Knowledge and attitudes of Mexican dentists regarding COVID-19 / Conocimiento y actitudes de dentistas mexicanos sobre la COVID-19

Dentists have a high risk of contracting COVID-19, they needed to be aware of the major challenge that represents the dental practice and COVID-19. Accordingly, this study aimed: 1) to investigate the knowledge of dentists regarding COVID-19, 2) to investigate the attitudes of dentists concerning the use of personal protective equipment and, 3) to investigate the attitudes of dentists on stopping their dental practices in the framework of a contingency plan for the COVID-19 outbreak. An online cross-sectional survey was applied to dentists (n=822). Dentists in Mexico answered the survey, which was administered before the contingency plan for the COVID-19 outbreak. Results were analyzed with descriptive statistics and with a Chi-square test (P≤0.05). Of the respondents, 99% of dentists indicated knowing what COVID-19 is, knowing most, but not all, of its signs and symptoms and knowing its mode of transmission. The 89% of dentists indicated that they always used personal protective equipment. But they did not use always wear face masks, protective eyewear, face shields, disposable gowns, and caps. Dentists were aware of the risk of performing dental procedures during the COVID-19 outbreak. The 90% of dentists indicated that they would treat only patients requiring emergency treatment, and 10% indicated that they would not treat any patients. The dentists had limited knowledge about the COVID-19 disease. They did not use personal protective equipment consistently, and they indicated that they might continue working during the COVID-19 outbreak.

Durante la pandemia por COVID-19, los dentistas han tenido un alto riesgo de contraer COVID-19. Los dentistas mexicanos tuvieron la necesidad de enfrentarse a la COVID-19 en la práctica dental con un posible conocimiento limitado sobre la enfermedad. De acuerdo con esa problemática, los objetivos de este estudio fueron: 1) investigar el conocimiento de los dentistas sobre la COVID-19, 2) investigar las actitudes de los dentistas sobre el uso de equipo de protección personal, 3) investigar las actitudes de los dentistas para detener la práctica laboral frente a la pandemia. Una encuesta fue aplicada a dentistas mexicanos en el inicio de la contingencia por COVID-19 (n=822). Se analizaron los resultados de con una prueba de Chi cuadrada (P≤0.05). El 99% de los participantes conocieron qué es la COVID-19, pero no todos los signos y síntomas de la enfermedad ni los modos de transmisión. El 89% de los dentistas indicaron que siempre usan equipo de protección personal. Pero no usan siempre careta, lentes de protección, cubreboca, guantes deshechables y gorro. Los participantes tenían conocimiento del riesgo de contraer COVID-19. El 90% indicó que sólo atenderían urgencias dentales y el resto indicó que no atendería pacientes. Los dentistas tuvieron un conocimiento limitado sobre la COVID-19. No usaron equipo de protección personal de forma consistente. Además indicaron que estarían dispuestos a seguir trabajando durante la pandemia.

A homemade simulation model improves the impact of e-learning for the practical administration of dental anaesthesia.

INTRODUCTION: A simulation model improves the learning of dental anaesthesia in dental students. This study explored first, the making at home of a dental anaesthesia simulation model by dental students, and second, the impact of that simulation model on the learning of dental students following an online course. We compared the level of knowledge, the level of perception of confidence to perform the basic injection technique (BIT) of dental anaesthesia, and the level of attitude towards e-learning of the BIT between a group of dental students who had an online course with a home-made dental anaesthesia simulation model (HMDASM) and a group of dental students who did not use that model. MATERIALS AND METHODS: A group of participants (n = 28) used the HMDASM to learn the BIT with an e-learning course. Another group of participants (n = 28) followed the same e-learning course, but that group used a lemon to practise the BIT. The two groups answered questionnaires that explored the level of theoretical knowledge on the BIT, the level of perception of confidence to perform the BIT, and the level of attitude towards e-learning of the BIT. Questionnaire scores from each group were compared by a Student's t-test (p ≤ .05). RESULTS: The group that used the HMDASM had a level of knowledge similar to that of the other group (p > .05). The group that used the HMDASM had a level of perception of confidence to perform the BIT and a level of attitude towards online learning of the BIT higher than those of the group that did not use the simulation model (p < .05). CONCLUSION: The use of a HMDASM had a positive effect on dental students following an online course to learn the BIT.

Synthesis of a PVA drug delivery system for controlled release of a Tramadol-Dexketoprofen combination.

