Postoperative pain after removal of gutta-percha from root canals in endodontic retreatment using rotary or reciprocating instruments: a prospective clinical study.

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.

Comparative Long-term Study of a Large Series of Patients with Invasive Ductal Carcinoma and Invasive Lobular Carcinoma. Loco-Regional Recurrence, Metastasis, and Survival.

Our aim was to compare histologic and immunohistochemical features, surgical treatment and clinical course, including disease recurrence, distant metastases, and mortality between patients with invasive ductal carcinoma (IDC) or invasive lobular carcinoma (ILC). We included 1,745 patients operated for 1,789 breast tumors, with 1,639 IDC (1,600 patients) and 145 patients with ILC and 150 breast tumors. The median follow-up was 76 months. ILC was significantly more likely to be associated with a favorable phenotype. Prevalence of contralateral breast cancer was slightly higher for ILC patients than for IDC patients (4.0% versus 3.2%; p = n.s). ILC was more likely multifocal, estrogen receptor positive, Human Epidermal Growth Factor Receptor-2 (HER2) negative, and with lower proliferative index compared to IDC. Considering conservative surgery, ILC patients required more frequently re-excision and/or mastectomy. Prevalence of stage IIB and III stages were significantly more frequent in ILC patients than in IDC patients (37.4% versus 25.3%, p = 0.006). Positive nodes were significantly more frequent in the ILC patients (44.6% versus 37.0%, p = 0.04). After adjustment for tumor size and nodal status, frequencies of recurrence/metastasis, disease-free and specific survival were similar among patients with IDC and patients with ILC. In conclusion, women with ILC do not have worse clinical outcomes than their counterparts with IDC. Management decisions should be based on individual patient and tumor biologic characteristics rather than on lobular versus ductal histology.

Guided Autotransplantation of an Immature Premolar to the Maxillary Incisor Region with Immediate Restoration of Esthetics: A Case Report.

This case report describes the treatment of two maxillary central incisors following a traumatic injury with tooth #8 developing replacement resorption and #9 developing inflammatory root resorption. A 10-year-old girl presented complaining of pain in her maxillary central incisors. Upon clinical examination, teeth #8 and #9 were tender to percussion and palpation of the buccal soft tissues. Thermal and electrical pulpal sensitivity tests for teeth #8 and #9 were negative. An intraoral periapical radiograph revealed resorptive defects in tooth #8, which were filled with bone-like tissue, while tooth #9 had radiolucent resorptive defects along the root surface and a periapical radiolucency. A diagnosis of replacement resorption was made for tooth #8 and external inflammatory root resorption for tooth #9. Tooth #8 was treated with a multidisciplinary approach utilizing a guided template for premolar autotransplantation with an immediate veneer restoration, while tooth #9 was managed with root canal treatment using a tricalcium silicate cement to fill the canal. At the 1, 4, 8, 12, and 24-month follow-ups, the patient remained asymptomatic, and there was no radiographic evidence of root or periapical pathosis on either tooth. The root-end of the donor tooth transplanted to the #8 site continued to develop. This case report highlights successful interdisciplinary management of two forms of root resorption using modern treatment strategies that provided immediate function and esthetics to the maxillary central incisors in a young patient following trauma.

Optical impressions assessment for overlay restorations with rubber dam: A clinical trial.

OBJECTIVE: The possibility of making impressions of teeth prepared with a rubber dam in place has been proposed; however, this requires trimming and rescanning the mesh, which has been described as a cause of accuracy loss. This study aims to clinically determine whether overlay restorations obtained from a scan with a rubber dam in place have equivalent marginal fit, contact points, and occlusal fit to the same type of restorations obtained from a scan without a rubber dam. MATERIAL AND METHODS: Thirty patients who underwent overlay restoration of a molar with at least one neighbouring tooth were selected. After tooth preparation, two scans were performed: one without a rubber dam and the other with a rubber dam. Restorations were randomly created from one scan or another. The marginal fit, interproximal contact points, and occlusal fit were evaluated clinically. Two meshes, with and without rubber dams, were also compared. RESULTS: No significant differences were observed in the clinical evaluation of the overlays made of the two meshes. The trueness of the mesh from the impression made with a rubber dam with respect to the mesh without a rubber dam was about 40 µm in the critical areas of the preparation (margins, intaglio, and interproximal contact points). CONCLUSIONS: The results of this study show that under the conditions performed and with the equipment used, there are no significant clinical differences between overlay restorations made from a scan with a rubber dam and those made from a scan without a rubber dam. CLINICAL SIGNIFICANCE: Scanning with a rubber dam in place may be a valid option for certain types of restorations under certain clinical conditions.

