Noninvasive control of dental caries in children with active initial lesions. A randomized clinical trial.

The aim of this study was to investigate whether DMFS increment can be decreased among children with active initial caries by oral hygiene and dietary counseling and by using noninvasive preventive measures. Except for mentally disabled and handicapped children attending special schools, all 11- to 12-year-olds in Pori, Finland, with at least one active initial caries lesion were invited to participate in the study and were then randomized into two groups. Children in the experimental group (n = 250) were offered an individually designed patient-centered preventive program aimed at identifying and eliminating factors that had led to the presence of active caries. The program included counseling sessions with emphasis on enhancing use of the children's own resources in everyday life. Toothbrushes, fluoride toothpaste and fluoride and xylitol lozenges were distributed to the children. They also received applications of fluoride/chlorhexidine varnish. The children in the control group (n = 247) received basic prevention offered as standard in the public dental clinics in Pori. For both groups, the average follow-up period was 3.4 years. A community level program of oral health promotion was run in Pori throughout this period. Mean DMFS increments for the experimental and control groups were 2.56 (95% CI 2.07, 3.05) and 4.60 (3.99, 5.21), respectively (p < 0.0001): prevented fraction 44.3% (30.2%, 56.4%). The results show that by using a regimen that includes multiple measures for preventing dental decay, caries increment can be significantly reduced among caries-active children living in an area where the overall level of caries experience is low.

Human growth differentiation factor 9 (GDF-9) and its novel homolog GDF-9B are expressed in oocytes during early folliculogenesis.

Growth differentiation factor 9 (GDF-9) is a transforming growth factor-beta family member that is required for normal folliculogenesis in female mice, but its role as a regulator of human fertility is still unclear. We determined here by in situ hybridization and immunohistochemical analyses the localization of the GDF-9 messenger ribonucleic acid (mRNA) and protein during human folliculogenesis. The GDF-9 transcripts were not detected in primordial follicles, but they are abundantly expressed in primary follicles in frozen sections of ovarian cortical tissue material obtained at laparoscopic surgery. We raised antipeptide antibodies against GDF-9 and showed by immunohistochemical studies on paraffin sections of whole human ovaries that the GDF-9 protein is most abundantly expressed in primary follicles. We recently demonstrated that a novel GDF-9-related factor, GDF-9B, is coexpressed with GDF-9 during murine folliculogenesis. We now isolated human GDF-9B complementary DNA and genomic clones and report the unusually restricted expression pattern of human GDF-9B. The human GDF-9B transcript can be detected only in the gonads by RT-PCR analysis, and in situ hybridization studies indicate that it is not expressed in small primary follicles but, rather, in the oocytes of late primary follicles. Functional studies using the Xenopus laeuis embryo model indicate that unlike the transforming growth factor-beta family members activin and bone morphogenetic protein-4, neither GDF-9 nor GDF-9B affects mesoderm induction, suggesting that they may use signaling pathways distinct from those well defined for activin and bone morphogenetic protein-4. We conclude that 1) both GDF-9 mRNA and protein are abundantly expressed in oocytes of primary follicles in human ovary, suggesting that the GDF-9 transcript is translated at this early stage of folliculogenesis; 2) human GDF-9B is specifically expressed in gonads at low levels; and 3) the expression of GDF-9 mRNA begins slightly earlier than that of GDF-9B in the human oocytes during follicular development. Our results are consistent with the suggestion that GDF-9 and GDF-9B may regulate human folliculogenesis in a manner specific to the ovary.

The effect of fluoride application on fluoride release and the antibacterial action of glass ionomers.