The local administration of analgesic combinations by means of degradable polymeric drug delivery systems is an alternative for the management of postoperative pain. We formulated a Tramadol-Dexketoprofen combination (TDC) loaded in poly(vinyl alcohol) (PVA) film. Films were prepared by the solvent casting method using three different molecular weights of PVA and crosslinking those films with citric acid, with the objective of controlling the drug release rate, which was evaluated by UV-vis spectrometry. Non-crosslinked PVA films were also evaluated in the experiments. Differential scanning calorimetry (DSC) analysis of samples corroborated the crosslinking of PVA by the citric acid. Blank and loaded PVA films were tested in vitro for its impact on blood coagulation prothrombin time (PT) and partial thromboplastin time (PTT). The swelling capacity was also evaluated. Crosslinked PVA films of higher-molecular weight showed a prolonged release rate compared with that of the lower-molecular-weight films tested. Non-crosslinked PVA films released 11-14% of TDC. Crosslinked PVA films released 80% of the TDC loaded (p < 0.05). This suggests that crosslinking films can modify the drug release rate. The blank and loaded PVA films induced PT and PTT in the normal range. The results showed that the polymeric films evaluated here have the appropriate properties to allow films to be placed directly on surgical wounds and have the capacity for controlled drug release to promote local analgesia for the control of postoperative pain.

Bacterial Percolation and Sealer Tubular Penetration in a Polymer-based Obturation System Compared with Warm Vertical Condensation Technique: An in Vitro Study.

Introduction: This study compared bacterial percolation and sealer penetration of a novel obturation technique with the ones of warm vertical condensation technique. Methods and Materials: A bacterial percolation test was carried out with 80 single rooted human teeth divided into 5 groups; A (n=20): warm vertical condensation and AH-Plus, B (n=20): CPoint with AH-Plus, C (n= 20): CPoint with EndoSequence BC, +ve Control (n=10): teeth with no canal obturation, -ve Control (n=10): teeth with no access cavity. The samples were inoculated with a multispecies bacterial incoulum. Bacterial percolation was evaluated by turbidity. Confocal laser scanning microscopy (CLSM) was used to observe the presence of gaps and voids. Further 48 extracted human mandibular single-canal premolars were used to determine the sealer penetration. Slices of the samples were observed by CLSM to evaluate tubules penetration of the sealer. Kaplan Meyer survival, ANOVA one way and Tuckey HSD test and a Wilcoxon signed-rank test were utilised. Results: A Kaplan-Meier test showed no significant difference overall (P>0.05) between groups A, B and C. At 43 days, the group B showed a significantly inferior ability to prevent bacterial passage (P<0.05). The group C showed a deeper sealer penetration than group A and B with statistically significant differences (P<0.05) for the total penetration (ANOVA one way and Tukey HSD). A Wilcoxon signed-rank test showed statistically significant differences for the penetration in the middle-and apical third of the 3 groups. Conclusion: Based on this in vitro study, the single polymer-cone obturation technique with a resin based- and bioceramic based-sealer behaved similarly to the warm vertical obturation technique in preventing bacterial passage. The bioceramic sealer showed the deepest penetration but did not fully prevent bacterial leakage.

Calcium sustained release, pH changes and cell viability induced by chitosan-based pastes for apexification.

We explored chitosan-based sustained release pastes for apexification. The study aimed to formulate chitosan-based pastes loaded with calcium hydroxide (CH) or with calcium chloride (CC), and to evaluate the sustained release of Ca2+ and pH changes in deionized water as well as the effect of the pastes on cell viability. The pastes were formulated by dissolution of the chitosan in 1% or 2% acetic acid (AAC) plus the addition of CH or CC, then were suspended in deionized water for 50 days; the released Ca(II) and pH were measured with an electrode probe. The effect of the pastes on viability of human dental pulp cells was evaluated with a MTS assay. The results showed that the pastes prepared with 1% and 2% AAC and loaded with CH released a 74.9% and a 76.1% of the Ca2+ content, respectively, while the pastes prepared with 1% and 2% AAC loaded with CC released a content of Ca2+ of 90.8% and 76.6%, respectively. A control paste (CH and polyethylene glycol) released a 95.4%; significant statistical differences were found between the percentage of the experimental pastes and the control. The CH-loaded pastes caused an alkaline pH at the starting of the study, but the pH became neutral at the ending. The pH of the CC-loaded pastes was neutral at the starting and was acid at the ending. The pastes no affected on the cell viability. The chitosan-based pastes showed a suitable sustained release profile and cytocompatibility.

Cell viability and hemocompatibility evaluation of a starch-based hydrogel loaded with hydroxyapatite or calcium carbonate for maxillofacial bone regeneration.

