Osteogenic Differentiation and Proliferation of Apical Papilla Stem Cells Using Chitosan-Coated Nanohydroxyapatite and Bioactive Glass Nanoparticles.

OBJECTIVE: The aim of this study was to evaluate the osteogenic differentiation ability and proliferation of apical papilla stem cells (SCAPs) using chitosan-coated nanohydroxyapatite and bioactive glass nanoparticles. MATERIALS AND METHODS: Hydroxyapatite, chitosan-coated nanohydroxyapatite, and bioactive glass 45S5 nanoparticles were prepared and characterized using a transmission electron microscope and X-ray diffraction. SCAPs were harvested from freshly extracted impacted wisdom teeth, cultured, and characterized using flow cytometric analysis. Tested nanomaterials were mixed and samples were classified into five equal groups as follows: negative control group: SCAP with Dulbecco's modified eagle's medium, positive control group: SCAP with inductive media, first experimental group: nanohydroxyapatite with SCAP, second experimental group: chitosan-coated nanohydroxyapatite with SCAP, third experimental group: bioactive glass nanoparticles with SCAP. Osteoblastic differentiation was assessed using an alkaline phosphatase (ALP) assay. Receptor activator of nuclear factor kappa beta ligand (RANKL) expression was evaluated using specific polyclonal antibodies by fluorescence microscope. The proliferation of SCAP was assessed using cell count and viability of trypan blue in addition to an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. RESULTS: Isolated SCAP showed a nonhematopoietic origin. Chitosan-coated nanohydroxyapatite showed the highest ALP concentration followed by nanobioactive glass, nanohydroxyapatite, and negative control. Chitosan-coated nanohydroxyapatite showed the highest H score followed by nanobioactive glass, nanohydroxyapatite, and negative control in RANKL expression. Chitosan-coated nanohydroxyapatite showed the highest viable cell count. CONCLUSION: SCAP isolation is achievable from extracted fully impacted immature third molars. All tested biomaterials have the ability to induce osteogenic differentiation and proliferation of SCAP. Composite nanoparticle materials show better osteogenic differentiation and proliferation of SCAP than single nanoparticles.

Multiple Endodontic Guides for Root Canal Localization and Preparation in Furcation Perforations: A Report of Two Cases.

Perforations are managed by surgical or nonsurgical approach depending on the relationship of the perforation site to the crestal bone level and attachment apparatus. Relocating the canal orifice or root canal close to the perforation site is quite challenging even with the aid of a dental operating microscope. In these two case reports, guided endodontics was applied in root canal localization and preparation in cases of furcation perforations. This is the report of two patients (42 and 15-year-old, respectively) who were referred for root canal treatment of the mandibular right first molar. The first case complained of pain on biting, foul odor, and bad taste. The referring dentist noted a furcation perforation and an inability to locate the mesial canals. Radiographic examination showed furcation radiolucency. Definitive diagnosis was symptomatic apical periodontitis. The second case complained of severe throbbing pain along with pain on biting. Mesial canals could not be detected due to a furcation perforation as noted by the referring dentist. Radiographic examination revealed a large furcation perforation and related bone resorption. Definitive diagnosis was acute apical abscess. In each case, a silicone impression of the mandibular arch was obtained and scanned along with cone-beam computed tomography scan to plan for localization and preparation of the mesiobuccal canals using implant planning software. Multiple guides were fabricated through rapid prototyping and allowed for the correct orientation and insertion of endodontic files through the canal. Canals were prepared and then obturated using warm vertical compaction technique and the perforation were repaired by mineral trioxide aggregate (MTA). Six-month and one-year follow-ups revealed no symptoms and evidence of radiographic healing. Thus, multiple endodontic three-dimensional guides can be successful in root canal localization and preparation in cases of furcation perforations.

Dynamic Cyclic Fatigue and Differential Scanning Calorimetry Analysis of R-Motion.

INTRODUCTION: The aim of this study was to assess the dynamic cyclic fatigue resistance of an R-Motion file at simulated body temperature and document corresponding phase transformations compared to OneCurve and HyFlex EDM (HFEDM). METHODS: R-Motion (25/.06), OneCurve (25/.06), and HFEDM (25/.06) files were selected and divided into 3 groups (n = 9) according to the file type. Dynamic cyclic fatigue testing was done with a custom-made artificial stainless-steel canal that had a 90° angle of curvature and a 5-mm radius of curvature. Files were operated continuously at body temperature until fracture in the artificial canal. The time to fracture was calculated. Statistical analysis was performed, and significance was set at 5%. Phase transformation temperatures for 2 instruments of each group were analysed by differential scanning calorimetry (DSC) analysis. RESULTS: The highest mean time to fracture value was measured in the HFEDM group (277.84 ± 2.51), followed by the R-Motion group (115.09 ± 0.01), whilst the lowest value was found in the OneCurve group (44.28 ± 3.63). Post hoc pairwise comparisons were all statistically significant (P < .001). DSC heating curves show austinite start temperatures to be 33.94 °C and 43.32 °C and austinite finish temperatures to be 35.09 °C and 50 °C for R-Motion and HFEDM, respectively. DSC cooling curves show martensite start temperatures to be 27.54 °C and 44.52 °C and martensite finish temperatures to be 29.13 °C and 37.68 °C for R-Motion and HFEDM, respectively. DSC curves of OneCurve failed to demonstrate transformation temperatures within the tested heat range. CONCLUSIONS: Crystalline arrangement of Ni and Ti atoms within the NiTi alloys greatly affects the dynamic cyclic fatigue resistance of the file.