Strict versus Liberal Use of Sentinel Node Biopsy in Breast Cancer Surgery: Any Clinical Outcome Differences? A 20-Year Clinical Experience.

Introduction: As applied to early breast cancer (BC) patients, sentinel node biopsy (SNB) has undergone major changes over the years, especially concerning the widening of indication criteria or skipping systematic axillary lymph node dissection (ALND) after a positive SN. We aimed to ascertain whether a strict versus a more liberal use of SNB resulted in different clinical outcomes in our clinical experience. Methods: We studied consecutive BC patients undergoing SNB between January 1, 2000, and March 31, 2020. There were 1,587 patients and 1,634 SNB procedures. Cases were divided into two study groups: the "strict" SNB group (unifocal tumors up to 35 mm in which ALND was always performed for a positive SN, amounting to 1,183 SNBs), and the "liberal" SNB group (extended tumor size up to selected T3 cases, as well as multifocal or bilateral disease, and patients with previous contralateral BC, not always followed by ALND after a positive SN, amounting to 451 SNBs). Patients were closely followed up to the end of the study. Results: Clinico-pathological variables were strikingly different between study groups, with the liberal group showing a higher risk profile. Cox regression analysis for disease recurrence did not show significant differences in axillary, lymph node, or locoregional recurrence rates or distant relapse. There were no differences in survival between groups. Conclusion: It seems reasonable to adopt the liberal SNB approach, as the goal of surgical management in early BC patients must be attaining optimal locoregional disease control, no matter the differences in distant metastatic spread rates across different BC risk profiles.

Differential survival and recurrence patterns of patients operated for breast cancer according to the new immunohistochemical classification: analytical survey from 1997 to 2012.

Breast cancer can no longer be considered only one condition. It should be regarded rather as a heterogeneous group of diseases with different molecular outlines. The aim of this study is to establish a correlation between immunohistochemical tumor sub-typing and surgical treatment, local recurrence rates, distant metastases, and cancer-specific mortality at 5 and 10 years. At least, four tumor sub-types have been described, which were associated with variable risk factors, different natural clinical course, and different response to both local and systemic therapies. For Luminal A: ER + and/or PR + HER2- Ki67 <15 %; Luminal B: ER + and/or PR + HER2- Ki67 ≥ 15 %; Pure HER2: ER-PR-HER2+; Triple Negative: ER-PR-HER2-. One thousand four hundred seventy-seven patients operated for 1,511 invasive breast tumors were included. Disease-free survival, overall mortality, and breast cancer-specific mortality at 5 and 10 years were calculated. Distant metastases prevalence ranged from 8 to 28 % across sub-types, increasing stepwise from Luminal A, Luminal B, and pure HER2 through triple negative. Conversely, larger tumors with significant axillary burden were more likely to belong to HER2 or triple negative groups. Luminal A sub-type patients showed significantly lower mortality rates both overall and specific at 5 and 10 years, as compared to the rest. Luminal B patients showed lower mortality rates only when compared with triple negative patients. Simple classification of breast cancer patients based on immunohistochemistry and other risk factors is quite useful to establish groups with bad or even worse prognosis. Although results from immunohistochemical classification were not taken into account for surgical procedure decision-making, we found that pure HER2 and triple negative patients received nevertheless higher rates of radical treatment.

Accuracy of CAD-CAM Surgically Guided Tooth Autotransplantation Using Guided Templates and Custom-designed Osteotomes in Human Cadaver Mandibles.

