Acid Susceptibility of Arrested Enamel Lesions: In situ Study

Abstract

Arrested lesions are more resistant to a new cariogenic challenge, but the degree of surface rehardening needed to achieve this is unknown. The aim of this in situ study was to analyze the acid susceptibilityof newly formed and arrested enamel lesions with known arrestment period and surface microhardness. Six individuals wore an oral appliance with human enamel blocks for 3 periods: (1) 21 days of demineralization due to plaque accumulation and cariogenic challenge, 4 blocks/person (nonfluoride dentifrice); (2) 75 days of arrestment, brushing with fluoride dentifrice, 2 blocks/person; (3) 21 days of demineralization, 5 blocks/person: 1 sound block, 2 demineralized blocks and 2 demineralized and arrested blocks (nonfluoride dentifrice). After period 1, all blocks showed a dull whitish surface characteristic of active, noncavitated lesions. After arrestment, the surfaces assumed a shiny and smooth aspect. The Knoop hardness number (KHN, mean ± SD) of the sound blocks was 307.6 ± 15.0. After period 1, microhardness decreased significantly to 162.6 ± 33.5 KHN (p < 0.001). The microhardness of subsequently arrested lesions (279.8 ± 23.1 KHN) was significantly greater than after demineralization, but lower than that of sound enamel. Arrested enamel did not show a decrease in microhardness when subjected to a new cariogenic challenge and after the same cariogenic challenge showed similar microhardness to sound enamel. The results showed that, although noncavitated lesions probably take years to reach microhardness levels like sound enamel, this does not imply that special care, in addition to the ones normally given to sound tooth surfaces, is necessary.

Validity of diode laser to monitor carious lesions in pits and fissures

“…One possible explanation is that the mineral gain observed during the lesion arrestment may be very slow, taking years to achieve the original hardness values. 26 Maltz et al 27 observed significantly lower micro hardness values in clinically arrested non-cavitated lesions compared to sound surfaces after 75 days of control. Other possibility is that the changes in lesions organic content may modify the fluorescence measurements rather than mineral content.…”

In Situ Study of In-office Bleaching Procedures Using Light Sources on Human Enamel Microhardness

“…This is possibly explained due to the mechanical properties that change with aging and the medical conditions of the subjects, as well as other conditions, such as exposure to fluoride and cariogenic challenges that occur in the oral cavity. 21 Additionally, the consistent, standardized preparation of specimens is laborious and time-consuming due to their small dimensions. Unfortunately, it is not possible to test the enamel surface without changing its morphology and microstructure, because microhardness testing requires a smooth, plane surface.…”

One-year evaluation of inactive occlusal enamel lesions in children and adolescents

“…In this context, in vitro and in situ studies applying different forms of topical fluoride demonstrated that, once inactivated, a lesion had higher acid resistance to new cariogenic challenges than sound enamel. This finding was to a large extent explained by the ability of fluoride to reduce demineralization and enhance remineralization [8][9][10][11][12].…”