Evaluation of various obturation techniques with bioceramic sealers in 3D-printed C-shaped canals.

This in vitro study compared various obturation techniques with bioceramic sealers for filling C-shaped 3D-printed replicas. A mandibular molar with a C-shaped root canal with a C1 configuration was obtained. After instrumenting with M3 Pro Gold files (United Dental, Shanghai, China) up to size #30/0.04, a CBCT scan of the tooth was taken. Sixty 3D-printed replicas of the tooth were created. The samples were obturated with EndoSeal TCS sealer (E. TCS; Maruchi, Wonju, Korea) or EndoSeal MTA (E. MTA; Maruchi, Wonju, Korea) (n = 30). The samples in each group were obturated with the following techniques (n = 10): (1) single-cone technique (SC), (2) SC with ultrasonic activation (UA), and (3) cold hydraulic compaction (CHC). Following incubation, the replicas' apical, middle, and coronal thirds were inspected under a digital microscope, and the proportion of filling material and void were calculated. Also, the obturation time and sealer extrusion were recorded. Data were analyzed using ANOVA, LSD post-hoc, and the chi-square tests (α = 0.05). The results indicated that in the apical third, E. TCS-SC, E. TCS-UA, and E. MTA-UA had the lowest void percentage among groups (p < 0.05). In the middle thirds, samples obturated with E. TCS-UA showed a significantly lower void percentage among all groups (p < 0.05). However, in the coronal third, E. TCS-CHC showed the least void percentage (p < 0.05), followed by E. TCS-UA and E. MTA-CHC. The E. TCS-SC and E. TCS-UA were the least time-consuming methods (p < 0.05). Sealer extrusion significantly differed among the groups, with E. MTA-UA and E. TCS-UA showing higher incidence (p = 0.019). It was concluded that E. TCS-UA was the most convenient obturation technique. However, care must be taken when obturating the canals with high flow and ultrasonic activation near the vital anatomical landmarks.

Ex vivo evaluation of the efficacy of depotphoresis method in root canal disinfection.

Background: Electrochemical disinfection of the root canal system (RCS) is introduced as an alternative to conventional irrigation. The aim of this study was to assess the efficacy of depotphoresis method in the disinfection of accessible and inaccessible RCSs. Materials and Methods: In this comparative in vitro study disinfection of Enterococcus faecalis-infected RCS using two methods, (1) depotphoresis and (2) sodium hypochlorite (NaOCl) irrigation plus passive ultrasonic agitation (PUA) took place on 40 extracted maxillary anterior teeth. Decoronation was done with a diamond disc, and the canals were instrumented. The roots were divided into two phases: the specimens with canal obstruction and the specimens without canal obstruction. The smear layer was removed, and the specimens were infected for 21 days with E. faecalis. After disinfection procedures, bacterial samples were taken using two sterile #35 paper points, and colony-forming units (CFU) were counted. Data were analyzed statistically using the Kruskal-Wallis test, with a significance level at P < 0.05, to indicate differences between depotphoresis and NaOCl plus PUA groups. Results: In both phases, Log CFU after depotphoresis treatment was significantly lower than NaOCl irrigation plus PUA treatment (P < 0.05). Conclusion: Treatment with depotphoresis was significantly more effective than NaOCl irrigation plus PUA treatment.

Investigation of the effect of hydrochloric acid with different concentrations on mineral trioxide aggregate plug and dentin.

