Comparative Evaluation of Microtensile Bond Strength in Three Different Dentin Luting Agents: An In vitro Study.

Aim: Long-term clinical success on indirect restorations is largely determined by bonding efficiency of the luting agent, with adhesion to dentin being the main challenge. Therefore, aim of this study was to assess the microtensile bond strength when using flowable resin composite, preheated resin composite and dual self-adhesive resin cement as dentin luting agents. Materials and Methods: Occlusal thirds of molar teeth were cut and randomly divided into 3 groups to be cemented: RelyX™U200, Filtek™ Z250 XT- preheated to 70° and Filtek Flow™ Z350XT. They were then thermocycled 5000 times between 5+/-2°C and 55+/-2°C. Subsequently, 10 microbars per group were prepared. The 30 samples were placed in saline solution for 24 hours at room temperature prior to microtensile test. This was performed with a digital universal testing machine at a crosshead speed of 0.5 mm/min. The bond strength values obtained were analyzed in Megapascals (MPa). Measures of central tendency such mean and measures of dispersion such standard deviation were used. In addition, the Kruskall Wallis non-parametric test with Bonferroni post hoc test was applied, considering a significance value of 5% (P < 0.05), with type I error. Results: The dentin microtensile bond strengths of preheated resin composite, flowable resin composite and dual self-adhesive cement were 6.08 ± 0.66 Mpa, 5.25 ± 2.60Mpa and 2.82 ± 1.26Mpa, respectively. In addition, the preheated resin composite exhibited significantly higher microtensile bond strength compared to the dual self-adhesive cement (P < 0.001). While the flowable resin composite showed no significant difference with the dual self-adhesive cement (P = 0.054) and the preheated resin composite (P = 0.329). Conclusions: The microtensile bond strength in dentin was significantly higher when using a preheated resin composite at 70°C as a luting agent compared to dual self-adhesive cement. However, the preheated resin composite showed similar microtensile bond strength compared to the flowable resin composite.

Tensile Strength and Elastic Modulus of Gutta-percha Cones Disinfected with Sodium Hypochlorite at Different Immersion Times: An In Vitro Comparative Study.

Aim: The tensile strength and modulus of elasticity of gutta-percha cones can be chemically altered due to disinfectant solutions. Therefore, the aim of the present study was to compare tensile strength and elastic modulus of gutta-percha cones subjected to sodium hypochlorite (NaOCl) disinfection at different times. Materials and Methods: This in vitro and longitudinal experimental study consisted of 45 gutta-percha cones, divided equally into three groups: Group 1 (disinfection with 2.5% NaOCl), Group 2 (disinfection with 5.25% NaOCl), and control group. All groups were subdivided according to immersion times for 1, 5, and 10 minutes. Tensile strength and elastic modulus were measured with a universal testing machine. For comparing more than two independent groups, parametric analysis of variance test with Sheffe's post hoc was used and for multivariate analysis, and multivariate analysis of variance test based on Pillai's Trace was used. In all statistical analysis, a significance level P ≤ 0.05 was considered. Results: When comparing the tensile strength of gutta-percha cones, no significant differences were observed after being immersed at 1, 5, and 10 minutes in NaOCl 2.5% (P = 0.715) and 5.25% (P = 0.585). Regarding the elastic modulus, a significant decrease (P < 0.05) was observed in those that were immersed in NaOCl 2.5% and 5.25% for 1, 5, and 10 minutes. Furthermore, increased NaOCl concentration significantly reduced the elastic modulus (P < 0.001). However, there were no significant differences in tensile strength (P > 0.05) and elastic modulus (P > 0.05), when evaluating the interaction between NaOCl concentration and time. Conclusion: Increasing NaOCl concentration significantly reduced the modulus of elasticity without affecting the tensile strength of gutta-percha cones, regardless of immersion time. Furthermore, the interaction of time and NaOCl concentration did not significantly affect the tensile strength and elastic modulus.

Sociodemographic Factors Associated with the Satisfaction Level of Peruvian Dental Students with Virtual Classes During the Covid-19 Pandemic: A Prospective Bicentric Study.