The aim of this study was to investigate whether the release of fluoride and the antimicrobial effect of freshly mixed glass ionomers could be prolonged by application of fluoride on aged material. Test slabs of freshly mixed and aged (14 d in water) conventional and silver glass ionomer (Ketac-Fil and Ketac-Silver, Espe, Seefeld, Germany) and composite (Silux Plus, 3M, St. Paul, MN) were fitted into the bottom of a test tube. A layer of S. mutans Ingbritt cells was centrifuged onto the test slabs, and the samples were incubated for 20 h in 1.7% sucrose solution. After the incubation, pH, F, and Ca contents of the fluid phase, and F, Mg, P, and K contents of the cells were determined. The aged glass-ionomer samples were then covered with toothpaste (0.1% F) or with fluoride gel (1.25% F), and the composite samples with fluoride gel. After being thoroughly rinsed, S. mutans cells were incubated on the samples as above. The pH fall was significantly inhibited by freshly mixed glass ionomers, and there were changes in cellular cation and phosphorus contents. Large amounts of fluoride were found in the fluid and cells. For old glass ionomers, no inhibitory effect on pH fall could be seen. Fluoride release had decreased to a low level.(ABSTRACT TRUNCATED AT 250 WORDS)

Post-treatment effect of fluoride varnishes in children with a high prevalence of dental caries in a community with fluoridated water.

Children with a high prevalence of dental caries living in a community with fluoridated water had received semi-annual half-mouth applications of one of two fluoride varnishes for three years. Two years after the applications were discontinued, we studied the post-treatment effect of the varnishes. The absolute reduction in caries found during the treatment was retained, but the cariostatic effect did not continue after treatment. This finding suggests that fluoride varnish applications should not be discontinued after three years.

Caries prevention in rats by fluoride varnish treatment combined with addition of fluoride to dietary sugar.

Osborne-Mendel rats were fed a cariogenic diet containing 43% sucrose for 48 days. The control group received no additional treatment. The teeth of the second group received topical treatment with a sodium fluoride varnish which was applied twice onto newly-erupted molars. The third group received topical treatment with the sodium fluoride varnish combined with a NaF + Mg addition to the diet. In both treatment groups, caries was significantly reduced as compared with caries in the control group. Combined treatment was significantly more effective than was the varnish alone. In spite of the high fluoride concentration in the varnish, no changes in the oral mucosa were found at the end of the study.

Effect of chlorhexidine-fluoride applications without and with Sr and Zn on caries, plaque, and gingiva in rats.

Molar teeth of four groups of Osborne-Mendel rats, kept on a cariogenic diet, were treated once per day for 48 days with either distilled water (solution C), a solution containing 0.05% chlorhexidine gluconate and 0.04% NaF, pH 5.8 (solution CXF), CXF plus 1000 ppm Sr (solution CXFS), or CXFS plus 1000 ppm Zn (solution CXFSZ). Caries of the hemi-sectioned lower molars was scored according to grades of severity, and the extent of the buccal plaque was estimated. Inflammatory cell infiltration, vascularity, and thickness of the oral mucosa were estimated from stained sections of the buccal oral mucosa to detect possible adverse effects of the treatments. Fissure caries lesions with involvement of the dentin were reduced by 57% (p less than 0.01) with the CXF treatment and by 68% (p less than 0.001) with the CXFS treatment. The CXFSZ treatment reduced the fissure caries least (44%, p less than 0.05), but it appreciably reduced the extent of plaque. The mucosal changes were greatest in the group receiving the CXFSZ treatment, but they were generally small and at a non-pathological level. Supplementation of the CXF solution with Sr thus appeared beneficial for caries reduction.

A scanning electron microscopic study of early subsurface bacterial penetration of human molar-fissure enamel.

Cross-sections of occlusal fissures in clinically-sound, partly-erupted human third molars were examined using scanning electron microscopy. In several specimens, microbes had invaded enamel under an apparently intact enamel surface and formed colonies within the prism structure. Bacteria were located also between enamel prisms. In some samples, colonies were observed in dentine. Most of the organisms were rod-shaped or filamentous. The results indicate that plaque bacteria can invade enamel before initiation of caries is clinically observable.

A scanning electron microscopic study of bacterial penetration of human enamel in incipient caries.

