ABSTRACT
OBJECTIVES: Composites with copper-doped mesoporous bioactive nanospheres (Cu-MBGN) were developed to prevent secondary caries by imparting antimicrobial and ion-releasing/remineralizing properties. METHODS: Seven experimental composites containing 1, 5 or 10 wt% Cu-MBGN, the corresponding inert controls (silica) and bioactive controls (bioactive glass 45S5) were prepared. The temperature rise during light curing, cross-linking density by ethanol softening test, monomer elution and their potential adverse effects on the early development of zebrafish Danio rerio was investigated. RESULTS: Materials combining Cu-MBGN and silica showed the highest resistance to ethanol softening, as did the bioactive controls. Cu-MBGN composites showed significant temperature rise and reached maximum temperature in the shortest time. Bisphenol A was not detected, while bis-GMA was found only in the control materials and TEGDMA in the eluates of all materials. There was no increase in zebrafish mortality and abnormality rates during exposure to the eluates of any of the materials. CONCLUSIONS: The composite with 5 wt% Cu-MBGN combined with nanosilica fillers showed the lowest ethanol softening, indicating the polymer's highest durability and cross-linking density. Despite the TEGDMA released from all tested materials, no embryotoxic effect was observed.
ABSTRACT
Clinical indications for the newly released Ti-Zr (Roxolid®) alloy mini-implants (MDIs) aimed for overdenture (OD) retention in subjects with narrow alveolar ridges are not fully defined. The aim of this study was to analyze peri-implant and posterior edentulous area microstrains utilizing models of the mandible mimicking a "real" mouth situation with two (splinted with a bar or as single units) or four unsplinted Ti-Zr MDIs. The models were virtually designed from a cone beam computed tomography (CBCT) scan of a convenient patient and printed. The artificial mucosa was two millimeters thick. After MDI insertion, the strain gauges were bonded on the oral and vestibular peri-implant sites, and on distal edentulous areas under a denture. After attaching the ODs to MDIs, the ODs were loaded using a metal plate positioned on the first artificial molars (posterior loadings) bilaterally and unilaterally with 50, 100, and 150 N forces, respectively. During anterior loadings, the plate was positioned on the denture's incisors and loaded with 50 and 100 N forces. Each loading was repeated 15 times. The means with standard deviations, and the significance of the differences (two- and three-factor MANOVA) were calculated. Variations in the MDI number, location, and splinting status elicited different microstrains. Higher loading forces elicited higher microstrains. Unilateral loadings elicited higher microstrains than bilateral and anterior loadings, especially on the loading side. Peri-implant microstrains were lower in the four-MDI single-unit model than in both two-MDI models (unsplinted and splinted). Posterior implants showed higher peri-implant microstrains than anterior in the four-MDI model. The splinting of the two-MDI did not have a significant effect on peri-implant microstrains but elicited lower microstrains in the posterior edentulous area. The strains did not exceed the bone reparatory mechanisms, although precaution and additional study should be addressed when two Ti-Zr MDIs support mandibular ODs.
ABSTRACT
BACKGROUND: Fulfilling aesthetic norms is an imperative of modern society. Accordingly, aesthetics has found its important role in dental medicine. The aim was to study whether there is a difference in the perception of tooth shade change and anatomical variations of anterior maxillary teeth among dental students depending on the level of education, gender, and experience in assisting in a dental office. METHODS: The research was conducted among dental students via the Google Forms platform. Students evaluated the aesthetic acceptability of a smile on the unaltered, reference photograph (RP) and on the other 28 photographs in which the tooth shade (lighter and darker teeth), length (shortened central incisors, elongated, and beveled lateral incisors, elongated canines) and position (atypical and typical rotations and diastemas) of the upper maxillary teeth were altered by digital manipulation. The 1-10 assessment scale was used. Statistical analysis comprised one-way Kolmogorov-Smirnov test, X2 tests, t-test, and 3-way MANOVA. RESULTS: In the research 208 students participated, 113 were preclinical students, 104 assisted in dental office and 175 were females. There were no significant effects of gender regarding length and position modifications (p > .05), while women were stricter in evaluation of lighter shade (p < .05). Clinical students were stricter in evaluating all manipulated photographs (MP) except those towards darker shade modifications, while assisting in a dental office or having a dentist in close family showed no significant effects (p > .05). CONCLUSIONS: With a higher level of targeted academic education, dental students sharpen their ability to notice deviations from the aesthetic norms of a smile.