Background: The pandemic caused by Covid-19 impacted all areas of social, economic and educational activity. When there is a high risk of spreading highly infectious diseases, education is usually the first service to be suspended. The objective was to evaluate the sociodemographic factors associated with the satisfaction level of Peruvian dental students with virtual classes during the Covid-19 pandemic. Methods: This observational, cross-sectional, analytical study evaluated 237 dental students from the capital city and one Peruvian province using a validated 13-item questionnaire to measure the level of satisfaction with virtual classes. Pearson's chi-square test and a logit model were used to evaluate the associated factors such as age group, sex, marital status, monthly family income, area of residence, place of origin, occupation and computer use, considering a significance level of p<0.05. Results: Of all students, 50.6%, 40.1% and 9.3% presented a good, average and poor level of satisfaction, respectively, with the virtual classes received. In addition, those with a monthly family income of less than 500 US dollars were 3.15 times more likely to have poor satisfaction compared to those with a monthly family income of more than 1000 US dollars (AOR = 3.15; 95% CI: 1.23-8.05). The rest of the variables evaluated were not considered influential factors in the levels of satisfaction with the virtual classes received. Conclusión: Of all students, 50.6% and 9.3% reported good and poor satisfaction with virtual classes during the COVID-19 pandemic, respectively. Monthly family income of less than 500 US dollars was an influential factor. In addition, the variables age group, sex, marital status, area of residence, place of origin, occupation and computer use were not found to be influential factors.

A Scalable Microfluidic Platform for Nanoparticle Formulation: For Exploratory- and Industrial-Level Scales.

Nanoparticle synthesis on microfluidic platforms provides excellent reproducibility and control over bulk synthesis. While there have been plenty of platforms for producing nanoparticles (NPs) with controlled physicochemical properties, such platforms often operate in a narrow range of predefined flow rates. The flow rate limitation restricts either up-scalability for industrial production or down-scalability for exploratory research use. Here, we present a universal flow rate platform that operates over a wide range of flow rates (0.1-75 mL/min) for small-scale exploratory research and industrial-level synthesis of NPs without compromising the mixing capabilities. The wide range of flow rate is obtained by using a coaxial flow with a triangular microstructure to create a vortex regardless of the flow regime (Reynolds number). The chip synthesizes several types of NPs for gene and protein delivery, including polyplex, lipid NPs, and solid polymer NPs via self-assembly and precipitation, and successfully expresses GFP plasmid DNA in human T cells.

Shear bond strength of three different metal bracket base designs on human premolars: An in vitro comparative study.

Background: Adequate bracket-enamel bonding is critical to prevent detachment during orthodontic treatment and minimize any potential delay in results. The aim was to compare the shear bond strength of three metal bracket base designs: laser-structured base, mesh base, and retention grooves base. Material and Methods: In this experimental in vitro study, 54 human premolars were immersed for one week in 0.1% thymol solution, then placed in distilled water with weekly replacement until the start of the study. The premolars were cemented with brackets of varying base designs: A. Discovery® Smart (laser structured), B. Mini Master® Series (base with mesh), and C. Roth Max (base with retention grooves). All brackets were cemented using TransbondTM XT. A universal testing machine was used to evaluate the shear bond strength at a crosshead speed of 0.75 mm/min. Welch's one-factor ANOVA with robust variance and Tukey's post hoc test were used to compare means, with a significance level of p<0.05. Results: The average shear bond strength values were for the bracket with laser-structured base (14.78 ± 5.79 MPa), the bracket with mesh base (9.64 MPa ± 2.54 MPa) and the bracket with retention groove base (15.38 MPa ± 2.67 MPa). It was found that brackets with mesh bases had significantly lower shear bond strength than brackets with laser-structured bases (p=0.001) and brackets with retention grooves bases (p<0.001). No significant differences were observed between the latter two types of brackets (p = 0.893). Conclusions: The bracket base design influenced in vitro shear bond strength with significantly higher values observed for Roth Max and Discovery® Smart brackets compared to Mini Master® Series brackets. Key words:Shear strength, laser-structured bracket, bracket with mesh base, bracket with retention groove base.

Impact of an Educational Intervention on Oral Health Knowledge and Bacterial Plaque Control in Male Secondary School Students in a Peruvian Province: A Quasi-Experimental Study.

