The effect of impacted third molars on second molar external root resorption, a cross-sectional cone beam computed tomography study.

BACKGROUND: Third molars have the highest prevalence of impaction in teeth and can cause pathological damage on the adjacent second molars. This study aims to evaluate the effects of factors related to impacted third molars on external root resorption (ERR) in adjacent second molars using cone-beam computed tomography (CBCT). MATERIAL AND METHODS: In CBCTs, the effect of impacted third molars on the root surface of adjacent second molars was investigated. Inclusion criteria for subjects were being older than 16 and younger than 55, presence of at least one impacted third molar and adjacent second molar. Exclusion criteria were pathology, a follicle gap greater than 5 mm, crowned second molar, severe decay, an artifact on a radiologic image, and previous surgery on the second or third molars. The investigations were made based on age range, gender, tooth inclination, Pell-Gregory classification, retention type, contact area, root formation, pericoronal width, and tooth absence on the same quadrant for potential risk factors. The collected data were statistically analyzed with R software. The Chi-Square test was used to find out any significant difference. Logistic regression analyses were done for potential risk factors for ERR. RESULTS: A total of 437 impacted third molars and adjacent second molars were investigated using CBCT. Of these, 381 met the inclusion criteria. Mesioangular and horizontal inclination, Pell-Gregory Class B-C, contact area, and retention type were found the statistically potential risk factors for ERR. CONCLUSIONS: The impacted third molar with horizontal or mesioangular position, and osseous retention, with Pell and Gregory Class B and C, are more likely to cause external root resorption in adjacent second molars.

The efficiency of different irrigation solutions and techniques for the removal of triple antibiotic paste from simulated immature root canals.

INTRODUCTION: The purpose of this study was to evaluate the efficiencies of different irrigation protocols in the removal of triple antibiotic paste (TAP) from root canals. MATERIALS AND METHODS: A total of 127 extracted human maxillary incisor teeth were prepared. Then, root-end resection of 3 mm was accomplished to simulate immature apex model. The root canals were filled with TAP, after 21 days, randomly divided into nine groups according to irrigation systems and solutions (n = 13). Conventional irrigation (CI) groups - Group 1: Root canal irrigation was performed with CI by Peracetic acid (PAA) solution, Group 2: Root canal irrigation was performed with CI by etidronic acid 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) + sodium hypochlorite (NaOCl) solution, Group 3: Root canal irrigation was performed with CI by ethylenediaminetetraacetic acid (EDTA)/NaOCl solutions. Vibringe system groups - Group 4: Root canal irrigation was performed with Vibringe system by PAA solution, Group 5: Root canal irrigation was performed with Vibringe system by HEBP + NaOCl solution, Group 6: Root canal irrigation was performed with Vibringe system by EDTA/NaOCl solution. EndoVac system groups - Group 7: Root canal irrigation was performed with EndoVac system by PAA solution, Group 8: Root canal irrigation was performed with EndoVac system by HEBP + NaOCl solution, Group 9: Root canal irrigation was performed with EndoVac system by EDTA/NaOCl solution. Control Group: (n = 0). Samples were sectioned vertically, and the amount of remaining medicament was scored for each root half and data were statistically analyzed. RESULTS: Among the irrigation systems, CI groups showed the highest scores at both apical and coronal parts (P < 0.05). In comparisons among the solutions, at the apical part, PAA groups showed the highest scores (P < 0.05). At the coronal part, EDTA + NaOCl groups showed the lowest score values (P < 0.05). CONCLUSION: The use of irrigation systems improved the removal of TAP from the simulated immature root canals. Also, as an irrigation solution EDTA gives more promising results than PAA and HEBP solutions.

Laboratory comparison of cyclic fatigue resistance of WaveOne Gold, Reciproc and WaveOne files in canals with a double curvature.