In 23 human teeth, cracked enamel under white spot lesions without any visible loss of tooth substance was examined. Bacterial contamination from the enamel surface was prevented by brushing and consequent fixing of the remaining surface coatings before the enamel was fractured. In 7 of 23 specimens, bacterial colonies were observed under the enamel surface, sometimes as deep as the enamel-dentine junction and the dentine. In most samples the subsurface enamel appeared to be partly disintegrated. Bacteria can thus be found under surface enamel at an early stage of caries while the surface is still intact.

Exchange of fluoride between bovine enamel and the surface-related cells of the oral bacterium Streptococcus mutans.

Standard areas of intact bovine enamel surface were fluoridated with dental F-varnish for 24 h and then cleaned from varnish residues and thoroughly rinsed with distilled water. Sucrose fermentation by a plaque-like layer of Streptococcus mutans cells covering such an enamel surface was accompanied by a rapid but transient accumulation of F of enamel origin by the Strep. mutans cells and by a pH drop in the plaque to pH 4.0. The uptake of F from the surface by the control cells, utilizing their carbohydrate stores and causing a smaller pH-drop, was slow but no release of F back to the cell exterior took place within 18 h. In a second experiment, F- varnished and placebo- varnished bovine enamel granules were used as above, but they were not thoroughly washed after being varnish-treated and cleaned. Both the sucrose-fermenting and the control layer of Strep. mutans rapidly released appreciable but equal amounts of fluoride from the F-treated enamel. The accumulation of F of enamel origin by the Strep. mutans cells with or without sucrose was rapid and of almost the same magnitude. In the model with the sucrose-utilizing Strep. mutans and the F-treated enamel granules, the plaque pH-drop was less and the dissolution of the enamel Ca and P completely prevented compared to the respective changes in the sucrose-utilizing model with placebo-treated enamel granules.

The effect of different strontium concentrations on the efficacy of chlorhexidine-fluoride-strontium gel in preventing enamel softening in vitro.

The effects were compared of strontium concentrations of 0, 15, 50 and 250 parts/10(6) in chlorhexidine(0.20%)-fluoride(0.16%) gel in preventing the softening of bovine enamel during bacterial fermentation. Fresh Streptococcus sobrinus cells were suspended in a buffer solution (pH 6.0) with 3.3% sucrose and centrifuged as a plaque-like layer on the top of enamel slabs covered with 10 microliters gel. AFter 24 h incubation, the pH fall of the fluid was significantly smaller in all test groups than in the placebo group. Strontium seemed to have an inhibitory effect on the pH fall. All test gels significantly prevented softening and dissolution of enamel during bacterial fermentation, which was directly related to strontium concentration. The amounts of calcium and phosphorus in the cells and fluid after incubation were the smallest in the group with 250 parts/10(6) strontium. In a second experiment without bacteria, new enamel slabs were covered with 10 microliters gel containing chlorhexidine and NaF with 0 and 250 parts/10(6) strontium to study the protective effect of strontium. After 24 h gel treatment, each enamel slab was dissolved in 1 ml 0.1 M lactic acid, pH 5.0, for 2 h. Significantly less calcium and phosphorus were dissolved from the enamel in both test groups than in the control and placebo groups. However, the placebo gel also prevented calcium and phosphorus dissolution significantly. These results suggest that the addition of strontium to chlorhexidine-fluoride gel improves the ability of this combination to prevent caries-like enamel softening. The inhibition of bacterial acid production by the strontium-containing gel may explain this enhanced protection of enamel.

In vitro abrasion resistance and hardness of glass-ionomer cements.

