RESUMEN
Objective: The objective of this study was to compare the sorption and solubility of heat‑cure and self‑cure acrylic resins in different solutions. Materials and Methods: One heat‑cure acrylic resin (Trevalon) and one self‑cure acrylic resin (Rapid Repair) were studied. Five groups of square‑shaped specimens (20 mm × 20 mm × 2 mm) were prepared for each acrylic resin and then immersed in five solutions: distilled water, artificial saliva, denture cleansing solution, distilled water, and denture cleaning solution for 12 h alternatively, artificial saliva and denture cleaning solution for 12 h alternatively at 37 ± 2°C, and tested sorption and solubility by weight gain/loss method, respectively, after 1, 6, and 11 weeks. The data were analyzed by one‑way analysis of variance followed by post hoc Tukey’s test. Results: Water sorption mean values varied from 17.5 ± 0.88 to 27.25 ± 1.04 μg/mm3 for heat cure and from 12.75 ± 0.55 to 19.75 ± 1.04 μg/mm3 for self‑cure in the different solutions after different interval periods of 1, 6, and 11 weeks. These values were statistically significant (P < 0.001). Water solubility mean values varied from 0.25 ± 0.55 to 1.5 ± 0.55 μg/mm3 for heat cure and from 1.5 ± 0.55 to 6.5 ± 0.55 μg/mm3 for self‑cure in the different solutions after different interval periods of 1, 6, and 11 weeks. These values were statistically not significant (P > 0.05). There was no linear correlation between sorption and solubility values. Overall, analysis of results showed the maximum sorption value in denture cleansing solution followed by alternative soaking in distilled water and artificial saliva. Least sorption was observed with artificial saliva followed by distilled water. Conclusion: Both heat‑cure and self‑cure acrylic resins showed varying water sorption and solubility. The results of both water sorption and solubility showed compliance with the International Standards Organization specification. No correlation was found between water sorption and solubility. Artificial saliva solution is a better storage medium than distilled water and denture cleansing solution for both heat‑cure and self‑cure acrylic resins.
RESUMEN
Introduction: Students, like anybody else differ from each other. As students they differ in their preferred mode of learning, i.e. their preferred modes in gathering, organizing and thinking about information. A recent classification proposed by Neil Fleming and associates state that students learning styles can be divided into Visual/graphic, Aural, Read/write and Kinesthetic types, VARK. Aim: The aim of the recent study is to investigate learning styles among dental students in two different dental colleges of India. Method: The VARK-questionnaire contains 15 multiple-choice- questions with four possibilities to select an answer. Each possibility represents one of the four modes of perception. But, one can select more than one answer to each question, which is necessary for the identification of poly modal modes of perception and learning. This is also a psychometric problem when trying to state a measure of the reliability of the questionnaire. The VARK-questionnaire was distributed among 200 students and was collected back. This sample size represents 100% response rate from the students in the class and is markedly above the level required to make conclusions about student preferences for receiving and processing information. The students spent about 10 minutes in an ordinary lesson to fill in the questionnaire. Students register number and name were used in the study and there was no blinding practiced. Study Design: Questionnaire based clinical study Results: The responses from the students in our University where classified into multi-modal (VARK), tri-modal (VRK, VAK, VAR, ARK), bi-modal (VR, VA, VK, RK) and uni-modal (V, A, R.K) categories. Results showed that subjects had a higher preference for multimodal learning. Conclusion: We conclude that students in our set up prefer multimodal and more of Kinesthetic of learning. To meet their needs, a variation in teaching, learning and examination must be implemented. If not, these students with a high kinesthetic preference for perception and learning may be at the losing end.
RESUMEN
Aim: In an effort to minimize tooth preparation, yet provide additional retention to compromised tooth structure, bonded amalgam restorations were introduced. Various resin-based adhesives have been tried earlier under bonded amalgam restorations. Still there are controversies regarding the outcome of bonded amalgam restorations regarding their adaptability to the tooth structure and microleakage. Therefore, this study was undertaken to compare the microleakage of bonded amalgam restorations using different adhesive materials. Materials and Methods: Standard Class I cavities were prepared on occlusal surfaces of 60 human molars. Teeth (n=60) were divided into three groups according to the material employed, as follows: group I: amalgam with glass ionomer cement (GIC) (type I); group II: amalgam with resin cement (Panavia F 2.0) and group III: amalgam with Copalex varnish as a control. Following restoration, the teeth were submitted to thermal cycling. The teeth were subsequently immersed in 2% rhodamine B dye under vacuum for 48 hours and sectioned to allow the assessment of microleakage under stereomicroscope. Results: The values were tabulated and the results were statistically analyzed using analysis of variance (ANOVA), Tukey's post hoc test and Kruskal-Wallis test. Amalgam with type I GIC showed the least leakage with no statistically significant difference (P value 0.226) when compared to amalgam with Panavia F 2.0 and amalgam with varnish (P value 0.107). Conclusion: It can be concluded that bonded amalgam with type I GIC is a good alternative to amalgam with resin cement (Panavia F 2.0) and amalgam with varnish for large restorations, with the added advantages of GICs. Clinical Significance: Bonded amalgam restorations prevent over-preparation and reduce the tooth flexure. GIC type I under amalgam provides chemical bonding in between amalgam and tooth structure and thus reduces the microleakage.