A practice-based study on the effect of a short sucrose/xylitol exposure on survival of primary teeth caries free.

BACKGROUND: In a randomized double-blinded clinical trial, preschool children used sucrose or xylitol chewing gum regularly for 2 months to study the preventive effect of xylitol on acute otitis media (AOM). Salivary mutans streptococci (sm) levels of the children were measured before the exposure. Those with ≥10(5) sm CFU in 1 mL saliva were considered to have high sm levels (sm+); and those with <10(5) CFU low sm levels (sm-). AIM: This practice-based study aims to evaluate long-term dental effects of the sucrose/xylitol exposure on primary teeth. DESIGN: For analyses, individuals were divided into sub groups according to their study group in the original AOM trial and baseline sm levels. Outcome events owing to dental caries of their all primary teeth were followed from dental records up to 12 years. Survival of teeth caries free was determined by Kaplan-Meier method and analysed statistically by Wilcoxon testing. RESULTS: Survival of primary teeth caries free of children with high sm levels in the sucrose group was significantly shorter compared with all other groups when followed until shedding. CONCLUSIONS: Two months' regular exposure to sucrose was sufficient to induce dental caries in primary teeth of children with elevated sm levels at baseline.

Use of statistical methods in dental research: comparison of four dental journals during a 10-year period.

OBJECTIVE: To investigate development of the use of statistical methods in dental journals in 1996, 2001, and 2006 hypothesizing that methods are becoming more sophisticated. MATERIAL AND METHODS: All original research articles in four dental journals in 1996, 2001, and 2006 were reviewed: Journal of Dental Research (JDR), Caries Research (CR), Community Dentistry and Oral Epidemiology (CDOE) and Acta Odontologica Scandinavica (AOS). Evaluation covered 928 articles reporting original research findings based on systematic collection and statistical analysis of research data. Aspects measured were: research design, statistical methodology, description of procedures, and presentation of results. Percentage frequencies of reported statistical procedures were compared between journals and between years. RESULTS: The main findings of the study are: 1) that use of multivariate or specific methods did not increase from 1996 to 2006, 2) that traditional statistical significance testing is still widely used in dental journals and that use of confidence intervals increased in the period 1996 to 2006, 3) that statistical procedures are usually extensively described, and 4) that dental journals have different profiles in their statistical content. CONCLUSIONS: The authors of articles in dental journals might apply these results when designing their dental research, i.e. to use statistical methods and to present results in line with the policy and presentation of the leading dental journals.

Comparison of dental health in sealed and non-sealed first permanent molars: 7 years follow-up in practice-based dentistry.

OBJECTIVES: The use of digital dental records enables the retrospective analysis of the effectiveness of the fissure sealants applied in everyday dental practice. We tested the hypothesis that sealant treatment of first permanent molars results in a diminished need for restorative treatment in sealant treated teeth compared to their non-sealed counterpairs tested in a "practice-based research" (PBR) protocol. METHODS: Kaplan-Meier survival analysis was used to estimate the survival of first permanent molars caries-free, either sealed or non-sealed, for children attending two health centers in Finland (Kemi and Vantaa). RESULTS: Non-sealed teeth were restored approximately 50% more frequently compared to their sealed counterparts in Vantaa. In Kemi, however the survival of non-sealed teeth was even greater compared to sealed teeth. This was thought to be due to successful targeting of selective sealant treatment to real high caries risk teeth in Kemi whereas in Vantaa the strategy was to seal all molars routinely. CONCLUSIONS: The results suggest that the use of fissure sealant treatment routinely, without caries risk determination, is not the treatment of choice in preventing dental restorations but it effectively reduces caries rates in real-life conditions.

Practice-based study of the cost-effectiveness of fissure sealants in Finland.

OBJECTIVE: To retrospectively analyze the cost-effectiveness of sealant treatment in two health centers with different caries preventive strategies in Finland using a practice-based research protocol. MATERIALS AND METHODS: The data of digital dental records were data-mined and analyzed retrospectively in the health center in Kemi where the preventive strategy was sealing selectively only high-caries risk patients, and in Vantaa where all patients were routinely sealed. Risk group determination in Kemi was based on the presence of Streptococcus mutans in dental plaque. Supervised use of xylitol was an additional caries preventive measure in Kemi. The subjects were divided into all-sealed and non-sealed groups in the beginning of the follow-up according to the sealant treatment status of their first permanent molars. The mean cumulative cost of restorations and sealing treatment was counted in children at 12 years of age. RESULTS: Sealing of risk children in Kemi resulted in a total cost of 185euro per child whereas the respective cost of routinely sealed children in Vantaa was 235euro. The cost of restorations was 76euro in Kemi and 150euro in 5 years in Vantaa. Risk determination and the use of xylitol did not affect significantly the total treatment cost in Kemi. CONCLUSION: The significant reduction in the cost of dental treatment can be achieved by leaving non-risk subjects unsealed and sealing only high-caries risk individuals.