INTRODUCTION: A major challenge in dentistry is the replacement of teeth lost prematurely due to trauma, caries, or malformations; especially in growing patients. The aim of this study was to assess the accuracy of CAD-CAM surgically guided tooth autotransplantation in cryopreserved cadaver mandibles using guided templates and custom-designed osteotomes. METHODS: Cryopreserved human cadaver heads were digitized and scanned using an intraoral optical scanner and a large-volume cone beam computed tomography device. First, virtual surgical planning was performed to create a 3D tooth replica, 2 surgical guides, and a custom-made osteotome for each single-rooted tooth autotransplantation procedure/case. Surgical sockets were created in the selected mandibles using guided tooling consisting of an initial guided osteotomy with implant burs and a final guided osteotomy using custom osteotomes. After tooth autotransplantation, second large-volume cone beam computed tomography images of the 5 cadaver mandibles were obtained. The discrepancy in mm within the 3D space (apical and mesiodistal deviations) between the final position of the autotransplanted teeth and their digitally planned 3D initial position was calculated and analyzed statistically (P < .05). RESULTS: All donor teeth were placed without incident within their newly created sockets in the real mandibles. The mean difference between the digitally planned root apex position and the final tooth position was 2.46 ± 1.25 mm. The mesiodistal deviation of the autotransplanted teeth was 1.63 ± 0.96 mm. CONCLUSIONS: The autotransplantation of single-rooted teeth with custom-designed and 3D-printed surgical tooling provided promising results. The technique was able to create surgically prepared sockets that could accommodate transplanted teeth in mandibles.

Successful Root Canal Treatment of an Atypical Mandibular Canine with a Boomerang-shaped Root and Canal System with a Large Periapical lesion-A Case Report with 9-year Follow-up.

AIM: This report describes an atypical mandibular canine with a single boomerang-shaped root and root canal system with a large periapical lesion managed by root canal treatment. METHODS: The chief complaint of a 16-year-old male was acute pain and an abnormal sensation in the right mandibular canine (tooth #27). The clinical examination revealed that tooth #27 had an unusual coronal morphology. The buccal aspect of the tooth resembled that of a normal canine but was significantly broader than expected. On the lingual aspect of the crown; however, there was an unusual cusp-like structure with ridges that was slightly less prominent than the buccal incisal tip. The intraoral periapical radiographs revealed a complex root with an obvious cow horn-shaped canal mesially and distally, but with the suggestion of a root structure joining the mesial and distal extensions. A large periapical lesion was present. Computed tomography revealed the presence of a single root and canal system shaped like a boomerang. Root canal treatment was performed and the patient was followed-up for 9 years. RESULTS: Following root canal treatment, the patient had no symptoms, no mobility, no periodontal pockets, or root resorption. At 9 years, the cone beam computed tomography images confirmed that satisfactory healing of the periapical tissues had occurred. CONCLUSION: The mandibular right canine had a unique boomerang-shaped root and canal system. Effective shaping and cleaning of the complex canal shape plus thermoplastic root filling aided the successful healing of the periapical lesion.

COVID-19 Incidence and Mortality in Patients Operated on for Breast Cancer. Comparison with the General Population.

BACKGROUND: Breast Cancer (BC) remains the most diagnosed malignancy and the most common cause of cancer-related mortality in women worldwide. Covid-19 mortality in BC patients has been linked to comorbid conditions rather than to cancer treatment itself, although this was not confirmed by a meta-analysis. Also, during Covid-19 outbreaks, a great deal of health care resources is reassigned to critical Covid-19 patients. PATIENTS AND METHODS: During 5 consecutive trimesters (from 1/12/2020 to 31/3/2021) 2511 BC patients older than 20 years from our institution were surveyed. 1043 of them had received a Covid test and these made our study group, which was conveniently compared with the Covid-19 tested background feminine Catalan population. RESULTS: 13.1% of our patients presented with a positive Covid-19 test, whereas confirmed COVID-19 infection amounted to 7.1% of the feminine Catalan tested population. The COVID-19-specific mortality rate was 11.7% (16/137) in the study group, which compares with a 4.7% rate for the overall population. Most deaths occurred in patients over 70. CONCLUSION: Three clinical factors were significantly associated with Covid-19 mortality in BC, namely lack of hormone therapy, distant metastases, and BC dwelling in nursing homes. BC patients are at a higher risk of Covid-19 infection and mortality in comparison with the reference group without BC.