Background: Mineral trioxide aggregate (MTA) becomes a hard mass after setting and making it difficult to remove and can cause significant problems in the retreatment process. The aim of this study was to evaluate the effect of different concentrations of hydrochloric acid (HCl) on MTA dissolution and its effect on dentin. Materials and Methods: In this in vitro study, 45 single-root premolars were selected. Artificially open apex was created in all samples with similar process. The samples were randomly divided into 4 experimental groups of 10, and a control group of 5. Four-millimeter thick apical plugs of Root MTA were placed in all samples in an orthograde manner. HCl was used at concentrations of 3.75%, 7.5%, 15%, and 22.5% (w/v) for the experimental groups and normal saline for the control group. Each sample was exposed to the desired solution for 15 min. Then, MTA retrieval and reaching the working length were attempted with k-file # 30. The times of each sample were recorded. Furthermore, after longitudinal incision of the roots with a disc, the dentin surfaces of canals were examined with a Dino-Lite microscope (×50). Results were analyzed by Shapiro-Wilk test and one-way analysis of variance tests. The level of significance P value was set at 0.05. Results: The lowest average time of reaching working length was observed with group 22.5% that was significantly lower than 15% and 7.5% concentrations (P = 0.005 and P = 0.011). Furthermore, by examining with ×50 of Dino-Lite microscope, no difference was observed on the canal walls. Conclusion: The optimum concentration of HCl was 7.5%. Furthermore, different concentrations of HCl had no significantly different effect on the dentinal canal wall using Dino-Lite microscope with ×50.

Evaluation of Jaw Osteonecrosis Following Intra-Ligament Anesthesia in Zoledronate-Treated Rats: a Histological Evaluation.

Statement of the Problem: One of the rare adverse effects in patients who take bisphosphonates is the osteonecrosis of the jaw in the oral cavity following any trauma such as tooth extraction. Purpose: The aim of this study is the histopathological evaluation of the jaw following intra-ligament anesthesia injection in Zoledronate-treated rats. Materials and Method: In this descriptive-experimental study, rats weighing 200-250 g were divided into 2 groups. The first group received a 0.6 mg/kg dose of zoledronate and the second group received normal saline. Five injections with a 28-day interval were performed. At the end of the injection, the animals were sacrificed. Then, five-micrometer histological slides were prepared from the first maxillary molars and the surrounding tissues. Hematoxylin and eosin staining was performed to evaluate osteonecrosis, infiltration of inflammatory cells, fibrosis, and root and bone resorption. Results: There was no difference between the macroscopic and clinical features in both groups and no evidence of osteonecrosis of the jaw was observed in the samples. From the histological point of view, all the samples had normal tissues and none of them showed any evidence of inflammation, tissue fibrosis, disorder, or pathological root resorption. Conclusion: According to the histological findings, the periodontal ligament space, the bone adjacent to the roots, and the dental pulp conditions were similar in both groups. Osteonecrosis of the jaw did not develop in the rats that took bisphosphonates after intraligamental injection.

The ameliorative role of ascorbic acid against blood disorder, immunosuppression, and oxidative damage of oxytetracycline in rainbow trout (Oncorhynchus mykiss).

This experiment was aimed to determine the possible beneficial effects of dietary ascorbic acid (AA) on hematological indices, immune responses, and antioxidative capacity of Oncorhynchus mykiss treated with antibiotic oxytetracycline (OTC). A total of 150 fish were divided evenly among five experimental groups (30 fish of each, in 3 replicates) receiving diets containing OTC (0 and 100 mg per kg fish weight) and AA (100, 200, 400, and 800 mg per kg fish diet) for 28 days. Treatments include group A or control (100 mg AA without OTC), group B (100 mg AA with OTC), group C (200 mg AA with OTC), group D (400 mg AA with OTC), and group E (800 mg AA with OTC). The results obtained showed that the hematological indices (red blood cells, white blood cells, hematocrit, hemoglobin, and neutrophils), immunological parameters (plasma lysozyme, plasma complement, and skin mucus alkaline phosphatase activities), and antioxidant enzymes activities (superoxide dismutase and catalase) were significantly decreased by OTC in O. mykiss fed control diet (P < 0.05). The results also revealed that OTC significantly increased the activity of biochemical enzymes (aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase) in the plasma of O. mykiss fed control diet (P < 0.05). However, in comparison to the control diet, feeding fish with higher amounts of AA (400 and 800 mg/kg diet) significantly restored the hematological, immunological, and antioxidative responses in OTC-treated groups (p < 0.05). These findings show that the dietary supplementation of AA at 400 or 800 mg/kg diet is beneficial in relieving O. mykiss from OTC-induced oxidative stress and immunosuppression.