Background: The purpose of this study was to evaluate the effect of an educational intervention on oral health knowledge and bacterial plaque control in male secondary school students in a Peruvian province. Methods: This quasi-experimental study evaluated 294 male secondary school students in southern Peru. Oral health knowledge was measured with a validated 20-item questionnaire. Bacterial plaque was measured with the Simplified Oral Hygiene Index (OHI-S). This was rated as Excellent: 0, Good: 0.1-1.2, Fair: 1.3-3.0 and Poor: 3.1-6.0, before receiving the educational intervention and after four weeks of receiving it. Variables such as age, area of residence, having health professionals as family members, educational level of mother and father, and living with parents were considered. A significance level of p<0.05 was considered. Results: The comparison between the level of oral health knowledge and the OHI-S, before and after 4 weeks of receiving the educational intervention, showed a significant improvement (p<0.05) in all the categories of the variables studied. Likewise, before the educational intervention, there were significant differences in global knowledge about oral health among the categories of the following variables: age group (p=0.040), area of residence (p<0.001), educational level (father) (p=0.011) and living with parents (p<0.001). However, after four weeks of receiving the educational intervention, no significant differences were observed in all the variables studied (p>0.05). Regarding the OHI-S, no significant differences were observed in any of the variables studied, both before (p>0.05) and after four weeks (p>0.05) of receiving the educational intervention. Conclusion: After four weeks, the educational intervention significantly improved oral health knowledge and significantly reduced plaque bacterial plaque in male secondary school students in a Peruvian province, regardless of age, area of residence, having health professional family members, educational level of mother and father, and living with parents.

Impact of a virtual educational intervention on knowledge and awareness of biomedical waste management among Peruvian dental professionals.

Waste from healthcare is a significant global issue, with around 85% of it being common waste and the remaining 15% being hazardous waste that is infectious and toxic. Dentistry uses various materials that create a substantial amount of biomedical waste capable of impacting the environment. Therefore, the purpose of this study was to assess the effects of a virtual educational program on the knowledge and awareness of dental material recycling and reuse, as well as biomedical waste management, among dental professionals in Peru. The current study was a longitudinal and quasi-experimental evaluation of 165 dentists from Peru. A validated questionnaire consisting of 30 items was administered at three different intervals (pre-test, immediate post-test, and 14-day post-test). Statistical analysis was conducted using the Mann Whitney U and Kruskal Wallis H tests to compare scores between categories of each sociodemographic variable, and the Cochrane's Q and Friedman test was used for related measures comparison. A significance level of p < 0.05 was considered. When comparing the percentage of correct responses regarding recycling and reuse of dental materials and biomedical waste management between the pre-test and the immediate post-test, a significant improvement in knowledge was observed for most of the questionnaire items (p < 0.05). At 14 days after the test, those who studied at a private university, unmarried, bachelors, non-specialists, non-teachers and have less than 10 years of professional experience did not did not retain knowledge on biomedical waste management (p < 0.05) or recycling and reusing dental materials (p < 0.05) to a significant extent. There was a significant enhancement in dentists' knowledge and awareness of managing biomedical waste, recycling, and reusing dental materials following the educational intervention. This improvement was observed across all sociodemographic variables considered in the study. However, this knowledge was not retained beyond two weeks for those who studied at a private university, unmarried, bachelor, with no specialty, non-teachers and with less than 10 years of professional experience. Government authorities should encourage oral health professionals to conduct research with educational interventions focused on improving and evaluating the sustainability and environmental impact of dental practices. This will enable professionals to better understand, control and evaluate the consequences of their practical work.

Sociodemographic factors associated with knowledge and attitudes of Peruvian dental interns about dental shade selection.

BACKGROUND: The dentist should have a thorough knowledge of the science, protocols and procedures for dental shade selection in order to mimic dental tissue with restorative materials, respecting the individual needs and attitudes of each patient and providing them with a pleasant and esthetically acceptable appearance. The present study evaluated the knowledge and attitudes of dental interns from two Peruvian universities about dental shade selection and its relationship with sociodemographic factors. METHODS: The present cross-sectional and analytical study was carried out on Peruvian dental interns from the Universidad Nacional Federico Villarreal and the Universidad Privada de San Juan Bautista during May to June 2022. Two validated questionnaires on knowledge and attitudes about dental shade selection were used. A Poisson regression model with robust variance using the adjusted prevalence ratio (APR) was used to assess the influence of the variables: age group, sex, place of origin and type of university, considering a significance level of p<0.05. RESULTS: The results showed that 40.8% (95% CI: 34.0% - 47.6%) of the interns presented unfavorable attitudes while 90.1% (95% CI: 86.0% - 94.2%) presented insufficient knowledge. It was also found that dental interns under 29 years of age were 32% less likely to have unfavorable attitudes (APR = 0.68, 95% CI 0.48 - 0.96) and 11% more likely to have insufficient knowledge (APR = 1.11, 95% CI 1.01 - 1.24) about tooth shade selection compared to dental interns aged 29 years and older. Finally, women were 55% more likely to have unfavorable attitudes about tooth shade selection compared to men (APR = 1.55; 95% CI: 1.08 - 2.22). CONCLUSION: The majority of dental interns presented insufficient knowledge and less than half had unfavorable attitudes about dental shade selection. In addition, being a student under 29 years of age was a risk factor for presenting insufficient knowledge and at the same time constituted a protective factor for presenting unfavorable attitudes. Likewise, being a female student was a risk factor for presenting unfavorable attitudes about dental shade selection.