Comparison of the effectiveness of fissure sealants in Finland, Sweden, and Greece.

OBJECTIVE: To evaluate the effectiveness of sealant treatment in preventing dental restorations due to caries in a practice-based research network in Finland, Sweden, and Greece. MATERIAL AND METHODS: Times of tooth emergence, sealing treatment, and dental caries were compiled from the dental charts of 4735 subjects born in 1970-72 in Finland and in 1980-82 in Finland, Sweden, and Greece. Survival time between tooth emergence and placement of first restoration was measured and estimated using survival analysis methodology. RESULTS: At the end of follow-up (7-10+ years), 30-40% of sealed molars and 60-80% of non-sealed molars were restored. Early sealant placement compared to late sealing did not result in significantly higher survival of 1st molars. The strategy of sealing the 1st molars only in high caries risk subjects was as effective as sealing all the molars and premolars routinely without caries risk determination. CONCLUSIONS: The sealing of all molar fissures proved to be no more effective than sealing risk fissures of subjects. Early sealing did not result in any better outcome than late sealing. The effectiveness of sealant treatment in preventing dental restorations is dependent on the caries risk of individuals and caries prevalence of the country.

Matrix metalloproteinase-8 (MMP-8) is the major collagenase in human dentin.

OBJECTIVE: Previously an unidentified collagenolytic metalloprotease together with gelatinase (matrix metalloproteinase-2, MMP-2), and enamelysin (MMP-20) have been detected in human dentin. The aim of the study was to characterize dentinal collagenolytic enzymes. Furthermore, we hypothesized that the dentinal MMPs are protected by the mineral phase, and studied the stability of dentinal MMPs. DESIGN: To characterize dentinal collagenolytic enzymes, we used Western blotting with specific antibodies against MMP collagenases (MMP-1, -8, and -13) and cathepsin K. MMP-8 immunofluorometric assay (IFMA) was also used for MMP-8 detection, and functional collagenase activity was examined with type I collagen degradation assay. The stability of dentinal MMPs was examined by autoclaving dentin blocks before protein extraction and subsequent examination of protein levels and the activities of dentin collagenase and gelatinases. RESULTS: MMP-8 (collagenase-2) was detected in dentin both with Western blot and IFMA, and dentinal samples also cleaved the intact type I collagen into characteristic 3/4(alphaA)-cleavage products in vitro. No other collagenases or cathepsin K were detected. In autoclaved samples no MMP-8 was found, but gelatinase activity was observed in protein fractions of mineralized dentin. CONCLUSIONS: MMP-8 represents the major collagenase in human dentin. Unlike MMP-8, dentinal gelatinases can be detected after autoclave treatment of dentin, indicating their high resistance to external sample treatment procedures.

A practice-based study of the sealant treatment effectiveness in Finns.

OBJECTIVES: The effectiveness of fissure sealing in preventing dental caries in a subject-specific fashion was studied in order to forge a link between the controlled trials and knowledge creation in clinical practice. METHODS: The subjects were divided retrospectively into three categories according to the sealant treatment status of their first permanent molars at the first examination after the eruption and the survival of first molars in each group were estimated using the Kaplan-Meier method. RESULTS: Sealing of all first molars in caries-prone subjects was an effective caries preventive method. The highest survival of first molars was observed in the unsealed subjects in the health center focusing on sealing risk-subjects only. The first molars of partly sealed subjects had the lowest probability of survival in both health centers. CONCLUSION: Sealing all four permanent first molars rather than some of them in high caries risk subjects and leaving unsealed the first molars of caries resistant subjects enable to decrease unnecessary sealant treatment by focusing it especially to those benefiting it.

Effects of protein deficiency induced by raw soy with and without sucrose on dentine formation and dentinal caries in young rats.