Evaluation of the outcome of apexogenesis in traumatised anterior and carious posterior teeth using mineral trioxide aggregate: a 5-year retrospective study.

The purpose of this study was to evaluate the outcome of apexogenesis with mineral trioxide aggregate (MTA) in traumatised anterior and carious posterior teeth over 5 years. A comprehensive chart review was performed to obtain a retrospective of sequential previously completed cases with recalls. Clinical and radiographic data were collected for 97 vital immature teeth (40 traumatised anterior and 57 carious posterior teeth) pulpotomised (partial or full pulpotomy) using MTA with an average follow-up time of 5 years. Chi-squared test and Fisher's exact test were implemented to analyse data. The success rate in anterior teeth and posterior teeth was 82.5% and 96.4% respectively. Crown discolouration was observed in 25 (62.5%) anterior teeth. There was a significant difference between the number of successful and unsuccessful cases (P < 0.05) and there was no correlation between type of treatment and success/failure (P > 0.05). The success rate of apexogenesis using MTA in immature teeth was relatively high.

Treatment Outcomes of Permanent Immature Teeth with Crown Fracture: A Retrospective Cohort Study.

INTRODUCTION: Crown fractures are a common type of traumatic dental injury. Various factors may affect the outcome of crown fractures. This study aimed to evaluate the treatment outcomes of immature teeth with a crown fracture. METHODS: This retrospective cohort study included patients who presented to a dental trauma center from 2008-2018 with a history of a crown fracture of immature teeth and at least 6 months of follow-up. Outcomes of primary endodontic or restorative interventions as well as reinterventions were evaluated. Kaplan-Meier curves were used to compare the unadjusted differences in survival time. Logistic and Cox regression analyses were performed to identify potential predictors for complication and survival time, respectively. RESULTS: The success rates of the primary interventions for 99 teeth (72 patients) after a median follow-up of 22 months were as follows: cervical pulpotomy (90.4%), partial pulpotomy (85.2%), mineral trioxide aggregate apical barrier (80.0%), root canal treatment (66.6%), and only restoration (47.2%). Teeth that received vital pulp therapy were less prone to complications (adjusted hazard ratio = 0.21; 95% confidence interval, 0.09-0.53; P < .05), whereas those with concomitant luxation injuries were more susceptible to complications (adjusted odds ratio = 2.90; 95% confidence interval, 1.01-8.29; P < .05). CONCLUSIONS: Crown fractures had a relatively high favorable prognosis. Vital pulp therapy (partial or cervical pulpotomy) had the highest success rate, whereas cases that received only restoration had the lowest success rate. Teeth with concomitant luxation injuries had more odds and hazards of complications.

A review of resilience variables in the context of disasters.

The increasing impacts of disasters, caused by more frequent extreme events coupled with the growth of adverse anthropogenic activities, has raised the importance of fostering more resilient communities. Measuring resilience is a vital step in the process of building and strengthening a community's resilience as it helps with identifying the priorities and monitoring the progress. The objective of the current research is to catalog variables proposed in the literature as measures of households' resilience to disasters. Searching the literature through content analysis and applying three selection criteria resulted in a list of 149 variables. These criteria required the variables to be influential on disaster resilience of households, to be quantitatively measurable, and to be obtainable from publicly available data sources. Additionally, a selection of resilience and vulnerability assessment models suggested in the literature were reviewed to highlight the importance of resilience variables in addressing their planned objectives. The variables were classified into five categories titled demographic, socioeconomic, infrastructural, environmental, and institutional. Further analysis of the variables led to identification of the most prevalent variables and commonalities among the categories, aimed to provide a more integrated approach toward resilience planning. This research can serve as an initial yet relatively extensive inventory for selecting variables that are deemed to be influential on households' resilience to extreme events. Further, quantifying a community's resilience using resilience variables can help with identifying and prioritizing the resilience needs, monitoring the progress, and justifying the costs of resilience programs.

