RESUMO
OBJECTIVE: The present study aimed to evaluate and compare the flexural strength and impact strength of heat-cured acrylic/Polymethyl methacrylate (PMMA) denture base resin and 3D printed denture base resin. METHODS: 60 rectangular specimens were fabricated from conventional heat-cured acrylic and 3D-printed denture base resins. 15 specimens each of heat-cured acrylic and 3D printed denture base resin were tested for flexural strength and impact strength. The flexural strength was assessed using three point bend test while impact strength was assessed by Izod impact test. RESULTS: The mean flexural strength of heat-cured acrylic resin was 92.01 ± 12.14 MPa and 3D printed denture base resin was 69.78 ± 7.54 MPa. The mean impact strength of heat-cured acrylic resin was 1.67 ± 0.79 kJ/m2 and 3D printed denture base resin was 1.15 ± 0.40 kJ/m2.The differences in mean impact and flexural strength between heat-cured acrylic and 3D printed denture base resins were statistically significant. CONCLUSION: Heat-cured acrylic denture base resin (DPI heat-cure) had greater flexural and impact strength than 3D printed denture base resin (Next Dent denture 3D+).
RESUMO
BACKGROUND: Chronic exposure to fluoride in drinking water causes an increase in plasma fluoride levels that is related to a reduction in calcium transport across the renal tubule endoplasmic reticulum and plasma membrane. In the present study, it was hypothesised that varying levels of fluoride present in drinking water are associated with serum levels of calcium and the related hormones vitamin D and parathyroid hormone in pregnant women and newborn infants. METHODS: This cross-sectional study included two groups based on the fluoride concentration in drinking water. One group was considered low/optimum in which the fluoride concentration in drinking water was <1 ppm, and the other group was considered a high fluoride group with ≥1 ppm fluoride in drinking water. In each group, 90 pregnant women were recruited at the hospital during delivery. The participants were given a questionnaire regarding their medical history, sunshine exposure duration, and supplement use and a food frequency questionnaire (FFQ). Fluoride was measured in drinking water, urine, maternal serum and cord blood. Serum calcium, vitamin D, and parathyroid hormone were measured in a fully automated analyser. RESULTS: In pregnant women, drinking water that contained fluoride was significantly positively correlated with urine and blood serum. Low mean concentrations of vitamin D and deficient (<10 ng/ml) vitamin D were more prevalent among the high fluoride group irrespective of diet, sunshine exposure and supplementation. Serum calcium and parathyroid hormone (PTH) levels were significantly lower in the high fluoride group than in the low/optimum fluoride group in both pregnant mothers' blood and cord blood. CONCLUSIONS: Drinking water with high fluoride levels was significantly associated with calcium and the related hormones vitamin D and parathyroid hormone.