The aim of this study was to compare the abrasion resistance and surface hardness of four glass-ionomer cements. The effects of hydration and dehydration on wear resistance were also studied. A composite material, enamel, and dentin were used as controls. For wear testing, the specimens were abraded on abrasion discs under water. All glass ionomers showed greater wear than composite and enamel, but less wear than dentin. Ketac-Fil showed the highest and Ketac-Silver the lowest wear resistance. Hydration or dehydration of the specimens did not significantly influence the wear rate of conventional glass ionomers, but the wear resistance of Ketac-Silver was increased due to dehydration. Ketac-Fil had the highest and Ketac-Silver the lowest hardness rating of the glass ionomers. The cement material did not show abrasion resistance better than that of the conventional glass ionomers, as has previously been suggested.

Wear of dental restorative and prosthetic materials in vitro.

The aim of this study was to evaluate the wear of some modern materials for fixed crown and bridge restorations and fillings in vitro. Eighteen commercial materials (8 composites, 4 alloys, 4 façade materials, and 2 denture-base resins) were tested. Enamel was used as the control. Test specimens were abraded on abrasion discs under water or in artificial saliva. There was a great variation in the wear rates of the tested materials. The greatest wear was shown by resins used for base material and the smallest by gold and Cr-Co alloys and porcelain. Most of the composites had a wear rate near that of enamel. The wear for amalgam was slightly greater than for most of the composites. When one is using several different materials for reconstructing occlusion, differences in wear resistance should be taken into account.

Caries frequency in permanent teeth before and after discontinuation of water fluoridation in Kuopio, Finland.

UNLABELLED: The piped water of Kuopio, Finland, was fluoridated in 1959. Owing to strong opposition by different civic groups, water fluoridation was stopped at the end of 1992. OBJECTIVES: The aim of this study was to examine the consequences of the discontinuation on dental health. METHODS: In 1992 and 1995, independent random samples of all children aged 6, 9, 12 and 15 years were drawn from Kuopio and Jyväskylä, a nearby low fluoride town whose distribution of demographic and socio-economic characteristics was fairly similar to Kuopio's. The total number of subjects examined was 550 in 1992 and 1198 in 1995. Caries was registered clinically and radiographically by the same two calibrated dentists in both towns. RESULTS: In 1992, the mean DMFS values were lower in the fluoridated town for the two older age groups, the percentage differences for 12- and 15-year-olds being 37% and 29%, respectively. For the two younger age groups no meaningful differences could be found. In 1995, the only difference with possible clinical significance was found in the 15-year-olds in favor of the fluoridated town (18%). In 1995, a decline in caries was seen in the two older age groups in the nonfluoridated town. In spite of discontinued water fluoridation, no indication of an increasing trend of caries could be found in Kuopio. The mean numbers of fluoride varnish and sealant applications decreased sharply in both towns between 1992 and 1995. In spite of that caries declined. CONCLUSIONS: These findings suggest that the decline of caries has little to do with professional preventive measures performed in dental clinics.

A follow-up study of the use of DIAGNOdent for monitoring fissure caries in children.

OBJECTIVES: The aim of this study was to evaluate the utility of the laser fluorescence device DIAGNOdent for monitoring occlusal caries longitudinally as part of a routine dental check-up in a public dental clinic. METHODS: Children aged 7-8 and 13-14 years at baseline participated in the study. As part of two consecutive dental check-ups with a mean interval of 1,19, years, 423 permanent molars and 315 primary molars in 81 children were examined visually and using DIAGNOdent by one dentist. In teeth where, as judged by visual examination, caries had emerged or progressed during the follow-up, the DIAGNOdent values had increased significantly from the baseline. RESULTS: In permanent teeth with a change in visual score from sound to enamel or dentin caries, the mean DIAGNOdent value increased from 24 to 37 and in primary teeth from 8 to 40. The increase in DIANGOdent values correlated positively with the increase in visual score. The mean DIAGNOdent value at baseline was significantly higher in teeth that became carious than in those that remained sound during the follow-up. For permanent teeth with a visual reversal from inactive or active enamel caries to a sound surface, the mean DIAGNOdent value decreased from 36 to 24. CONCLUSIONS: These results suggest that DIAGNOdent is useful in monitoring occlusal caries in both permanent and primary molars.

