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This study aimed to evaluate the micro-mechanical and macro-mechanical properties of self-cured and light-cured alkasite and to investigate how accelerated degradation in acidic, alkaline, and ethanol solutions affects the macro-mechanical properties of self-cured and light-cured alkasite. The specimens of the alkasite material (Cention Forte, Ivoclar Vivadent) were prepared according to the following three curing modes: (1) light-cured immediately, (2) light-cured after a 5-min delay, and (3) self-cured. Microhardness was tested before and after immersion in absolute ethanol to indirectly determine crosslink density, while flexural strength and flexural modulus were measured using a three-point bending test after accelerated aging in the following solutions: (1) lactic acid solution (pH = 4.0), (2) NaOH solution (pH = 13.0), (3) phosphate-buffered saline solution (pH = 7.4), and (4) 75% ethanol solution. The data were statistically analyzed using a two-way ANOVA and Tukey post hoc test. The results showed that the microhardness, flexural strength, and flexural modulus were significantly lower in self-cured specimens compared to light-cured specimens. A 5-min delay between the extrusion of the material from the capsule and light curing had no significant effect on any of the measured properties. A significant effect of the accelerated aging solutions on macro-mechanical properties was observed, with ethanol and alkaline solutions having a particularly detrimental effect. In conclusion, light curing was preferable to self-curing, as it resulted in significantly better micro- and macro-mechanical properties, while a 5-min delay between mixing the capsule and light curing had no negative effects.
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This study evaluated the flexural properties of an experimental composite series functionalized with 5-40 wt% of a low-Na F-containing bioactive glass (F-series) and compared it to another experimental composite series containing the same amounts of the conventional bioactive glass 45S5 (C-series). Flexural strength and modulus were evaluated using a three-point bending test. Degree of conversion was measured using Fourier-transform infrared spectroscopy. Weibull analysis was performed to evaluate material reliability. The control material with 0 wt% of bioactive glass demonstrated flexural strength values of 105.1-126.8 MPa). In the C-series, flexural strength ranged between 17.1 and 121.5 MPa and was considerably more diminished by the increasing amounts of bioactive glass than flexural strength in the F-series (83.8-130.2 MPa). Analogously, flexural modulus in the C-series (0.56-6.66 GPa) was more reduced by the increase in bioactive glass amount than in the F-series (5.24-7.56 GPa). The ISO-recommended "minimum acceptable" flexural strength for restorative resin composites of 80 MPa was achieved for all materials in the F-series, while in the C-series, the materials with higher bioactive glass amounts (20 and 40 wt%) failed to meet the requirement of 80 MPa. The degree of conversion in the F-series was statistically similar or higher compared to that of the control composite with no bioactive glass, while the C-series showed a declining degree of conversion with increasing bioactive glass amounts. In summary, the negative effect of the addition of bioactive glass on mechanical properties was notably less pronounced for the customized bioactive glass than for the bioactive glass 45S5; additionally, mechanical properties of the composites functionalized with the customized bioactive glass were significantly less diminished by artificial aging. Hence, the customized bioactive glass investigated in the present study represents a promising candidate for functionalizing ion-releasing resin composites.
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Objectives: The aim of the study was to evaluate the attitude and perspectives of dental students of four Croatian universities towards online learning during the COVID-19 pandemic. Material and methods: An anonymous internet-based survey was administered to undergraduate dental medicine students at the Universities of Zagreb, Rijeka, Split and Osijek. The 29-item questionnaire collected data on students' demographics, online learning organization and management, and perception of online classes. Results: Five hundred and four participants (85.1% female) took part in the survey. The majority of the participants (63.5%) were from the University of Zagreb. 39.6% of students reported agreement regarding online learning satisfaction. Individual university satisfaction ratings on overall online learning were: Osijek 3.69, Zagreb 3.22, Split 3.05 and Rijeka 2.64. Most students considered that lectures (82.9%) and seminars (78.9%) could be successfully delivered in an online learning format. The online learning format cannot successfully deliver laboratory, preclinical, clinical practicals or clinical clerkship, as agreed by more than 80% of the total student sample. 60% of students consider online learning a valuable alternative to face-to-face instruction. Conclusion: Online learning was highly praised for educational formats such as lectures and seminars, and was considered a useful substitute for conventional learning. Conventional practical courses cannot be substituted with online learning. Overall perspective about online learning was mixed among the students of four universities. The findings of the present study can serve to help individual universities address the shortcomings and reinforce the strengths of their OL programs.
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PURPOSE: Dental education institutions worldwide experienced disruptive changes amid the COVID-19 pandemic, with a rapid switch to the online learning format. Thus, this study aimed to assess the impact of the COVID-19 pandemic on dental education and evaluates the perceptions and attitudes of students towards the introduction of online learning in the School of Dental Medicine in Zagreb, Croatia. METHODS: A survey was conducted on a population of undergraduate students. It was comprised of perceptions and attitudes of students on the impact of the COVID-19 pandemic on their psychoemotional status, changes introduced in the educational system, and online learning in particular. RESULTS: Of the 352 students that completed the survey, 66.2% of students reported being psychoemotionally affected by the lockdown. The most significant impact of the switch from in-person to online learning was observed in terms of missing contact with lecturers (60.3%) and peers (90.3%) and loss of practical courses, regarding which 65% of students agreed that they could not be compensated. While only 36.1% reported that online teaching fully met their expectations, the majority of the students (61.9%) agreed that online lectures were as valuable as in-person lectures and that the theoretical courses could be carried out online in the future as well (69.9%). CONCLUSIONS: Students reported relative satisfaction with changes in the learning format and a positive attitude towards online learning; however, several challenges and obstacles were identified.
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As future healthcare professionals, dental medicine students are expected to exhibit healthy lifestyle behaviors. This study aims to assess the health-promoting behaviors among undergraduate dental medicine students of all six academic study years at the University of Zagreb, and determine their predictors. Students were invited to complete a two-part survey, consisting of a self-reported sociodemographic questionnaire and the Health-Promoting Lifestyle Profile II (HPLP II). Three hundred and forty-nine students completed the survey; the response rate was 60.3%. The total mean HPLP II score was 2.64 ± 0.34. Students in the second academic study year scored the lowest (2.50 ± 0.33), and students in the sixth academic study year scored the highest (2.77 ± 0.32). Health responsibility was the overall lowest scored subcategory, while interpersonal relations was scored the highest. Female students reported lower spiritual growth and stress management than male students. Higher body mass index (BMI) was related to lower health responsibility. Smoking, place of residence and the age of participants did not seem to have an impact on health-promoting behaviors. Dental students at our faculty exhibit moderate health-promoting behaviors, even in the absence of a formal health-promoting course in the existing curriculum.
