Vitamin D status and its seasonal variations and association with parathyroid hormone concentration in healthy women in Riga

Copyright: Copyright 2020 Elsevier B.V., All rights reserved.The aim of the study was to describe the vitamin D status and its seasonal variations in women living in Riga, Latvia, to examine an association between the concentrations of plasma 25-hydroxyvitamin D [25(OH)D] and parathyroid hormone (PTH), and to determine the threshold for plasma 25(OH)D above which there is no further suppression of PTH. Material and Methods: The data of 189 healthy Caucasian women were analyzed. The serum levels of 25(OH)D, PTH, and phosphorus were measured twice a year. All the participants were divided into 3 groups according to vitamin D supplementation and the reproductive status. Results: The overall mean level of 25(OH)D was 32.8 ng/mL with significantly lower levels being in winter when compared with those in summer (28.2 ng/mL vs. 37.5 ng/mL, respectively; P>0.05). PTH was negatively associated with 25(OH)D. A threshold level of plasma 25(OH)D above which no further suppression of PTH occurred was found to be 38 ng/mL. Postmenopausal women not taking vitamin D supplements and without exposure to sunlight had 25(OH)D deficiency in winter and summer (92% and 88%, respectively). The most significant seasonal fluctuations were seen in the women of the reproductive age not taking vitamin D supplements and without exposure to sunlight, of which 47% had 25(OH)D deficiency in summer and 69% in winter. Conclusions: An optimal concentration of 25(OH)D was found to be 38 ng/mL. According to this definition, 70.4% of all the healthy women were classified as vitamin D deficient in winter and 59.8% in summer. The highest proportion of vitamin D deficient individuals was found in the group representing the postmenopausal women not taking vitamin D supplements.publishersversionPeer reviewe

Resin Cement Residue Removal Techniques : In Vitro Analysis of Marginal Defects and Discoloration Intensity Using Micro-CT and Stereomicroscopy

The objective was to compare marginal defects and evaluate discoloration for adhesively cemented veneers in vitro when using two cement removal techniques. Twenty premolars were prepared with chamfer and borders in enamel. IPS e.max CAD veneers were cemented using Panavia V5 and divided in two groups (n = 10): cement excess removed with a probe after tack-curing for 3-5 s, or cement excess removed with a brush, then completely polymerized. All teeth were stored in alginate gel until micro-CT examination. Scanning was performed twice: directly after cementation and after thermocycling (5000 cycles, between 5 and 55 degrees C). To analyze discoloration, teeth were colored using 0.5% basic fuchsine and examined under a stereomicroscope. Depth of dye infiltration was scored 0 (no discoloration) to 5 (discoloration along the entire margin). Statistically significant differences of cement defects before thermocycling were reported, where brushing showed more defects than probing (p = 0.0161). After thermocycling, the defects increased for both groups. Extensive discoloration was the most common (55.56%) when removing excess by probing; by brushing, 90% of the specimens exhibited slight discoloration (p = 0.008). Regression analysis showed no relationship between type of defect and degree of discoloration. Removing cement with a brush causes more marginal defects, however less discoloration after thermocycling

Effect of Temporary Cement, Surface Pretreatment and Tooth Area on the Bond Strength of Adhesively Cemented Ceramic Overlays-An In Vitro Study

Several viewpoints have been reported regarding the effect of temporary cements, different surface pretreatment protocols before adhesive cementation, and predictive factors. This in vitro study tested if temporary cement, pretreatment of the tooth surface, the size of enamel or dentine influence adhesive cementation to zirconia ceramics. Twenty premolars were prepared for determination of enamel and dentin area, bond strength test and failure analysis. The samples were divided into two groups: untreated prior adhesive cementation (n = 10) and with temporary cementation done, pretreated prior adhesive cementation (n = 10). Zirconia overlays (Katana Zirconia STML) were cemented on the grounded flat teeth surfaces using Panavia V5. An additional six premolars underwent dentine tubule analysis with SEM to detect temporary cement residues after temporary cementation on an untreated tooth surface (n = 3) and on a pretreated surface (n = 3). The independent sample t-test was used to compare the two groups and the means of the total tooth, dentin or enamel areas did not differ significantly between the untreated and pretreated specimens. The mean tensile bond strength was significantly (p = 0.005) higher in the pretreated specimens (337N) than in the untreated ones (204N). The overall multivariable linear regression model with three predictors (surface pre-treatment, enamel area and dentine area) was significant (p = 0.003), among which the size of enamel was the strongest predictor (beta = 0.506; p = 0.049), followed by the pretreatment effect (beta = 0.478; p = 0.001) and the size of dentin area (beta = -0.105; p = 0.022)

Effect of Temporary Cement, Surface Pretreatment and Tooth Area on the Bond Strength of Adhesively Cemented Ceramic Overlays : An In Vitro Study

Several viewpoints have been reported regarding the effect of temporary cements, different surface pretreatment protocols before adhesive cementation, and predictive factors. This in vitro study tested if temporary cement, pretreatment of the tooth surface, the size of enamel or dentine influence adhesive cementation to zirconia ceramics. Twenty premolars were prepared for determination of enamel and dentin area, bond strength test and failure analysis. The samples were divided into two groups: untreated prior adhesive cementation (n = 10) and with temporary cementation done, pretreated prior adhesive cementation (n = 10). Zirconia overlays (Katana Zirconia STML) were cemented on the grounded flat teeth surfaces using Panavia V5. An additional six premolars underwent dentine tubule analysis with SEM to detect temporary cement residues after temporary cementation on an untreated tooth surface (n = 3) and on a pretreated surface (n = 3). The independent sample t-test was used to compare the two groups and the means of the total tooth, dentin or enamel areas did not differ significantly between the untreated and pretreated specimens. The mean tensile bond strength was significantly (p = 0.005) higher in the pretreated specimens (337N) than in the untreated ones (204N). The overall multivariable linear regression model with three predictors (surface pre-treatment, enamel area and dentine area) was significant (p = 0.003), among which the size of enamel was the strongest predictor (β = 0.506; p = 0.049), followed by the pretreatment effect (β = 0.478; p = 0.001) and the size of dentin area (β = −0.105; p = 0.022).Dentistry, Faculty ofNon UBCReviewedFacultyResearche