[Root caries. An important problem in the elderly].
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Aged↗
Biomedical subjects
B Nyvad
Publications and source records attributed to B Nyvad.
Active and inactive root surface caries lesions in a selected group of 60- to 80-year-old Danes.
In 90, 60- to 80-year-old patients with teeth retained in both jaws (mean 20.4 +/- 4.3), a total of 1,092 root surface lesions were recorded. Of these 156 were diagnosed as active caries lesions, whereas 509 were considered inactive, and 427 were filled. About 60% of the elderly had one or more active lesions and 79% had fillings. Seventy percent had more than 8 filled or carious (active or inactive) surfaces. The percentage of carious and filled root surfaces in relation to surfaces at risk demonstrated that the buccal surfaces of lower molars and premolars and upper canines were the most severely affected (RCI = 70%) with fillings predominating on easily accessible surfaces. A constant relationship between active and inactive lesions was found on all other surfaces but third molars and upper incisors. The data suggest that active and inactive root caries lesions must be diagnosed as separate entities if the dynamic nature of root surface caries is to be explored in epidemiological studies and clinical trials.
Aged↗
A quantitative analysis of mineral loss and shrinkage of in vitro demineralized human root surfaces.
Demineralization of dentin specimens proceeds at a faster rate than that of enamel. Although this is generally accepted, a quantification of the rate of formation of root lesions is hampered by the shrinkage of the lesions when these are dried prior to microradiographic analysis. This leads to a significant underestimation of the lesion depth and total mineral loss. The aim of this paper was to quantitate the rate of mineral loss during root lesion formation in vitro and to determine the shrinkage of root specimens as a result of drying. Unerupted roots of human teeth were subjected to a demineralizing system of 0.1 mol/L lactate buffer (pH = 4.8) with 0.2 mmol/L methanehydroxydiphosphonate during four, 11, 22, and 44 days. The root lesions were assessed by quantitative microradiography. The demineralizing solutions were analyzed to determine the amounts of root tissue dissolved. A comparison of these two sets of data showed that, with the demineralizing system used, root lesions may shrink up to 62%. Fixation of the specimens in fixative did not affect this shrinkage. Chemical analysis showed that mineral loss proceeded linearly with time. From the data-sets of this study, a model was developed to compensate for the shrinkage in the dentin specimens. In this way, it was possible to calculate the lesion depth at four demineralization times as being 130, 220, 320, and 530 microns, respectively. These values were in agreement with a microscopic determination of the lesion depth.
Decalcification Technique↗
Microflora associated with experimental root surface caries in humans.
This study describes the microflora from actively progressing root surface caries lesions, in which mineral loss had been determined by quantitative microradiography. The caries lesions were produced experimentally in root surface specimens from human molars inserted in lower partial dentures carried for 3 months by six elderly individuals. A total of 780 bacterial isolates were identified from 13 plaque samples, collected with a punch technique, and six dentin samples. The composition of the microflora showed distinct individual differences. The microflora from plaque samples associated with the highest mineral loss was dominated by either Actinomyces viscosus or a combination of mutans streptococci (serotypes c, d, and f) and Lactobacillus species (L. casei and L. brevis). Plaque from root surfaces with less pronounced mineral loss harbored a more complex microflora comprising gram-positive rods, mutans streptococci, Streptococcus mitis biovar 1, Veillonella spp., gram-negative rods, and low numbers of lactobacilli. In the latter samples, individual variations in the proportions of mutans streptococci (serotypes c, d, and g), Actinomyces species (A. viscosus and A. naeslundii), and Veillonella parvula biotypes were observed. These findings suggest that certain species or combinations of species are more cariogenic than others and that dominance of single acidogenic species in particular is conducive to high caries activity.
Aged↗
Ability to bind salivary alpha-amylase discriminates certain viridans group streptococcal species.
A collection of 144 viridans group streptococcal strains recently characterized as part of a taxonomic study was examined for the ability to bind salivary alpha-amylase. This property was found in most strains of Streptococcus gordonii and Streptococcus mitis and in occasional strains of Streptococcus anginosus and Streptococcus salivarius. In contrast, all strains of Streptococcus sanguis, Streptococcus oralis, Streptococcus vestibularis, and Streptococcus mutans lacked alpha-amylase-binding capacity. A rapid and easy assay described in this paper may be an important supplementary test for identification of oral streptococci.
Bacteriological Techniques↗
Comparison of the initial streptococcal microflora on dental enamel in caries-active and in caries-inactive individuals.