Application of the high-risk strategy to control dental caries.

OBJECTIVE: The aim of this prospective study was to determine whether a child population with low overall caries frequency benefits when prevention is targeted to high-risk individuals. METHODS: Data from clinical examinations and salivary tests were used to assess caries risk in 12-year-olds (n=1465). Children who were regarded as being at high risk of developing caries were randomized into two groups. Half (HRI group) were offered intensive prevention (counseling, F-varnish applications, F-lozenges, sealants, chlorhexidine), and the other half (HRB group) were provided the same basic prevention given to low-risk children (counseling, one F-varnish application/year). A random sample of the low-risk children (LRB) was followed up for the same 3-year period as the high-risk children. The number of children completing the study was 216 in the LRB group, 199 in the HRI group and 174 in the HRB group. RESULTS: The mean (SD) 3-year DMFS increment was 2.0 (2.4), 4.4 (4.7) and 5.1 (5.0) in the LRB, HRI and HRB groups, respectively. Comparison between the LRB and HRB groups revealed that risk assessment was fairly successful in terms of mean DMFS increment. However, 63% of the children in the LRB group developed at least one new lesion (max. 12). CONCLUSIONS: The negligible difference between the HRI and HRB groups implies that intensifying prevention produced practically no additional benefit. By offering all children only basic prevention, virtually the same preventive effect could have been obtained with substantially less effort and lower costs.

Caries in the primary dentition, after discontinuation of water fluoridation, among children receiving comprehensive dental care.

UNLABELLED: The city of Kuopio in central Finland had fluoridated piped water for 33 years, beginning in 1959. Due to strong opposition by various civic groups, water fluoridation was stopped at the end of 1992. There is little information on the consequences of stopping fluoridation in a community with comprehensive dental care for all children and adolescents, who are frequently exposed to different fluoride measures both at home and in the dental office. OBJECTIVES: The aim of this repeated cross-sectional survey was to examine how discontinuation of water fluoridation in Kuopio affected caries in the primary dentition. Changes in the mean dmfs values between 1992 and 1995 in Kuopio were compared to those in Jyväskylä, a low-fluoride community that has repeatedly been used as the reference area for Kuopio. METHODS: In 1992 and 1995, independent random samples of all children aged 3, 6 and 9 years were drawn in Kuopio and Jyväskylä. The total number of subjects examined was 421 in 1992 and 894 in 1995. Calibrated dentists registered caries clinically and radiographically. RESULTS: In all age groups both in 1992 and 1995, the point estimates for mean dmfs values were lower in the non-fluoridated town. In both towns, the observed mean dmfs values were smaller in 1995 than in 1992. CONCLUSION: Despite discontinuation of water fluoridation, no increase of caries frequency in primary teeth was observed in Kuopio within a three-year period.

Comparison of glass-ionomer and resin-based fissure sealants: a 2-year clinical trial.

In recent years, the interest in the use of glass-ionomer materials as fissure sealants has increased. The aim of this study was to compare the retention and caries-preventive effect of glass-ionomer (Fuji III) and resin-based light-cured (Delton) fissure sealants. Three health center dentists applied the sealants to 166 children; glass-ionomer sealants on one side and resin-based sealants on the contralateral side of the mouth. After 2 yr, one pair of molar teeth in the mouths of 151 children was compared. Twenty-six percent of glass-ionomer and 82% of resin-based sealants were totally present (P < 0.001). During the 2 yr, in both groups 4.6% of the sealed surfaces became carious. The results show that the retention of glass-ionomer sealants is markedly inferior to the resin-based sealants. In this study, however, no difference in caries increment on the sealed surfaces was observed. This may be due to the different mechanism of caries prevention for the sealant materials, or to the overall low caries activity of the participants.

Past caries recordings made in Public Dental Clinics as predictors of caries prevalence in early adolescence.

