The solubility, pH value, chemical structure, radiopacity, and cytotoxicity of four different root canal sealers: an in vitro study.

OBJECTIVE: The aim of this study was to investigate solubility, pH value, chemical structure, radiopacity, and cytotoxicity of AH Plus BC, TotalFill BC, AH Plus, and AH Plus Jet sealers. MATERIALS AND METHODS: Cytotoxicity analysis with direct and extraction tests at 3 different concentrations (1:1, 1:2, 1:4 v/v%) and time (24 h, 48 h, and 72 h) on Saos-2, PdLF, and THP-1 cell lines, chemical structure with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analysis, solubility, pH, and radiopacity values of AH Plus BC, TotalFill BC, AH Plus, and AH Plus Jet were evaluated. For statistical analyses of the groups, repeated measures, factorial, and one-way ANOVA tests were used. The statistical significance level was set at p < .05. RESULTS: Resin-based sealers showed higher cytotoxicity values than the bioceramic-based sealers (p < 0.05). Time and concentrations were effective on the cell viabilities for cell lines. Higher peaks of calcium were detected bioceramic-based sealers and higher amount of zirconium was detected in AH Plus BC (p < 0.05). AH Plus BC showed similar radiopacity value with AH Plus, AH Plus Jet, whereas TotalFill BC showed the lowest radiopacity (p < 0.05). Bioceramic-based sealers had higher pH values in all experiment periods, and the difference between resin- and bioceramic-based sealer groups was significant (p < 0.05). However, the solubility values of the tested root canal sealers revealed no differences (p > 0.05). CONCLUSIONS: The newly produced AH Plus BC Sealer showed similar properties with TotalFill BC, and their biological properties were better than AH Plus and AH Plus Jet. CLINICAL RELEVANCE: AH Plus BC could be a possible alternative to other bioceramic- or resin-based sealers.

Assessment of the validity and reliability of a novel dental trauma index.

BACKGROUND/AIMS: Traumatic dental injuries (TDI) are one of the most commonly encountered dental health complications. In order to standardize the evaluations and compare the findings of TDI, a carefully defined dental trauma index may serve as a good tool for the correct recording of dental trauma. A new dental trauma index, the Modified Eden & Baysal dental trauma index (MEBTI), has been introduced. It is an expanded index to record soft tissue injuries in addition to dental injuries. The aim of this study was to assess the validity and reliability of the MEBDTI. MATERIALS AND METHODS: The archival data of 20 patients with different traumatic injuries were selected. A web-based form including the radiographs and photographs of selected cases was created. Following a training session, 12 dentists with a minimum of 10 years of clinical experience were asked to score the cases using the MEBDTI on an online form. The Kolmogorov-Smirnov test was used to test the normality. The Kruskal-Wallis Test was used for intergroup comparisons. Inter-observer agreement was investigated by reliability analysis. The intraclass correlation coefficient (ICC) was used to evaluate the agreement among observers. The Chi-Square test of independence was used to determine if there is a significant relationship between two nominal variables (p < .05). RESULTS: The rate of correctly assessing the alveolar bone fracture was 96.9% followed by apex maturity (92.7%), root fracture (85.4%), luxation injury (76.5%), crown fracture (76.2%), and soft tissue injury (50%). Considering all parameters, the soft tissue injuries were statistically different in terms of the answers given by the 12 dentists (p < .05). CONCLUSION: The accuracy of the scores of participants was high and in accordance with each other except for the identification of soft tissue injuries. In favor of this novel index, the data on dental trauma cases could be recorded practically and reliably.

A sustainable, self-sufficient peer review algorithm for health-related YouTube videos: A proposal.

YouTube has recently become one of the major sources of information in the field of health. Not only healthcare professionals but also laypersons can upload videos to YouTube and this fact creates a significant heterogeneity in the content, viewpoint, and accuracy of the available videos. Particularly, those videos presenting personal experiences and inferences on health problems may not rely on scientific evidence thus create inaccurate information. This commentary aims to propose an algorithm to improve the accuracy and reliability of health-related YouTube videos.

