Smooth Surface Lesions Research Articles

The Effects of Egg-Derived Antibodies to Glucosyltransferases on Dental Caries in Rats

The role of Streptococcus mutans in the development of dental caries is well recognized. Important virulence factors include the glucosyltransferases (gtf), essential for production of glucans. We evaluated the anticariogenic effects of orally administered chicken anti-cell-associated (CA) Gtf antibodies in desalivated rats. The animals were infected with S. mutans MT8148R and treated with chicken anti-CA-Gtf egg yolk antibodies (IgY) or nonimmune egg yolk powder. Smooth surface lesions were significantly lower in the anti-CA-Gtf-treated group in comparison to the control groups. Sulcal surface caries was also decreased and of less severity. Our study suggests that chicken anti-CA-Gtf antibodies may have promise as a prophylaxis for high caries risk patients.

In vivo Repeatability and Reproducibility of the Quantitative Light-Induced Fluorescence Method

In vivo repeatability and reproducibility of the quantitative light-induced fluorescence (QLF) method were tested with respect to three variables: lesion area, and average and maximum changes in lesion fluorescence. To test the image-capturing stages, three analysts each captured images of 15 incipient smooth surface lesions in vivo, and the images were analysed by one of the analysts. To test the analytical stage of the method, three analysts analysed the images of 15 in vivo incipient smooth surface lesions. For the image-capturing stage, inter-examiner reliability showed an intra-class correlation coefficient (r) between 0.95 and 0.98. For the analytical stage, intra-examiner reliability for all three analysts showed a value of r between 0.93 and 0.99. Inter-examiner reliability showed a value of r between 0.95 and 0.99. It was concluded that the in vivo repeatability and reproducibility of the QLF method are excellent.

Laser Fluorescence Detection of Demineralization in Artificial Occlusal Fissures

Laser fluorescence (LF) has been used previously to detect early smooth-surface lesions. Although its use for detection of occlusal demineralization has been implicated, it has not been demonstrated. The aim of this study was to determine whether LF could detect demineralization in the base of artificial fissures. To employ LF for detection of occlusal demineralization an apparatus was devised to direct laser light into fissures and simultaneously detect fluorescence from the base of the fissures. Three groups (n = 40/group) of differing fissure types were prepared (straight wall, converging and diverging wall) with either a sound or lesioned base. One half of each group was examined with LF and dye-enhanced LF (DELF); the other half was examined with LF, exposed to plaque, examined with LF and DELF, air-polished and examined with DELF. All images were scored twice as either (1) carious; (2) sound, or (3) undetermined, by a group of 3 examiners. For fissures without plaque, the average sensitivity was higher for DELF (0.76) than for LF (0.54) (p < 0.05). Likewise, the average specificity was higher for DELF (0.64) than for LF (0.29) (p < 0.05). In the presence of plaque, sensitivity was higher for DELF (0.91) compared to LF (0.43); however, specificity was lower for DELF (0.05) compared to LF (0.55). When the fissures were air-polished and then examined with DELF, sensitivity averaged 0.82 (p < 0.05), and specificity increased consistently (average 0.51, p < 0.05). It was concluded that, in the absence of plaque, DELF was a better diagnostic tool than LF for detection of demineralization in artificial fissures.

Sucrose-derived exopolymers have site-dependent roles in Streptococcus mutans-promoted dental decay

We have constructed a panel of mutants of S. mutans V403 which are defective in one or more of the glucosyltransferase genes ( gtfB,C or D) or the fructosyltransferase gene ( ftf). These strains have been tested for virulence in a gnotobiotic rat caries model with reference to both buccal (smooth surface) and sulcal (pit and fissure) carious lesions. Our data suggest differing roles for degradable and non-degradable polymers at buccal and sulcal sites. Non-degradable polymers (made by products of the gtfB and C genes) contributed significantly to the severity of smooth surface lesions. However, our studies suggested their role in pit and fissure lesions was not as important as the role of degradable polymers. Specifically, a mutant deficient in the major insoluble glucan synthesizing activity (product of the gtfB gene) was 25% more cariogenic on sulcal surfaces than was the wild-type V403 strain. We propose that extracellular glucosyltransferases and fructosyltransferase compete for sucrose and that this competition influences pathogenicity at differing tooth sites.