Inferior part of rectus abdominis muscle flap: A case report.

Background: Abdominoperineal resection (APR) is the standard surgical treatment for low-lying anorectal malignancies. It seems that immediate flap reconstruction has fewer complications compared to primary closure. There are several options for local flap reconstruction of perineal wound closure, and each specific flap method has its own advantages and disadvantages. Case presentation: In this case report, a new method of reconstruction is presented which contains only the inferior part of the rectus abdominis muscle in 2 patients, one with unilateral and the other with bilateral involvement and they both underwent APR. Both patients were referred to the colorectal surgery clinic for APR by an oncologist. Both patients had severe constipation and both reported pain on defecation and rectorrhagia. Patient 1 received a unilateral inferior part of rectus abdominis muscle flap and patient 2 received a bilateral flap. Conclusion: Immediate flap reconstruction after APR has fewer complications than primary closure and the inferior part of rectus abdominis muscle flap seems to be a possible means of reconstruction after APR.

Influence of Two Preparation Techniques on Transportation of Simulated Type II Root Canals.

INTRODUCTION: The purpose of this study was to evaluate the changes of canal configuration in simulated type II root canals that were instrumented by two different techniques using ProTaper Universal rotary files. METHODS AND MATERIALS: Sixty simulated type II root canal in resin blocks were made and randomly divided into two groups. Pre and post-instrumentation images of resin blocks were prepared using stereomicroscope from three surfaces of blocks included two longitudinal section (mesiodistally and buccolingually), and one cross sectional surface. In the first group (G1) the straight canal was instrumented to the working length and the other canal was instrumented up to the area of canals junction. In second group (G2) both canals were instrumented to working length. The superimposed pre and post instrumentation images were assessed by the Adobe Photoshop software. The degree of transportation, centering ability, perimeter, surface and aspetic ratio (AR) in cross section and longitudinal section at apex, 3 mm and 5 mm above the apex, were measured. SPSS software, t-test and Mann-Whitney test were used for statistics analysis. RESULT: In mesiodistal direction, canal transportation was more (P=0.024) only in junction point in G2 which both canals were instrumented to working length. Also, surface changes were more significant (P=0.02) in G2 in cross sectional direction. The other parameter and also apical transportation had not significant difference in two groups. CONCLUSION: According to the results of this study, it can be concluded that both two preparation methods of type II canals can be used by rotary instruments.

The effects of anxiety and external attentional focus on postural control in patients with Parkinson's disease.

BACKGROUND: Although anxiety is a common non-motor outcome of Parkinson's disease (PD) affecting 40% of patients, little attention has been paid so far to its effects on balance impairment and postural control. Improvement of postural control through focusing on the environment (i.e. external focus) has been reported, but the role of anxiety, as a confounding variable, remains unclear. OBJECTIVES: This study aimed to investigate the influence of anxiety and attentional focus instruction on the standing postural control of PD patients. METHODS: Thirty-four patients with PD (17 with high anxiety (HA-PD) and 17 with low anxiety (LA-PD)), as well as 17 gender- and age-matched healthy control subjects (HC) participated in the study. Postural control was evaluated using a combination of two levels of postural difficulty (standing on a rigid force plate surface with open eyes (RO) and standing on a foam surface with open eyes (FO)), as well as three attentional focus instructions (internal, external and no focus). RESULTS: Only the HA-PD group demonstrated significant postural control impairment as compared to the control, as indicated by significantly greater postural sway measures. Moreover, external focus significantly reduced postural sway in all participants especially during the FO condition. CONCLUSION: The results of the current study provide evidence that anxiety influences balance control and postural stability in patients with PD, particularly those with high levels of anxiety. The results also confirmed that external focus is a potential strategy that significantly improves the postural control of these patients. Further investigation of clinical applicability is warranted towards developing effective therapeutic and rehabilitative treatment plans.