Influence of Cone-beam Computed Tomography in Clinical Decision-making among Different Specialists in External Cervical Resorption Lesions: A Before-After Study.

INTRODUCTION: Inadequate management of external cervical resorption (ECR) lesions may impact the treatment outcome. This study aimed to ascertain the influence of cone-beam computed tomography (CBCT) in clinical decision-making choices in cases of ECR among dentistry specialists (endodontics, prosthodontics, oral surgery, periodontics orthodontics, and general dentistry). A secondary objective was to evaluate the self-reported level of difficulty in choosing a treatment plan before and after viewing the CBCT images. METHODS: Sixty examiners from different specialties were chosen to evaluate 12 cases of ECR lesions. Each case included clinical photographs, digital periapical radiographs, and a small-volume CBCT scan. In the first assessment, the examiners were given all the relevant information of each case, except the CBCT scan. Each examiner was asked to select 1 of the proposed treatment options and assess the difficulty of decision-making. Four weeks later, the examiners randomly reviewed the same 12 cases with additional information from the CBCT data. RESULTS: After the CBCT evaluation, the clinicians changed their treatment plan in 72.2% of the cases (P < .05). The self-reported level of difficulty in choosing a treatment changed in all groups after evaluating the CBCT scans (P < .05). After viewing the CBCT scan, the extraction option increased significantly in all groups (P < .05). CONCLUSIONS: CBCT scan had a significant impact on clinical decision-making in cases of ECR evaluated by different specialists.

Clinico-pathologic factors associated with the occurrence of early and late metastatic spread in a cohort of breast cancer patients.

BACKGROUND AND OBJECTIVE: Distant metastatic spread in breast cancer patients is a complex phenomenon involving several prognostic factors. We focused our analysis on early metastatic breast cancer (EMBC) (occurring during the first 36 months) versus late metastatic breast cancer (LMBC) (occurring beyond 3 years) in order to ascertain their possible differential predictive factors. METHODS: diagnostic, surgical, and follow-up data were assessed for consecutive patients with breast cancer undergoing surgery between 1997 and 2019. We analysed the predictive factors for distant metastasis using both univariate and multivariate analysis. RESULTS: The median follow-up for this cohort of 2708 patients was 89 months. The median metastasis-free interval (FMI) for metastasis patients was 38 months (17 months for EMBC group and 76 months for LMBC group). Distant metastases developed in 12.9% (350/2708); 48% (168/350) of them as EMBC and 52% (182/350) as LMBC. Loco-regional recurrence and nodal extracapsular extension were the only common predictors for both. CONCLUSIONS: EMBC and LMBC appeared as two separate conditions, with a different outcome. In the EMBC group, tumour proliferation related factors were significant (histological grade, tumour size, body mass index), whereas for LMBC, other slow-acting factors seemed to be involved (screening program, tumour burden, bilateral tumour).

Cone-beam Computed Tomographic Analysis to Detect the Association between Primary and Secondary Endodontic Infections and Mucosal Thickness of Maxillary Sinus.

INTRODUCTION: This retrospective study used cone-beam computed tomographic (CBCT) imaging to evaluate the differences in the mucosal thickness of the Schneiderian membrane in primary and secondary endodontic lesions. METHODS: A total of 121 CBCT scans were analyzed. Clinical features such as sex, age, size and volume of the periapical lesion, dimension of the bone, morphology, and relationship between the roots and the mucosal thickness were recorded and analyzed in primary and secondary endodontic lesions in CBCT sagittal and coronal planes. Data were analyzed using the chi-square test, the Mann-Whitney U test, and multiple logistic regression (P < .05). RESULTS: Statistical analysis revealed no significant differences in membrane thickness between the primary and secondary lesions in the sagittal and coronal planes (P = .08 and .06). Differences between age groups were statistically significant in both groups (P < .05). The volume of the periapical lesions of the secondary endodontic lesions were statistically greater than that of the primary lesions (P < .05). Mucosal thickness prevalence increased when the volume of the lesion was greater, and the bone dimension was narrower in maxillary second premolars and first and second molars. Teeth with 2 or more affected roots were directly related to increased sinus mucosa thickening. CONCLUSIONS: CBCT images showed no differences in mucosal thickening between primary and secondary endodontic lesions.