Role of the Streptococcus mutans gtf genes in caries induction in the specific-pathogen-free rat model.

The role of each of the Streptococcus mutans gtf genes coding for glucan synthesis in cariogenesis was evaluated by using strain UA130 in the specific-pathogen-free (SPF) rat model system. Mutants defective in either or both of the genes required for insoluble glucan synthesis, the gtfB and gtfC genes, exhibited markedly reduced levels of smooth-surface carious lesions relative to that of the parental organism. Likewise, the mutant defective in the gtfD gene coding for the glucosyltransferase-S enzyme synthesizing water-soluble glucans also produced significantly fewer smooth-surface lesions than strain UA130. None of these mutations markedly altered the rate of sulcal caries induction relative to that of the parental organism. In addition, a mutant of strain UA130 defective in the gtfA gene was reexamined in the SPF rat model. In contrast to previous results from a gnotobiotic rat system, these mutants also induced significantly fewer smooth-surface carious lesions compared with that by strain UA130. These results suggest that all four genes are important for smooth-surface caries formation. Furthermore, these results are discussed relative to the differences in the diets utilized in the SPF and gnotobiotic rat model systems for assessing the virulence factors of S. mutans.

Relative Consumption of Sucrose and Other Sugars: Has it Been a Factor in Reduced Caries Experience?

This paper examines the impact on the development of caries, especially on the proximal and the free smooth surfaces, that follows the reduction in sucrose consumption and the increase in consumption of the monosaccharides in the United States and Great Britain. Laboratory evidence shows that sucrose has a special role in proximal- and smooth-surface caries because of its ability to produce extracellular polysaccharides with the mutans streptococci, thus increasing plaque's ability to adhere to the enamel surface. Evidence from human studies, however, is less clear about the relative cariogenicity of the various sugars, possibly because experimental conditions are difficult to maintain in such studies. In the USA sucrose consumption has been diminishing for some year and is now only 47% of the total sugar consumption of 61 kg per person annually. The change in Britain has been less pronounced, sucrose there in 1984 constituted 83% of total consumption of 47.9 kg per person. Sucrose consumption in Britain is, therefore, higher than in the United States, even though the average total consumption of all sugars is higher in the USA. Limited data suggest that proximal- and smooth-surface lesions also constitute a higher proportion of caries incidence in Britain than in USA, and a cause-and-effect hypothesis between these factors is explored. Dietary education for oral health should harmonize with that for general health by emphasizing sensible food choices, which generally means selection of low-fat, low-sugar foods.

The clinical behaviour of free smooth surface carious lesions monitored over 2 years in a group of Scottish children

As far as the authors are aware, no large-scale clinical studies of free smooth surface caries have been carried out in the past, although carious lesions on these surfaces can be diagnosed at an 'early' stage. In this study on a group of 2854 13-year-old children, caries affecting the free smooth surfaces (buccal and lingual) was found to be a common problem, with a total of 2917 lesions observed on molar teeth at the first examination. Most of the lesions involved no macroscopic loss of tooth contour. When the children were examined 2 years later, three-quarters of the lesions had either remained static or regressed. Free smooth surface lesions were more likely to develop initially, and more likely to progress, in individuals with poor oral hygiene. Free smooth surface caries experience showed a positive correlation with occlusal and approximal decay experience. The number of free smooth surface carious lesions can be used as a predictor of caries risk. Strategies for diagnosis and prevention are suggested for patients presenting with free smooth surface caries on molar teeth.