Immunohistological Evaluation of Revascularized Immature Permanent Necrotic Teeth Treated by Platelet-Rich Plasma: An Animal Investigation.

OBJECTIVE: Pulp regeneration within the root canal of necrotic teeth is considered an ideal treatment to allow for continued root development and recover teeth vitality. This study aims to evaluate the inductive effect of platelet-rich plasma (PRP) on expression of angiogenesis factors and pulpal revascularization of immature necrotic teeth. MATERIALS AND METHODS: In this experimental animal study, we randomly divided 28 immature premolars from two mixed breed dogs into four groups, two experimental, negative and a positive control. Premolars in negative control group were left intact to develop normally. In the positive control and experimental groups, we removed the pulps and induced pulp necrosis, after which the chambers were sealed. Then, we applied the revascularization protocol in the experimental teeth located in the right quadrant. Two months later, the same protocol was applied to the left quadrant. The root canals were disinfected by irrigation with sodium hypochlorite (NaOCl) solution and application a triple antibiotic past. Following the induction of a blood clot (BC) inside the canal space, the coronal portion of the canals was assigned to either of two experimental groups: group 1 [BC+PRP+ mineral trioxide aggregate (MTA)], group 2 (BC+MTA). Access cavities were sealed with a Glass Ionomer. The jaws that held the teeth were processed for histologic analysis of newly formed tissue and immunohistochemical evaluation according to vascular endothelial growth factor (VEGF) and factor VIII expressions in the canals. RESULTS: Histological analysis demonstrated no significant difference in the formation of new vital tissue inside the root canals between groups1 (42.8%) and 2 (43.5%, P>0.05). Based on immunohistochemical evaluation, micro-vessel density (MVD) of the granulation tissues in both groups were similar and were higher compared with the normal pulp. We observed strongly positive expressions of VEGF and factor VIII in the stromal and endothelial cells, with severe intensity after one month. Both factors showed downregulation at three months postoperative. CONCLUSION: PRP could not increase the formation of new vital tissue. The immunohistochemical results showed that VEGF and factor VIII played a pivotal role in the formation of new vessels inside the root canals of immature, non-vital teeth.

Immunohistochemical Evaluation of Fibronectin and Tenascin Following Direct Pulp Capping with Mineral Trioxide Aggregate, Platelet-Rich Plasma and Propolis in Dogs' Teeth.

INTRODUCTION: The aim of the present study was to evaluate the expression of fibronectin (FN) and tenascin (TN) after direct pulp capping (DPC) in dogs' teeth with either mineral trioxide aggregate (MTA), Propolis or Platelet-rich plasma (PRP), by means of immunohistochemistry. METHODS AND MATERIALS: A total of 48 sound molars and premolars with mature apices from four dogs, were included. The teeth were randomly divided into 4 groups according to the material used for DPC: PRP, Propolis, MTA, and glass-ionomer (as the negative control group). Each group was divided into two 7-day and 30-day subgroups. The teeth were restored at the same session. The animals were sacrificed at the mentioned time intervals and the expression of FN and TN in each test group and between each time intervals was assessed with Wilcoxon and Mann-Whitney U tests, respectively. The Kruskal-Wallis test was used to compare FN and TN staining among the test groups. The significance level was set at 0.05. RESULTS: The amount of FN in the MTA group in the 30-day interval was significantly higher than the 7-day interval; however, there were no significant differences among the other groups. The amount of TN in the MTA and Propolis groups in the 30-day interval was significantly higher than that in the 7-day interval; no recognizable difference was observed in the other groups. Moreover, the difference in expression of FN and TN in the 7-day interval was not significant in the experimental groups. Nevertheless, the difference was significant in the 30-day interval, with the highest and lowest expressions belonging to the MTA and glass-ionomer groups, respectively. CONCLUSION: Based on the results of the present animal study, MTA is still a better choice for direct pulp capping.

