ABSTRACT
BACKGROUND: Model alignment in cases of erosive tooth wear can be challenging, and no method has been reported to outweigh the others. METHODS: Extracted human teeth were mounted on two models and scanned at different times, from 1 h to 2 weeks, with an intraoral scanner (3Shape TRIOS 4) before and after immersion in Monster® energy drink and tap water. The scans were superimposed (3Shape TRIOS Patient Monitoring, Version 2.2.3.3, 3Shape A/S, Copengagen, Denmark). Best fit, best-fit tooth comparison, reference best fit using fillings, and palatal rugae as reference points were used for alignment. Surface profile differences were calculated in a cross-section view. The nonparametric Bland-Altman and Kruskal-Wallis tests were used. RESULTS: First, statistically significant differences were marked after 4 days of immersion. The measurements obtained after 2 weeks of immersion were statistically significantly different from the measurements obtained at the different time points until 1 week. No statistically significant differences (p < 0.05) were observed among the alignment methods at any time. CONCLUSION: In comparison to the best-fit model, both palatal rugae and fillings can be used. The best-fit tooth comparison method is a reliable option; however, it should be used with caution in cases of major surface loss.
ABSTRACT
Saliva consists of organic and inorganic constituents. During exercise, analysis of the saliva can provide valuable information regarding training stress, adaptation and exercise performance. The objective of the present article was to review the effect of physical exercise on saliva composition. The shift in the composition of the saliva, during and after a workout, reflects the benefits of exercise, its potential risks and the capability of the saliva to serve as a health indicator. The type and the frequency of training, the physical condition and the athletes' general health influence the hormones, immunoglobulins and saliva enzymes. The correlation between saliva and physical exercise has to be further investigated and the available knowledge to be applied for the benefit of the athletes during sports activities.
ABSTRACT
The aim of the present laboratory study was to mechanically characterize the interface between two dental resin-based composite (RBC) increments, and to investigate if elevated temperatures have an influence on the quality of the interface mimicking clinical filling procedure. Four RBCs (CLEARFIL MAJESTY™ Posterior, Kuraray (CMP)/Filtek™ Supreme XTE, 3M (FSX)/Grandio®SO, VOCO (GSO)/VisCalor® bulk, VOCO (VCB)) were tested with a fracture toughness test using Chevron notched beams (KI,CNB) at 23, 37 and 54 °C. KI,CNB specimens (3 × 4x25mm) with a V-shaped notch at the incremental interface were loaded until failure in a 4-point bending set-up. Failure modes were characterized using light microscopy, microstructural interface was analyzed using SEM. Statistical analysis was performed using Kolmogorov-Smirnoff test, two-way ANOVA and Tukey Post-Hoc test (p = 0.05). Mean KI,CNB ranged between 0.73 ±0.14 MPam0.5 (VCB, 23 °C) and 1.11 ± 0.11 MPam0.5 (FSX, 23 °C). The tested conventional highly filled RBCs presented fracture toughness at the incremental interface comparable to the cohesive strength of the bulk materials. VCB showed reduced interfacial fracture toughness at 23 and 37 °C, but performed well at elevated temperature of 54 °C.
Subject(s)
Composite Resins , Dental Stress Analysis , Humans , Materials Testing , Surface Properties , TemperatureABSTRACT
OBJECTIVE: To investigate the influence of pre-heating different classes of dental resin composites on viscosity and stickiness at five different temperatures. METHODS: Six flowable, five conventional packable, and one thermo-viscous bulk-fill resin composites were heated up to 54°C in a plate-plate rheometer to determine their complex viscosity. Normal force measurements were carried out for the six packable materials to determine the unplugging force and unplugging work (stickiness) over the same temperature range. Data were analyzed using Kolmogorov-Smirnoff test, one-way ANOVA and Tukey Post Hoc test with α=0.05 as level of significance. RESULTS: At 23°C packable composites showed viscosity between 6.75 and 19.14kPas, while flowable composites presented significantly lower viscosities between 1.31 and 2.20kPas. Pre-heating led to a drop of 30-82% in the viscosity of packable materials. The thermo-viscous material dropped to the level of flowables at 45 and 54°C thus behaving as a packable composite at room temperature with flowable-like viscosity at higher temperatures. No statistically significant differences for viscosity were observed among flowable composites at any temperature. The unplugging force decreased for packable composites, while their unplugging work generally increased at elevated temperature. At 23°C unplugging force was measured between 7.50 and 19.18N, while pre-heating up to 54°C led to values between 2.9 and 6.2N. Regarding unplugging work at 23°C the calculated values were between 3.0 and 8.9×10-3J and at 54°C between 8.8 and 13.0×10-3J. SIGNIFICANCE: Pre-heating significantly reduced viscosity of highly viscous resin composites, while no influence was shown for flowable composites. In general stickiness, measured as unplugging work, increased at elevated temperatures. The thermo-viscous material showed low viscosity comparable to flowable composites at 45 and 54°C, yet its stickiness did not increase significantly compared to the values at 23°C.