Mm Of Working Length Research Articles

Efficacies of mineral trioxide aggregate and bioceramic root canal sealer with two types of gutta-percha toward the apical leakage

Background: Mineral trioxide aggregate (MTA) is the most widely used material in endodontics, and recently, it has been used as an endodontic sealer. Bioceramic (BC) is a newly developed material based on calcium silicate, which is already used as a biocompatible root canal obturation material to overcome the weakness of MTA. However, there have been no studies comparing the materials used to seal the root canal. Objective: This study aimed to determine the apical leakage differences between BC and MTA sealers with BC-coated gutta-percha (GP) and conventional GP. Methods: In total, 40 mandibular premolars were cut coronally to 14 mm of working length. All samples were randomized and sorted into four groups: BC sealer with BC-coated GP, bioceramic sealer with conventional GP, MTA sealer with BC-coated GP, and MTA sealer with conventional GP. The samples were stored in an incubator, and nail varnish was applied to all root surfaces except for a 1 mm area from the apex. The samples were also soaked in methylene blue for 72 h before undergoing diaphanization. A stereomicroscope was used to measure the methylene blue penetration. All data were analyzed using analysis of variance. Results: There were significant differences in apical leakage between the BC and MTA sealers (P

Comparison of Two Techniques for Selection of Master Gutta-Percha Cone Using Micro-Computed Tomography

This study used micro-computed tomography (micro-CT) to evaluate the fit of the master gutta-percha cone at time of cone fit, gutta-percha volume in the filling material, and the filling material volume in relation to the canal at the apical limit of the working length. Root canals of 20 maxillary central incisors were prepared with rotary instruments and distributed into two groups (n=10). The gutta-percha cone tip was either plasticized (apical thermal impression technique - ATI) or not (conventional technique - CT), and its apical fit was checked. The apical 1 mm of working length was examined with a micro-CT, canals were filled with gutta-percha and sealer, and new micro-CT scans were obtained. In CT, gutta-percha filled 35.83 ± 15.05% of the canal at cone selection and 38.72 ± 11.64% after filling. In ATI, these values were 23.14 ± 7.74% and 26.98 ± 20.40%, respectively. Gutta-percha volume in the filling material, and filling material volume in relation to the canal were, respectively, 61.28 ± 11.64% and 87.76 ± 9.98% for CT, and 73.00 ± 20.41% and 89.96 ± 9.08% for ATI. No significant difference was found between cone selection and after canal filling, for either CT (p=0.593) or ATI (p=0.4975). The techniques did not differ significantly with respect to gutta-percha volume in the filling material (p=0.132) and filling material volume in relation to the canal (p=0.612). An ideal fit of the master gutta-percha cone at working length was not achieved regardless of the cone selection technique, and the material-filled area was similar for both techniques.

A Comparative Reliability and Performance Study of Different Stent Designs in Terms of Mechanical Properties: Foreshortening, Recoil, Radial Force, and Flexibility

This study seeks to improve the mechanical performance of stents by conducting reliability performance testing and finite element method (FEM)-based simulations for coronary stents. Three commercially available stent designs and our own new design were tested to measure the factors affecting performance, specifically foreshortening, recoil, radial force, and flexibility. The stents used in the present experiments were 3 mm in working diameter and 18 mm of working length. The results of the experiments indicate that the foreshortening of stents A, B, C, and our new design, D, was equivalent to 2.25, 0.67, 0.46, and 0.41%, respectively. The recoil of stents A, B, C, and D was 6.00, 4.35, 3.50, and 4.36%, respectively. Parallel plate radial force measurements were A, 3.72 ± 0.28 N; B, 3.81 ± 0.32 N; C, 4.35 ± 0.18 N; and D, 4.02 ± 0.24 N. Radial forces determined by applying uniform pressure in the circumferential direction were A, 28.749 ± 0.81 N; B, 32.231 ± 1.80 N; C, 34.522 ± 3.06 N; and D, 42.183 ± 2.84 N. The maximum force of crimped stent at 2.2-mm deflection was 1.01 ± 0.08 N, 0.82 ± 0.08 N, 0.92 ± 0.12 N, and 0.68 ± 0.07 N for each of stents A, B, C and D. The results of this study enabled us to identify several factors to enhance the performance of stents. In comparing these stents, we found that our design, stent D, which was designed by a collaborative team from seven universities, performed better than the commercial stents across all parameter of foreshortening, recoil, radial force, and flexibility.