Outcome and Survival of Endodontically Treated Cracked Posterior Permanent Teeth: A Systematic Review and Meta-analysis.

INTRODUCTION: The aim of the present systematic review and meta-analysis was to evaluate the success and survival rate of endodontically treated cracked posterior teeth and to assess the preoperative factors that affect teeth survival. METHODS: The study protocol was registered on the PROSPERO international prospective database of systematic reviews (CRD42019119091). Electronic search was performed for studies up to November 30, 2018 in the following databases: PubMed, Scopus, and Cochrane. All searches were done following the PRISMA guidelines. Clinical studies evaluating the success and/or the survival rate of cracked teeth that were endodontically treated with at least 1-year follow-up were selected. The Newcastle-Ottawa scale was used to evaluate risk assessment. Publication bias was evaluated with funnel plots, and the Egger's test was performed to test asymmetry. RESULTS: From the 410 studies identified through the initial search, 7 studies qualified for the final analysis, all of which were longitudinal cohort studies. The results of the meta-analysis indicated a survival rate of 88% (confidence interval, 0.81-0.94) and a success rate of 82% (confidence interval, 0.78-0.86) after 1 year of follow-up. The presence of a periodontal pocket associated to a crack (relative risk, 1.11) resulted in a higher risk of tooth loss. Patient sex, tooth type, position, the number of cracks present, and preoperative pulp status did not affect treatment survival rate (P > .05). Most of the included studies did not have an accurate record of many variables that could affect the tooth survival. Plus, studies did not present extended follow-up periods or an adequate dropout rate to properly assess treatment outcome and survival. CONCLUSIONS: According to the results of the present systematic review and meta-analysis, root canal treatment in cracked posterior teeth can be considered a suitable treatment option. The presence of an associated periodontal pocket results in a lower survival rate.

Development of Periapical Lesions in Endodontically Treated Teeth with and without Periodontal Involvement: A Retrospective Cohort Study.

INTRODUCTION: The purpose of this study was to investigate the incidence of apical periodontitis (AP) in endodontically treated teeth with and without periodontal involvement. METHODS: The records of 602 patients with 775 root canal-treated teeth were initially examined. Only teeth with adequate root canal filling, adequate coronal restoration, and no AP (periapical index = 1) were selected for further investigation. A total of 194 teeth were included in this cohort study. Age, sex, history of diabetes mellitus, smoking, hypertension, and immunodeficiency disorders were recorded. Two groups were made according to the periodontal status of the patients. The control group included periodontally healthy patients and the periodontal group patients with periodontal disease receiving nonsurgical periodontal treatment. After an observation period of at least 2 years, the incidence of AP was scored using the periapical index. The relationship between patients' variables and AP was conducted using the Cohen kappa test, the chi-square test, odds ratio (OR), and logistic regression analysis. RESULTS: Newly emerged AP was found in 14% of periodontally involved teeth and in 3% of nonperiodontal involved teeth (P < .05, OR = 5.19, 95% confidence interval). The periodontal condition and hypertension were the only significant factors associated with the presence of AP in the follow-up after univariate logistic regression. Adjusting for hypertension, multivariate logistic regressions showed that periodontal status remained significant (OR = 5.25, 95% CI, P < .05). CONCLUSIONS: The risk of developing AP in endodontically treated teeth is 5.19 times higher for patients with periodontal disease compared with patients without periodontal disease.

Comparison of postoperative pain after root canal treatment using reciprocating instruments based on operator's experience: A prospective clinical study.

