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Multimedia resources, such as instructional videos, are currently enjoying a certain popularity in the training programs for medical and dental students. The major challenge is to create such resources with quality content that is approved by students. In order to answer this challenge, it is imperative to find out which features of instructional videos are considered to be necessary and useful by students, thus being able to excite them, to hold their attention, and to stimulate them in learning with pleasure. AIM: We investigated the opinions of a sample of 551 students from four medical universities in Romania, in order to identify the students' preferred characteristics in instructional videos, both globally and comparatively on genders and age groups and also according to their general preferences for using internet services. MATERIAL AND METHODS: We used univariate (hypothesis testing) and multivariate (two-step clustering) data analysis techniques and revealed three clusters of students, primarily determined by their perceptions of the visual appearance of the instructional videos. RESULTS: The structure of the clusters by gender and age group was relatively similar, but we recorded differences associated with the students' expressed preferences for certain internet services compared to others. The first identified cluster (35.4% of the cases) contains students who prefer instructional videos to contain images used only for aesthetic purposes and to fill the gaps; they use internet services mainly for communication. The second cluster of students (34.8%) prefers videos designed as practical lessons, using explanatory drawings and diagrams drawn at the same time as the explanations; they also use internet services mainly for communication. The last cluster of students (29.8%) prefer videos designed as PowerPoint presentations, with animated pictures, diagrams, and drawings; they are slightly younger than the others and use internet services mainly for information and communication, but also for domestic facilities. CONCLUSIONS: The students' preferences for certain features of instructional videos depend not only on gender and age but are also related to their developmental background and general opinions about modern technologies.
RESUMEN
INTRODUCTION: The aim of this in vitro study was to compare the quality of marginal sealing at the cervical margins of indirect and direct composite resin restorations in mesio-occluso-distal (MOD) cavities. MATERIAL AND METHOD: MOD preparations were performed on 30 extracted teeth. The mesial cervical margin of each tooth was relocated using a flow composite resin (Enamel Plus HRi Flow, Micerium, Avegno, GE, Italy), then the samples were divided into three groups. In group A, the cavities were directly restored using a nanohybrid composite resin (Miris 2 Coltène Whaledent, Altstaetten, Switzerland) and a universal adhesive (ScotchBond Universal, 3M ESPE, St. Paul, MN, USA) by the etch-and-rinse strategy, for group B, the restoration procedure was similar but the self-etch strategy was used, and the samples in group C were filled using the inlay technique. Each sample was stored for 48 h in a 2% methylene blue solution, then it was cut in a mesio-distal direction using a Struers Secotom 50 device (Cleveland, OH, USA). The marginal sealing and adhesive interface were assessed for each sample at the cervical margin by optical microscopy (OM) and scanning electron microscopy (SEM). One-way ANOVA and Bonferroni post-hoc tests were used with a significance level of 0.05. RESULTS: Significant differences were recorded within groups A and C, between mesial and distal margins (p = 0.02 in group A and p = 0.043 in group C). CONCLUSIONS: The marginal sealing is more effective in MOD inlay restoration compared to direct restorations. Relocation of the cervical margin with flow composite resin and the use of different adhesive strategies do not improve the marginal sealing.
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The goals of this research are: (1) to compare the survival and prosthetic success of metal-ceramic 3-unit tooth- versus implant-supported fixed dental prostheses; (2) to evaluate the influence of several risk factors on the prosthetic success of tooth- and implant-supported fixed dental prostheses (FPDs). A total of 68 patients with posterior short edentulous spaces (mean age 61.00 ± 1.325 years), were divided into two groups: 3-unit tooth-supported FPDs (40 patients; 52 FPD; mean follow-up 10.27 ± 0.496 years) and 3-unit implant-supported FPDs (28 patients; 32 FPD; mean follow-up 8.656 ± 0.718 years). Pearson-chi tests were used to highlight the risk factors for the prosthetic success of tooth- and implant-supported FPDs and multivariate analysis was used to determine significant risk predictors for the prosthetic success of the tooth-supported FPDs. The survival rates of 3-unit tooth- versus implant-supported FPDs were 100% and 87.5%, respectively, while the prosthetic success was 69.25% and 68.75%, respectively. The prosthetic success of tooth-supported FPDs was significantly higher for patients older than 60 years (83.3%) vs. 40-60 years old (57.1%) (p = 0.041). Periodontal disease history decreased the prosthetic success of tooth- versus implant-supported FPDs when compared with the absence of periodontal history (45.5% vs. 86.7%, p = 0.001; 33.3% vs. 90%, p = 0.002). The prosthetic success of 3-unit tooth- vs. implant-supported FPDs was not significantly influenced by gender, location, smoking, or oral hygiene in our study. In conclusion, similar rates of prosthetic success were recorded for both types of FPDs. In our study, prosthetic success of tooth- versus implant-supported FPDs was not significantly influenced by gender, location, smoking, or oral hygiene; however, history of periodontal disease is a significant negative predictor of success in both groups when compared with patients without periodontal history.
RESUMEN
UNLABELLED: Hygroscopic expansion of resin materials is a common phenomena due to water adsorption into the resin matrix. This expansion is dependent upon the chemical structure of the material. Water sorption of resin dental material may contribute to stress release immediately after polymerization shrinkage has occurred. The aim of this study was to evaluate the influence of water storage on nanohybrid composite by assessment of marginal enamel sealing of restorations. MATERIAL AND METHOD: 30 human teeth extracted for periodontal or orthodontic reasons were used in these study. Cavities were prepared and restored using a nanohybrid composite (Ceramix Mono, Dentsply DeTrey) and a total-etch adhesive system (Prime&Bond NT, Dentsply DeTrey). The teeth were then randomly divided in three groups which were stored for various times in deionized water (one hour, 24 hours and 7 days). After the storage period, the teeth were immersed in methylen blue 1% for 24 h. Then specimens were axially cut and the dye penetration within the occlusal enamel interface was evaluated using optic microscope. RESULTS: Kruskal-Wallis test showed significant differences of dye penetration between the long-term hydrated groups and the group hydrated for only one hour (p < 0.05). The mean value of dye penetration decreased from 0.04 mm to 0.1 mm after water storage for both 24 hours and 7 days. However, good sealing in enamel margins of restorations was observed even without hydration. CONCLUSION: Our results confirm that nanohybrid composites used with total etch adhesives systems have good ability to seal the enamel margins and water sorption can improve this sealing.