OBJECTIVES: The effects of protein deficiency and sucrose on formation and mineralization of dentine and dental caries in the molars of young rats were investigated. MATERIALS AND METHODS: Two groups of weaning Wistar rats received raw soy flour to induce protein deficiency with sucrose or starch as the carbohydrate source; the other two groups received skim milk powder as the protein source with sucrose or starch as the carbohydrate source. At the onset, tetracycline was injected to mark the dentine formed at that moment. After 6 weeks, lower molars were sectioned sagittally, and the areas of dentine formation and dentinal caries developed during the experiment were quantified separately in the first and second molars. Dental caries was also classified according to Schiff's reaction. Calcium (Ca), phosphorus (P) and total mineral elements were analyzed using an electron probe microanalyzer. RESULTS: Rats in both protein-deficient groups and normal protein sucrose group had significantly larger areas of dentine formed compared with rats fed with normal protein starch diet. Ca, P and total mineral elements in dentine were significantly reduced by normal protein sucrose diet. P content was significantly reduced in dentine of rats in protein-deficient sucrose group. Rats in normal protein sucrose group had significantly more and larger dentinal caries lesions than in any other group. CONCLUSION: This study suggests that protein deficiency induced by soy prevents the progression of dental caries even in highly cariogenic environment.

Enzymes, dentinogenesis and dental caries: a literature review.

OBJECTIVES: Search in PubMed with keywords "enzymes, dentinogenesis, and dental caries" revealed only 4 items, but when combined with "enzymes, osteogenesis, and osteoporosis" as high as 404 items resulted. Dental caries was associated with an order of magnitude fewer studies than the chronic bone disease, osteoporosis. This observation motivated this review. MATERIAL AND METHODS: A comprehensive review of the available literature on role of enzymes in dentinogenesis and dental caries was undertaken using MEDLINE (PubMed) and Scopus. Keywords for the search were: enzymes and odontoblasts, enzymes and different forms of dentinogenesis as well as dental caries. RESULTS: Search revealed studies which described odontoblasts harbouring numerous enzymes (hydrolases, including metalloproteinases, transaminases and dehydrogenases) during primary dentinogenesis. Alkaline phosphatase activity sharply decreased when odontoblasts turned into quiescent odontoblasts. Tertiary dentinogenesis was characterized first by reactionary dentine formation when alkaline phosphatase was highly reactivated. Then later some of these odontoblasts may die out and be replaced by other progenitor cells of pulpal origin. This tertiary dentine was called reparative dentine. Pulpal progenitor/stem cells revealed alkaline phosphatase activity in areas encircling inflamed pulp sections. Soft carious dentine revealed high hydrolase, transaminase and dehyrogenase activities that may have originated from invading microbes, saliva or were endogenous. Proteolytic activity was especially demonstrable using histochemical and biochemical means. Specifically, matrix metalloproteases may have originated partly from activated proenzymes of host origin. CONCLUSIONS: Though dental studies are scanty when compared to bone, the active role of large spectrum of enzymes in healthy and carious dentine was given support.

The use of time-to-event methods in dental research: a comparison based on five dental journals over a 11-year period.

OBJECTIVES: Time-to-event methods are used in multivariate data analysis to describe the relationship between patient variables and the timing of an outcome event. The aims of this study were to evaluate the reporting of statistical techniques and results in dental research papers with special reference to time-to-event (TTE) methods and to create guidelines for the appropriate reporting of these methods. METHODS: All the original research reports published in five dental journals in 1996, 2001, 2005, 2006, and 2007 were reviewed. The evaluation covered 1985 articles that were based on the systematic collection and statistical analysis of research data. Differences between TTE approaches and others were assessed in terms of the justification for the number of cases, description of procedures, statistical references, software used, and statistical figures and tables provided. RESULTS: Fifty-six papers (2.8% of the total) used time-to-event methods, the frequency of which increased slightly from 1996 to 2007 (P = 0.061). Statistical procedures were described more extensively in the papers, which used TTE methods. Reporting of the statistical methodology in papers using other methods was in general inadequate. CONCLUSIONS: TTE methods are underused in dental research. Authors could well take heed of these results when designing their research, so as to make more use of such methods and to present the results in a manner that is in line with the policy and presentation of the leading dental journals. Authors could also improve their statistical reporting with the help of the guidelines presented here.

Data mining of clinical oral health documents for analysis of the longevity of different restorative materials in Finland.