Resonance Frequency Analysis Mapping During Implant Healing Using a Nanostructured Hydroxyapatite Surface.

Aim: Stability measured by resonance frequency analysis (RFA) is an important factor to be considered in the success of dental implant treatments, which can be evaluated from the implant stability quotient (ISQ). The aim of the present case series was to map the RFA during healing of implants with nanostructured hydroxyapatite surface to describe the behavior of ISQ values related to individual factors. Materials and Methods: Twenty-three implants were placed in eight patients by conventional surgical protocol, and ISQ values were monitored from the day of implant placement until week 20. To obtain the ISQ values, an Osstell device was used and the placed implants were grouped in proportional amounts to describe the ISQ behavior considering the length (≤10 or >10 mm), the diameter (3.5 or 4.3 mm), the insertion torque (<40 N-cm or ≥40 N-cm), and the placement area (maxilla or mandible). Results: All the implants assessed decreased their values in the first 3 weeks after placement. Subsequently, the ISQ values increased by amounts similar to those obtained at the time of the placement and even more. Implants with length >10 mm, diameter 4.3 mm, and insertion torque ≥40 N-cm showed the highest ISQ values. Conclusions: A decrease in the ISQ values of dental implants with nanostructured hydroxyapatite surface was evidenced between weeks 2 and 3 considering length, diameter, insertion torque, and maxillary or mandibular placement site.

Sociodemographic Factors Associated with Knowledge About Management of Cleft Lip and Palate Patients in Peruvian Dental Students: A Logistic Regression Analysis.

Background: Cleft lip and palate are relatively frequent craniofacial alterations caused by the lack of union of the frontonasal processes with the maxillary processes during the first weeks of intrauterine life. This study evaluated the sociodemographic factors associated with the level of knowledge about management of cleft lip and palate (CLP) patients in Peruvian dental students. Methods: This analytical, observational, cross-sectional and prospective study evaluated 191 dental students belonging to two branches of a private Peruvian university (one branch in the capital city and the other in a province), from September to November 2022. A validated questionnaire of 14 closed multiple-choice questions was used. A logit model was used to evaluate the influence of the variables: sex, age, academic year of study, marital status, relationship with CLP persons, place of origin and area of residence, on the level of knowledge of the students considering a significance level of p<0.05. Results: Of the total, 77%, 22.5% and 0.5% presented a poor, fair and good level of knowledge, respectively, on the dental management of the patient with cleft lip and palate. In addition, those who lived in urban areas were 2.8 times more likely to have poor knowledge about the dental management of patients with CLP, compared to those who lived in non-urban areas (OR = 2.83; 95% CI: 1.26-6.33). Finally, sex, age, marital status, place of origin, academic year of studies and relationship with CLP persons were not considered influential factors (p>0.05). Conclusion: Most of the students showed a poor level of knowledge about the dental management of patients with cleft lip and palate, a risk factor being that the students live in an urban area. It is recommended that educational authorities include selected topics on CLP in subjects related to infant, child and adolescent care.

Epidemiology of Mycobacterium abscessus.

BACKGROUND: Nontuberculous mycobacteria (NTM) are highly abundant in soil, dust, and water sources, making human-pathogen contact frequent and recurrent. NTM represents over 200 species/subspecies; some are considered strict or opportunistic pathogens. Mycobacterium abscessus, often regarded as one of the most antibiotic-resistant mycobacteria, is the second most frequent NTM pulmonary disease pathogen. OBJECTIVES: To describe the epidemiology of M. abscessus through a literature review focusing on clinical aspects. SOURCES: We conducted searches on PubMed and Web of Knowledge for articles published from 2010 to the present using the keywords 'Mycobacterium abscessus', 'Nontuberculous mycobacteria', and 'epidemiology'. Our search prioritized original reports on the occurrence of NTM and M. abscessus infection/disease. CONTENT: Advanced molecular and genetic diagnostic techniques have refined the M. abscessus complex (MABC) microbiological classification over the last few decades. MABC can adhere to surfaces and form a biofilm. This characteristic and its resistance to common disinfectants allow these microorganisms to persist in the water distribution systems, becoming a constant reservoir. The frequency and manifestation of NTM species vary geographically because of environmental conditions and population susceptibility differences. MABC lung disease, the most frequent site of NTM infection in humans, is often seen in patients with underlying lung diseases such as bronchiectasis, whereas MABC disseminated disease is related to immunosuppression. Skin and soft tissue infections are associated with surgical or injection procedures. Epidemiological evidence suggests an overall increase in MABC infection and disease in the last decade. IMPLICATIONS: Establishing the burden of this disease is challenging because of varying measures of incidence and prevalence, referral bias, and differences in medical practices and reporting. Furthermore, environmental and structural determinants, infection routes, and MABC pulmonary disease mechanisms require additional investigation. This review contributes to a better understanding of the epidemiology of MABC, which could inform clinical practice and future research.

