METHODS: As a preliminary work, water droplets of 1.5 μL were placed on the surfaces of hydroxyapatite (HA) discs of different densities. The water droplet profile was dynamically recorded every second over a period of 10 s using a contact angle meter to determine the relationship between sorptivity and density. To measure and calculate sorptivity on enamel surfaces, varnish was painted on the labial surface of 96 extracted caries-free human teeth, leaving two 1.4 ± 0.1 mm diameter circular exposed test sites. The specimens were randomly divided into 6 groups (n = 16) and subjected to 0(G0), 7(G7), 14(G14), 21(G21), 28(G28) and 35(G35) days of pH cycling, respectively. A 0.7 μL water droplet was placed on each exposed site and Optical Coherence Tomography was used to measure its height every 10 seconds for 2 min. Sorptivity was computed by considering sorption equations and Washburn's analysis of capillary kinetics and correction for evaporation was also performed. Micro-Computed Tomography scans of the specimens were obtained and delta Z (ΔZ) is the parameter used to measure mineral loss. ΔZ at 10 μm (ΔZ10) and 50 μm (ΔZ50) from the surface were calculated. One-way ANOVA and Post-hoc Tukey tests were used to compare sorptivity between groups and bivariate correlations were used to analyze the association between sorptivity and ΔZ.
RESULTS: Sorptivity was found to be inversely and linearly correlated with HA density with R2 value of 0.95. With enamel, there is a general trend of increase in mean sorptivity from G0 to G35, except for a decrease in G21. The same trends were observed for both ΔZ10 and ΔZ50. The decrease in sorptivity in G21 coincided with the presence of a surface hypermineralized layer in G21 samples. Post-hoc Tukey showed significant differences in mean sorptivity between G0 and G14, G0 and G21 as well as G14 and G21. Post-hoc Dunnett's T3 showed significant differences for ΔZ10 between G0 and G14 as well as G14 and G21. Significant correlation between mean sorptivity and ΔZ10 was detected with Pearson correlation coefficient of 0.461. For ΔZ50, post-hoc Tukey showed significant differences between G0 and G14 but no significant difference was detected between G14 and G21. No correlations were detected between mean sorptivity and ΔZ50.
SIGNIFICANCE: Sorptivity was found to be inversely and linearly correlated with HA density with R2 value of 0.95. With enamel, there is a general trend of increase in mean sorptivity from G0 to G35, except for a decrease in G21. The same trends were observed for both ΔZ10 and ΔZ50. The decrease in sorptivity in G21 coincided with the presence of a surface hypermineralized layer in G21 samples.
AIMS: To compare TEWL and skin hydration in patients with DM and controls, and to investigate associations between TEWL and skin hydration with glycated haemoglobin (HbA1c), fasting blood sugar (FBS), treatment, peripheral neuropathy (PN) and age in patients with diabetes.
METHODS: This was a prospective, case-control study carried out at a tertiary medical centre in Kuala Lumpur, Malaysia. TEWL and skin hydration measurements were taken at six different body sites in both groups.
RESULTS: In total, 146 patients (73 cases, 73 controls) were included (24 men and 49 women in each group). No significant difference in TEWL or skin hydration was seen between patients with DM and controls, but there were significant reductions in skin hydration in patients with DM who had FBS > 7 mmol/L (P 6.5% (P 1 U/kg/day (P 45 years old, there was a significant reduction in TEWL (P = 0.04) and hydration (P 8 mmol/L and increased in patients with higher insulin requirement.