USAGE OF CHLORHEXIDINE AS A FINAL IRRIGANT IN ONE-VISIT ROOT CANAL TREATMENT IN COMPARISON WITH CONVENTIONAL TWO-VISIT ROOT CANAL TREATMENT IN MANDIBULAR MOLARS: A RANDOMIZED CLINICAL TRIAL.

OBJECTIVES: The effectiveness of 1-visit root canal treatment (RCT), especially for teeth with large periapical lesions, are still being debated. Although, the use of chlorhexidine (CHX) as a final irrigant have been recommended to provide an optimized approach in 1-visit RCT, there is limited knowledge about the outcome of 1-visit RCT using CHX as the final irrigant. AIM: The aim of this randomized clinical trial was to evaluate the healing of mandibular molar teeth with large periapical lesions after RCT that was completed in 1 visit using 2% CHX as a final irrigant, comparing the results with a conventional 2-visit RCT as a control group. METHODOLOGY: This study is a prospective, parallel-designed, and single-blinded randomized clinical trial. One-hundred asymptomatic mandibular molar teeth with large periapical lesions were randomly assigned to 2 groups. All teeth were instrumented with Reciproc files with 2.5% sodium hypochloride (NaOCl) and 5% ethylenediaminetetraacetic acid (EDTA) as irrigants. In the intervention group, half of the teeth were treated in 1 visit, receiving an additional final rinse with 2% CHX before obturation; the other half of the teeth, however, were treated in 2 visits with calcium hydroxide (CH) dressings, in the control group. All root canals were obturated with Reciproc gutta-percha cones and AH Plus root canal sealer. All patients were recalled and investigated clinically and radiographically for 48 months. Periapical healing was evaluated statistically using the Mann-Whitney U test, followed by the Friedman and the Wilcoxon tests (α = 0.05). RESULTS: During the 48-month follow-up process, 86 teeth (44 in 1-visit and 42 in 2-visit group) were examined. There were no significant differences between the 2 groups regarding the radiographic healing rates (1-visit group 91% and 2-visit group 88%) (P > .05). CONCLUSION: In this study, 1-visit RCT using 2% CHX as final irrigant in asymptomatic mandibular molars with large periapical lesions produced favorable healing results, similar to 2-visit root canal treatment with calcium hydroxide.

Quality of root canal treatment performed by undergraduate students using nickel-titanium reciprocating versus hand instruments.

PURPOSE: To compare the technical quality of root canal treatment (RCT) depending on the incidence of procedural errors performed by undergraduate students using nickel-titanium reciprocating and conventional hand instrumentation techniques, and to assess the impact of case difficulty and localization of the teeth (maxillary or mandibular molars). METHODS: Dental records and periapical radiographs of molars that were treated with either hand or reciprocating WaveOne (WO) instruments were evaluated retrospectively. The technical quality of RCTs, the incidence of ledge formation, perforation, instrument fracture, overinstrumentation, underfilling, overfilling, inadequate root canal filling, and the effects of case difficulty and tooth localization were compared using the chi-square test with a significance of 5% (α = 0.05). RESULTS: While overinstrumentation was more frequent in the WO group (247 teeth), the incidence of inadequate root canal fillings was higher in the hand instrumentation group (245 teeth) (p < 0.01). No significant difference was observed in the incidence of other procedural errors (p > 0.05). The number of teeth with acceptable technical quality in preparation and obturation was 172 (69.6%) in the WO group, whereas it was 142 (58%) in the hand instrumentation group, presenting a significant difference between the instrumentation techniques (p < 0.01). Higher technical quality rates were observed with WO instrumentation in the high difficulty category and in maxillary teeth (p < 0.01). CONCLUSION: Higher technical quality in preparation and obturation can be achieved with WO reciprocating instruments and file-matched greater tapered gutta-percha cones. No significant difference was observed between the groups in the incidence of procedural errors except for overinstrumentation and insufficient root canal filling. WO instrumentation and obturation with file-matched greater tapered gutta-percha cones provided better technical quality in the high difficulty category and in maxillary teeth.

IL-1ß, IL-6 and TNF-α expression levels of macrophage cells induced by benzydamine hydrochloride, benzydamine hydrochloride with chitosan, calcium hydroxide and chlorhexidine medicaments: An ELISA study.

