Apical extrusion of sodium hypochlorite activated with two laser systems and ultrasonics: a spectrophotometric analysis.

BACKGROUND: The aim of the present study was to compare the effect of ultrasonically or laser (Nd:YAG or diode) activated irrigation on the irrigating solution extrusion compared to non-activated syringe irrigation. METHODS: Extracted mandibular premolar teeth (n = 48) with single canals were instrumented. The teeth were secured through the lid of an Eppendorf tube filled with 1.0 mL distilled water to collect the apically extruded irrigating solution. The teeth were randomly divided into four groups: non-activated syringe irrigation, diode laser, Nd:YAG laser and passive ultrasonic irrigation (PUI) using 2% NaOCl. The irrigating solution extruded through the apical foramen was collected in the Eppendorf tube and evaluated by a chemical reaction with using a spectrophotometer. The data was analyzed using one-way ANOVA and Tukey's post hoc test (α = 0.05). RESULTS: All the groups showed apically extruded irrigating solution. There were significant differences among the groups (p < 0.05). Nd:YAG laser activated irrigation showed greater extrusion (p < 0.05), while the non-activated syringe irrigation showed less extrusion (p < 0.05). Only the difference between diode laser and PUI was not statistically significant (p > 0.05). CONCLUSION: Within the limitations of this in vitro study, the researchers concluded that non-activated syringe irrigation caused less apically extruded irrigating solution than PUI and LAI using Nd:YAG or diode lasers.

Evaluation of surface alterations in different retreatment nickel-titanium files: AFM and SEM study.

The aim of this study was to evaluate the surface changes of nickel titanium (Ni-Ti) rotary retreatment files after three and five uses. Furthermore, the effects of 2% sodium hypochlorite and chloroform solutions and sterilization procedures on the NiTi rotary retreatment surfaces were investigated. ProTaper Retreatment files, R-endo files, and Mtwo retreatment files were used for this study. The palatinal roots of maxillary molar teeth were obturated with gutta percha and Ah26. Retreatment procedures were performed with these retreatment file systems. The surface changes of untreated NiTi rotary files that were used three and five times, immersed in NaOCl and chloroform and subjected to sterilization procedures were investigated with atomic force microscopy (AFM) and scanning electron microscopy (SEM). The RMS values, three dimensional images and SEM images at various magnifications were obtained. RMS values showed that all three NiTi rotary retreatment file systems showed significant deteriorations after three and five uses. Cracks, damages and spiral construction deteriorations were detected in the SEM images after three and five uses. Furthermore, the Mtwo 15 file was broken off after five uses. AFM data indicated that 2% NaOCl caused significant surface deteriorations on NiTi rotary files and both AFM and SEM evaluation showed that chloroform solution and sterilization procedures did not cause significant surface deteriorations. In conclusion, ProTaper retreatment, R-endo, and Mtwo retreatment files showed surface damages depending on retreatment procedures. Clinicians have to consider that retreatment files always have a tendency to break off after the third time they have been used.

Effects of different irrigation solutions on root dentine microhardness, smear layer removal and erosion.

This study aimed to compare the effects of different irrigants on root dentine microhardness, erosion and smear layer removal. A total of 72 root dentine slices were divided into six groups, according to the final irrigants used: Group 1: 17% ethylenediamine tetra-acetic acid (EDTA) + 2.5% NaOCl, Group 2: 7% maleic acid (MA) + 2.5% sodium hypochloride (NaOCl), Group 3: 1.3% NaOCl + mixture of tetracycline, acid and detergent (MTAD), Group 4: Smear Clear + 2.5% NaOCl, Group 5: 5% NaOCl, Group 6: saline. Vickers microhardness values were measured before and after treatment. In total, 42 root-halves were prepared for scanning electron microscope to evaluate the amount of smear and erosion in the coronal, middle and apical thirds. Data were analysed using two-way anova, Duncan and two-proportion z-tests. Maleic acid showed the greatest reduction in dentine microhardness (P < 0.05), followed by EDTA and MTAD. EDTA, maleic acid, MTAD and Smear Clear removed smear layer efficiently in the coronal and middle thirds of root canal. However, in the apical region, maleic acid showed more efficient removal of the smear layer than the other irrigants (P < 0.05).