Comparison of fluid filtration and bacterial leakage techniques for evaluation of microleakage in endodontics.

BACKGROUND: Apical leakage assessment is a way to compare the efficiency of a filling material to seal the apical region of the tooth. Many microleakage testing techniques have been introduced through the years, but there has been no agreement as to which technique gives the most accurate results. The aim of this study was to compare the accuracy of fluid filtration and bacterial leakage techniques in the assessment of the apical sealing ability of mineral trioxide aggregate (MTA) and calcium enriched mixture (CEM). MATERIALS AND METHODS: A sample of 34 extracted single-rooted human teeth were selected and prepared. The samples were divided in to 2 experimental groups. The apical 3 mm of each root was resected at 90° to its long axis and root end preparation was done with ultrasonic tips to a depth of 3 mm and filled with MTA and CEM, respectively. Assessment of apical sealing ability was done with fluid filtration technique and bacterial leakage technique along 90 days with Enterococcus faecalis bacteria. Mann-Whitney U-test and Chi-square test were used to analyze the data using SPSS (SPSS Inc., Chicago, IL, USA). P less than 0.05 was considered as significant. RESULTS: There was no significant difference in apical sealing ability between MTA and CEM in bacterial leakage and fluid filtration techniques. Samples which had bacterial leakage showed higher leakage values by fluid filtration technique. CONCLUSION: Both techniques showed same results and there was no significant difference between fluid filtration and bacterial leakage techniques in assessment of apical microleakage.

Sealing ability of mineral trioxide aggregate and calcium-enriched mixture cement as apical barriers with different obturation techniques.

INTRODUCTION: Endodontic treatment in pulpless immature teeth is challenging due to the lack of an apical stop. Insertion of an apical plug is an alternative to conventional long-term apexification with calcium hydroxide. The aim of this study was to compare the apical microleakage of mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement as apical plugs with three different obturation techniques. METHODS AND MATERIALS: This experimental study was conducted on 130 single rooted human teeth with one canal. Samples were randomly divided into 2 experimental groups (n=60) and two negative and positive control groups containing 5 samples each. After cleaning and shaping, an open apex configuration was prepared in all samples. MTA or CEM cement apical plugs with 5 mm thicknesses were placed. Then, each group was divided to 4 subgroups and the remaining space of root canals were filled with either lateral compaction or thermoplasticized injectable gutta-percha or was obturated by filling the entire canal with apical plug material. In one remaining subgroup the canal space was left unfilled. Microleakage was measured by the fluid filtration method and results were analyzed by means of the two-way ANOVA test. RESULTS: There were no significant differences between microleakage of MTA and CEM cement apical plugs (P=0.92). The difference between three obturation methods was not significant, either (P=0.39). CONCLUSION: MTA and CEM cement have similar sealing ability as apical plugs and no significant difference was found in microleakage of the three groups.

Radiographic quality of root canal treatment performed by 6(th) year undergraduate students in Mashhad, Iran.

BACKGROUND: The aim of the present study was to investigate the quality of root canal obturation performed by 6(th) year undergraduate dental students at the Dental School, University of Mashhad, Iran. MATERIALS AND METHODS: A random 200 sample records of patients who received endodontic treatment at the Dental School, University of Mashhad between 2009 and 2010 was investigated. The quality of root canal filling was determined in relation to the adequate density and length of root filling. Statistical analysis of the data was carried out using statistical package for the social sciences (SPSS 12.0, SPSS Inc., Chicago, IL, USA) with Chi-square test. P < 0.05 was considered as significant. RESULTS: About 38% of teeth fulfilled the criteria of an acceptable root canal filling. Adequate length and density of root filling was found in 73% and 66% of teeth respectively. There was significant difference between maxillary and mandibular teeth according to the quality (P = 0.009), length (P = 0.039) and density (P = 0.005) of root filling. The frequency of root canals with an acceptable filling was significantly greater in the anterior teeth than in molars. CONCLUSION: The technical quality of root canal treatment performed by undergraduate dental students was found to be less than ideal. Thus, the training course of the students at the preclinic and clinic has to be revised.

