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Introduction The aim of this study was to evaluate under scanning electronic microscopy the enlargement and deformation of the apical foramen of curved mesiobuccal roots with both reciprocating and rotary single-file systems made of a newly heat-treated alloy through the use of Reciproc Blue (REC Blue; VDW, Munich, Germany) and XP-endo Shaper (XPS; FKG Dentaire, La Chaux-de-Fonds, Switzerland). Methods Forty mesiobuccal roots of mandibular and maxillary molars presenting a curvature ranging from 20°–40° were used in this study. The apical foramens were initially scanned with a scanning electronic microscope under 200× magnification. Roots were divided into 2 groups (n = 20): the REC Blue group instrumented with the REC Blue system and the XPS group instrumented with the XPS system. Both groups were instrumented at the foramen. The apical foramens were scanned after root canal preparation. The area, circularity, and ratio of the Feret diameters were calculated from each image. The Kolmogorov-Smirnov, Mann-Whitney, and Wilcoxon tests were used for statistical analysis (P ≤ .05). Results The area of the foramen increased significantly after canal shaping with REC Blue and XPS. The variation of the area was significantly greater with XPS. However, there were no significant differences in circularity and the ratio of the Feret diameters with both instruments. Conclusions No transportation was found when using REC Blue and XPS. The newly heat-treated nickel-titanium alloy did not promote deformation of the apical foramen in curved canals.

The aim of this in vitro study was to evaluate the dentinal tubule penetration of two calcium silicate-based sealers used in warm vertical compaction (WVC) obturation technique in comparison with the single cone (SC) technique by confocal laser scanning microscopy (CLSM). The null hypothesis was that both obturation techniques produced similar sealer penetration depths at 1 and 5 mm from the apex. Forty-four mandibular single-rooted premolars were randomly divided into four equally experimental groups (n = 10) and two control groups (n = 2) according to the type of sealer (Bio-C Angelus, Londr&iacute, na, PR, Brazil or HiFlow Brasseler, Savannah, GA, USA) with either SC or WVC. The sealers were mixed with a fluorescent dye Rhodamine B (0.1%) to enable the assessment under the CLSM. All the specimens were sectioned horizontally at 1 and 5 mm from the apex. The maximum penetration depth was calculated using the ImageJ Software (ImageJ, NIH). Data were analyzed by Mann&ndash, Whitney U and Kruskal&ndash, Wallis tests (p &lt, 0.05). A significant difference was shown between the four groups at 1 mm (p = 0.0116), whereas similar results were observed at 5 mm (p = 0.20). WVC allowed better diffusion for both sealers at 1 mm (p = 0.01) and 5 mm (p = 0.034). The maximum penetration of the Bio-C and HiFlow sealers was more important at 5 mm with the two obturation techniques. Within the limitations of this study, WVC enhanced the penetration of calcium silicate-based sealers into the dentinal tubules in comparison with the SC technique at both levels.

The purpose of this study was to evaluate and compare canal transportation of curved root canals by using 3 nickel-titanium systems: Reciproc, WaveOne, and Twisted Files Adaptive (TF).Twenty-four extracted human mandibular molars with 2 separate mesial canals and severe angle of curvature were selected. Individual canals were divided randomly to 1 of the 3 experimental groups: Reciproc group, reciprocating instrumentation with Reciproc R25; WaveOne group, reciprocating instrumentation with the Primary WaveOne file; and TF Adaptive group, Adaptive Rotary Motion with the TF files. Each group consisted of 16 root canals. Specimens were scanned before and after root canal preparation with an isotropic resolution of 20 μm by using micro-computed tomography. The degree of canal transportation, in addition to instruments' centering ability, was recorded.Less transportation occurred with TF Adaptive rotary instruments (P.0001). The mean degree of canal transportation in the apical third was significantly lower with TF Adaptive group (P.0001). No significant difference was found between Reciproc and WaveOne systems (P = 1.000). Mean centering ratio was the highest statistically with TF Adaptive (P.0001), followed by WaveOne, and was minimal with Reciproc (P.05).The TF Adaptive system was found to have less canal transportation and better centering ability when compared with the reciprocating groups.

Gambarini G, Gergi R, Naaman A, Osta N, Al Sudani D. Cyclic fatigue analysis of twisted file rotary NiTi instruments used in reciprocating motion. International Endodontic Journal, 45, 802–806, 2012. Abstract Aim To evaluate the cyclic fatigue fracture resistance of engine-driven twisted file (TF) instruments under reciprocating movement. Methodology A sample of 30 size 25, 0.08 taper NiTi TF instruments was tested in a simulated canal with 60˚ angle of curvature and a 3 mm radius. During mechanical testing, different movement kinematics were used at a constant speed, which resulted in three experimental groups (each group n = 10). The instruments from the first group (G1) were rotated until fracture occurred. The instruments in the second (G2) and third group (G3) were driven under reciprocating movement with different angles of reciprocation. The time of fracture for each instrument was measured, and statistical analysis was performed using one-way analysis of variance followed by Tukey’s Honestly Significant Different test. Results Reciprocating movement resulted in a significantly longer cyclic fatigue life (P

The purpose of this study was to compare canal transportation and centering ability of 2 rotary nickel-titanium (NiTi) systems (Twisted Files [TF] and Pathfile-ProTaper [PP]) with conventional stainless steel K-files.Ninety root canals with severe curvature and short radius were selected. Canals were divided randomly into 3 groups of 30 each. After preparation with TF, PP, and stainless steel files, the amount of transportation that occurred was assessed by using computed tomography. Three sections from apical, mid-root, and coronal levels of the canal were recorded. Amount of transportation and centering ability were assessed. The 3 groups were statistically compared with analysis of variance and Tukey honestly significant difference test.Less transportation and better centering ability occurred with TF rotary instruments (P.0001). K-files showed the highest transportation followed by PP system. PP system showed significant transportation when compared with TF (P.0001).The TF system was found to be the best for all variables measured in this study.

Aim An experimental comparison of the Root ZX apex locator with the real measurement of the root canal length was carried out using a saline gel to simulate the periodontium. Methodology Lengths were taken when the needle reached the 0.5 mark and the Apex mark on the meter. These measurements were then compared with a calculated reference length representing the real length of the root canal. Reliability was assessed using Student’s t-test. Precision was assessed using the mean and standard deviation of differences. Results The Root ZX gave measurements within a range of 0.5 mm in 84.72% of the cases. The intra-operator and inter-operator variabilities were not statistically significant (P > 0.05). Conclusions The Root ZX is not capable of detecting the ‘0.5 mm from the foramen’ position and thus, should only be used to detect the foramen (major diameter).