Effect of post-space treatments on the push-out bond strength and failure modes of glass fibre posts.

The aim of this study was to evaluate the effect of different post-space treatments on the push-out bond strength and failure modes of glass fibre posts. Forty mandibular premolar roots were cut and endodontically treated. Post spaces were prepared and roots were divided into four groups. In group 1 distilled water irrigation (control), in group 2 2.25% NaOCl irrigation, in group 3 2.25% NaOCl + 17% EDTA irrigation were done and in group 4 diode laser was applied to the prepared post spaces. Scanning electron microscope (SEM) analysis was made for each group. Fibre posts were then luted with resin cement. Each root was prepared for push-out test. Data were statistically analysed with anova (P = 0.05). After push-out test, the failure modes were observed but not statistically analysed. There were statistically significant differences between Group 3 and Group 2 in both regions (P < 0.05), also in the middle region of Group 4 and Group 2 (P < 0.05). Cervical root segments showed higher bond strengths than middle ones in all groups (P < 0.05). The highest bond strength values were obtained from NaOCl/EDTA and the lowest bond strength values were obtained from NaOCl for both regions.

Determination of the effect of Nd:YAG laser irradiation through dentinal tubules on several oral pathogens.

The effects of Nd:YAG laser irradiations at different power settings on several oral pathogens were evaluated. A total of 252 dentin samples were divided into seven groups consisting of 36 dentin specimens each. In each group, 9 of the 36 specimens were used as controls, thereby including a control in every group. The remaining 27 specimens were divided into three subgroups consisting of nine specimens according to different Nd:YAG laser settings (1.5, 1.8, and 2 W). Each group was inoculated on the nonpulpal side with one of the following microorganisms: Candida glabrata, Candida tropicalis, Candida krusei, Candida sake, Candida lusitaniae, Candida kefyr, and Rhodotorula mucilaginosa. The following irradiation procedure was used: the specimens were irradiated on the bacteria-free side (the side consisting of the pulpal wall) using contact mode under the constant scanning movement of the optical fiber at an angle of 10°. One lasing cycle consisted of four irradiation cycles of 10 s each, with 15-s intervals in between each irradiation cycle. The remainder of the controls and the lased specimens of each group were prepared for the microbiological investigation. After incubation for 24 h at 37 °C, the colonies were counted, and the total number of surviving microorganisms was statistically assessed. Microorganisms irradiated with Nd:YAG laser at power settings 2 W, 15 pps did not survive. Although there was a significant reduction of microorganisms at 1.5 and 1.8 W, when comparing Nd:YAG laser irradiation with the control group, sterilization did not occur.

The effect of the application of gaseous ozone and ND:YAG laser on glass-fibre post bond strength.

The aim of this study was to investigate the effects of the application of gaseous ozone and Nd:YAG laser on glass-fibre post bond strength. Forty-two madibular premolar roots were cut, endodontically instrumented and irrigated with 2.5% NaOCl. Post spaces were prepared and roots were divided into three groups (n = 14). The antimicrobial pretreatment was conducted as follows: gaseous ozone, Nd:YAG laser and control (no additional disinfection methods). Scanning electron microscope analysis was made for each group (n = 2). A resin cement was used for luting the posts. For push-out test, each root was cut horizontally (two cervical, two middle and two apical). Statistical analyses were performed with one-way anova (α = 0.05). Fracture types were observed. There was no statistically significant difference between the groups (P > 0.05). There were statistically significant differences in cervical and apical segments of laser and control groups (P < 0.05). The disinfection of the post spaces with Nd:YAG laser and ozone had no adverse effects on bond strength of glass-fibre post.

Effect of light-activated bleaching on pulp chamber temperature rise: an in vitro study.

