Studies of dental root surface caries 2: The role of cementum in root surface caries

Abstract

Artificial caries lesions were produced in roots of teeth using an acetate buffer system, when the layer of cementum was either normal in thickness, excessively thickened by hypercementosis, or had been removed completely. The rates of lesion progression were measured in each case using polarized light microscopy to measure lesion depth. Analysis of calcium (Ca) and phosphorus (P) loss during the demineralizing process was carried out. The removal of cementum was found to significantly increase the initial rate of penetration of the lesion into the root, although this rate progressively reduced to a level consistent with that found in normal roots after seven days of demineralization. The overall depth remained consistently greater than that observed in normal roots, or when lesions were produced entirely within hyperplastic cementum. Chemical analysis also showed removal of cementum resulted in an initial doubling of the Ca and P lost from the root surface. Prior direct exposure of segments of normal roots to the oral environment was found not to significantly alter the rate of artificial lesion progression, in comparison with that in the originally protected segment of the root surface. It was concluded that an intact cementum layer has the intrinsic ability to protect the underlying dentine of exposed tooth roots against acidic demineralization and that prior exposure to the oral environment does not significantly alter this ability.

Formation of Caries-Like Lesions in vitro on the Root Surfaces of Human Teeth in Solutions Simulating Plaque Fluid

“…This confirms the findings of McIntyre et al [2000b], although the difference was much less than they reported, and deeper lesions were not found on all root surfaces. McIntyre et al [2000b] suggested that removal of the cementum layer accelerated the initial rate of lesion progression, and that the rate was subsequently the same as on the intact surfaces. This suggestion is supported by the fact that, in the present study, at all pI HA /pH, the groups showed similar mean differences between the ground and intact surfaces.…”

“…as pI HA increased). The mechanism proposed by McIntyre et al [2000b] for cementum removal affecting only initial demineralization rate is not very convincing. A simpler explanation for a uniform difference is that the process of grinding off the cementum creates a smear layer and a subsurface region of mechanical damage which are more vulnerable to dissolution.…”

Development of an in situ root caries model. A. In vitro investigations

“…In the buffer system however cementum removal 20 who showed that cementum can protect the underlying dentine from demineralisation. Although both tissues react similarly to an acid challenge, 21,22 the matrix of cementum is less permeable than that of dentine and may retard transport processes in demineralisation.…”

Tooth-surface-specific Effects of Xylitol

“…Smooth (buccal and lingual) coronal and root surfaces are more readily exposed to saliva's remineralizing potential than are proximal surfaces and occlusal fissures. Additionally, because the critical pH for demineralization is higher for dentin than it is for enamel (Fejerskov and Kidd, 2008), root surfaces are considered to be at a higher caries risk than coronal surfaces (McIntyre et al, 2000). Therefore, when one is studying the effectiveness of interventions on caries prevention, it is important to examine their effects on these different tooth surfaces as a whole as well as separately (McDonald and Sheiham, 1992).…”