Effect of root resection on sealing ability of orthograde apical plugs of mineral trioxide aggregate and calcium enriched mixture.

OBJECTIVE: There is some concern that root resection may alter the seal of the previously set orthograde material. The aim of this study was to evaluate the apical sealing ability of orthograde mineral trioxide aggregate (MTA) and calcium enriched mixture (CEM) plugs after resection of the roots. MATERIALS AND METHODS: The fluid filtration method was carried out on a total of 51 roots in three experimental (n=15) and two control (n=3) groups. The root canals were prepared 3 mm shorter than the working length. In groups A and B, 4 mm of MTA and CEM were placed in an orthograde technique, respectively, and after setting, 3 mm of the root end was resected. In group C, the apical 3 mm of each root was resected, root end preparation was carried out to a depth of 3 mm and filled with MTA. Apical microleakage values of each group were measured. Data was analyzed using Kruskal-Wallis test. RESULTS: Means and standard deviations of apical microleakage in groups A (MTA orthograde), B (CEM orthograde) and C (MTA retrograde) were 2.31×10(-4) (0.32×10(-4)), 3.33×10(-4) (0.29×10(-4)) and 4.42×10(-4) (0.40×10(-4)) µl.min(-1).cmH2o(-1), respectively. The mean values were greater in group C; however, statistical analysis revealed no significant differences between these groups (P>0.05). CONCLUSION: Based on the results of this study, when there is an orthograde access to the root canal and surgery is likely to be necessary in the future, MTA and CEM can be placed in an orthograde technique and it just resects the root during surgery.

Sealing Ability of Orthograde MTA and CEM Cement in Apically Resected Roots Using Bacterial Leakage Method.

INTRODUCTION: The aim of this in vitro study was to determine the sealing ability of orthograde ProRoot mineral trioxide aggregate (MTA) and calcium enriched mixture (CEM) cement as root-end filling materials. MATERIALS AND METHODS: Fifty four extracted single-rooted human teeth were used. The samples were randomly divided into 3 experimental groups. In group A and B, 4 mm of WMTA and CEM cement were placed in an orthograde manner and 3 mm of apices were resected after 24 hours. In group C the apical 3 mm of each root was resected and the root-end prepared with ultrasonic tips to a depth of 3 mm and subsequently, then filled with MTA. The apical sealing ability was performed with bacterial leakage method. Statistical analysis was carried out with Chi-square test. RESULTS: There were no significant differences in the extent of bacterial leakage between the three experimental groups (P>0.05). CONCLUSION: Based on the limitations of this in vitro study, we concluded that MTA and CEM cement can be placed in an orthograde manner when there is a potential need for root-end surgery.

Use of fluid filtration method to evaluate the effect of master cone size on the apical seal of severely curved root canals.

The apical third of most root canals shows some degree of curvature, which is important in cleaning/shaping and obturation during root canal treatment. The present study evaluated the effect of master cone size on the apical seal of severely curved root canals. Thirty-eight mesial roots of human mandibular first molars were prepared using the crown-down technique. All samples were mature roots with closed apices, had no carious lesions or resorption, and had a canal curvature of > 45º to 60º. Two samples were used as a negative and positive control to evaluate the fluid filtration equipment, and the remaining 36 samples were equally divided into groups A, B, and C based on master cone size, namely, gutta-percha #20, #25, and #30, respectively. The fluid filtration method was used to evaluate microleakage. No significant difference in microleakage was observed among groups (P = 0.31). In conclusion, an increase in master cone size up to #30 does not significantly influence apical microleakage.