フッ化物局所応用法実施児童の脱落乳歯のフッ素量と結晶性について

The purpose of this study was to investigate in vivo the effect of topical fluoride application on deciduous tooth enamel. Experimental materials were physiologically dropped deciduous teeth of school children who recieved the topical fluoride application once a year and fluoride mouth rinsing 5 times a week for four years. The cariostatic effect was already confirmed in these children. Electron probe X-ray microanalysis, acid solubility test, and X-ray crystallographic analysis were performed.Fluoride determination were performed on the smooth surface, fissures and caries lesions of enamel and dentin by electron probe X-ray microanalysis. An acid solubility test was done to determine the released calcium content from intact enamel surface of milk cuspid into 0.4 M acetate-sodium acetate buffer (pH 4.0) during three hours every thirty minutes. Microfocus X-ray diffraction was performed on the smooth surface, fissures, cusps and caries lesions of enamel. The (310), (002) reflections of microfocus Laue photographs were charted by microphotometer and, the crystallinity of enamel apatite were evaluated by estimating these half maximun breadth.Electron probe X-ray microanalysis showed that the fluorine concentration of surface enamel was increased not only in smooth surfaces but also in fissure areas by fluoride application and repeated fluoride mouth rinsing for four years. Caries lesions also revealed fluoride uptake. An acid solubility test proved that the acid resistance was increased about 1.5 times more in the fluoride group than in the control group. In the X-ray diffraction analysis, no reaction products were detected, and all specimens showed almost the same pattern of hydroxyapatite. The crystallinity of the deciduous teeth was different in different tooth areas, especially in c-axis directions. The crystallinity of enamel apatite was increased in both the a- and c-axis directions in the smooth surface areas, and in the c-axis in the inner layer of fissures, and in the outer and inner layer of caries lesions.As a result, it could be seen that topical fluoride application was effective in the portions of high caries incidence in deciduous teeth.

Caries levels and patterns in head start children in fluoridated and non-fluoridated, urban and non-urban sites in Ohio, USA.

The purpose of the study was to determine caries levels and prevalences of previously identified caries patterns in low income children in the primary dentition in Ohio, USA. Children were examined from urban fluoridated (n = 505), urban non-fluoridated (n = 395), non-urban optimal fluoride (n = 183), and non-urban suboptimal fluoride (n = 227) sites. Caries scores were similar for the two sites having optimal fluoride; scores from fluoridated sites were lower than scores from the two suboptimal fluoride sites. Children from all four sites were caries-free ranging from 36% in the urban non-fluoridated site to 50% in the non-urban optimally fluoride site. More children in the suboptimal fluoridated sites had smooth surface lesions than in the optimally fluoridated sites. More children with defect associated lesions had fewer than six (chi 2 = 222; P less than 0.01) carious surfaces than did children with smooth surface lesions.

In-vivo dental plaque-forming ability and relative cariogenicity of the bacteria Streptococcus mitis and Streptococcus sanguis I and II in mono-infected gnotobiotic rats

Sixteen strains of Streptococcus mitis, Streptococcus sanguis I and Strep. sanguis II were tested for cariogenic potential and in-vivo plaque-forming ability in a gnotobiotic WAG/RIJ rat test system. All strains produced far less fissure plaque in vivo than strains of Streptococcus milleri or Streptococcus mutans. There was less extracellular matrix around cells of Strep. mitis or Strep. sanguis than around Strep. mutans, in the fissures. Dense sheets of cells were observed only with Strep. mutans. Some localized colonization of exposed smooth surfaces occurred with most strains. Strep, mitis produced no caries in three tests, low-caries scores in two tests and high-caries scores in one test. A single strain of Strep. mitis produced a highly-cariogenic variant able to ferment raffinose. Strep. sanguis I induced low-levels of caries in 12 tests; one test of NCTC 7865 produced moderate levels of caries, and another test of 311 produced no caries. Strep. sanguis 311 was dextran-negative. Strep. sanguis II strains induced no caries in three tests, low caries scores in six tests and moderate levels of caries with Strep. sanguis 402. No strain of Strep. mitis or Strep. sanguis was able to induce smooth-surface lesions.

Preliminary studies on calcium lactate as an anticaries food additive.

