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Background/Purpose: Whether YouTube videos contain precise and adequate information on certain orthodontic procedures remains unclear. This study aimed to investigate the content and quality of YouTube videos on orthodontic elastics and identify the predictors of high-level content YouTube videos. Materials and Methods: Two hundred YouTube videos were screened for eligibility, and after applying the inclusion criteria, 133 videos were excluded. Student's t-test was used to compare the characteristics, quality parameters, and total content of the low-level and high-level content videos. Chi-square or Fisher's exact tests were implemented to identify the source and content element differences across low-level and high-level content videos. Pearson's correlation coefficients were used to determine the relationship between the total content score, video information and quality index (VIQI), and YouTube characteristics. Stepwise linear multiple regressions with forward selection were used to test the association of the YouTube characteristics and VIQI with the total content score. Results: Among 67 included videos, only 19.4% of videos were classified as high-level content videos. High-level content videos had significantly higher mean number of likes (MD = 4041.7; SD = 4680.7; P-value=0.0068), VIQI score (MD = 4.17; SD = 4.87; P-value=0.0073), and total content score (MD = 4.04; SD = 1.23; P-value=<0.0001). The adjusted linear regression model demonstrated a significant association between the total content score and VIQI, where 1 unit increase in the VIQI was significantly associated with a 0.16 increase in the total content score (B = 0.16; standard error [SE]=0.04; P = 0.0003). Further, a significant association was observed between the total content score and video duration, where 1 minute increase in the video duration was significantly associated with a 0.15 increase in the total content score (B = 0.15; SE = 0.05; P = 0.008). Conclusion: This study demonstrated that YouTube content quality concerning orthodontic elastics is poor. Thus, future implementation of online visual content provided by certified orthodontists will ensure accurate and thorough information delivery.
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PURPOSE: To evaluate the effect of different printing orientations and post-polymerization time with thermal cycling on the translucency of 3D-printed denture base resins. METHODS: Heat-polymerized (HP) acrylic resin specimens were fabricated and 3D-printed denture base materials (NextDent, ASIGA, FormLabs) were printed with different printing orientations (0, 45, 90 degrees) and subjected to different post-polymerization times (15-, 30-, 60-, and 90-min). All specimens were polished and immersed in distilled water for 1 day at 37°C. CIEDE2000 was used to measure the translucency parameters (TP00) before and after thermal cycling (5000 cycles) recording the color parameters (L*, a*, b*) against a black and white background using a spectrophotometer. k-factors ANOVA followed by post hoc Tukey's test (α = .05) was performed for statistical analysis. RESULTS: The k-factors ANOVA test showed a significant effect of resin material, post-polymerization time, and printing orientation on translucency (p < 0.001). In comparison to HP, all 3D-printed resins showed lower translucency with all post-polymerization times and printing orientation (p < 0.001) except FormLabs resin (p > 0.05). For all 3D-printed resins, the translucency increased, with increasing the post-polymerization time (p < 0.001) and 60- and 90-min showed the highest translucency. For printing orientation, 90 and 45 degrees significantly showed high translucency in comparison to 0 degrees (p < 0.001). FormLabs showed significantly higher translucency when compared with NextDent and ASIGA per respective printing orientation and post-polymerization time. The translucency significantly decreased after thermal cycling for all tested resins (p < 0.001). CONCLUSION: The findings of this study demonstrated that the translucency of 3D-printed resins is influenced by the printing orientation, post-polymerization time, and resin type. As a result, choosing a resin type, and printing orientation, with a longer post-polymerization time should be considered since it may improve the esthetic appearance of the 3D-printed resins.
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Three-dimensionally (3D)-printed fabricated denture bases have shown inferior strength to conventional and subtractively fabricated ones. Several factors could significantly improve the strength of 3D-printed denture base resin, including the addition of nanoparticles and post-curing factors. This study evaluated the effect of TiO2 nanoparticle (TNP) addition and the post-curing time (PCT) on the flexural properties and hardness of three-dimensionally (3D)-printed denture base resins. A total of 360 specimens were fabricated, with 180 specimens from each type of resin. For evaluating the flexural properties, bar-shaped specimens measuring 64 × 10 × 3.3 mm were used, while, for the hardness testing, disc-shaped specimens measuring 15 × 2 mm were employed. The two 3D-printed resins utilized in this study were Asiga (DentaBASE) and NextDent (Vertex Dental B.V). Each resin was modified by adding TNPs at 1% and 2% concentrations, forming two groups and an additional unmodified group. Each group was divided into three subgroups according to the PCT (15, 60, and 90 min). All the specimens were subjected to artificial aging (5000 cycles), followed by testing of the flexural strength and elastic modulus using a universal testing machine, and the hardness using the Vickers hardness test. A three-way ANOVA was used for the data analysis, and a post hoc Tukey's test was used for the pairwise comparisons (α = 0.05). Scanning electron microscopy (SEM) was used for the fracture surface analysis. The addition of the TNPs increased the flexural strength in comparison to the unmodified groups (p < 0.001), while there was no significant difference in the elastic modulus and hardness with the 1% TNP concentration. Among the TNP groups, the 2% TNP concentration significantly decreased the elastic modulus and hardness (p < 0.001). The SEM showed a homogenous distribution of the TNPs, and the more irregular fracture surface displayed ductile fractures. The PCT significantly increased the flexural strength, elastic modulus, and hardness (p < 0.001), and this increase was time-dependent. The three-way ANOVA results revealed a significant difference between the material types, TNP concentrations, and PCT interactions (p < 0.001). Both concentrations of the TNPs increased the flexural strength, while the 2% TNP concentration decreased the elastic modulus and hardness of the 3D-printed nanocomposites. The flexural strength and hardness increased as the PCT increased. The material type, TNP concentration, and PCT are important factors that affect the strength of 3D-printed nanocomposites and could improve their mechanical performance.
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OBJECTIVES: To evaluate the dental and skeletal effects of chin cup using two different force magnitudes in the management of Class III malocclusion cases. MATERIALS AND METHODS: Fifty growing patients (26 males and 24 females) with skeletal Class III and mandibular prognathism were selected. The patients were divided into three groups. Patients in group 1 (n = 20) were treated with a chin cup and occlusal bite plane using 600 g of force per side. Patients in group 2 (n = 20) were subjected to the same treatment as in group 1 but using 300 g of force per side. In group 3 (n = 10) no treatment was performed. For all patients, lateral cephalograms were taken before treatment and after 1 year. Cephalograms were traced and analyzed. The collected data were analyzed statistically using one-way analysis of variance and the Tukey test. RESULTS: In the treatment groups, the SNB angle and ramus height decreased significantly. The ANB angle, Wits appraisal, anterior facial height, mandibular plane angle, and retroclination of the mandibular incisors were significantly increased in comparison to the control group. Utilization of either force showed no significant differences, except that the reduction in the ramus height was significantly greater with the use of higher force. CONCLUSIONS: The use of a chin cup improved the maxillomandibular base relationship in growing patients with Class III malocclusion but with little skeletal effect. The utilization of either force had the same effects, except that the higher force had a more pronounced effect in reduction of ramus height.