BACKGROUND: The aim of the present study was to compare clinically the incidence of postoperative pain after endodontic treatment using the Reciproc System, taking into account the operator's experience. MATERIAL AND METHODS: One hundred patients scheduled for routine endodontic treatment were enrolled in this study. Endodontic treatment was carried out in a single visit by undergraduate and postgraduate students. The chemomechanical preparation of root canals was performed with Reciproc instruments. Pretreatment and postoperative pain was recorded using a visual analogue scale (VAS). Postoperative pain and the need for analgesic consumption were assessed at 4, 8, 16, 24, 48 and 72 hours post-treatment. The data were analyzed using the Mann-Whitney U and Chi-Square test, and the significance was set at P<0.05. RESULTS: The mean value of pain after root canal treatment was 1.13±1.94 and 1.91±2.07 on a VAS between 0 and 10 in treatments performed by undergraduate and postgraduate students, respectively. There was a significant difference in the incidence of postoperative pain between the two groups (P<0.05). CONCLUSIONS: The prevalence of postoperative pain was high in the treatments performed by postgraduate students in comparison with undergraduate students. This suggests that operator experience has an influence on the prevalence of postoperative pain after root canal treatment. Key words:Post-endodontic pain, root canal treatment, reciprocating systems, Expert operators Inexperienced operators.

Danger zone analysis using cone beam computed tomography after apical enlargement with K3 and K3XF in a manikin model.

BACKGROUND: The objective of the study was to evaluate and compare how apical enlargement with K3 and K3XF nickel-titanium (NiTi) rotary instruments reduces the root thickness in the danger zone and affects canal transportation and centering ability in mandibular molar mesial canals in a manikin extracted tooth model. MATERIAL AND METHODS: Seventy-two mesial root canals of first mandibular molars were instrumented. Initial and post-instrumentation Cone Beam Computed Tomography scans were performed after root canal preparation up to size 25, 30, 35 and 40 files. Canal transportation, canal centering and remaining root dentin thickness toward the danger zone were calculated in sections 1, 2 and 3 mm under the furcation level. Data were analyzed using non-parametric Kruskal-Wallis analysis of variance at a significance level of P < 0.05. RESULTS: K3 instruments removed more dentin toward the danger zone compared with K3XF instruments (P< .05) and significant differences in dentin thickness were found when canal enlargement was performed to a #35-40 with both systems (P< 0.05). No significant differences in canal transportation and centering ability were found between systems, except when canal enlargement was performed to a #40 (P = 0,0136). No differences were observed when comparing the number of uses in both systems (P> 0.05). CONCLUSIONS: Under the conditions of this study K3 removed a significant amount of dentin at the furcation level compared with the R-Phase K3XF rotary system in curved root canals. Enlargement to a 35-40/04 file removed significantly more dentin with both systems. Key words:K3, K3XF, R-phase, center ability, canal transportation, dentin thickness, increased apical enlargement, danger zone, dentin thickness.

Effect of manual dynamic activation with citric acid solutions in smear layer removal: A scanning electron microscopic evaluation.

BACKGROUND/PURPOSE: Chelating agents have been used for the removal of the smear layer on teeth. However, due to inadequate volume and/or penetration of the solutions during irrigation, smear layer removal is less effective in the apical third. The purpose of this study was to compare the efficacy of three chelating solutions with and without manual dynamic irrigation in smear layer removal. MATERIALS AND METHODS: Sixty-six single-root canal teeth were decoronated, instrumented, and divided into six experimental groups (n = 10) and two control groups (n = 3). The groups received a final rinse with 1 mL of 17% EDTA and 5% or 10% citric acid (CA) for 1 minute, with or without manual dynamic activation, followed by a final 3-mL rinse with 4.2% NaOCl (5 minutes). The teeth were then longitudinally split and prepared for environmental scanning electron microscopy analysis. Digital images (500×) were taken for smear layer removal evaluation at 2 mm, 6 mm, and 10 mm from the working length. RESULTS: The most effective smear layer removal occurred with 5% and 10% CA combined with manual dynamic activation (Groups 7 and 8), where significant differences were observed when compared with the EDTA groups (Groups 2 and 6; P < 0.05). We found no significant differences between manual dynamic activation with 5% and 10% CA (Groups 7 and 8) in smear layer or debris removal (P > 0.05). CONCLUSION: Manual dynamic activation of CA improves smear layer removal, and a reduction in CA concentration to 5% does not compromise smear layer removal in comparison with higher concentrations.