This study compared the initial (4 h) microflora on enamel in 7 caries-active and in 7 caries-inactive adolescents. In both groups the microflora was dominated by streptococci which comprised 61 and 78% (median values) of the total viable counts in caries-active and caries-inactive individuals, respectively (p less than 0.01). Identification of a total of 700 streptococcal isolates according to a recently revised classification showed that the predominant streptococci belonged to the species Streptococcus oralis, Streptococcus mitis biovar 1, and Streptococcus sanguis. Early plaque from caries-inactive individuals differed from that of caries-active individuals by significantly higher proportions of S. sanguis (p less than 0.05) and IgA1 protease producing streptococci (p less than 0.05). In caries-active individuals, there was a tendency to elevated levels of S. mitis biovar 1 (p less than 0.10). In addition, caries-active individuals were colonized by significantly higher numbers of mutans streptococci on the enamel surfaces (p less than 0.01). However, in both groups Streptococcus mutans (serotype c) comprised less than or equal to 2% of the early streptococcal flora. Streptococcus gordonii, S. mitis biovar 2, and Streptococcus salivarius were present in low proportions and did not show differences in distribution that could be related to caries activity. The observed differences in the composition of the early streptococcal microflora may be a factor that governs the eventual cariogenic potential of dental plaque.
Adolescent↗
An ultrastructural study of bacterial invasion and tissue breakdown in human experimental root-surface caries.
This study describes the structural features of the interface between microbial deposits and root cementum in actively progressing root-surface caries lesions developed experimentally in six elderly individuals. A total of 18 specimens was examined by microradiography, and a further 18 by light and transmission electron microscopy after intra-oral periods of one, two, and three months. All specimens showed various degrees of subsurface dissolution of mineral and bacterial invasion of the cementum. Although the microradiographic pattern of mineral loss was subsurface in nature, transmission electron microscopy showed dissolution of crystals in the outermost layers of the cementum, with a distinct gradient inward. Bacterial invasion occurred along the borders between bundles of relatively well-mineralized extrinsic collagen fibers in which the characteristic cross-banding remained intact. The pattern of bacterial invasion was influenced by the incremental lines and the cemento-dentinal junction. The invading bacteria were almost exclusively Gram-positive, of various shapes, and possessed thick, moderately electron-dense cell walls and electron-lucent "vacuoles" in the cytoplasm. It is concluded that because of pronounced mineral loss of the outermost cementum, accompanied by bacterial invasion, the surface of an active cementum caries lesion, as observed by transmission electron microscopy, is not identical to that seen in microradiograms.
Aged↗
[Sugar and sugaralcohols role in caries prophylaxis].
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Dental Caries↗
Structure of dental plaque and the plaque-enamel interface in human experimental caries.
This study describes the ultrastructure of dental plaque and the plaque-enamel interface after 2 and 3 weeks' exposure to a cariogenic challenge. Five dental students carried a total of 25 specimens of smooth surface enamel in intraoral acrylic appliances. During the initial 3 days the volunteers refrained from oral hygiene and performed nine daily mouthrinses with 10% (w/v) solutions of sucrose. After the 3rd day the volunteers cleaned their natural teeth, whereas the experimental sites were left undisturbed except for nine daily extraoral 5-min immersions in 5% (w/v) solutions of sucrose. Clinically, three patterns of colonization were observed after 3 days. At the histological level the experimental bacterial deposits also exhibited three distinctly different structural patterns after 2 and 3 weeks. Individual patterns consistently differed with regard to the microbial composition, the structural organization of the deposits, and the presence or absence of crystal-like material. However, in all individuals a layer of densely packed gram-positive bacteria resembling Actinomyces was consistently present close to the enamel surface. In 1 individual the microbial deposits were dominated by large bacteria, the ultrastructure of which conformed to the description of Stomatococcus mucilaginosus. These findings may partly explain pronounced individual variations in the rate of caries lesion development and progression in vivo.
Bacteria↗
IgA1 proteases of oral streptococci: ecological aspects.
The ecology and identity of IgA1 protease-producing streptococci in the human oral cavity were studied in an attempt to obtain insight into the significance of IgA1 proteases for host-parasite relationships. Contrary to previous observations, a detailed taxonomic analysis of oral streptococci revealed that all strains of S. sanguis and S. oralis ("S.mitior") produced IgA1 protease. In addition, IgA1 protease activity was observed in some isolates of S.mitis. Of the streptococci that initiate plaque formation on dental enamel 88% (median value) had IgA1 protease activity. Low proportions of the streptococci that colonize the tongue and oropharyngeal mucosae produced IgA1 protease, in contrast to 60% of streptococci isolated from buccal mucosa. The IgA1 proteases from S. sanguis I-III, S. sanguis IV, S. oralis, and S.mitis were distinct as revealed by studies using enzyme-neutralizing antibodies.
Adult↗