In Vitro Comparisons of Debris Removal of the EndoActivator TM System, the F File TM, Ultrasonic Irrigation, and NaOCl Irrigation Alone after Hand-rotary Instrumentation in Human Mandibular Molars

Introduction The purpose of this in vitro study was to compare the debris removal efficacy of the EndoActivator TM system, the F file TM, ultrasonic irrigation, or 6% NaOCl irrigation alone in human mandibular molars after hand-rotary instrumentation. Methods A custom brass cube (K-Kube) was used to create a sealed canal system, allowing each tooth to serve as its own control. Forty extracted mandibular molars were randomly divided into 4 equal experimental groups. Each tooth was mounted, sectioned at 1, 3, and 5 mm from the working length, and then reassembled into the K-Kube, and the mesial roots were similarly prepared by using hand-rotary instrumentation. For final debridement, group 1 used F file for 30 seconds, group 2 used EndoActivator system for 30 seconds, group 3 used ultrasonic irrigation for 30 seconds, and group 4 used irrigation with 6% NaOCl within 1 mm of working length. All groups received a final irrigation with 6% NaOCl in each canal. Specimens were evaluated at 1, 3, and 5 mm from the working length for cleanliness by capturing a digital image with a stereomicroscope. All specimens had the percent cleanliness for each canal and isthmus calculated both before and after final debridement. Statistical analysis was completed by using a repeated-measures analysis of variance with Tukey post hoc tests. Results and Conclusions The results showed no statistically significant difference in canal or isthmus cleanliness among the 4 groups, but there was a statistically significant difference ( P < .001) in canal cleanliness between the 1-mm level versus the 3-mm and 5-mm levels for all of the groups.

Efficacy of Different Irrigation and Activation Systems on the Penetration of Sodium Hypochlorite into Simulated Lateral Canals and up to Working Length: An In Vitro Study

Introduction The removal of vital and necrotic pulp tissue, microorganisms, and their toxins is essential for endodontic success. However, the complex anatomy of the root canal system has limited our ability to debride it completely. Hence the purpose of this study was to evaluate the effect of currently used irrigation and activation systems on the penetration of sodium hypochlorite into simulated lateral canals and to working length in a closed system. Methods One hundred single-rooted teeth were used in this study. A total of 600 simulated lateral canals were created, 6 in each tooth, with 2 lateral canals at 2, 4.5, and 6 mm of working length. To resemble the clinical situation, a closed system was created by coating each root with soft modeling wax. Roots were then randomly assigned to 4 experimental groups: group 1 (n = 20), Endoactivator (sonic activation); group 2 (n = 20), passive ultrasonic (PUI) activation; group 3 (n = 20), F file; group 4 (n = 20), apical negative pressure (ANP) irrigation; and control group 5 (n = 20), positive pressure irrigation. The samples were evaluated by direct observation of the images recorded under the dental operating microscope. Results The results demonstrated that the ANP irrigation group was superior at reaching working length, and PUI was the most effective at lateral canal penetration. Conclusions The ANP irrigation system demonstrated limited activation of the irrigant into lateral canals but reached the working length significantly more than the other groups tested. In contrast, PUI group demonstrated significantly more penetration of irrigant into lateral canals but not up to the working length.

Effect of EDTA, Sonic, and Ultrasonic Activation on the Penetration of Sodium Hypochlorite into Simulated Lateral Canals: An In Vitro Study

