An X-ray Microtomographic Study of Natural White-spot Enamel Lesions

Abstract

White-spot enamel lesions are an early presentation of dental caries and are ideally managed by non-invasive procedures. The aim of this study was to characterize white-spot enamel lesions by x-ray microtomography. In particular, mineral content across the lesion from the surface to the base of the lesion was measured and surface layers defined. Molars with long buccal white-spot enamel lesions were collected, photographed, and each sectioned to produce 3 500-µm-thick sections. The sections were mounted and imaged by quantitative x-ray microtomography at a 15-µm voxel size. We analyzed line profiles through the middle of each 3D image to determine mineral content and depth. The surface layer thickness of the lesions ranged from 35 to 130 µm, with the maximum mineral content in this layer being 74% to 100% of that of sound enamel. The average mineral content across the lesions ranged from 1.73 to 2.48 g/cm(3). No significant differences could be found between lesions clinically categorized as active and those categorized as inactive. However, for depth-matched active and inactive lesions, the active lesions exhibited a more porous surface layer than the inactive lesions. White-spot enamel lesions are highly variable, with surface layers of considerable thickness.

Infiltration of Natural Caries Lesions in Relation to Their Activity Status and Acid Pretreatment in vitro

“…The observation that active lesions were better infiltrated than inactive lesions does not come as a surprise. Active enamel lesions have bigger pores and less mineralized surface layers than inactive enamel lesions [Thylstrup et al, 1994;Cochrane et al, 2012]. This allows the infiltrant to penetrate deeper and fill out more of the body of the lesion.…”

Measurement of surface hardness of primary carious lesions in extracted human enamel —Measurement of Knoop hardness using Cariotester—

“…These studies demonstrated that surface mineral levels only decreased slightly but subsurface mineral levels declined considerably 9,10) , while comparison of active and inactive white spots failed to show any significant differences in surface mineral levels (g/cm 3 ) 10) . However, when the white spots are continuously exposed to plaque accumulation and other factors that trigger caries progression, the surface mineral level declines until the lesions become porous, resulting in decreased enamel surface hardness followed by partial surface decay classified as ICDAS code 3 caries.…”

“…Previous studies on early-stage enamel caries (white spots) in extracted teeth investigated depthrelated changes in mineral content by creating mineral profiles based on transverse microradiography (TMR) and micro computed tomography (CT) images 9,10) . These studies demonstrated that surface mineral levels only decreased slightly but subsurface mineral levels declined considerably 9,10) , while comparison of active and inactive white spots failed to show any significant differences in surface mineral levels (g/cm 3 ) 10) .…”

“…The thickness of the white spot surface layer is presumed to be 35 to 130 μm 10) , so these indentations would not be expected to penetrate this layer and reach the demineralized subsurface layer. However, even though Cariotester indents are minute, they still cause damage to the enamel.…”

Observations of mineralised tissues of teeth in X-ray micro-computed tomography

“…Other authors also found that examination of initial caries in the enamel using micro-CT showed no significant differences between the lesions clinically qualified as active and inactive. Only the active lesions had a more porous surface in comparison with inactive lesions [7]. Another pathology imaged in the micro-CT scan is the dentinal dead tracts extending from the exposed, damaged surface of the molar around the tooth neck to the pulp.…”