Effect of different apical actions of new integrated endodontic motors on apical debris extrusion: An in vitro study.

The new generation endodontic motors can perform different kinematics when they reach a certain predetermined level thanks to the integrated apex locator system. These actions consist of apical reverse, apical slow down and apical stop. The aim of this study is to compare this action's effect on apical debris extrusion. Sixty extracted human lower premolars were selected. Teeth are divided into four random groups (n = 15). Groups are prepared accordance to their group names as continuous rotation, apical slow down, apical reverse and apical stop. Extruded debris is collected into preweighted Eppendorf tubes and then calculated. One-way ANOVA test showed no statistically significant result between experimental groups. Similar debris extrusion values of all motion modes of the integrated endodontic motor can be interpreted that there will be similar debris extrusion and consequently similar postoperative pain on clinical setting. More in vitro and in vivo research is needed to make a conclusion.

Fractal analysis and periapical index evaluation of multivisit nonsurgical endodontic retreatment: A retrospective study.

OBJECTIVE: This retrospective study compared changes in periapical trabecular patterns using fractal analysis and the periapical index (PAI) on the periapical radiographs of patients who underwent multivisit nonsurgical endodontic retreatment of persistent periapical disease. STUDY DESIGN: In total, 50 participants were included in the study. For each patient, baseline periapical radiographs were acquired just before retreatment and postoperative radiographs were acquired 1 year later. The region of interest, located in the abnormal tissue around the root apex, was selected from each of the paired radiographs and the fractal dimension (FD) was calculated. Periapical status was classified using the PAI as "healed" (PAI <3) or "unhealed" (PAI ≥3). RESULTS: According to the PAI scores, retreatment after 1 year had a healing rate of 70%. In healed cases, the FD values increased significantly (P < .001), whereas FD decreased significantly in unhealed cases (P = .021). Change in FD was significantly different between healed and unhealed cases (P < .001). However, change in FD did not have a significant correlation with PAI in either healed or unhealed cases (P > .05). There was no significant effect of sex on the change in FD values in either healed or unhealed cases (P ≥ .690). CONCLUSIONS: The significant differences in FD suggest that this parameter may be useful in detecting increased trabeculation and estimating retreatment prognosis.

Retrospective fractal analyses of one-year follow-up data obtained after single-visit nonsurgical endodontic retreatment on periapical radiographs.

OBJECTIVES: The aim of retrospective study was to evaluate the changes to the periapical bone sites after non-surgical endodontic retreatment by using fractal analysis on periapical radiographs. MATERIALS AND METHODS: Thirty patients whose teeth had periapical lesions and underwent primary endodontic treatment were selected for nonsurgical single-visit endodontic retreatment. Two radiographs were taken, the first immediately after retreatment and the second at the 1-year follow-up. An identical region of interest close to the infected root apex was selected from each radiograph. FD was measured using the box-counting method. Periapical status was evaluated using the periapical index (PAI). Treatment outcomes were categorized into healed (PAI < 3), or not healed (PAI ≥ 3) based on radiographic criteria. RESULTS: The mean FD value significantly increased at the 1-year follow-up compared to baseline. No significant sex biases were apparent. According to the PAI, retreatment after 1 year resulted in a 63.3% healed. CONCLUSION: The extent of periapical trabecular bone evident radiographically increased, as revealed by FD data, 1 year after endodontic retreatment. Clinical relevance The use of fractal analysis as a quantitative method to evaluate changes in periapical trabecular bone (such as healing and inflammation) after endodontic retreatment can be an important marker in determining the prognosis of endodontic retreatment.

The Effect of Root Canal Preparation Size and Taper of Middle Mesial Canals on Fracture Resistance of the Mandibular Molar Teeth: An In Vitro Study.