The objective of this study is to evaluate the cell viability and hemocompatibility of starch-based hydrogels for maxillofacial bone regeneration. Seven starch-based hydrogels were prepared: three loaded with 0.5, 1 and 2% calcium carbonate (Sigma Aldrich, St. Louis, MO, USA); three loaded with 2, 3 and 4% hydroxyapatite (Sigma Aldrich); and one not loaded as a control. A 10 M NaOH was then added to induce hydrogel formation. Human osteoblasts were cultured on each hydrogel for 72 h. An MTS assay (Cell Titer96; PROMEGA, Madison, WI, USA) was used to assess cell viability. Hemocompatibility testing was conducted with normal human blood in the following conditions: 100 mg of each hydrogel in contact with 900 µL of whole blood for 15 min at 37 °C under lateral stirring. Higher percentages of cell viability were observed in starch-based hydrogels loaded with hydroxyapatite as compared with the control. The hemolysis test showed a hemolysis level lower than 2%. Activated partial thromboplastin time and prothrombin time were unchanged, while platelet counting showed a slight decrease when compared with controls.

Sustained release of calcium hydroxide from poly(DL-lactide-co-glycolide) acid microspheres for apexification.

Calcium hydroxide (CH) loaded poly(DL-lactide-co-glycolide) acid (PLGA) microspheres (MS) might be used for apexification requiring a sustained release of Ca(2+). The aim of this study was to formulate and characterize CH-PLGA-MS. The CH-loaded MS were prepared by either oil-in-water (O/W) or water-in-oil/in-water (W/O/W) emulsion solvent evaporation technique. MS produced by the O/W technique exhibited a larger diameter (18.63 ± 7.23 µm) than the MS produced by the W/O/W technique (15.25 ± 7.37 µm) (Mann-Whitney U test P < 0.001). The CH encapsulation efficiency (E e) and Ca(2+) release were calculated from data obtained by absorption techniques. Ca(2+) release profile was evaluated for 30 days. To know the E e, the CH-loaded MS were dissolved in 1 M NaOH to release all its content and a Ca(2+) colorimetric marker was added to this solution. The reagent marked the Ca(2+) in blue color, which was then measured by a UV-Vis system (650 nm). The percentage of E e was calculated on the basis of the theoretical loading. The E e of the O/W-produced MS was higher (24 %) than the corresponding percentage of the W/O/W-produced MS (11 %). O/W- and W/O/W-produced MS released slower and lower Ca(2+) than a control CH paste with polyethylene glycol 400 (Kruskal-Wallis test). O/W-produced MS released higher Ca(2+) than W/O/W-produced MS (statistically significant differences; P < 0.05). In conclusion, the CH-PLGA-MS were successfully formulated; the technique of formulation influenced the size, encapsulation efficiency and release profile. The MS were better sustained release system than the CH paste.

La publicación científica en estomatología: un desafío para los investigadores / The scientific publication in stomatology: a challenge for researchers

La publicación de artículos científicos en odontología constituye la forma más apropiada para que un investigador dé a conocer los resultados de su trabajo; este reporte escrito representa la culminación del proceso de un estudio y resume los aspectos más relevantes del trabajo realizado –como son las características de los pacientes incluidos, el diseño empleado para dar respuesta a la pregunta planteada inicialmente, los materiales o procedimientos utilizados, los resultados y conclusiones emanados del estudio– en una forma coherente y estructurada. El propósito del presente artículo es dar a conocer algunos elementos de la definición de la publicación científica, la importancia de publicar en revistas de reconocido prestigio, el proceso de la publicación, la estructura de un artículo científico y los principales lineamientos para la publicación.

In dentistry, publishing scientific papers is the most effective way for researchers to disseminate the results of their work; these written reports represent the culmination of the research process and provide a summary of the most relevant aspects of the work carried out, such as the characteristics of the patients included, the design used to find the answer to the initial question, the materials or procedures used, and the results and conclusions of the study, all presented in a cohe­rent and structured manner. The purpose of this article is to examine the definition of scientific publication in dentistry, the importance of publishing in prestigious journals, the publication process, the structure of a scientific article, and the main guidelines for publication.

Poly(2-dimethylamino ethylmethacrylate)-based polymers to camouflage red blood cell antigens.

