Effects of an interactive simulation material for clinical dentistry on knowledge acquisition and memory retention in dental residents.

With the development of technology, the knowledge and skills needed to become a dentist are increasing. Computer-assisted simulation learning materials have been utilized for dental education because of their high efficiency and efficacy. However, it is not well understood which material design is strongly associated with an education effect. We therefore investigated the effects of interactivity with learning materials on learners' knowledge acquisition, memory retention, and anxiety reduction. Learning effects and degree of anxiety were compared between dental residents who learned using an interactive-type material, which required decision making and provided feedback (Group I, n=26), and those who learned using a display-type material, which merely displayed the appropriate action on a computer screen (Group D, n=23). Quiz scores immediately after learning and 3 weeks later were significantly higher in Group I than those in Group D (p<0.001 and 0.016, espectively). Regarding anxiety, state anxiety after learning with interactive material was significantly decreased in Group I (p<0.05), whereas no significant change was observed in Group D. Our results suggest that interactivity with computerassisted simulation materials is more effective for knowledge acquisition, memory retention, and anxiety reduction.

[Development of an Enterococcus faecalis periapical biofilm model for in vitro morphological study].

OBJECTIVE: This study aims to develop and observe a model system of the periapical biofilm structure of Enterococcus faecalis (E. faecalis). METHODS: A total of 24 intact human single-rooted premolars extracted for orthodontic reasons were collected and randomly divided into eight groups (n = 3). The specimens were subjected to ultraviolet disinfection, inoculated with E. faecalis (ATCC 29212) suspension adjusted to 1 x 10(8) CFU x mL(-1), and incubated at 37 degrees C for 1, 2, and 7 d. Specimen groups were prepared for scanning electron microscope to examine the biofilm formation. The specimens in the confocal laser scanning microscope (CLSM) groups were stained with propidium iodide (PI) and ConA-fluorescein isothiocyanate (ConA-FITC) to examine the biofilm formation. The images were randomized, and biofilm coverage (%) was assessed using Photoshop CS5. RESULTS: The biofilm coverage (%) on the cementum increased with increasing incubation period. The biofilm coverage of the 7 d group was significantly higher than those of the 1 and 2 d groups (P < 0.05). The values of the latter two groups were not significantly different (P > 0.05). Dense aggregations composed of E. faecalis and the amorphous matrix were observed on the root cementum surfaces of the specimens in the 7 d group. The bacteria were stained red by PI, and the matrix was stained green by ConA-FITC under CLSM observation. The biofilm coverage (%) on the samples in the 7 d group was 17.23% +/- 1.52%, showing multi-level space structure and water channels. CONCLUSION: E. faecalis forms bacterial biofilms on the root cementum surface in 7 d. The biofilms were composed of E. faecalis and the amorphous matrix.