Microleakage in indirect onlay restorations cemented with three different types of adhesives: An in vitro study.

Background: To evaluate the in vitro degree of marginal microleakage in indirect Class II onlay restorations cemented with dual self-adhesive, universal adhesive and dual adhesive. Material and Methods: In the present in vitro experimental study, a total of 54 human premolar teeth were prepared and divided into three equal groups (n = 18) for placement of onlay-type restorations cemented with A: Allcem™ dual-cure adhesive cement), B: RelyX™U200 dual-cure self-adhesive cement and C: RelyX™ Ultimate universal adhesive cement. All restorations were subjected to 10,000 thermocycles between 5°C and 55°C and immersed in a 1M silver nitrate solution for 6 hours. The crowns were then sectioned mesiodistally and observed under a stereo microscope to determine the degree of marginal microleakage in the cervical area. Results: The onlay restorations cemented with RelyX Ultimate did not present microleakage in the majority of cases (77.8%). Restorations cemented with RelyX U200 showed predominantly microleakage up to the pulp floor in 83.3% of the total, being this significantly higher microleakage than in restorations cemented with RelyX Ultimate and Allcem Dual (p<0.001 and p<0.001 respectively). There was no significant difference in microleakage between the last two mentioned cements (p=0.255). Conclusions: Allcem dual adhesive cement and RelyX Ultimate universal adhesive showed significantly less microleakage than RelyX U200 dual-curing self-adhesive cement at the cervical level, with predominantly no microleakage and microleakage down to the enamel, respectively. The use of RelyX Ultimate cement in indirect restorations is recommended as it showed better marginal adaptation. Key words:Microleakage, human teeth, adhesion, adhesive cement, thermal cycling, onlay restoration.

Establishment of a 7-gene expression panel to improve the prognosis classification of gastric cancer patients.

Gastric cancer (GC) ranks fifth in incidence and fourth in mortality worldwide. The high death rate in patients with GC requires new biomarkers for improving survival estimation. In this study, we performed a transcriptome-based analysis of five publicly available cohorts to identify genes consistently associated with prognosis in GC. Based on the ROC curve, patients were categorized into high and low-expression groups for each gene using the best cutoff point. Genes associated with survival (AUC > 0.5; univariate and multivariate Cox regressions, p < 0.05) were used to model gene expression-based scores by weighted sum using the pooled Cox ß regression coefficients. Cox regression (p < 0.05), AUC > 0.5, sensitivity > 0.5, and specificity > 0.5 were considered to identify the best scores. Gene set enrichment analysis (KEGG, REACTOME, and Gene Ontology databases), as well as microenvironment composition and stromal cell signatures prediction (CIBERSORT, EPIC, xCell, MCP-counter, and quanTIseq web tools) were performed. We found 11 genes related to GC survival in the five independent cohorts. Then, we modeled scores by calculating all possible combinations between these genes. Among the 2,047 scores, we identified a panel based on the expression of seven genes. It was named GES7 and is composed of CCDC91, DYNC1I1, FAM83D, LBH, SLITRK5, WTIP, and NAP1L3 genes. GES7 features were validated in two independent external cohorts. Next, GES7 was found to recategorize patients from AJCC TNM stages into a best-fitted prognostic group. The GES7 was associated with activation of the TGF-ß pathway and repression of anticancer immune cells. Finally, we compared the GES7 with 30 previous proposed scores, finding that GES7 is one of the most robust scores. As a result, the GES7 is a reliable gene-expression-based signature to improve the prognosis estimation in GC.

Depression, Anxiety and Stress Associated With Fear of COVID-19 in Peruvian Dental Students: A Multivariate Analysis With 12 Sociodemographic Factors.