INTRODUCTION: The aim of the present study was to investigate the influence of root canal preparation size and taper of middle mesial (MM) canals on fracture resistance of mandibular molars. METHODS: Fifty-five mandibular molar teeth having an MM canal were selected based on the cone-beam computed tomographic analysis. After the decoronation and distal root separation procedure, the lengths of the mesial roots were standardized to 13 mm. The specimens were randomly distributed into 5 groups (n = 11). Mesiobuccal and mesiolingual canals were prepared up to size 30.06 using VDW.ROTATE rotary files (VDW, Munich, Germany). The MM canal was prepared up to size 25.04, 25.06, 30.04, and 30.06, respectively. No preparation was done in the MM canal in the control group. After the irrigation protocol, the canals were obturated with the single-cone technique. A thin layer of silicone-coated specimens was embedded in acrylic resin and subjected to a fracture strength test by a universal testing machine. A vertical force was applied to the roots until they fracture. Statistical analysis was performed with 1-way analysis of variance and post hoc Duncan tests (P = .05). RESULTS: There was no significant difference between group 25.04 and the control group, but the fracture strengths of these groups were found to be significantly higher than that of groups 25.06, 30.04, and 30.06 (P < .05). CONCLUSIONS: Within the limitations of this study, we concluded that increasing the apical diameter and taper in the MM canal reduces the fracture strength of mandibular molar teeth. Among the tested instrumentation sizes, fracture strength decreased significantly when greater than 25.04 instrumentation sizes were chosen.

Middle Mesial Canal Preparation Enhances the Risk of Fracture in Mesial Root of Mandibular Molars.

INTRODUCTION: The aim of this investigation was to evaluate the effect of the presence and preparation of middle mesial (MM) canals on the fracture resistance of the mesial root of mandibular molars. METHODS: Forty intact mesial roots of mandibular first molars having 2 (n = 20) or 3 (n = 20) independent canals from the furcation level for up to at least 5 mm apically were selected based on preoperative micro-computed tomographic scanning. The selected roots were then distributed into 2 experimental (n = 10) and 2 control groups (n = 10) according to the root length, canal configuration (2 or 3 independent canals), and root thickness at the furcation level. In the experimental groups 1 (2 independent canals) and 3 (3 independent canals), root canals were enlarged up to the ProTaper Next X3 rotary instrument (Dentsply Sirona, Ballaigues, Switzerland), whereas in groups 2 (2 independent canals) and 4 (3 independent canals) root canals were not prepared. The specimens were embedded in acrylic resin after their surfaces were coated with a thin layer of silicone and subjected to a fracture strength using a universal testing machine. The types of fracture extension and course were recorded and statistically compared with the chi-square test, whereas fracture strength was analyzed using 1-way analysis of variance and post hoc Tukey tests (α = 5%). RESULTS: No statistical difference in fracture strength was observed between nonprepared roots with 2 (group 2, 696.1 ± 186.3 N) or 3 (group 4, 558.4 ± 154.6 N) independent canals (P > .05), whereas the lowest values were obtained in the prepared roots with an MM canal (groups 3, 377.1 ± 77.2 N) (P < .05). The mean fracture strength observed in the prepared roots with 2 canals (group 1, 528.4 ± 134.3 N) showed no statistically significant difference compared with nonprepared roots with 3 canals (group 4, 558.4 ± 154.6 N) (P > .05). The chi-square test revealed no significant differences in fracture extent, types, and courses among groups (P > .05). Fracture extensions in all groups were mostly central and buccal-central types, whereas the highest frequency of fracture course was the curved and zigzag types. CONCLUSIONS: The fracture resistance of the mesial roots of the mandibular molars decreased after the preparation of mesial canals with large-tapered instruments. Preparation of the MM canal further diminished the fracture resistance of the mesial roots. The resultant fracture displayed a distinct pattern in the buccolingual plane.

Influence of Trigonella foenum graecum seed extract as root canal irrigation agent on root surfaces: A scanning electron microscope/energy dispersive X-ray analysis study.

