Cross-Sectional Hardness of Enamel from Human Teeth at Different Posteruptive Ages

Abstract

This study evaluated, by cross-sectional hardness (CSH), enamel maturation at different depths in sound human teeth at different posteruptive ages (12 per age group): unerupted (molars; control), 2–3 years (premolars), 4–10 years (premolars) and >10 years (molars). Cross-sectional Knoop hardness was measured at 10, 30, 50, 70, 90, 110, 220 and 330 mm depth from the surface. The data were subjected to two-way ANOVA followed by Bonferroni’s pairwise tests (a = 0.05). The CSH significantly increased with posteruptive age, indicating that the time of exposure in the oral cavity might result in deep enamel maturation.

Spatial distribution of the human enamel fracture toughness with aging

“…Similar changes in the mechanical properties of enamel have been found with aging (Park et al, 2008b;Cardoso et al, 2009). Cardoso et al (2009) revealed that the Knoop hardness of a cross-section of human enamel significantly increased with an increase in the posteruptive age.…”

“…Similar changes in the mechanical properties of enamel have been found with aging (Park et al, 2008b;Cardoso et al, 2009). Cardoso et al (2009) revealed that the Knoop hardness of a cross-section of human enamel significantly increased with an increase in the posteruptive age. Park et al (2008aPark et al ( , 2008b reported that older human enamel is more brittle and that the mean hardness and elastic modulus of older enamel near the occlusal surface are greater than that of younger enamel.…”

“…Thus, the difference in the fracture toughness between the outer and the middle enamel, which is approximately 0.34 MPa m 0.5 in the direction perpendicular to the occlusal surface, is mainly due to the structure. Studies have revealed that the aging process may affect the physical properties of enamel (Park et al, 2008a;Cardoso et al, 2009). In this study, the cross-sectional fracture toughness of enamel was found to change with aging.…”

“…To avoid excessive damage to the teeth and to protect them from cyclic contact with dental materials, more attention should be paid to the selection of tooth restoration materials during the treatment of senior patients. In addition, the posteruptive enamel maturation is suggested to occur even 10 years after eruption (Cardoso et al, 2009), but it is unclear whether this mineral deposit continuously increases over time. Thus, to provide more precise instructions to clinicians, further studies should be conducted to identify whether the posteruptive maturation stops at a specific age and whether the decrease in the fracture toughness ceases with aging.…”

Effectiveness of Fluorescence-based Methods in Monitoring Progression of Noncavitated Caries-like Lesions on Smooth Surfaces

“…43 Transverse microradiography (TMR) provides a quantitative measure of the mineral content, lesion depth, and attributes of the surface layer in enamel lesions. 44 CSMH measures the mechanical resilience (physical strength) of enamel, which cannot be determined by TMR. 45 According to ten Bosch and Angmar-Mansson, 46 SMH is a noninvasive technique and does not damage the enamel's macrostructure.…”