Aims and Objectives: Excessive fear of coronavirus disease 2019 (COVID-19) in dental students could cause mood disorders, especially if there are factors in the environment that generate feelings of anxiety or uncertainty. The aim of this study was to evaluate the fear of COVID-19 and its association with depression, anxiety, and stress in Peruvian dental students according to their sociodemographic factors. Materials and Methods: This analytical, observational, and cross-sectional study was conducted in 398 dental students of a public university in the Peruvian capital during April 2021 to July 2021. The Depression, Anxiety and Stress Scale-21 items was used to diagnose depression, anxiety, and stress. The Fear of COVID-19 Scale was used to detect fear of COVID-19. The Pearson's chi-square test was used for statistical analysis. In addition, a logit model using odds ratio (OR) was performed to evaluate depression, anxiety, and stress of students with the associated factors: fear of COVID-19 and 12 sociodemographic variables (gender, age group, marital status, year of study, origin, companion, living with vulnerable people, history of mental illness, history of COVID-19, loss of close relatives due to COVID-19, occupation, and area of residence). A significance level of P < .05 was considered. In addition, predictive models were developed for the variables depression, anxiety, and stress, considering all possible significant causes. Results: The prevalence of fear of COVID-19, depression, anxiety, and stress was 19.6%, 36.2%, 40.7%, and 19.6%, respectively. According to the adjusted logit model, students who had fear of COVID-19 had OR = 2.74 (95% confidence interval [CI]: 1.62-4.64), OR = 5.59 (95% CI: 3.14-9.97), and OR = 3.31 (95% CI: 1.88-5.83) for developing depression, anxiety, and stress, respectively. In addition, those who reported history of mental illness were four times more likely to develop depression (OR = 4.02, 95% CI: 1.96-8.25) and anxiety (OR = 4.50, 95% CI: 2.06-9.82), whereas those living with people vulnerable to COVID-19 were twice as likely to develop stress (OR = 2.06, 95% CI: 1.16-3.66). Conclusion: The highest prevalence of mood disorders among dental students was anxiety. In addition, those who were afraid of COVID-19 had three times the probability of developing depression and stress, and five times the probability of developing anxiety. On the other hand, the most influential factor in the development of depression and anxiety was history of mental illness, whereas the factor of living with vulnerable people was the most influential factor in the development of stress.

Factors Associated with the Level of Knowledge about Biosafety against COVID-19 in Peruvian Dental Students: A Cross-Sectional Study under a Multivariable Regression Model.

AIM: Biosafety is a set of preventive measures aimed at controlling risk factors arising from biological, physical, and/or chemical agents. This topic is particularly important in the dental field since saliva is the main biological agent of the transmission of coronavirus. The present study aimed to determine the factors associated with the level of knowledge about biosafety against COVID-19 in Peruvian dentistry students. MATERIALS AND METHODS: The present observational, cross-sectional, and analytical study evaluated 312 Peruvian dentistry students. A validated 20-question questionnaire was used to measure the level of knowledge. The nonparametric Mann-Whitney U and Kruskal-Wallis tests were used to compare levels of knowledge between categories of each variable. A logit model was used to evaluate associated factors such as sex, age, marital status, place of origin, academic year of study, being in the academic upper third, history of COVID-19, and living with vulnerable family members. A significance level of p < 0.05 was considered. RESULTS: 36.2%, 31.4%, and 32.4% presented poor, fair, and good knowledge levels, respectively. Students under 25 years of age were 64% less likely to pass the biosafety against COVID-19 questionnaire than students 25 years of age and older (OR = 0.36; CI: 0.20-0.66). Students in the academic upper third were nine times more likely to pass the test than other students (OR = 9.38; CI: 4.61-19.07). Finally, third-year students were 52% less likely to pass the exam than fifth-year students (OR = 0.48; CI: 0.28-0.83). CONCLUSION: Only a minority of dentistry students had a good level of knowledge about biosafety against COVID-19. Younger and less educated students were more likely to fail the questionnaire. On the other hand, those students with outstanding academic performance were more likely to pass the questionnaire.

Factors associated with the perception of university professors about academic dishonesty in dental students from two peruvian universities: analysis under multivariable regression model.