Influence of traverse and waveone gold glider glide path files on the amount of apically extruded debris / Influência das limas glide path Traverse e Wave One Gold Glider na quantidade de detritos extruídos apicalmente

Objective: The aim of this study was to evaluate the effect of different glide path files on the amount of apically extruded debris. Material and Methods: Sixty single-canaled mandibular premolars were accessed and randomly divided into three groups (n= 20) according to the file used for glid path creation; group A using Traverse file, group B using WaveOne Gold Glider, group C using stainless steel K file. All teeth were then instrumented using the Reciproc system. The debris extruded apically during instrumentation were collected into pre-weighed Eppendorf tubes which 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 weights of the Eppendorf tubes. The data were analyzed using one-way ANOVA test, and post hoc analysis. Results: WaveOne Gold Glider produced the least amount of apical extruded debris (0.41±0.25) followed by the Traverse group (0.59±0.20) then the K-file group (0.64±0.16) with a statistically significant difference (p=0.003). Conclusion: Apical extrusion of debris is inevitable during root canal cleaning and shaping. Creation of glide path using engine-driven files produces less amount of apically extruded debris compared to hand-driven K-files. (AU)

Objetivos: O objetivo deste estudo foi avaliar o efeito de diferentes limas glide path na quantidade de detritos extruídos apicalmente. Metodologia: Sessenta pré-molares inferiores com canal único foram acessados e divididos aleatoriamente em três grupos (n= 20) de acordo com a lima utilizada para criação do glid path; grupo A usando lima Traverse, grupo B usando WaveOne Gold Glider, grupo C usando lima K de aço inoxidável. Todos os dentes foram então instrumentados usando o sistema reciprocante. Os detritos extruídos apicalmente durante a instrumentação foram coletados em tubos Eppendorf pré-pesados que foram então armazenados em uma incubadora a 70°C por 5 dias. O peso dos detritos secos extruídos foi estabelecido subtraindo-se os pesos dos tubos Eppendorf antes e após instrumentação. Os dados foram analisados por meio do teste one-way ANOVA e análise post-hoc. Resultados: WaveOne Gold Glider produziu a menor quantidade de detritos apicais extruídos (0,41±0,25) seguido pelo grupo Traverse (0,59±0,20) e depois pelo grupo K-file (0,64±0,16) com uma diferença estatisticamente significativa (p=0,003). Conclusão: A extrusão apical de detritos é inevitável durante a limpeza e modelagem do canal radicular. A criação do glide path usando limas acionadas por motores produz menos quantidade de detritos extruídos apicalmente em comparação com as limas K manuais. (AU)

Financial Impact of COVID-19 Pandemic on Endodontic Clinics in Egypt: A Questionnaire-Based Report.

OBJECTIVE: To evaluate the financial impact of the COVID-19 pandemic on endodontic clinics in Egypt. METHODS: Two hundred Egyptian endodontists holding a minimum of a master's degree were invited to participate in an online survey in March 2021. Participants accessed the survey link shared on the social media group of the Egyptian Society of Endodontology. Participants read and signed an electronic informed consent before participating in this study. The questionnaire was designed exclusively by the authors. A draft was pilot tested on a sample of 15 endodontic masters' students at The British University in Egypt. Suggestions and comments to improve clarity, content, and validity were incorporated into the revised survey. The questionnaire was divided into five sections; the first section comprised of questions about the participants' demographic details. The second section targeted the current and future financial impact of COVID-19 on practices. The third section included information about the average patient flow and the introduction of teledentistry in clinical practice. The fourth section assessed the effect of COVID-19 on the staff in the dental clinics and the changes made in response to COVID-19. The last section estimated COVID-19 prevalence among endodontists and staff. Categorical data were presented as frequencies (n) and percentages (%) and were analysed using Fisher's exact test. Quantitative data were presented as mean and standard deviation values. P-values were adjusted for multiple comparisons utilising Bonferroni correction. RESULTS: A total of 141 endodontists participated in the survey. The negative financial impact of COVID-19 was reported by 84.39% of the participants. Seventy-eight endodontists (55.3%) suffered from the increased cost of endodontic materials. Of the endodontist respondents, 90.8% suffered from the increased cost of PPE, 82.3% did not charge their patients more, and only 14.4% planned to charge more. A decrease in the number of referred cases for endodontic treatment has been noticed by 58.9%. About 47.5% noticed increased patient phone calls replacing patient visits. Only 12.8% have dismissed staff because of financial problems. CONCLUSION: COVID-19 has negatively affected most endodontists financially and significantly affected their practices' strategies.

Perceptions of Clinical Dental Students Toward Online Education During the COVID-19 Crisis: An Egyptian Multicenter Cross-Sectional Survey.

Objectives: To evaluate the perceptions of clinical dental students on the role of online education in providing dental education during the COVID-19 crisis. Materials and Methods: A cross-sectional online survey was sent to four Egyptian dental schools from the 20th of January 2021 to the 3rd of February 2021. Survey questions included the demographics, uses, experiences, perceived benefits, and barriers of distance learning in dentistry during the COVID-19 pandemic. Responses were collected from the clinical dental school students. Categorical data were presented as frequencies (n) and percentages (%) and were analyzed using Fisher's exact test. Results: Three hundred thirty-seven clinical dental students across four Egyptian dental schools responded. Most students used either Google Classroom or Microsoft Teams to access the online content. The data showed that the COVID-19 pandemic affected the academic performance of most participants (97.4%) with varying degrees. On average, students were neutral when asked to rate the online lectures, but did not find online practical education as effective (81.3%) as online theoretical teaching. The commonly described barriers to online teaching included loss of interaction with educators, inappropriateness in gaining clinical skills, and the instability of the internet connection. Conclusion: Despite the reported benefits, clinical dental students in Egypt preferred the hybrid approach in dental education as distance learning represented a prime challenge to gain adequate clinical dental skills.