Abstract
The complex, dynamic, and hydrated microstructures of human dentin serve as the major determinant for the restorative performance of biomaterials. This study aimed to evaluate the mechanical properties of human dentin under different hydration conditions. The occlusal dentin of five third molars was exposed and cut into 1 mm2 dentin slabs. The slabs were then polished and further cut into 1 mm2 dentin beams and stored in distilled water. Two beams/tooth were used for testing their hardness (H) and elastic modulus (E) at 5 min (baseline), 1 h, and 24 h after dehydration (23 °C and 30% RH), and also for measuring weight at following dehydration times: 0 min, 5 min, 1 h, and 24 h. Five additional molars were employed to prepare 0.4 mm2 dentin beams (3/tooth) for determining ultimate tensile strength (UTS) at 5 min (baseline), 1 h, and 24 h post-dehydration. Statistical significance was set at α = 0.05. Dehydration time significantly affected H, E, weight-loss, and UTS of dentin (p < 0.05). H and E values showed a strongly positive and significant correlation (r > 0.5, p < 0.05). Dehydration can substantially modify the mechanical properties of dentin, leading to misinterpretation of restorative outcomes in vitro.
Highlights
Within the limitations of the present study, we conclude that dehydration of human dentin results in the increase of elastic modulus and concurrent increase of hardness, and enhances the ultimate tensile strength
There to no significant differences between the 1 h and hand values
Dehydration can substantially modify the mechanical properties of dentin, constituting a critical factor in the interpretation of in vitro restorative studies
Summary
Human teeth are composed of three mineralized tissues: cementum, dentin, and enamel. Enamel is a highly mineralized structure that, in a healthy condition, covers the exposed part of the tooth, forming the anatomical crown. Dentin is a hydrated mineralized tissue that forms the bulk of a human tooth. Together with its unique hydration status, the complex structural organization of human dentin contributes to its biomechanical properties [1]. These properties, in Minerals 2021, 11, 336 dentin contributes to its biomechanical properties [1]. These properties, in turn, act as major determining factors in almost all restorative procedures performed both in vitro and turn, asAt major determining factors indentin almostisall restorative performed both in vivoact [2]
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