BACKGROUND: Academic dishonesty is an intentional behavior that transgresses ethics in the teaching-learning process. The present study aimed to evaluate the factors associated with the perception of university professors about academic dishonesty in dental students from two universities in the Peruvian capital. METHODS: This cross-sectional, analytical study evaluated 181 professors from two Peruvian universities between March and July 2022. A validated 28-item questionnaire was used to measure the perceived academic dishonesty of their students. A logit model was used to evaluate the influence of the variables gender, marital status, place of origin, academic degree, specialization, academic area, years of teaching experience, scientific publications, ethical training and university of origin, considering a significance level of p < 0.05. RESULTS: According to the median, professors perceived that their students sometimes had attitudes and motivations to commit academic dishonesty. The professors whose origin was the capital city were twice as likely to perceive dishonest attitudes in dental students as those whose origin was a province (OR = 2.04; 95% CI: 1.06-3.93). University professors in pre-clinical courses were 0.37 times less likely to perceive dishonest attitudes than those teaching in the dental clinic (OR = 0.37; CI: 0.15-0.91). University professors in basic science courses and professors in preclinical courses were 0.43 times (OR = 0.43; CI: 0.19-0.96) and 0.39 times (OR = 0.39; CI: 0.15-0.98) less likely to perceive dishonest motivations in their students compared to university professors in the dental clinic. Gender, marital status, academic degree, specialty, years of teaching experience, scientific publications and ethical training were not found to be influential factors (p > 0.05). CONCLUSION: Although all university professors surveyed perceived dishonest attitudes and motivations in their students, university professors from the capital city perceived such attitudes more. In addition, being a preclinical university professor was a hindered factor for perceiving such dishonest attitudes and motivations. It is advisable to implement and constantly disseminate regulations that empower academic integrity as well as to manage a system for reporting misconduct and to make students aware of the impact of dishonesty in their professional training.

Prognostic utility of the chest computed tomography severity score for the requirement of mechanical ventilation and mortality in hospitalized patients with COVID-19.

Purpose: To correlate the chest computed tomography severity score (CT-SS) with the need for mechanical ventilation and mortality in hospitalized patients with COVID-19. Materials and methods: The chest CT images of 224 inpatients with COVID-19, confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR), were retrospectively reviewed from April 1 to 25, 2020, in a tertiary health care center. We calculated the CT-SS (dividing each lung into 20 segments and assigning scores of 0, 1, and 2 due to opacification involving 0%, <50%, and ≥50% of each region for a global range of 0-40 points, including both lungs), and collected clinical data. The receiver operating characteristic curve and Youden Index analysis was performed to calculate the CT-SS threshold and accuracy for classification for risk of mortality or MV requirement. Results: 136 men and 88 women were recruited, with an age range of 23-91 years and a mean of 50.17 years; 79 met the MV criteria, and 53 were nonsurvivors. The optimal threshold was >27.5 points for mortality (area under ROC curve >0.96), with a sensitivity of 93% and specificity of 87%, and >25.5 points for the need for MV (area under ROC curve >0.94), with a sensitivity of 90% and specificity of 89%. The Kaplan-Meier curves show a significant difference in mortality by the CT-SS threshold (Log Rank p < 0.001). Conclusions: In our cohort of hospitalized patients with COVID-19, the CT-SS accurately discriminates the need for MV and mortality risk. In conjunction with clinical status and laboratory data, the CT-SS may be a useful imaging tool that could be included in establishing a prognosis for this population.

Bond Strength and Failure Mode of Glass Fiber Posts with Different Surface Treatments Prior to Silanization: An In Vitro Comparative Study.

Aim: The use of chemical agents in the surface treatment of glass fiber posts can improve their bond strength to the root canal. The aim of this study was to assess the bond strength and failure mode of glass fiber posts that received different surface treatments prior to silanization. Materials and Methods: In this cross-sectional and in vitro experimental study, 50 human lower premolar roots were randomly divided into five groups and subsequently prepared to receive the cementation of a fiberglass post prior to silanization. They were distributed as group 1 (with 24% hydrogen peroxide), group 2 (with 37% phosphoric acid), group 3 (with 1.23% acidulated phosphate fluoride for 2 minutes), group 4 (with 1.23% acidulated phosphate fluoride for 6 minutes), and group 5 (without pretreatment). After cementation, the roots were sectioned into two discs for each cervical, middle, and apical region. Bond strength was assessed using the push out technique. Adhesive, mixed, and cohesive failure modes were also assessed. For data analysis, ANOVA and Tukey's post hoc tests were used, as well as Pearson's chi-square test. A significance of P < 0.05 was considered in all statistical analyses. Results: When comparing the bond strength of root regions, significant differences were obtained in groups pretreated with phosphoric acid (P = 0.018) and acidulated phosphate fluoride for 2 and 6 minutes (P = 0.001 and P = 0.000, respectively). Furthermore, significant differences were obtained between posts treated only with silane and those that received phosphoric acid pretreatment (P = 0.006) and acidulated phosphate fluoride for 6 minutes (P = 0.001). Significant association of mixed failure mode was observed with hydrogen peroxide (P = 0.014) and phosphoric acid (P = 0.006) pretreatments. Cohesive failure was significantly associated with acidulated phosphate fluoride pretreatment for 2 minutes (P = 0.032) and with posts that did not receive treatment prior to silanization (P = 0.000). Conclusion: Posts treated only with silane and pretreated with hydrogen peroxide and acidulated phosphate fluoride for 2 minutes presented significantly higher bond strength with respect to those pretreated with phosphoric acid and acidulated phosphate fluoride for 6 minutes. However, acidulated phosphate fluoride for 2 minutes and silane were associated with a better bonding type.

