Accuracy of two apex-locating handpieces in detecting simulated vertical and horizontal root fractures.

The aim of this study was to evaluate in vitro the effectiveness of TCM Endo V and Tri Auto ZX handpieces in detecting simulated horizontal and vertical root fractures. Forty extracted maxillary incisor teeth were randomly divided into 2 groups as simulated incomplete horizontal and vertical root fractures. Auto reverse and electronic apex locator functions of the 2 handpieces were used in both groups. Repeated measures of analysis test and pairwise comparisons were used for statistical analyses. Both handpieces detected the root fractures in an acceptable range. Furthermore, electronic apex locator function of both devices was more efficient in the process than auto reverse function.

Apical accuracy of two apex-locating handpieces in root canal retreatments of root-end resected teeth.

We aimed to evaluate the accuracy of 2 apex locator integrated endodontic motors during retreatment of root-end resected teeth by using 40 extracted incisor teeth. The apical 3 mm of the roots were resected, and the root lengths were recorded as resected length of the roots. Forty roots were randomly divided into 2 groups of 20 to evaluate the 2 handpieces, Tri Auto ZX and TCM Endo V. The working lengths measured during the auto reverse function and during the electronic apex locator function with Tri Auto ZX and TCM Endo V were recorded and compared with resected length of the roots. The repeated measures analysis of variance was used for statistical analyses. Electronic apex locator functions of both devices might be used for apical accuracy, but the auto reverse functions might not be useful to 0.0-mm accuracy in retreatment procedures of root-end resected teeth.

Evaluation of the smear layer removal effectiveness of EDTA using two techniques: an SEM study.

Obtaining the cleanest canal possible before obturation is one of the goals of endodontic treatment. The purpose of this study was to compare the smear layer removal capability of ethylenediamine tetra-acetic acid (EDTA) application with passive ultrasonic and cotton wrapped on reamer activation. Twelve extracted human teeth with single root canals were used for the study. They were conventionally hand instrumented using reamers and K files. The apical aspect of the canals was enlarged to a #40 file. The teeth were divided into 4 four groups, instrumented and irrigated as follows: Group-A EDTA agitated at the end of preparation with cotton wrapped on a reamer for 1 min; Group-B EDTA applied with ultrasonic agitation for 1 min; Group-C irrigated with EDTA+sodium hypochlorite (NaOCl) (negative control group); and Group-D irrigated with distilled water (positive control group). After scanning electron microscopic study at three different levels, smear layer and dentinal tubules were scored. Means were tested for significance using the Z test. When the techniques were compared, the cotton wrapped on reamer agitation method was as successful as the ultrasonic activation of the files. Although all groups had significantly higher smear layer scores at apical compared to coronal sections, no significant differences were recorded.

Effects of Nd: YAG laser irradiation on the adaptation of composite resins to root dentin.

One of the most important goals of the restoration of endodontically treated teeth with a composite resin post system is to achieve good adaptation of the composite material to dentin walls to prevent microleakage apically and coronally. In post core systems, to avoid microleakage between the dentin wall and resin material, laser irradiation may seem to be an alternative therapy for increasing adaptation quality. The aim of this study was to investigate the adaptation of a packable composite resin to lased root canal dentin when it was used as post material. Forty-five freshly extracted human teeth were selected and post spaces were prepared. The teeth were divided into three groups. In group 1 the dentin of the post spaces were etched with 35% phosphoric acid, in group 2 the dentin surfaces were irradiated with an Nd: YAG laser, and in group 3 the dentin surfaces were initially treated with the laser and then etched. The teeth of all groups were obturated with a bonding agent and composite. The groups were divided into two subgroups: a group for the scanning electron microscope (SEM) study and a group for the microleakage study. The lased group showed poor adaptation and more microleakage was detected (p<0.05; variance analysis). The laser beam and acid-etching showed no advantage compared to the acid-etching alone (p>0.05). The Nd: YAG laser irradiation adversely affects adhesion to dentin for using composite resin as a post material and does not constitute an alternative to acid-etching.

Lateral perforation in parallel post space preparations.

This study evaluates the amount of remaining tooth structure and possibility of producing lateral perforation following the use of different diameters of parallel-sided Parapost drills in groups of different canal curvatures (0 degrees-15 degrees, 16 degrees-25 degrees, 26 degrees <) in distal canals of first and second mandibular molar teeth. After enlargement of root canals using the crown-down pressureless technique, Parapost drills #1, #2, and #3 were used in the different canal groups for the preparation of a post space. Standardized digital radiographs were taken before the post space preparation and after each Parapost drill application. Four horizontal lines (a, b, c, and d) were drawn at equal distances on these images, starting from the pulp chamber floor moving apically at 2 mm increments. There were no significant differences between the different curvature groups at the a, b, c, and d levels for the critical level of the remaining tooth structure (multiple comparison test; p>0.05). However, in considering root perforation, both at the inner and outer side of the roots, there were statistically significant differences at "c" and "d" levels in group 3 (#3 drill) without taking into account the root curvature (ANOVA; p< 0.5). None of the specimens showed strip perforation.

Microhardness of packable composites used as posts condensed with different methods.