Enamel dissolution, Orofax and rat caries studies were carried out to assess the effects of calcium lactate in reducing the cariogenicity of four commercially used candies. When used at the 5% level, calcium lactate was effective in reducing enamel dissolution by as much as 43% in fermenting candy-saliva mixtures. In Orofax studies it reduced the amount of in vitro caries by as much as 87%. In a rat caries study, a test group fed a chocolate caramel candy containing 1.5% calcium lactate produced reductions of 38 and 17% in number and 47 and 31% in severity of smooth surface (buccolingual) and sulcal lesions, respectively, as compared to a control group fed the same candy without additive. These findings plus the fact that calcium lactate is a tasteless, nontoxic chemical compound, commonly used in a number of food products, all indicate that calcium lactate my be considered an effective anticaries food additive.

Statistical Relationship of Morsal to Bucco-lingual, Approximal and Sulcal Caries in Rats

The correlation of morsal with sulcal, bucco-lingual and approximal caries scores of rats was compared. The morsal with bucco-lingual plus approximal correlation was significantly better than the morsal with sulcal correlation. When reporting rat caries, sulcal scores should be reported alone; morsal scores should be grouped with bucco-lingual and approximal to demonstrate total smooth surface lesions.

A comparison between different methods for prediction of caries activity

The aim of the study was to find out if any of the following factors, alone or in combination, could be used for prediction of caries activity: salivary S. mutans, salivary lactobacilli, buffer capacity, saliva secretion rate, salivary pH, the amount of plaque and the caries frequency. The patient material consisted of 300 children between 9 and 12 years old. The increment of caries after 1 and 2 years was compared with all the above factors registered at baseline. Only the factors caries frequency and S. mutans showed a significant correlation to caries activity. In one of the tests the lactobacillus count approached significance. The combination of high numbers of incipient smooth surface lesions, S. mutans and lactobacilli gave a mean value of caries activity almost three times that of the whole group (8.4 versus 3.1).

Investigation of plaque flora of human carious teeth using a microsampling technique

54 punch samples of enamel with adherent plaque, each representing approximately 0.2mm 2 of the tooth surface area, were removed from 12 primary and 23 permanent, freshly-extracted teeth. The areas sampled were occlusal and smooth-surface lesions and sound enamel surfaces. Bacteriological examination of the homogenized samples, using selective and nonselective media, incubated aerobically and anaerobically, led to the isolation of a range of microorganisms. The frequency of isolation of some known cariogenic species of lactobacilli, streptococci and actinomyces at the different sample sites was compared. The results show that this accurate sampling of a microscopically-identified area of the tooth surface can demonstrate differences in the plaque flora of sound and carious enamel, of different types of lesion in the same dentition, and of similar lesions in primary or permanent teeth.

Diets Based on Autoclaved Skim-Milk Powder

Two distinct effects of the ingestion of diets based on heated skim-milk powder were observed in growing rats: an increase in the number and severity of smooth-surface carious lesions and an increase in the absorption of dietary calcium. The former effect was reversed by supplementation of lysine and was not related to the mineral content of the diets; pair feeding was without significant effect on the incidence and severity of caries development. The increase in dietary calcium absorption was independent of dietary lysine content.

Effective immunity to dental caries: studies of active and passive immunity to Streptococcus mutans in malnourished rats.

The present studies suggest that rat dams passively transfer IgG to their offspring via milk. Furthermore, rat dams hyperimmunized to S mutans after intravenous administration of this bacterium have serum-precipitating antibody to S mutans group-specific antigen. This serum precipitin was also observed in serums of their offspring during the suckling period and was detectable for a week after weaning. When these offspring were infected with S mutans on the day of weaning, significantly fewer smooth surface lesions developed in them than in infected rats reared on nonimmunized mothers. These results suggest that anti-S mutans antibody, perhaps of the IgG2a class, is passively transferred from mother to offspring via the milk. Furthermore, this antibody is probably important in protection against S mutans infection. In this regard, recent studies by Lehner, Challacombe, and Caldwell have suggested that crevicular fluid transudating serum antibodies are important in the prevention of dental caries in rhesus monkeys. From our studies and others, it is becoming clear that at least two sources and classes of antibody are important in caries immunity. Secretory IgA, produced and secreted into saliva after local injection can be correlated with protection. At the same time, serum antibody (presumably IgG) either passively or actively derived also gives immune protection. Further studies must clarify the precise role of these Ig's and their possible synergistic activity with other specific immune factors in saliva in order to determine the mechanism(s) involved in effective caries immunity.