The aim of the present study was to evaluate IL-1ß, IL-6 and TNF-α expression levels of macrophage cells induced by benzydamine hydrochloride (BNZ), BNZ with chitosan, calcium hydroxide (CH) and chlorhexidine (CHX) medicaments. Half maximal inhibitory concentrations (IC50) were assessed on THP-1, Saos-2, and CRL-2014 cells using MTT assay. THP-1 cells were differentiated into macrophages with phorbol12-myristate13-acetate and activated with lipopolysaccharide. IL-1ß, IL-6 and TNF-α levels in supernatants were determined using enzyme-linked immunosorbent assay (ELISA). The data were examined with one-way ANOVA and Tukey's multiple comparison test (p=0.05). At the selected concentrations, the cell viability was higher than 50% for chitosan and CH, whereas CHX presented lower IC50 values than BNZ and BNZ+chitosan. According to ELISA results, the lowest IL-1ß, IL-6 and TNF-α values were observed with BNZ+Chitosan 50 µg/mL and BNZ 50 µg/mL. BNZ+chitosan 50 µg/mL combination has revealed promising anti-inflammatory effects. Nevertheless, these findings need to be examined in clinical conditions.

YouTube™ as an information source for regenerative endodontic treatment procedures: Quality and content analysis.

BACKGROUND: Regenerative endodontic procedures (REPs) are one of the most important developments in dental practice, and in the era of Covid 19 pandemic, audio-visual contents of YouTube™ could be an information source for dental students, practitioners and patients. The aim of this study was to evaluate the quality, content and the demographics of YouTube™ videos about REPs. METHODS: A search on YouTube™ was performed for REPs using "endodontic regeneration", "pulp regeneration", "regenerative endodontics", "regenerative endodontic procedures", "revascularization" and "revitalization" keywords. Totally 531 videos were found and 60 videos met the inclusion criteria. Following the assessment of the demographic features of the videos and the viewing rate of the videos were calculated. The content of the videos was evaluated based on the selected headings. The quality of the videos was assessed using the video information, quality index (VIQI), Global Quality Score (GQS) and DISCERN. The statistical analysis was performed using Spearman Correlation and linear regression analysis. RESULTS: Majority of the videos about REPs were created by dental professionals (91.7%). The most commonly covered topic was "clinical application" (76.7%). Total content score showed a positive correlation with total VIQI (r = 0.795; p < 0.001) and GQS (r = 0.952; p < 0.001). There were significant relationships between total content score, duration, GQS, total VIQI score and DISCERN. CONCLUSION: The findings revealed that YouTube™ videos about REPs provide predominantly clinical information about patient chairside practice of REPs and they could be considered as a supplementary information source for dental students and practitioners.

Energy-Dispersive X-Ray Spectrometry Analysis and Radiopacity of Five Different Root Canal Sealers.

Root canal sealers should have optimum adhesion to the root dentin, low cytotoxicity, sufficient radiopacity and high dimensional stability, which depend mainly on their chemical composition. The aims of this study were to evaluate the chemical composition of Syntex (Cerkamed, Stalowa Wola, Poland), Adseal (Meta Biomed, Cheongju-si, Korea), Sealapex (SybronEndo, Scafati, Italy), MTA Fillapex (Angelus, Londrina, Brazil) and GuttaFlow Bioseal (Coltene/Whaledent, Altstätten, Switzerland) and to determine their radiopacity comparatively. Stainless steel molds with an inner diameter of 5 mm and a depth of 2 mm were constructed. Tested root-canal sealers were mixed and poured into the molds. Following setting, digital periapical radiographs of the specimens (n=12) were taken under standard exposure conditions and the mean gray-values of specimens were measured using a computer graphics program. Then the specimens were examined by scanning electron microscopy, and Energy-dispersive X-ray analysis was performed. The data were analyzed using One-way ANOVA followed by Holm-Sidak multi-comparison test (p = 0.05). Sealapex showed higher calcium peak than MTA Fillapex, GuttaFlow Bioseal, Adseal and Syntex sealers. MTA Fillapex contained a highest amount of tungstate. Sealapex presented the highest radiopacity value among the tested materials (p < 0.05), whereas MTA Fillapex was the least radiopaque material (p < 0.05). Each root canal sealer contains different compositions of radiopacifiers including bismuth oxide, calcium tungstate and zirconium oxide. The tested root canal sealers had radiopacity values above the ISO-specified limit. Sealapex was the most radiopaque root canal sealer followed by GuttaFlow Bioseal, Syntex, Adseal and MTA Fillapex.

