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Title: 3259 - Sorptivity of Water in Sound and Demineralized Enamel

Authors:

Siew Chen Gan (Presenter)
University Malaya

Alex Fok, University of Minnesota
Hooi Pin Chew, University of Malaya

Abstract:

Objectives: To explore the association of sorptivity of water with the state of mineralisation of enamel.

Methods: 24 extracted caries-free human teeth were cleaned and mounted on resin. Nail varnish was painted on the surfaces leaving two 1.4±0.1 mm diameter circular exposed windows on the crown. The teeth were randomly divided into 6 groups (n=4), which were subjected to 0(G0), 7(G7), 14(G14), 21(G21), 28(G28) and 35(G35) days of pH cycling respectively in order to induce caries of different stages. All teeth were stored in saline prior to measurement. A 0.5 microliter droplet of water was placed with a micropipette on the exposed enamel. Thorlabs Swept-Source OCT system (OCS 1300SS) was used to measure the height of the drop every 10 s for 2 minutes. Sorptivity of each test site was then computed after accounting for evaporation. Micro-Computed Tomography (Micro-CT) scans were obtained for the exposed enamel and processed using ImageJ. Grey value at the center of the exposed area was measured at depths of 20 µm (MCT20) and 50 µm (MCT50). One-way ANOVA was used to compare mean sorptivity between groups and correlation between sorptivity and MCT20 and MCT50 was determined.

Results: Mean sorptivity increased from G0 to G14 and from G21 to G35, juxtaposed by a decline between G14 and G21. One-Way ANOVA showed significant differences in mean sorptivity between groups (p<0.05). Post-hoc Tukey test showed that G0 was only significantly different from G14, while G21 was significantly different from all other groups. Significant negative linear correlation was found between sorptivity and MCT20 and MCT50 (p=0.006 and p=0.011) with a Pearson correlation coefficient of -0.407 and -0.380.

Conclusions: Sorptivity of water is linearly and negatively correlated with the state of mineralization at the immediate sub-surface of enamel.

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Disclosure Statement:
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONE

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