This study aimed to compare the pulp chamber temperature changes that occur with the use of different light sources during vital bleaching with and without application of bleaching agents. One hundred and forty-four mandibular incisor teeth were divided into four groups (n = 36) according to the use of halogen light, light-emitting diode, 3 W and 1.5 W diode laser. The teeth in the main groups were divided into three subgroups (n = 12). First subgroup had no bleaching gel application. By White and Whiteness HP were applied with a thickness of 2 mm to the other subgroups respectively. The labial surfaces of the teeth were irradiated with a total time of 20 s. Temperature changes in the pulp chamber were measured and analysed by using anova and Tukey test. The 3 W diode laser induced the highest pulp chamber temperature rise (P = 0.000). Bleaching gel application reduced the temperature changes in the diode laser groups (P < 0.05). Diode laser activation during vital bleaching induces pulp chamber temperature rise, which may cause thermal tissue damage.

Effects of sodium hypochlorite on gutta-percha and Resilon cones: an atomic force microscopy and scanning electron microscopy study.

The aim of this study was to evaluate the effects of 6% sodium hypochlorite (NaOCl) on gutta-percha (GP) and Resilon cones. Six standardized GP and Resilon cones were selected and cut 3mm from their tip. One GP and 1 Resilon cone were used as control samples. Cones were immersed in 6% NaOCl for 1, 5, 10, 20, and 30 minutes, thoroughly rinsed with nanopure water, and dried with filter paper. Then, surface topography was analyzed by atomic force microscopy and scanning electron microscopy coupled to an energy-dispersive x-ray (EDX) spectrometer. According to the root mean square and depth analysis values obtained from atomic force microscopic evalution, there were no significant differences found among the GP groups. However significant differences were found among Resilon cones (P ≤ .05). SEM images and EDX graphics showed that there were no prominent differences between GP and Resilon groups. These results showed that 6% NaOCl solution can be used in the disinfection of GP and Resilon cones. No alterations were observed on the GP cones, but it can change the surface of Resilon cones.

Fracture resistance of premolars with one remaining cavity wall restored using different techniques.

The aim of the study was to compare the fracture resistance of maxillary premolars with one remaining cavity wall restored using different post systems. Forty-eight maxillary premolars were endodontically treated and randomly assigned to four groups for postcore restoration. The first three test groups were restored with polyethylene woven fiber posts, custom-made glass fiber-reinforced composite posts, and titanium posts respectively. In the control Group 4, standardized cavities (3.5 x 1.5 mm) were prepared in the palatal canal entrance and filled with a resin composite. All the specimens were then restored with a resin composite crown seated on the post. Load was applied with a stainless steel ball (1 mm/min), and the failure modes of all specimens were evaluated. There were no significant differences in fracture resistance and failure mode among the different restorative materials (p>0.05). Within the limitations of this in vitro study, it was concluded that the presence and type of post did not influence the fracture load and failure mode of maxillary premolar teeth with one remaining cavity wall.

Fracture resistance of teeth restored with different post systems using new-generation adhesives.

AIM: The aim of this study was to investigate the fracture strength of three post systems cemented with a dual cure composite resin luting cement by using different adhesive systems. METHODS AND MATERIALS: In this study 63 extracted anterior teeth with single roots were endodontically prepared and filled. Teeth were randomly assigned to one of three post systems placed into the prepared canals: Group I - titanium posts (n=21) (Filpost); Group II - glass fiber posts (n=21) (Mirafit White); and Group III zirconia posts (n=21) (CosmoPost). Each group was again randomly divided into three subgroups according to the bonding materials used [Single Bond (n=7), Clearfil SE Bond (n=7), and Prompt L Pop (n=7)]. A dual cured resin cement (Rely X ARC) was used for bonding the posts into the root canals. Standard cores were made by a composite resin (Clearfil Photocore) using core build-ups. The samples were tested in the compression test machine for 1 mm/min and fracture resistance of the teeth were recorded. The data was analyzed by using two-way analysis of variance (ANOVA) and Duncan's New Multiple Range Tests. A significance level of p<.05 was used for all comparisons. RESULTS: There was a significant difference in fracture resistance between the post systems (p<0.05) and the interaction of adhesive resins and post systems (p<0.05). Mirafit White was more resistant to fracture than other groups; Filpost showed the least resistance to fracture. CosmoPost post system bonded with Single Bond recorded the lowest fracture resistance (p<0.05). CONCLUSION: Endodontically treated anterior teeth restored with glass fiber posts exhibited higher failure loads than teeth restored with zirconia and titanium posts. Self-etching adhesives are better alternatives to etch-and-rinse adhesive systems for luting post systems. CLINICAL SIGNIFICANCE: Under the condition of this study, glass fiber posts are preferable to restore endodontically treated anterior teeth.