A prospective cohort study evaluating the outcome of root canal retreatment in symptomatic mandibular first molars with periapical lesions.

AIM: To evaluate the impact of various predictors on the outcome of root canal retreatment in symptomatic mandibular first molars with periapical lesions after a minimum of 2 years. METHODOLOGY: One hundred and twenty previously root canal treated symptomatic mandibular first molars with periapical lesions which were diagnosed as symptomatic apical periodontitis or acute apical abscess with localized intraoral swelling were included. Root canal retreatment was performed by an experienced endodontist using a standardized treatment protocol. The teeth were followed up clinically and radiographically and the radiographic outcome was assessed using a modified periapical index scale (PAI). The cumulative success proportion and the influence of predictors on the outcome of the root canal retreatment were analysed using Kaplan-Meier analyses and log-rank tests, and the hazard ratios for the predictors were also investigated using Univariate Cox Proportional Hazard regression analysis at a significance level of 5%. RESULTS: Of the 120 teeth, 103 teeth were re-examined with an 85% recall rate. The cumulative success rate was 88% in which 64% were healed and 24% were healing, and failure rate was recorded as 12%. None of the preoperative predictors, including age, gender, soft tissue tenderness, intraoral swelling, size of the lesion, PAI score, apical level and density of root canal filling before root canal retreatment, nor intraoperative predictors, such as active exudate drainage, density of root canal filling after root canal retreatment and restoration type had an influence on the outcome of root canal retreatment (p > .05). The only factor that significantly reduced the success rate of root canal retreatment was the apical level of the root canal filling; when it was more than 2 mm short of the radiographic apex in teeth where apical patency was not established, the success was significantly lower (p = .023). CONCLUSIONS: Root canal retreatment in symptomatic mandibular first molars with periapical lesions resulted in a success rate of 88%. None of the predictors had a significant influence on the outcome, except for the apical level of the root canal filling after root canal retreatment with short root fillings being associated with significantly more post-treatment endodontic disease.

Energy-Dispersive X-Ray Spectrometry Analysis and Radiopacity of Five Different Root Canal Sealers

Abstract Root canal sealers should have optimum adhesion to the root dentin, low cytotoxicity, sufficient radiopacity and high dimensional stability, which depend mainly on their chemical composition. The aims of this study were to evaluate the chemical composition of Syntex (Cerkamed, Stalowa Wola, Poland), Adseal (Meta Biomed, Cheongju-si, Korea), Sealapex (SybronEndo, Scafati, Italy), MTA Fillapex (Angelus, Londrina, Brazil) and GuttaFlow Bioseal (Coltene/Whaledent, Altstätten, Switzerland) and to determine their radiopacity comparatively. Stainless steel molds with an inner diameter of 5 mm and a depth of 2 mm were constructed. Tested root-canal sealers were mixed and poured into the molds. Following setting, digital periapical radiographs of the specimens (n=12) were taken under standard exposure conditions and the mean gray-values of specimens were measured using a computer graphics program. Then the specimens were examined by scanning electron microscopy, and Energy-dispersive X-ray analysis was performed. The data were analyzed using One-way ANOVA followed by Holm-Sidak multi-comparison test (p = 0.05). Sealapex showed higher calcium peak than MTA Fillapex, GuttaFlow Bioseal, Adseal and Syntex sealers. MTA Fillapex contained a highest amount of tungstate. Sealapex presented the highest radiopacity value among the tested materials (p < 0.05), whereas MTA Fillapex was the least radiopaque material (p < 0.05). Each root canal sealer contains different compositions of radiopacifiers including bismuth oxide, calcium tungstate and zirconium oxide. The tested root canal sealers had radiopacity values above the ISO-specified limit. Sealapex was the most radiopaque root canal sealer followed by GuttaFlow Bioseal, Syntex, Adseal and MTA Fillapex.