The purpose of this in vitro study was to investigate the effect of Trigonella foenum graecum seed extract (TFGSE) as a root canal irrigation agent on the surface of instrumented root canals and on changes in the mineral contents of the root dentin. A total of 90 extracted human mature maxillary central incisor teeth with a single root and without root resorption were selected. The specimens were subdivided into five groups according to irrigation protocol groups G0: distilled water (n = 15): G1: Sodium hypochlorite (5.25% NaOCl); G2: 1% TFGSE G3: NaOCl +17% EDTA (3 min); G4: NaOCl+1% TFGSE; G5: 1% TFGSE +17% EDTA. All the roots were sectioned longitudinally into two halves and examined under scanning electron microscope/energy dispersive X-ray analysis (SEM/EDX) to assess changes in the mineral content of the tooth. Smear layer removal from root canals was evaluated with scanning electron microscopy (SEM). A statistical analysis was performed using the Kruskal-Wallis test. The most effective irrigation protocols in removing smear layer occurred with TFGSE and NaOCl, both with rinsing with 17% EDTA. TFGSE was more effective than NaOCl for removing the smear layer. The results showed the ability of 1% TFGSE to remove the smear layer from the root canals. TFGSE is a promising alternative irrigation agent for root canals.

Influence of canal curvature on the amount of apically extruded debris determined by using three-dimensional determination method.

The aim of this study was to introduce a new three-dimensional curvature classification method to evaluate the canal curvature and analyse its effect on the amount of debris extrusion during reciprocating preparation. Freshly extracted mandibular molar teeth were collected. After performing access cavities, periapical radiographs were taken on both mesio-distal and bucco-lingual planes of each tooth using a digital sensor. The radii of the curvature were calculated and a new three-dimensional classification method was used to classify canal curvature, based on radius as follows: Three-dimensionally slight, moderate and severe curve root canal. Fifteen teeth for each curvature sort were randomly chosen for canal instrumentation. The extruded debris was collected in pre-weighed Eppendorf tubes and calculated. A significant difference was noted between root canals with slight and severe three-dimensional curvatures (P < 0.001). It can be concluded that root canal curvature plays a significant role in the amount of extruded debris.

Evaluation of canal transportation after preparation with Reciproc single-file systems with or without glide path files.

BACKGROUND: Canal transportation is a common sequel caused by rotary instruments. AIMS: The purpose of the present study is to evaluate the degree of transportation after the use of Reciproc single-file instruments with or without glide path files. METHODS: Thirty resin blocks with L-shaped canals were divided into three groups (n = 10). Group 1 - canals were prepared with Reciproc-25 file. Group 2 - glide path file-G1 was used before Reciproc. Group 3 - glide path files-G1 and G2 were used before Reciproc. Pre- and post-instrumentation images were superimposed under microscope, and resin removed from the inner and outer surfaces of the root canal was calculated throughout 10 points. RESULTS: Statistical analysis was performed with Kruskal-Wallis test and post hoc Dunn test. For coronal and middle one-thirds, there was no significant difference among groups (P > 0.05). For apical section, transportation of Group 1 was significantly higher than other groups (P < 0.05). CONCLUSION: Using glide path files before Reciproc single-file system reduced the degree of apical canal transportation.

Apical extrusion of Enterococcus faecalis in different canal geometries during the use of nickel titanium systems with different motion types.

BACKGROUND/PURPOSE: Extrusion of intracanal bacteria leads to treatment failures. Compare the apical extrusion of intracanal bacteria (Enterococcus faecalis) during canal preparation with three different instrumentation techniques [RECIPROC, One Shape (OS), and Twisted-File Adaptive (TFA)] with different motion types. MATERIALS AND METHODS: Ninety teeth with different canal morphologies were divided into three main groups, each including 30 teeth (10 mandibular incisors, 10 mandibular premolars, and 10 curved roots). Roots were resected until 13-mm working length was obtained and fixed to glass vials filled with brain-heart infusion broth. Each canal was filled with E. faecalis suspension. The three main groups were further grouped into three subgroups. Each group was further subgrouped into three, with each subgroup including 10 roots from each type of teeth (10 incisors/subgroup, 10 premolars/subgroup, and 10 curved canals/subgroup). These subgroups were prepared with one of RECIPROC, OS, or TFA. Bacterial colonies extruded into each vial were incubated in brain-heart infusion agar at 37°C for 5 days and counted using a colony counter as the number of colony-forming units per milliliter. Statistical analyses were performed using one-way analysis of variance, post hoc Tukey honest significant difference, and Kruskal-Wallis tests. RESULTS: Apically extruded bacteria were not statistically different from each other (P > 0.05). The amount of apically extruded bacteria was statistically similar for both different instruments in the same type of tooth (P > 0.05) and same instrument in different types of teeth (P > 0.05). CONCLUSION: Neither the motion type of instrument nor the canal morphology affected the degree of bacterial extrusion.