The aim of the present study was to evaluate the power of past caries experience in primary and permanent dentition in predicting caries prevalence at the age of 13 yr. Clinical and radiographical examination was performed in 512 13-yr-olds by a trained research team. The 6-12-yr dmfs and DMFS values were obtained from the Public Dental Care records. For evaluating the accuracy of predictions, the children were cross-classified according to each past caries score and the 13-yr score. The cutting points were selected to that the children in the upper quartile of caries experience formed the predicted and true high caries groups, leaving about 75% in the low caries groups. Pearson correlations were also calculated. Sensitivity and specificity of caries in primary teeth (6 yr) were 57% and 85%, respectively. For permanent dentition, sensitivity was the lowest (28%) at the age of 6, reached 68% at the age of 9 and remained at that level until age 12. Specificity decreased from 92% (6 yr) to 85% (9 yr) and then steadily increased to 93% (12 yr). Correlation increased with age from 0.37 to 0.82. When screening for high caries increment in young children, caries in primary dentition seems a better screening criterion than caries in permanent first molars. When the aim is to identify those subjects with high caries increment later on, screening at age 9 seems as accurate as that done later.

Dental check-up intervals and caries preventive measures received by adolescents in Finland.

OBJECTIVE: The aim was first to estimate the mean length of dental examination intervals and the mean number of preventive procedures in two Finnish towns during the periods of 1990-1992 and 1993-1995. Secondly, to ascertain whether the length of the check-up interval and the intensity of prevention varied according to the caries experience at the beginning of a treatment period. Participants A random sample of all 12- and 15-year-old children was drawn in 1992 and 1995 in the towns of Jyväskylä and Kuopio. METHOD: Oral health records obtained from public dental clinics were used for gathering the data on dental check-ups, DMFT and all preventive and treatment measures during the previous three years. The data were available for 267 and 590 subjects in 1992 and 1995, respectively. RESULTS: For 12-year-old children in 1990-1992, the mean length of check-up interval was 13.0 months in Kuopio and 12.4 months in Jyväskylä, while in 1993-1995 it was 18.1 months and 16.1 months, respectively. Among 15-year-old children in 1990-1992, the mean was 12.3 in Kuopio and 14.7 in Jyväskylä. During the latter period the interval was 1.2 months longer (P<0.05) in Kuopio, but there was no lengthening in Jyväskylä. Fluoride varnish applications, sealants, and instruction in oral hygiene were the most commonly used preventive measures. Practically no other fluoride methods than varnish applications were performed in dental clinics. Prevention seemed to be based mainly on procedures performed by the staff at the dental clinics and less attention was paid to the promotion of self-care. There was very little difference in the mean length of check-up interval and prevention between children who were caries free at the beginning of the treatment period and those with present or past caries experience. CONCLUSION: Between 1990-1992 and 1993-1995, the frequency of dental check-ups and the number of preventive procedures decreased. There was no indication of an increased caries frequency. Prevention appeared to be stereotyped and often had little relevance to the actual needs of the individual patient.

Resistance of occlusal fissures to demineralization after loss of glass ionomer sealants in vitro.

Seventy-one caries-free human occlusal fissures were used for this study. Twenty-two fissures were sealed with a glass ionomer sealant (Fuji Ionomer Type III--G-C Dental Industrial Corp., Tokyo, Japan), 24 were widened with a diamond bur and sealed with the glass ionomer sealant, and 25 were left unsealed. After one week, the sealants were removed as completely as possible with a probe. All fissures were demineralized for seven weeks. Sections made from the fissures were examined with a polarizing microscope, and the depths of the fissure lesions were measured. The mean lesion depths for controls, sealed natural fissures, and sealed widened fissures were 143, 93, and 75 microns, respectively. A statistically significant difference was noted between the two experimental groups and the control group (no sealant). The results suggest that fissures sealed with glass ionomer are more resistant to demineralization than control fissures, even after macroscopic sealant loss. This may be the result of the combined effect of fluoride released by glass ionomer and residual material in the bottom of the fissures.