Resumo Os cimentos endodônticos devem conter ótima adesão à dentina radicular, baixa citotoxicidade, radiopacidade suficiente e estabilidade dimensional elevada, que dependem principalmente da sua composição química. Os objetivos deste estudo foram avaliar a composição química de Syntex (Cerkamed, Stalowa Wola, Polônia), Adseal (Meta Biomed, Cheongju-si, Coreia), Sealapex (SybronEndo, Scafati, Itália), MTA Fillapex (Angelus, Londrina, Brasil) e GuttaFlow Bioseal (Coltene/Whaledent, Altstätten, Suíça) e determinar comparativamente a sua radiopacidade. Foram construídos moldes de aço inoxidável com um diâmetro interior de 5 mm e uma profundidade de 2 mm. Os cimentos testados foram misturados e vertidos em moldes. Após a fixação, foram feitas radiografias periapicais digitais dos espécimes (n=12) em condições de exposição padrão e os valores médios de cinza dos espécimes foram medidos utilizando um programa de computação gráfica. Em seguida, as amostras foram examinadas por microscopia eletrônica de varredura, e foi realizada uma análise de raios X dispersiva de energia. Os dados foram analisados utilizando a ANOVA unidirecional seguida do teste de comparação múltipla Holm-Sidak (p = 0,05). O Sealapex mostrou um pico de cálcio mais elevado do que os cimentos MTA Fillapex, GuttaFlow Bioseal, Adseal e Syntex. O MTA Fillapex continha uma quantidade mais elevada de tungstato. O Sealapex apresentou o maior valor de radiopacidade entre os materiais testados (p < 0,05), enquanto que a MTA Fillapex foi o material menos radiopaco (p < 0,05). Cada cimento endodôntico contém diferentes composições de radiopacificadores incluindo óxido de bismuto, tungstato de cálcio e óxido de zircônio. Os cimentos testados apresentaram valores de radiopacidade acima do limite especificado pela ISO. Sealapex foi o cimento obturador mais radiopaco seguido por GuttaFlow Bioseal, Syntex, Adseal e MTA Fillapex.

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.

Evaluation of Postoperative Pain Following Single-Visit Root Canal Treatment with Rotary and Reciprocal Ni-Ti File Systems in Children.

Background and Objectives: Postoperative pain is a common symptom of a flare-up after root canal treatments (RCTs). Insufficient instrumentation, extrusion of irrigation solutions and debris, and the existence of a periapical lesion are the factors affecting postoperative pain after root canal treatments. The aim of this study was to evaluate the postoperative pain and instrumentation time of the single-file reciprocating system and multiple-file Ni-Ti rotary system in children ages 9-12 years old. Materials and Methods: Our study was conducted on 51 permanent mandibular molars with the diagnosis of irreversible pulpitis. Patients were randomly assigned into two groups, and RCTs were completed with either the Reciproc Blue or Protaper NEXT file systems. Instrumentation time for each system was noted, and patients were given a pain scale that included a visual analog scale for 6, 24, 48, and 72 h after treatment. Postoperative pain scores and instrumentation times were analyzed statistically with a chi-square test and Student's t-test. Results: There was no statistically significant difference in postoperative pain between the Reciproc Blue and Protaper NEXT systems at all time intervals. Instrumentation time was significantly shorter in the Reciproc Blue group in comparison with the Protaper NEXT group. Conclusions: Postoperative pain findings following RCT using single-file reciprocating systems were similar to the rotary system group. However, chair time in the reciprocating system group was significantly lower. This provided a comfortable and patient-friendly treatment approach for children, and could enhance their cooperation.

Extra-Short Implants with Osteotome Sinus Floor Elevation: A Prospective Clinical Study.