Effects of voxel size and resolution on the accuracy of endodontic length measurement using cone beam computed tomography.

An accurate determination of the working length is indispensable for successful endodontic treatment. The aim of this study was to determine the influence of the voxel size and resolution of CBCT on measuring root canal working length. Thirty extracted single-rooted permanent teeth were used for this study. The working lengths of the teeth were determined by a researcher inserted a K-file into each canal until the tip became visible through the major foramen. The file was withdrawn until its tip was seen at the level of the coronal-most border of the major foramen under. The rubber stop was adjusted to the occlusal reference and the distance from the stop to the false tip was measured with digital calipers and recorded as the actual working length. The CBCT images were obtained with a Planmeca ProMax 3D Mid (Planmeca, Helsinki, Finland) using four sets of settings: from voxel size 0.5mm to voxel size 1.0mm. These measurements were compared with actual lengths (as a control group) using Analysis of Variance and the Dunnett Post Hoc Test. The Pearson correlation coefficient (r) and 95% confidence intervals were calculated to compare all measurement methods. The significance level was set at P<0.05. No significant difference was found among CBCT groups and working length. A highest correlation was found between the actual length and smallest voxel size and highest CBCT measurements (r=0.94). CBCT imaging can be used endodontic working length measurement and the smallest voxel size and highest resolution yielded more accurate results.

In vitro evaluation of Root ZX and Raypex 6 in teeth with different apical diameters.

BACKGROUND: There is a growing interest about electronic apex locators for working length determination. There are several studies dealing with their performance in different conditions. AIMS: The aim of this study is to evaluate the accuracy of Root ZX and Raypex 6 in teeth with different apical diameters. MATERIALS AND METHODS: Actual working length (AWL) of 80 single rooted teeth were determined as 0.5 mm short of apical foramen. The teeth were divided into 4 groups (n = 20). First group (G 0) included teeth with mature apices. Root canals of the other groups (G 32, G 57 and G 72) were enlarged until apical sizes of 0.32, 0.57 and 0.72 mm were obtained. Samples were embedded in alginate and electronic measurements (EM) were performed. STATISTICAL ANALYSIS: was achieved with Fisher exact test. RESULTS: Both devices revealed a high rate of success in G 0 and G 32. Their accuracy decreased significantly in G 57 and G 72 groups (P < 0.05). Intra-group results of Root ZX and Raypex 6 were similar (P > 0.05). CONCLUSIONS: Root ZX and Raypex 6 are reliable in teeth with mature apices. At foramen diameters exceeding 0.57 mm, their accuracy is susceptible.

Effect of ethylenediaminetetraacetic acid gel on the incidence of dentinal cracks caused by three novel nickel-titanium systems.

The aim of this study is to evaluate the incidence of crack formation while using Reciproc, WaveOne and Twisted File Adaptive with and without ethylenediaminetetraacetic acid (EDTA) gel. Seventy extracted mandibular premolars were included. The teeth were decoronated until roots of 16 mm were obtained. Samples were distributed into seven groups: group 1, no canal preparation (control); other groups were instrumented so; group 2, Reciproc; group 3, Reciproc + EDTA; group 4, WaveOne; group 5, WaveOne + EDTA; group 6, Twisted File Adaptive; group 7, Twisted File Adaptive + EDTA. Roots were horizontally sectioned from 3, 6 and 9 mm from apex and observed under stereomicroscope. The number and the incidence of cracks were recorded and statistically analysed with chi-squared and Kruskal-Wallis tests. Control group did not reveal any cracks. Crack formation with three novel Ni-Ti instruments was similar. Using EDTA gel did not reduce crack occurrence.