AIM: To compare the resistance to cyclic fatigue of WaveOne Gold (WOG), Reciproc and WaveOne (WO) nickel-titanium files in an artificial root canal with a double (S-shaped) curvature. METHODOLOGY: A total of 120 new WOG primary, Reciproc R25 and WO primary files were tested in an artificial, stainless steel canal with an S-shape (diameter, 1.4 mm and length, 18 mm). Forty files from each system were rotated until fracture to calculate the number of cycles to failure (NCF). The length of each fractured fragment was recorded. Data were analysed using one-way analysis of variance and Tukey's post hoc tests. RESULTS: The WOG primary (apical curvature: 928.87 ± 293.69; coronal curvature 1102.32 ±397.39 NCF) had higher cyclic fatigue resistance than Reciproc R25 and WO primary in the apical and coronal curvatures (P < 0.05). The Reciproc R25 file (745.63 ± 253.49 NCF) had significantly greater cyclic fatigue resistance than the WO primary (583.89 ± 183.38 NCF) in the apical curvature (P < 0.05). There was no significant difference in the cyclic fatigue resistance of the Reciproc R25 and WO files in the coronal curvature (883.63 ± 282.56 and 916.53 ± 268.21 NCF, respectively) (P > 0.05). There was no difference in fractured fragment lengths of the WOG primary, Reciproc R25, and WO primary files in either the apical or coronal curvature (P > 0.05). CONCLUSIONS: WaveOne Gold primary files exhibited greater cyclic fatigue resistance than Reciproc R25 and WO primary in an artificial canal with an S-shape.

Comparative evaluation of cyclic fatigue resistance of D-RaCe and ProTaper retreatment instruments in curved artificial canals.

AIM: To compare the cyclic fatigue resistance of D-RaCe and ProTaper rotary nickel-titanium (NiTi) retreatment files when used in curved artificial canals. METHODOLOGY: A total of 120 new D-RaCe DR2 and ProTaper D3 retreatment files were tested in stainless steel artificial canals having 45° and 60° angles of curvature. Thirty instruments of each of the file systems were tested in both angles of curvature (n = 30). The retreatment instruments were rotated until fracture to calculate the number of cycles to failure. The length of each fractured fragment was recorded. Data were analysed by independent sample t-test. Fractured surfaces of the instruments were analysed by scanning electron microscopy. RESULTS: In the canal with 45° angle of curvature, no significant difference was observed between the retreatment systems (P > 0.05); on the other hand, in the canal with 60° angle of curvature, D-RaCe DR2 instruments had greater cyclic fatigue resistance than ProTaper D3 (P < 0.05). No difference was observed between the retreatment instruments regarding the lengths of fractured fragments (P > 0.05). The fracture surfaces of the instruments had morphologic characteristics of ductile fracture. CONCLUSIONS: D-RaCe DR2 instrument exhibited greater cyclic fatigue resistance than ProTaper D3 only in root canals with 60° angle of curvature.

Effect of coronal flaring on apical extrusion of debris during root canal instrumentation using single-file systems.

AIM: To evaluate the effect of coronal flaring on the amount of debris extruded apically during root canal preparation using the Reciproc, WaveOne (WO) and OneShape (OS) single-file systems. METHODOLOGY: Ninety extracted single-rooted mandibular incisor teeth were randomly assigned to six groups (n = 15 for each group) for canal instrumentation. Endodontic access cavities were prepared in each tooth. In three of the six groups, coronal flaring was not performed; coronal flaring was performed with Gates-Glidden drills on all teeth in the remaining three groups. The canals were then instrumented with one or other of the following single-file instrument systems: Reciproc, WO and OS. Debris extruded apically during instrumentation was collected into pre-weighed Eppendorf tubes. The tubes were then stored in an incubator at 70 °C for 5 days. The weight of the dry extruded debris was established by subtracting the pre-instrumentation and post-instrumentation weight of the Eppendorf tubes for each group. Data were analysed using one-way analysis of variance (anova) and Tukey's post hoc tests (P = 0.05). RESULTS: Reciproc and WO files without coronal flaring produced significantly more debris compared with the other groups (P < 0.05). There was no significant difference in apical extrusion of debris amongst the other groups (P > 0.05). CONCLUSIONS: All single-file systems caused apical extrusion of debris. Performing coronal flaring prior to canal preparation reduced the amount of apically extruded debris when using Reciproc or WO systems.

Influence of a glide path on apical extrusion of debris during canal preparation using single-file systems in curved canals.

