A microradiographic comparison of sound and carious human dental cementum

Superficial root caries lesions of incisors and premolars of 24 patients aged 52–60 years were studied by scanning electron microscopy and transmission electron microscopy. In the predominantly gram-positive bacteria of the root dental plaque, a great number of corncob configurations were observed. Bacterial infiltration into cementum occurred without any gradient of demineralization and mainly followed the borders between calcified cementum bundles as well as incremental lines. The narrow channels which were filled initially by a single row of gram-positive bacteria broadened progressively with simultaneous destruction of the apatite minerals and the collagenous matrix. Root dentin invasion showed great similarities to coronal dentin with an important gradient of demineralization. In the deep layers, sclerosed tubules contained sometimes rhombohedral crystals. In more superficial layers, bacterial invasion occurred initially in still partially sclerosed tubules. Tubular lumens as well as lateral side branches which had lost their peritubular dentin were filled with gram-positive microorganisms. An important diffuse destruction of the apatite minerals was observed at this stage in the intertubular dentin which still presented typical cross-banded collagen fibrils. The confluence of enlarged dentinal tubules filled by numerous microorganisms led to large bacterial zones with complete destruction of root dentin.

Section: Discussionsupporting

confidence: 52%

Ultrastructural Study on Human Root Caries

Frank¹,

Steuer²,

Hemmerlé³

1989

“…The microradiographic image of the early root car ies lesions in this study, showing a surface layer of varying radiopacity and a brush-like pattern of ce mentum, corresponds to previous descriptions of nat ural root surface caries by Furseth and Johansen [1968] and Hals and Selvig [1977], Of particular inter est was the consistent finding of a continuous band of demineralization. This pattern of demineralization indicates that possible variations in mineral content along the root surfaces are not of a magnitude suffi cient to influence the rate of lesion progression.…”

Section: Discussionmentioning

confidence: 67%

“…Firstly, the low mineral content of the outer part of the experimental root surfaces (unerupted and not previously exposed to the oral environment) in this study differed from the often highly mineralized sur face layer of root surfaces which have been exposed to the oral environment for a considerable period of time [Furseth and Johansen, 1968;Selvig, 1969;Hals and Selvig, 1977]. There is experimental evidence that this in vivo uptake of mineral may decrease the acid susceptibility of cementum and dentin surfaces [Al-Joburi and Koulourides, 1984;ten Cate et al, 1987].…”

Section: Discussionmentioning

confidence: 84%

“…Early caries lesions in human dental cementum are characterized by subsurface demineral ization deep to a 20-to 35-pm-thick, well-mineralized surface layer [Furseth and Johansen, 1968;Hals and Selvig, 1977]. However, in most clinically visible root surface caries lesions dental cementum is missing and subsurface demineralization is confined to dentin only [Westbrook et al, 1974;Wefel et al, 1985;Nyvad and Fejerskov, 1987], Except for one study [Nyvad and Fejerskov, 1987] none of the above-mentioned studies have provided a description of the clinical sta tus of the root caries lesions examined.…”

mentioning

confidence: 99%

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Microradiography of Experimental Root Surface Caries in Man

Nyvad¹,

Cate

Fejerskov³

1989

The aim of this study was to describe the pattern and rate of mineral loss during experimental root surface caries in situ without giving frequent sucrose rinses as a supplementary cariogenic challenge. Six elderly persons carried at total of 18 specimens of unerupted human root surface in recessions of lower partial dentures for 1, 2 and 3 months. Another six root surfaces served as controls. No cleaning of the specimens was allowed during the experimental period whereas the natural dentition was cleaned with a nonfluoride toothpaste. All the specimens, as observed by quantitative microradiography, exhibited subsurface caries lesions. Despite variation between individuals the depth of subsurface demineralization increased linearly with time, the average depth of the lesions being 240 μm after 1 month and 630 μm after 3 months. ΔMC, calculated as the difference in total mineral content between control and test specimens throughout the lesions, increased linearly with time from 2,000 to 8,400 vol% μm after 1 and 3 months, respectively. Preparation for microradiography induced a certain shrinkage of the lesions which resulted in an underestimation of the acutal loss of mineral. It is concluded that this experimental model is suitable for studying the etiology and prevention of root surface caries provided the interindividual variation is taken into account.

“…The F-rich outer zone of the root lesion is frequently hypermineralised [Furseth and Johansen, 1968;Takuma et al, 1975;Tohda et al, 1996] but we were not able to detect any increase in Ca concentration in this zone. The reason for this is not clear, but it is also not always apparent with the electron probe in sections that clearly show a hypermineralised zone by microradiography [Tohda et al, 1996].…”

Section: Discussionmentioning

confidence: 49%

Fluoride Distribution in Sound and Carious Root Tissues of Human Teeth

Shu

Pearce²,

Sissons³

et al. 1998

Proton probe analysis has been used to provide for the first time quantitative F concentration data in carious root tissues from subjects consuming water containing 1 ppm F. In small lesions at the neck of the tooth with minimal tissue loss the F concentration was significantly higher at the outer lesion edge than at the outer edge of adjacent sound root tissue. In one sample with high F values the lesion edge had 19,000 ppm F and the adjacent sound root surface 5,400 ppm F (μg F/g apatite). In large lesions with extensive cavitation F was again concentrated in the outer edge of the lesion and was significantly higher (1,800–4,100 ppm) than in adjacent sound inner dentine (190–290 ppm). Fluoride concentrations varied markedly along the outer edge of both normal and carious root tissues. Fluoride increase at the lesion edge is not an effect of tissue shrinkage but probably a result of remineralisation events during caries. This additional F may be expected to increase tissue resistance to further acid attacks.