Water loss at normal enamel histological points during air drying at room temperature

Abstract

SummaryThis in vitro study aimed to quantify water loss at histological points in ground sections of normal enamel during air drying at room temperature (25• C) and relative humidity of 50%. From each of 10 ground sections of erupted permanent human normal enamel, three histological points (n = 30) located at 100, 300 and 500 μm from enamel surface and along a transversal following prisms paths were characterized regarding the mineral, organic and water volumes. Water loss during air drying was from 0 to 48 h. Drying occurred with both falling and constant-drying rates, and drying stabilization times (T eq ) ranged from 0.5 to 11 h with a mean 0.26 (±0.12)% weight loss. In some samples (n = 5; 15 points), T eq increased as a function of the distance from the enamel surface, and drying occurred at an apparent diffusion rate of 3.47 × 10 −8 cm 2 s −1 . Our data provide evidence of air drying resulting in air replacing enamel's loosely bound water in prisms sheaths following a unidirectional water diffusion rate of 3.47 × 10 −8 cm 2 s −1 (from the original enamel surface inward), not necessarily resulting in water evaporating directly into air, with important implications for transport processes and optical and mechanical properties.

Enhanced Transport of Materials into Enamel Nanopores via Electrokinetic Flow

“…The study was approved by the ethical committee on research in humans at the Hospital Lauro Wanderley of the Federal University of Paraíba (Brazil). Two types of samples of mature normal enamel were used: undemineralized ground sections with a thickness of ~100 μm (for experiments with microfluidic chips), prepared as described elsewhere (De Medeiros et al 2013), and a whole tooth crown (for the resin infiltration only).…”