Virulence of Streptococcus mutans: a sensitive method for evaluating cariogenicity in young gnotobiotic rats

Gnotobiotic rats infected with Streptococcus mutans 6715 at 19 days of age and fed a purified diet (305) containing 5% sucrose developed extensive caries lesions on all molar surfaces within 16 days (35 days of age). Approximately twice as many lesions developed when infected rats were maintained until 45 days of age, whereas noninfected rats did not develop caries when fed diet 305. Gnotobiotic rats infected with S. mutans 6715 and fed a purified diet containing no sucrose (300) until day 25 and subsequently fed diet 305 for 10 days developed lesions similar to rats fed diet 305 for 16 days. Furthermore, rats infected with S. mutans 6715 and fed diet 300 until 45 days of age developed approximately one-half the smooth surface lesions as infected rats fed diet 305 for the same length of time. The level of caries on buccal and proximal molar surfaces in 45-day-old gnotobiotic rats varied when animals were infected with S. mutans AHT, BHT, NCTC 10449, 6715, or LM-7. Animals infected with S. mutans AHT showed more severe lesions on the buccal surfaces than those observed in animals infected with the other strains of S. mutans tested, whereas S. mutans 6715 caused significantly more caries on proximal surfaces. On the other hand, rats infected with S. mutans LM-7 exhibited the lowest level of caries on all molar surfaces of the five strains of S. mutans tested.

Reduction of rat caries by trimetaphosphate on different tooth surfaces: Variations produced by diet and oral flora

Osborne-Mendel rats fed coarse particle Diet 585 developed mostly sulcal lesions and showed no increase in caries as a result of being inoculated with exogenous mixed cariogenic flora including a strain of Streptococcus mutans. Uninoculated rats fed high sucrose Diet 2000 developed mostly sulcal lesions, while the inoculated animals showed some increase in the sulci and a very pronounced increase on the smooth surfaces. The addition of TMP to both of the diets was associated with a limited, but significant, reduction in sulcal caries and almost complete elimination of smooth surface lesions, which were already low on Diet 585 and a highly significant reduction on Diet 2000.

The retardation of spontaneous periodontal disease and the prevention of caries in hamsters with dextranase.

showed that dex­ tranase produced by a culture of Penicillium funiculosum was able to remove plaques grown in vitro. These plaques were products of cariogenic streptococci in su­ crose containing broths. Later the same investigators working with Keyes2 showed that dextranase reduced plaque formation and retarded caries development in albino hamsters previously infected with cariogenic organisms. Smooth surface lesions in the third molars did not form when administration of dextranase was begun prior to the eruption of this tooth. The present communication is concerned with the capacity of dextranase to prevent smooth surface caries completely in all molar teeth of golden hamsters fed a test diet containing 56% sucrose. The formation of plaque in the gingival sulcus and the development of periodontal pathosis was greatly reduced during the test period. Also a curative experiment is described in which dextranase removed preformed plaque in hamsters after 2 days of treatment.

Development of caries in the Hung-Hoppert caries-susceptible and caries-resistant rats under different experimental conditions.

Rats of both Hunt-Hoppert lines, originally designated as caries-susceptible (Ca-S) and caries-resistant (Ca-R) lines, were highly susceptible to caries when subjected to a combination of diet and microflora that provided a challenge to the resistance of all surfaces of the teeth. Strain differences were indicated by the predominance of sulcal lesions in the Ca-S line and smooth-surface lesions in the Ca-R line.