Impact of mini-driver genes in the prognosis and tumor features of colorectal cancer samples: a novel perspective to support current biomarkers.

Background: Colorectal cancer (CRC) is the second leading cause of cancer-related deaths, and its development is associated with the gains and/or losses of genetic material, which leads to the emergence of main driver genes with higher mutational frequency. In addition, there are other genes with mutations that have weak tumor-promoting effects, known as mini-drivers, which could aggravate the development of oncogenesis when they occur together. The aim of our work was to use computer analysis to explore the survival impact, frequency, and incidence of mutations of possible mini-driver genes to be used for the prognosis of CRC. Methods: We retrieved data from three sources of CRC samples using the cBioPortal platform and analyzed the mutational frequency to exclude genes with driver features and those mutated in less than 5% of the original cohort. We also observed that the mutational profile of these mini-driver candidates is associated with variations in the expression levels. The candidate genes obtained were subjected to Kaplan-Meier curve analysis, making a comparison between mutated and wild-type samples for each gene using a p-value threshold of 0.01. Results: After gene filtering by mutational frequency, we obtained 159 genes of which 60 were associated with a high accumulation of total somatic mutations with Log2 (fold change) > 2 and p values < 10-5. In addition, these genes were enriched to oncogenic pathways such as epithelium-mesenchymal transition, hsa-miR-218-5p downregulation, and extracellular matrix organization. Our analysis identified five genes with possible implications as mini-drivers: DOCK3, FN1, PAPPA2, DNAH11, and FBN2. Furthermore, we evaluated a combined classification where CRC patients with at least one mutation in any of these genes were separated from the main cohort obtaining a p-value < 0.001 in the evaluation of CRC prognosis. Conclusion: Our study suggests that the identification and incorporation of mini-driver genes in addition to known driver genes could enhance the accuracy of prognostic biomarkers for CRC.

Surface Roughness in Nanoparticle Resin Composites Subjected to Two Polishing Systems: An In vitro Comparative Study.

Aim: The surface roughness of dental restorations can decrease resin durability, since it leads to its deterioration, color variation, and loss of gloss. Therefore, the aim was to assess the surface roughness of nanoparticle resin composites, subjected to two different polishing systems. Materials and Methods: This longitudinal in vitro experimental study consisted of 32 resin specimens made according to ISO 4049-2019 and divided equally into four groups: A1: Palfique LX5 / Sof-Lex, A2: Palfique LX5 / Super Snap, B1: Filtek Z350 XT / Sof-Lex, and B2: Filtek Z350 XT / Super Snap. The samples were stored in distilled water at 37°C for 24 h. Surface roughness was measured with a digital roughness tester, both before and after the polishing procedure. The data were analyzed with the Student's t-test for related samples, and with the inter-subject ANOVA test with two factors; considering significance at P < 0.05. Results: The surface roughness of Palfique LX5 resin with the Sof-lex system was 0.330 (CI: 0.282-0.378 µm) and 0.170 (CI: 0.087-0.253 µm) before and after polishing, respectively. With the Super Snap system, values of 0.448 (CI: 0.346-0.549 µm) and 0.206 (CI: 0.130-0.282 µm) were obtained before and after polishing, respectively. For the Filtek Z350 XT resin, the surface roughness obtained with the Sof-lex system was 0.353 (CI: 0.278-0.427 µm) and 0.134 (CI: 0.095-0.172 µm) before and after polishing, respectively. With the Super Snap system, values of 0.334 (CI: 0.247-0.421 µm) and 0.171 (CI: 0.122-0.221 µm) were obtained before and after polishing, respectively. Surface roughness did not show significant differences in all groups assessed both before (P = 0.068) and after (P = 0.335) polishing. However, before and after the application of the polishing systems, all groups significantly decreased their surface roughness (P < 0.05). Further, when comparing this decrease among all groups, no significant differences were observed (P = 0.437). Conclusion: The surface roughness of the Filtek Z350 XT and Palfique LX5 nanoparticle resin composites showed no significant differences when using the Sof-lex and Super Snap polishing systems. However, both polishing systems significantly decreased the surface roughness of the nanoparticulated resins, with this decrease being similar in all groups.