The purpose of this in vitro study was to evaluate the microhardness of packable composite compacted with hand or ultrasonic pluggers in post spaces. A total of 168 extracted human anterior teeth were prepared with Gates Glidden and ParaPost drills after obturation. A primer and a dentin-bonding agent were applied to the etched surface. Half of the specimens were compacted with an ultrasonic tip and the other half with a mechanical hand compactor and all specimens were polymerized for each increment. The roots were then sectioned horizontally from 0, 2.5, 3, 3.5, 4, 4.5, and 5 mm starting from the coronal and sliced 2.5-mm long. The microhardness test was applied to each specimen. There were statistically significant differences between ultrasonically and hand-condensed groups in whole specimens (p < 0.001). There were no significant differences between groups of 0, 2.5, and 3 mm until 3.5 mm was reached. After 3.5-mm depth, there were significant differences between the groups (p < 0.001). Ultrasonic condensation of packable composites provided mechanical advantage over hand condensation in root canals measuring microhardness in different depths. However, when microhardness was measured at different depths, values decreased after the depth of 3.5 mm in both condensation groups.

Influence of passive ultrasonic activation on the penetration depth of different sealers.

Correct use of instruments and irrigating solutions are major factors during chemo-mechanical preparation of root canals. Ultrasonically activated files and solutions are used for debridement of canals. In this study 42 single rooted anterior human teeth were used. The roots were divided into two groups. One group received an application of 17% ethylenediamine tetra acetic acid (EDTA) of 1 ml for 1 min using an ultrasonically energized file. The other group received an application of 17% EDTA of 1 ml for 0.5 min using an ultrasonically energized file. The groups were divided again into two subgroups. The roots were filled with a resin based sealer, AH26 and a glass ionomer sealer--Endion with lateral condensation technique. The roots were separated into two halves. The specimens were viewed through a scanning electron microscope (SEM). Statistical differences between the groups and regions were analyzed with Variance and Duncan tests. Under the conditions of this study, it can be said that ultrasonically activated irrigation did not reduce the smear layer effectively at 1 min and 0.5 min time intervals. According to this result, no difference was observed between the penetration of sealers.

Microleakage of packable composites used in post spaces condensed using different methods.

The aim of this in vitro study was to evaluate the apical and coronal microleakage of a packable composite material compacted by either hand or ultrasonic condensers when placed in post spaces. Forty-two extracted anterior teeth were used. After conventional obturation of the root canals, parallel post spaces 5 mm in depth and 2 mm in diameter were prepared using Gates Glidden and diamond burs. A primer and a dentin bonding agent (Prime & Bond NT) was applied to the etched surface for 30 seconds and light polymerized for 40 seconds. Surefil packable composite resin was inserted in four equal increments and each polymerized for 40 seconds. Half of the specimens were compacted with an ultrasonic tip and the other half with a mechanical hand compactor. After immersion in the dye, the teeth were sectioned longitudinally and dye penetration was evaluated using a stereomicroscope and microleakage recorded in mm. A One-Way Analysis of Variance indicated the two condensing methods were not statistically different (p>0.05). When microleakage was compared within groups, there was also no statistical difference between coronal or apical microleakage (p>0.05). In an in vitro environment, ultrasonic condensers do not offer any advantage over hand condensers. Both the coronal and apical portions of the root had microleakage indicating that regardless of the condensation method and the use of a packable composite, there is still microleakage that could potentially create further clinical problems.

Evaluation of apical leakage of root canals obturated with Nd: YAG laser-softened gutta-percha, System-B, and lateral condensation techniques.

In endodontics, a laser can be used as a heat source and gutta-percha can be softened by a laser and used in the root canals. The System-B endodontic heat source unit was designed for the obturation of the root canal system with a single continuous wave of thermoplasticized gutta-percha. The aim of this study was to compare the apical leakage of lateral condensation; Nd: YAG laser-softened gutta-percha and System-B techniques. Fifty-five extracted, single root human maxillary anterior and premolar teeth were used in this study. After working length determination, the "step-back technique" was used to prepare the root canals. The teeth were randomly divided into three experimental groups of 15 each and two control groups of 5 specimens each. The first group was obturated by lateral condensation, the second group by gutta-percha softened with an Nd: YAG laser, and the third group was obturated using the System-B technique. Apical leakage of the roots was evaluated by dye penetration using a stereomicroscope after sectioning the roots. The results of the first and third groups were similar, and the results of the second group showed differences when compared with the other groups. However, variance analysis revealed there was no statistically significant difference among the results.

The effects of sodium hypochlorite concentrations on the accuracy of an apex locating device.

This study aimed to evaluate Root ZX accuracy with different NaOCl concentrations and to observe effects of the alginate model when NaOCl was used in the canal during electronic measurements. Fifty extracted single-rooted, single-canal human teeth were used in five experimental groups. NaOCl concentrations of 5.25%, 2.65%, 1.00%, and 0.50%, respectively, were injected into the root canals of teeth in four groups and distilled water in control group 5. After measuring root lengths with Root ZX, the files were locked in place. There were no statistically significant differences among all the groups (p > 0.95) when evaluating the distance of the file tips and apical constriction or for the distance from file tip to apical foramen. Root ZX could be used in root canal length measurements with various NaOCl concentrations. Designation of apical constriction needs more care. The alginate model could be used for in vitro electronic measurements with various NaOCl concentrations.