PURPOSE: The aim of this study was to assess the radiographic and clinical outcomes of extra-short implants either alone or in conjunction with osteotome sinus floor elevation and to compare these with regular-sized implants in the posterior atrophic maxilla. MATERIALS AND METHODS: Systemically healthy, nonsmoker individuals having at least one tooth gap in the posterior maxilla were included in the study. When the residual bone height was < 4 mm, an extra-short implant (4 to 6 mm) in conjunction with osteotome sinus floor elevation was placed; when the residual bone height was between 4 and 7 mm, an extra-short implant alone was placed; and when it was ≥ 8 mm, a regular implant (8 to 10 mm) was placed. The implants were uncovered at 4 months, and porcelain-fused-to-metal crowns were fabricated. Crestal bone level, change in the crestal bone level, crown-to-implant ratio, and residual bone height were measured at baseline and 6 and 18 months postloading. RESULTS: Thirty patients (15 men, 15 women, age range: 30 to 73 years) received 80 implants. One implant in the extra-short implant (n = 27 implants) and regular implant (n = 24 implants) groups and two implants in the extra-short implant with osteotome sinus floor elevation group (n = 29 implants) failed before loading. Crestal bone level was significantly higher in the regular implant group compared with the extra-short implant with osteotome sinus floor elevation group at 18 months (P < .028). Crestal bone level change between 6 and 18 months was significantly lower in the extra-short implant + osteotome sinus floor elevation group compared with the regular implant group (P = .003). There was no correlation between the crestal bone level, crestal bone level change, and prosthetic and implant characteristics (P > .05). CONCLUSION: Extra-short implants placed either in native bone or in conjunction with osteotome sinus floor elevation may provide similar clinical and radiographic outcomes that are comparable to those obtained with regular implants. Both extra-short implant placement methods can be promising noninvasive treatment options for the posterior maxilla, and implant dimension, crown length, crown-to-implant ratio, and residual bone height may not affect the crestal bone level change, at least in the short term.

Cyclic fatigue resistance and energy dispersive X-ray spectroscopy analysis of novel heat-treated nickel-titanium instruments at body temperature.

The aim of this study was to evaluate the cyclic fatigue resistance of Dia-X, WaveOne Gold and One Curve files in a water bath at intracanal temperature (35°C). Thirty-nine instruments Dia-X, WaveOne Gold, and One Curve systems (n = 13) were tested in an artificial canal with a curvature angle of 60° and a radius of 3 mm. A water bath setup at a temperature of 35°C was used to simulate the intracanal temperature and time to fracture (TTF) as seconds was recorded. The mean data were analyzed statistically using one-way ANOVA, and post hoc Tukey test (p = .05). The fractured surface of the instruments was examined with scanning electron microscopy (SEM) and chemical composition of the instruments were investigated with energy dispersive X-ray spectroscopy (EDS). Statistically significant differences were detected in TTF values of all the systems as follows: One Curve > WaveOne Gold > Dia-X (p < .05). One Curve instruments demonstrated the highest TTF values in all the tested instruments. The EDS microanalysis revealed similar NiTi composition of on the surface of One Curve, WaveOne Gold, and Dia-X instruments. The novel manufacturing process, including C-wire heat treatment and the variable cross-section of the One Curve files, could be the main factors affecting the fatigue life of the instruments.

Cyclic Fatigue Resistance of Multiused Reciproc Blue Instruments during Retreatment Procedure.

INTRODUCTION: Root canal retreatment procedure may reduce the mechanical resistance of nickel-titanium instruments and increase the frequency of instrument fracture. The aim of the present study was to evaluate the effect of multiuse of Reciproc Blue R25 instruments on cyclic fatigue resistance during retreatment procedure in mandibular molar teeth. METHODS: Forty-eight Reciproc Blue R25 files were included in the study. In control group, 12 new Reciproc Blue R25 instruments were subjected to cyclic fatigue test by using a stainless steel artificial canal with a 90° angle and 3-mm radius of curvatures. In experimental groups, Reciproc Blue R25 files (n = 12) were used to remove the root canal filling (RCF) material of 1, 2, and 3 molar teeth, respectively. Then cyclic fatigue tests of these 36 instruments were performed. The number of cycles to fracture (NCF) and the length of the fractured fragment were calculated for each instrument. Working time for retreatment procedures was determined in seconds with a digital chronometer. The data were analyzed by using one-way analysis of variance followed by post hoc Tukey test and mixed-effect analysis (P = .05). RESULTS: No significant difference was found between NCF values of new and first time used files (P > .05), but NCF values of new and first time used files were significantly higher than those of second and third time used files (P < .05). The second and third time used files revealed no difference (P > .05). As the number of uses increased, the average time for retreatment procedure statistically extended (P < .05). CONCLUSIONS: Reciproc Blue R25 instrument can be used to remove RCF material of 2 molar teeth. However, because of its decreased NCF values, multiple use over 2 molars may not be suggested.