Staining potential of calcium hydroxide and monochlorophenol following removal of AH26 root canal sealer.

AIM: The focus of this study was to examine the staining potential of calcium hydroxide (Ca(OH)2) on tooth structure following the removal of AH26 root canal sealer. METHODS AND MATERIALS: Fifty maxillary anterior teeth were prepared and obturated with AH26 and gutta percha. The sealers were then removed 24 hours later and the teeth were randomly divided into two groups. Ca(OH)2 was then placed in the root canals of the first group of teeth as a medicament and camphorated monochlorophenol (CMCP) was placed in the second group of teeth after the filling material was removed. The color of the external tooth surfaces was determined before tooth preparation and two weeks after the placement of the medicaments. The Z test was used for statistical analysis. RESULTS: All experimental teeth showed varying degrees of coronal discoloration with the Ca(OH)2 group showing more discoloration than the CMCP group (p<0.05). CONCLUSION: Using Ca(OH)2 as a medicament after removing AH26 caused progressive discoloration of the teeth, whereas using CMCP caused only slight discoloration. CLINICAL SIGNIFICANCE: To avoid staining of the treated tooth, AH26 root canal sealer must be completely removed from the dentin walls before using a medicament.

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.

Effects of Er:YAG laser and Nd:YAG laser treatment on the root canal dentin of human teeth: a SEM study.

The objective of the study was to observe the morphological changes on root canal dentin after Er:YAG laser and Nd:YAG laser treatment. Twenty-one teeth biomechanically prepared were divided into three groups with seven teeth of each. Group A was unlased as a control. In group B, Er:YAG laser and in group C, Nd:YAG laser was applied to the root canal dentin. The roots were split longitudinally and examined using a scanning electron microscopy for the evaluation of debris, smear layer, and recrystallization. There was no statistically significant difference between the groups. This study indicates that laser beam is not effective in removing debris and smear layer.

Fracture resistance of roots obturated with three different materials.

OBJECTIVE: The aim of this study was to compare the fracture resistance of roots obturated with different materials. STUDY DESIGN: Sixty root canals were instrumented and divided into 4 equal groups (n = 15 each). The root canals in group 1 were filled with AH26 sealer and gutta-percha, in group 2 with Resilon and Epiphany, and in group 3 with Ketac-Endo Aplicap and gutta-percha. Fifteen root canals had no obturation. The force required to fracture was recorded. The data was analyzed with analysis of variance and Duncan test. RESULTS: The mean force of fracture for group 1 was significantly higher than for the other 3 groups (P < .05). There was significant difference between group 2 and group 3 (P < .05). Group 2 and group 3 were not significantly different from the control group (P > .05). CONCLUSION: The use of AH26 + gutta-percha increased the fracture resistance of instrumented root canals compared with Resilon + Epiphany and Ketac-Endo Aplicap + gutta-percha.

Endodontic treatment of a maxillary second molar with 2 palatal roots: a case report.

The incidence of second palatal root in the maxillary second molar is very rare. This case report describes the treatment of a 4-rooted maxillary second molar with 2 distinct palatal roots. Clinical examination and radiographs showed the presence of a second palatal root. After biomechanical preparation, the root canals were filled with gutta-percha cones and AH26 sealer. One year later, the restored tooth and periodontal tissues were healthy both clinically and radiographically.

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.

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.

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.