Introduction The purpose of this study was to evaluate the penetration of 5.25% sodium hypochlorite alone or in combination with 17% EDTA in simulated lateral canals using sonic and ultrasonic activation. Methods Four hundred and eighty simulated lateral canals were created in 80 single rooted cleared teeth by inserting 06 K-files at 2, 4.5 and 6 mm of working length. Samples were mounted on clear silicon to simulate the presence of surrounding periodontal tissues and its effects on fluid dynamics and then randomly assigned to four experimental groups: 1 ( n = 20) 5.25% NaOCl + sonic activation; 2 ( n = 20) 5.25% NaOCl + ultrasonic activation; 3 ( n = 20) 5.25% NaOCl + 17% EDTA + sonic activation and 4 ( n = 20) 5.25% NaOCl + 17% EDTA + ultrasonic activation. Sonic activation was delivered using the Endoactivator® inserted 2 mm short of working length and activated for 1 minute. Ultrasonic activation was performed with a stainless steel ultrasonic file inserted 2 mm short of working length and passively activated for 3 cycles of 20 seconds each. Samples were evaluated by direct observation of the images recorded under the operating microscope and by radiographic evaluation after irrigation with a contrast solution. Results Sonic and ultrasonic activation resulted in a better irrigation of the lateral canals at 4.5 and 2 mm from working length compared to traditional needle irrigation alone. Traditional needle irrigation alone demonstrated significantly less penetration of irrigant into the lateral canals and was limited to the level of penetration of the needle. Conclusion The addition of EDTA did not result in better penetration of irrigants into the lateral canals.

Effect of customization of master gutta‐percha cone on apical control of root filling using different techniques: an ex vivo study

(i) To compare the prevalence of extrusion of root filling material when placed using different root filling techniques, with or without customization of the master gutta-percha (GP) cone; and (ii) to investigate the effects of some factors influencing root filling extrusion and presence of voids. A total of 180 roots were selected, prepared and randomly allocated to three groups. Five general dental practitioners performed the root fillings; each filled one group of roots (n = 60) using each of three techniques; 'cold lateral compaction' (n = 20), 'warm vertical compaction' (n = 20) and 'continuous-wave' (n = 20) techniques. For each obturation technique, the master GP cone was customized using chloroform in 10 samples. Two groups of the roots were recycled to allow all five operators to fulfill their remit. Two observers, blind to operator and obturation technique, examined the radiographs (master apical file, post-obturation) to determine the presence of root filling extrusion and voids within the apical 5 mm, independently. Root filling extrusion was also confirmed by direct inspection of the root apex after obturation. The data were analysed using logistic regression models. A total of 300 root fillings were performed; nine were excluded from the analysis. Most of the root fillings (80%, n = 233) were placed within 0.5 mm of the working length; only 20% (n = 58) were placed >0.5 mm beyond the working length. The odds of prevalence of extrusion (>0.5 mm) were significantly reduced by about 50% when cold lateral compaction or customization of GP were used. One operator produced 2.5 times more extruded root fillings than others. Curvature & length of root canal, apical size of prepared canal, as well as operator's preferred obturation technique had no significant influence on the prevalence of extrusion. Customization of GP was the sole factor to significantly reduce the prevalence of voids within the apical 5 mm of working length. Root filling extrusion was significantly influenced by 'operator' and was reduced by cold lateral compaction and customization of the master cone. Customization of master cone was the only factor that reduced voids apically.

Comparison of Nickel-Titanium and Stainless-Steel Spreader Penetration and Accessory Cone Fit in Curved Canals

The purpose of this study was to compare nickel-titanium and stainless-steel spreader penetration in curved canals. Twenty prepared plastic blocks with a 30 degrees curvature were used for each part of the study. In part 1, the force required to insert each spreader to within 1 mm of working length in an empty canal was measured. In part 2, the force required to insert each spreader to within 3 mm of working length was measured in a canal containing a master cone. In part 3, the depth of penetration of each spreader with a master cone in place using a 1.5 kg force was measured. Additionally, in part 3, the depth of penetration of the first accessory cone was measured. The results from part 1 showed that a nickel-titanium spreader required significantly less force than a stainless-steel spreader (0.30 kg vs. 0.59 kg). In part 2, a nickel-titanium spreader required significantly less force than a stainless-steel spreader (1.56 kg vs. 2.42 kg). In part 3, a nickel-titanium spreader penetrated significantly deeper than a stainless-steel spreader (15.0 mm vs. 14.0 mm). There was no significant difference in the depth of penetration of the first accessory cone used after either spreader (0.8 mm vs. 0.7 mm). Therefore, the potential for vertical root fracture in curved canals during lateral condensation may be minimized by using nickel-titanium spreaders.