Efficacy of Two Different Nickel-Titanium Rotary Systems in Retreatment Procedure With or Without Laser-Activated Irrigation: An In Vitro Study.

Objective: The aim of this study was to compare the efficacy of HyFlex EDM (Coltene/Whaledent, Altstätten, Switzerland) and ProTaper Universal Retreatment Nickel-Titanium (NiTi) Systems [The ProTaper Universal Retreatment (PTR), Dentsply Maillefer, Ballaigues, Switzerland] in the removal of the root canal filling materials with or without laser activated irrigation. Materials and methods: The root canals of 60 human mandibular premolars were instrumented with K files up to size 35 at a working length; the step-back procedure was performed in 1 mm increments up to size 50. Next, the teeth were obturated using the lateral compaction technique with gutta-percha and resin-based sealer, and they were randomly divided into two groups (n = 30) according to the retreatment systems: PTR and HyFlex EDM NiTi rotary files. Then, each group was divided into two subgroups (n = 15), laser [photon-induced photo-acoustic streaming (PIPS); Fotona, Ljubljana, Slovenia] activated irrigation and conventional needle irrigation group. Following these procedures, the specimens were evaluated using micro-computed tomography. Results: There was no significant difference between the instrumentation systems regarding the cleaning efficacy (χ2 = 0.754; p = 0.86). Additionally, PIPS method did not have a significant effect on the removal of the filling material compared to conventional needle irrigation. Conclusions: Both instrumentation systems were effective in removing the filling material, but neither was able to remove the filling material completely. PIPS method did not show a significant additional effect regarding the removal of filling material.

Cyclic Fatigue Resistance of Novel Glide Path Instruments with Different Alloy Properties and Kinematics.

INTRODUCTION: The aim of the present study was to evaluate the cyclic fatigue resistance of the WaveOne Gold Glider (Dentsply Maillefer, Ballaigues, Switzerland), R-Pilot (VDW, Munich, Germany), and ProGlider (Dentsply Maillefer) glide path instruments. METHODS: Ten instruments from each glide path system were included in the study. A stainless steel artificial canal with a 90° angle and a 3-mm radius of curvature was used for the testing process. The working lengths of the instruments were fixed at 19 mm, and the instruments were operated using an endodontic motor (X-Smart Plus, Dentsply Maillefer) at recommended setting for each. A digital camera (Sony HDR-XR260; Sony Corporation, Minato, Tokyo, Japan) was positioned on the top of the cyclic fatigue test device, and the time to fracture was recorded in seconds by means of the video camera. For each instrument, the number of cycles to failure was calculated, and the length of the fractured fragment was measured. The data were analyzed using 1-way analysis of variance followed by the post hoc Tukey test. RESULTS: Statistically significant differences in the number of cycles to failure values were observed across the tested groups; the ranking of the instruments was as follows: WaveOne Gold Glider > R Pilot > ProGlider (P < .05). There was no significant difference in the mean length of the fractured fragment of the instruments (P > .05). CONCLUSIONS: Within the limitations of the present study, it can be concluded that improved alloy properties and reciprocating motion could enhance the cyclic fatigue resistance of glide path instruments.

Radiopacity of Esthetic Post Materials: Evaluation with Digital Analysis Technique.