AIM: To evaluate the effect of a glide path on the amount of apically extruded debris during canal preparation using single-file systems in curved canals. METHODOLOGY: Ninety extracted mandibular molar teeth were randomly assigned to six groups (n = 15 for each group) for canal instrumentation. Endodontic access cavities were prepared in each tooth. In three of the six groups, a glide path was not created whereas a glide path was created using PathFile instruments on the mesial canals of all teeth in the remaining three groups. The mesial canals of the teeth were then instrumented with the following single-file instrument systems: WaveOne, Reciproc and OneShape. Debris extruded apically during instrumentation was collected into pre-weighed Eppendorf tubes. The tubes were then stored in an incubator at 70 °C for 5 days. The weight of the dry extruded debris was established by subtracting the pre-instrumentation and post-instrumentation weight of the Eppendorf tubes for each group. The data obtained were analysed using one-way analysis of variance (anova) and Tukey's post hoc tests. RESULTS: The OneShape file was associated with less debris extrusion than the Reciproc and WaveOne files when canal instrumentation was performed without a glide path (P < 0.05). However, no significant difference was found between the Reciproc and WaveOne files (P > 0.05). There was no significant difference amongst the OneShape, Reciproc and WaveOne files when a glide path was created before canal preparation in curved root canals (P > 0.05). All systems extruded significantly less debris in groups with a glide path than in groups without a glide path (P < 0.05). CONCLUSIONS: All instruments were associated with apical extrusion of debris. Creating a glide path prior to canal instrumentation reduced the amount of apically extruded debris in curved canals.

Apically extruded debris during root canal preparation using Vortex Blue, K3XF, ProTaper Next and Reciproc instruments.

AIM: To assess the amount of debris extruded apically during root canal preparation using various nickel-titanium instrumentation systems. METHODOLOGY: Sixty extracted single-rooted mandibular premolar human teeth were randomly assigned to four groups (n = 15 teeth for each group). The canals were then instrumented with the following instrument systems: Vortex Blue (VB; Dentsply Tulsa Dental, Tulsa, OK, USA), K3XF (SybronEndo, Orange, CA, USA), Reciproc (VDW, Munich, Germany) and ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland). Apically extruded debris during instrumentation was collected into pre-weighed Eppendorf tubes. The Eppendorf tubes were then stored in an incubator at 70 °C for 5 days. The weight of the dry extruded debris was established by subtracting the pre-instrumentation and post-instrumentation weight of the Eppendorf tubes for each group. The data were analysed using one-way analysis of variance (anova) and Tukey's post hoc tests. RESULTS: Vortex Blue and PTN files were associated with significantly less apically extruded debris than the K3XF and Reciproc files (P < 0.05), but there was no significant difference between the VB and PTN files or between the K3XF and Reciproc files (P > 0.05). CONCLUSIONS: All instruments were associated with apical extrusion of debris. VB and PTN files were associated with less debris extrusion compared to the other systems.

Efficacy of different irrigation techniques in the removal of calcium hydroxide from a simulated internal root resorption cavity.

AIM: To evaluate the efficacy of six irrigation techniques to remove calcium hydroxide (CH) from a simulated internal root resorption cavity. METHODOLOGY: The root canals of 100 single-rooted teeth were prepared using the ProTaper system to size F5. The roots were split longitudinally, and standardized simulated internal root resorption cavities were prepared in the two root halves. The root halves were reassembled, and CH was placed into the root canals, with the exception of five teeth that served as the negative control group. Another five teeth (the positive control group) were not subjected to the CH removal procedure. Ninety teeth were randomly divided into six experimental groups (n = 15), according to the final irrigation techniques used: conventional syringe irrigation (CSI), CanalBrush (CB), passive ultrasonic irrigation (PUI), self-adjusting file (SAF) system, EndoActivator (EA), and apical negative pressure irrigation (EndoVac system). Five millilitres of 3% NaOCl and 17% EDTA were used in all experimental groups during the CH removal procedure. The amount of remaining CH was evaluated under a stereomicroscope at 20 ×magnification, using a 4-grade scoring system. The data were statistically compared using the Kruskal-Wallis and Mann-Whitney U-tests (P < 0.05). RESULTS: Remnants of CH in simulated internal root resorption cavities were found in all experimental groups. SAF and PUI were superior to the other groups (P < 0.05); however, there was no significant difference between the SAF and PUI (P > 0.05). There were also no significant differences between the CSI, CB, EA and EndoVac groups (P > 0.05). CONCLUSIONS: None of the irrigation techniques was able to completely remove CH from a simulated internal root resorption cavity.