Poly(2-dimethylamino-ethylmethacrylate) (PDMAEMA) is a cationic polymer when dissolved in a 7.4 pH fluid. Owing to its ionic nature, this polycation interacts with the negatively charged cell membrane surface of red blood cells (RBCs). The electrostatic self-assembly of PDMAEMA on RBCs membrane can be employed for inducing the formation of a polymeric shield camouflaging blood group antigens on RBCs as a valuable strategy for developing "universal RBCs" for blood transfusion. The purpose of this research was to evaluate the camouflaging ability of PDMAEMA homopolymers and PDMAEMA-co-poly(ethylene glycol) copolymers differing in molecular weight and architecture. Surprisingly, the PDMAEMAs caused a partially masking, no masking, and sensitization of the same RBCs population. The MW and architecture of the polymers as well as temperature of PDMAEMA-RBCs treatment influenced the results observed. Herein, the very particular reactivity of PDMAEMAs and RBCs is analyzed and discussed.

Hemocompatibility assessment of poly(2-dimethylamino ethylmethacrylate) (PDMAEMA)-based polymers.

Poly(2-dimethylamino-ethylmethacrylate) (PDMAEMA), a cationic polymer, has been widely reported as a nonviral carrier. Despite the fact that the cytotoxicity of this polymer has been extensively studied, there is a lack of information about its blood compatibility. Hence, this work evaluates the hemocompatibility of free-form PDMAEMA homopolymers differing in molecular weight (Mw) with or without a poly(ethylene glycol) (PEG) sequence in the form of a palm tree-like structure. Poly(ethylenimine) (PEI) was used as a reference in order to compare its hemoreactivity. Hemagglutination, hemolysis, platelet number, blood coagulation, and the complement systems were assessed in normal human whole blood according to the ISO 10993-4. Results showed that Mw, concentration, and incubation time strongly affected the hemocompatibility of the polymers evaluated. Our in vitro observations highlight that PDMAEMA homopolymers interacted strongly with the surface of the red blood cells but not with the inner structure of the membrane, while PEI behaved in the opposite way. No clear correlation has been evidenced between PDMAEMA-induced hemagglutination, PEI-induced hemagglutination, and hemolysis. Interestingly, if these polyelectrolytes strongly affect the platelets and blood coagulation cascades in a dose dependent way, none of them significantly affects the complement system. Our work reveals new knowledge on the toxicology of 2 families of polycations largely explored for gene delivery and on their mechanisms of cellular and humoral interactions.

The effect of Emdogain and 24% EDTA root conditioning on periodontal healing of replanted dog's teeth.

Controversies still exist as for the regenerative role of enamel matrix derivatives and the need for removal of the periodontal ligament in replanted teeth. The purpose of this study was to evaluate the effect of Emdogain and 24% ethylenediamine tetraacetic acid (EDTA) root conditioning on periodontal healing of replanted dog's teeth. Teeth were extracted, endodontically treated and preconditioned as follows: group 1, Emdogain; group 2, Emdogain + EDTA and group 3, EDTA. Teeth were replanted after 30 min extraoral time, splinted for 15 days and animals sacrificed after 8 weeks of observation. Histological evaluation was performed using hematoxylin/eosin and Masson trichrome and results scored based on previously reported criteria for histological evaluation. Replacement root resorption was histologically diagnosed in all groups except in the negative control. A parametric analysis showed no statistically significant differences between experimental groups. Root preconditioning with Emdogain alone or in combination with 24% EDTA showed no evidence of regeneration of collagen fibers and consequently did not prevent the development of replacement root resorption on replanted dog's teeth.

Reparo de reabsorção radicular externa associada com queratocisto odontogênico; relato de caso / Healing of external root resorption associated with odontogenic keratocyst: case report

Introduction and Objective: A case of external root resorption associated to an Odontogenic Keratocyst is presented. Case Report and Conclusion: A review of the literature revealed that this cyst is not considered a common etiological factor for external root resorption. A X-ray examination showed root resorption in the teeth involved in an odontogenic keratocyst. Root canal treatment with calcium hydroxide mixed with propylenglicol was performed. The paste was applied at definite intervals during a 10 month period. X-rays were taken at each interval. At final X-rays examination there were no signs of root resorption and the filling was completed.

Introdução e Objetivo: O presente trabalho apresenta um caso de reabsorção externa associada a um Queratocisto Odontogênico. Relato do caso e Conclusão: A revisão da literatura pertinente revelou que tal cisto não é comumente associado à reabsorção externa da raiz. Exames radiográficos apresentaram reabsorção externa da raiz nos dentes envolvidos com a lesão cística.O tratamento endodôntico instituído utilizou hidróxido de cálcio associado ao propilenoglicol aplicado como medicação intra-canal em intervalos definidos durante 10 meses. Ao final do referido período o exame radiográfico demonstrou o reparo da reabsorção.