PURPOSE: To evaluate the radiopacity of five post materials using a digital image analysis method. MATERIALS AND METHODS: Twelve specimens from each post type (two zirconia and three fiber based) of 2 mm in thickness were obtained using a diamond blade mounted on a cutting machine, and digital radiographs were taken along with aluminum step-wedge and dentin discs under standard exposure conditions. The mean gray-values of specimens were measured using a computer graphics program. Data were analyzed using one-way ANOVA followed by Holm-Sidak multicomparison test (p = 0.05). RESULTS: The highest radiopacity was observed in custom zirconia (5.842 millimeters of equivalent Al [mmAl]), and the lowest value was detected with FRC-Postec (Ivoclar Vivadent) (1.716 mmAl). Significant differences were revealed between the radiopacity values among all groups (p < 0.05), except the Zr post materials (p = 0.56). CONCLUSIONS: All tested post materials had higher radiopacity than dentin. Further studies will be required to clarify optimum radiopacity properties of the post materials to provide a precise clinical observation.

Comparative evaluation of cyclic fatigue resistance of four different nickel-titanium rotary files with different cross-sectional designs and alloy properties.

OBJECTIVE: The purpose of the present study was to evaluate the cyclic fatigue resistance of F6 SkyTaper (Komet Brasseler, Lemgo, Germany), K3XF (SybronEndo, Orange, CA, USA), new generation OneShape (Micro Mega, Besancon, France) and TRUShape 3D conforming files (Dentsply Tulsa Dental Specialties, Tulsa, OK, USA). MATERIAL AND METHODS: Ten instruments from each group were selected and allowed to rotate using a low-torque motor in a stainless steel block with 1.5 mm diameter, 3 mm radius of 60° angle of curvature at the manufacturer's recommended speed, and the number of cycles (NCF) from the beginning to the fracture was recorded. The data were analyzed using one-way ANOVA followed by post-hoc Tukey's test (P = 0.05). RESULTS: The ranking of the groups from the highest to the lowest NCF was as follows: F6 SkyTaper (959 ± 92), K3XF (725 ± 71), TRUShape (575 ± 84) and OneShape (289 ± 58). Statistically significant differences were detected between all groups (P < 0.05). CONCLUSION: Within the limitations of this study, F6 SkyTaper instruments presented the highest cyclic fatigue resistance among the tested instruments. The S-shaped cross-sectional design of F6 SkyTaper instruments could be the most important factor on the superior cyclic life span of these instruments. CLINICAL RELEVANCE: In endodontic practice, preferring the instruments with higher cyclic fatigue resistance would help to minimize the risk of instrument fractures; therefore especially during the preparation of curved canals, instruments with smaller core area and less cross-sectional metal mass, which could lead higher flexibility, can be proposed.

Evaluation of the Cyclic Fatigue and Torsional Resistance of Novel Nickel-Titanium Rotary Files with Various Alloy Properties.

INTRODUCTION: The purpose of this study was to evaluate the cyclic fatigue and torsional resistance of Hyflex EDM, ProTaper Gold (PTG), and ProTaper Universal (PTU) instruments. METHODS: For the cyclic fatigue test, 10 instruments from each group were tested by using a stainless steel block with 1.5-mm diameter and 3-mm radius of 60° angle of curvature. The instruments were allowed to rotate by using a low-torque motor, and number of cycles from the beginning to the fracture was recorded. Torsional resistance of the instruments (n = 10) was evaluated according to ISO 3630-1. The rotational speed of the instruments was set in the clockwise direction at 2 rpm. The maximum torque and angular deflection until fracture of the instrument were recorded. The data were analyzed by using one-way analysis of variance followed by post hoc Tukey test (P = .05). RESULTS: HyFlex EDM instruments exhibited the highest cyclic fatigue resistance and were followed by PTG and PTU groups, respectively. The mean fragment length for PTU instruments was significantly shorter than that for Hyflex EDM and PTG instruments. PTG instruments demonstrated significantly higher torsional resistance than HyFlex EDM files (P = .025), and the distortion angle of the instruments ranged as follows: PTU < PTG < Hyflex EDM files. CONCLUSIONS: Hyflex EDM files demonstrated significantly higher cyclic fatigue resistance. Although PTG and PTU have similar cross-sectional design, PTG instruments presented higher cyclic fatigue and torsional resistance than PTU instruments. The enhanced alloy properties of PTG might be considered as the main reason for those differences.