RESUMEN
Introduction: The aim of this study was to compare the effect of two educational methods: live practical and multimedia demonstrations of dental cast trimming. Methods: In this quasi-experimental study, all 44 dental students from Zanjan University Dental School who were studying in the 8th semester entered the study. Using simple randomization, we assigned them to two groups. Multimedia and live demonstrations were used in the intervention (n=21) and control (n=23) groups, respectively. Knowledge of students was assessed using pre-test and post-test. Practical skills were compared using the students' final semester scores. The Individual Development and Educational Assessment questionnaire was used to assess the students' reaction to instruction. For data analysis, mean and standard deviation, and independent and paired t-tests were used. Statistical analysis was performed using SPSS software. Results: In terms of knowledge, the pre-test scores of the intervention and control groups were not significantly different (p-value= 0.457), and the post-test scores of the two intervention and control groups had no significant difference (p-value= 0.053); however, in both intervention and control groups there was a significant difference between the scores before and after the test, and the scores of both groups increased after training (p-value= 0.001, p-value= 0.001). In terms of practical skills, no significant difference was observed in the mean and standard deviation of the scores in the two groups (p-value=0.902). There was no significant difference in terms of the students' reaction to instruction. Conclusion: All students passed this course successfully. Further, their knowledge and skills were improved in both groups. Similar to the live practical demonstration, that of the multimedia led to a positive reaction to instruction in students. Therefore, multimedia education can be used well with the traditional method and even replaces it.
RESUMEN
BACKGROUND: The heat from laser can lead to the destruction of organic components of enamel and consequently changes in the mechanical properties of enamel. The purpose of this study was to evaluate the effect of diode laser on the nanomechanical properties of enamel in the process of debonding the ceramic brackets. MATERIALS AND METHODS: In This in vitro study Eighteen ceramic brackets were bonded on the intact premolars in 3 groups of 6 (one control and two study groups). To debond the brackets in the study groups, laser diode was used for 3 s with 1W and 3W power. Shear bond strength and adhesive remnant index were recorded for all groups. Hardness and elastic modulus were measured in 1-31 µ depth from enamel surface in each debonded area. Analysis of variance was used for determining the difference in shear bond strength (SBS), hardness, and elastic modulus and was followed by post hoc Tukey's honest significant difference test. One-sample t-test was used to compare the changes in the pulp temperature with the standard threshold (5.5°C). The significance level was set at %5 in this study. RESULTS: SBS was significantly greater in the control group compared to the study groups. There was no significant difference in the average of hardness and elastic modulus of enamel between the groups. Pulp temperature elevation in the study groups was significantly < 5.5°C (P = 0.000). CONCLUSION: The diode laser with either 1W or 3W power for 3 s is effective in debonding the ceramic brackets without any detrimental effect on the pulp or mechanical properties of enamel. In regard to the pulp health, the 1W power laser is rather recommended for debonding the ceramic brackets than the 3W laser power.
