. Methods: Thirty endodontically treated teeth with post-treatment apical periodontitis were selected. The specimens were divided into three groups according to the system used: WaveOne ( n = 10), Reciproc instrument ( n = 10), and ProTaper Universal Retreatment system ( n = 10). Samples were collected before and after chemomechanical preparation. The irrigation was performed by using 2.5 % sodium hypochlorite. A chromogenic limulus amebocyte lysate assay test was used to quantify endotoxins. Culture techniques were used to determine bacterial colony-forming unit counts. Results: At baseline, endotoxins and cultivable bacteria were recovered from 100 % of the root canal samples in a median value of 5.84 EU/mL and 4.98 × 10 CFU/mL, respectively. After CMP, no differences were found in the median percentage values of endotoxin reduction achieved with reciprocating systems-WaveOne [94.11 %] and Reciproc [93.29 %] and with rotary systems-ProTaper [94.98 %] ( P > 0.05). Both single-file reciprocating systems [WaveOne (98.27 %) and Reciproc (99.54 %)] and rotary system [ProTaper (98.73 %)] were effective in reducing bacterial load ( P > 0.05). Moreover, no differences were found among the systems tested. Conclusions: The Reciproc and WaveOne reciprocating systems were as effective as the ProTaper system for removal of endotoxins and bacteria in endodontic retreatment. Clinical relevance: All systems tested were effective to remove cultivable bacteria and endotoxin in endodontic retreatment. As no differences among systems were observed, it is possible to suggest that clinicians should choose the preferred technique to perform endodontic. [ABSTRACT FROM AUTHOR]

Objectives: Vertical root fractures (VRFs) are a common cause of tooth loss. Little evidence exists though, relating the incidence of VRFs to the type of endodontic retreatment. This retrospective study aimed at evaluating the impact of conventional versus surgical endodontics on root canal-filled teeth with VRFs. Materials and methods: Over a period of 13 years, 200 endodontically retreated teeth from 192 patients with VRFs were extracted and further examined. VRFs were assessed in relation to age, gender, tooth group, clinical signs, extension on the root surface, patency, as well as type of endodontic retreatment and restoration. Statistical analysis was conducted using a Cox PH Model, Chi-squared, Wilcoxon rank-sum, and Log rank tests at a significance level of 5 %. Results: The majority of teeth with VRFs (62.31 %) had undergone the combination of conventional root canal retreatment and apical surgery. Women (64.06 %) presented VRFs more frequently than men (35.94 %) at the mean age of 51.1 and 55.1 years, respectively. Maxillary first (17.5 %) and second (16.5 %) premolars, restored by a resin-based material without a post (56.28 %) were more susceptible to VRFs. Apically initiated (84.1 %) VRFs could be diagnosed more easily on radiographs. Conclusions: The type of endodontic treatment strongly correlated with VRFs. The prevalence of VRFs in teeth having undergone both conventional and surgical endodontic retreatment could be attributed, among others, to additive dentin damage related to the aforementioned endodontic procedures. Clinical relevance: The possible involvement of endodontic retreatment in the multifactorial etiology of VRFs needs to be taken into consideration in clinical practice. [ABSTRACT FROM AUTHOR]

This study evaluated the incidence of postoperative pain after intracanal dressings with either 0.12% chlorhexidine digluconate gel (CHX) or a calcium hydroxide/camphorated paramonochlorophenol/glycerin paste (CH/CPMC). Overall, 138 asymptomatic teeth had their canals instrumented under irrigation with 2.5% NaOCl and then dressed with either CH/CPMC or CHX. The incidence of different intensity levels of postoperative pain was registered for the period between appointments. Data revealed that 84% of the total number of cases treated with either medicament showed absence of any level of pain. No case medicated with CH/CPMC and four cases (5.8%) medicated with CHX were categorized as flare-ups. There were no statistically significant differences between all possible comparisons involving the two medicaments in treatment/retreatment cases and teeth with/without apical periodontitis lesions. The low incidence of postoperative pain after the use of both medications, coupled to their antimicrobial effectiveness, gives support to using one or the other in routine treatment/retreatment. [ABSTRACT FROM AUTHOR]