Evidence-based dentistry has shown that different restorative materials have different survival times. Our primary hypothesis is that this should be revealed from normal dental records by the use of data mining technique and a practice-based dentistry approach analysed in a scientifically sound way. Dental records from 1626 patients and altogether 19,892 restorations in three Finnish age cohorts were analysed. Survival curves (Kaplan-Meier) were drawn for each of the restorative materials. Median survival times for amalgam and resin-based composites were more than 15 years in older cohorts. More than 60% of silicate cement restorations were replaced within 5 years, and more than 50% of glass ionomers within 7 years. There was a significant reduction in the longevity of amalgams in the 1980 cohort. Data mining of digital oral heath documents would be a useful tool to analyse survival curves of new restorative materials in a practice-based manner in real-life conditions.

A seven-year survival analysis of caries onset in primary second molars and permanent first molars in different caries risk groups determined at age two years.

OBJECTIVE: To investigate in a group of children (n=183) the effect of possible risk factors registered at the age of 2 years on caries development in 7 years of follow-up, and to study associations between risk groups. MATERIAL AND METHODS: Consumption of candies, use of a nursing bottle at night, use of fluorides, toothbrushing, pacifier sucking, and prolonged breastfeeding (>or=12 months) were recorded at the age of 2 years. The timing of caries onset in different groups was compared by applying a survival analysis method--the survival curves produced separately for selected teeth in different risk groups. RESULTS: The survival curves of caries onset for both primary and permanent molars were consistently lower for children who consumed candies more than once a week, did not brush their teeth daily, were given a nursing bottle at night or a pacifier at age 2 years. The multivariate survival analysis confirmed that consumption of candies and lack of daily toothbrushing were the factors that had the major impact on caries onset in both primary and permanent molars. Prolonged pacifier sucking (>or=2 years) was related only with short duration of breastfeeding. Children with prolonged use of a nursing bottle at night also consumed candies more than once a week, did not brush their teeth regularly, and did not use fluoride tablets. CONCLUSIONS: Consumption of candies and inadequate oral hygiene at age 2 years are important long-term risk factors for caries development in both primary and permanent molars.

Computed online determination of life-long mean index values for carious, extracted, and/or filled permanent teeth.

OBJECTIVE: The purpose of this study was to develop and test a data-mining system for the online determination of mean DS, M, and FS or DMFS values per subject at different ages from electronic patient records at two health centers to see if there are north-south differences in oral health in Finland. MATERIAL AND METHODS: The mean index values were determined at two health centers using the codes of dental charts and progress notes of electronic dental records during the digital era of more than 10 years in a total of 153,619 subjects of all ages. Extracted teeth, as well as sound, carious, and restored tooth surfaces, were recorded from the dental charts. Treatments were then additionally registered from progress notes of the records when performed. RESULTS: The cumulative DS and FS values were similar in subjects under the age of 20 years at both health centers. In adults, caries was more abundant in northern Finland, where there was a higher number of restored surfaces (>40) registered, compared to only 30 in southern Finland at the age of 40 years. A high increase in the number of extractions began at age 45 in the north compared to age 70 in the south. These changes were clearly reflected in the DMFS index. CONCLUSIONS: Online determination of health parameters is a feasible methodology. The results revealed that north-south regional differences in dental health still occur in adults in Finland, but not in subjects younger than 20 years of age.

Analysis of gene and protein expression in healthy and carious tooth pulp with cDNA microarray and two-dimensional gel electrophoresis.

Complementary DNA (cDNA) microarray and two-dimensional (2-D) gel electrophoresis, combined with mass spectrometry, enable simultaneous analysis of expression patterns of thousands of genes, but their use in pulp biology has been limited. Here we compared gene and protein expression of pulp tissues from sound and carious human teeth using cDNA microarray and 2-D gel electrophoresis to evaluate their usefulness in pulp biology research and to identify the genes with changes in carious teeth. The cDNA microarray revealed several differentially expressed genes and genes with a high expression in both tissues. These genes have various functions, e.g. effects on vascular and nerve structures, inflammation, and cell differentiation. Variability between cDNA hybridizations indicates that the overall gene expression pattern may vary significantly between individual teeth. The 2-D gel electrophoresis revealed no change between healthy and diseased tissue. The identification of 96 proteins in the pulp tissue revealed none of the gene products with corresponding high/different mRNA expression in cDNA microarray. Interestingly, we detected also a hypothetical protein (putative nucleoside diphosphate kinase), and present therefore the first evidence for the existence of this protein. Even though the methods reveal potentially important gene expression, they may currently have only limited value in in vivo pulp biology research.

Dental age and dental health determined longitudinally from patient records in three towns in Finland.

The aims of this study were to test the suitability of normal dental records in determining the eruption times of teeth and to compare the retrospective longitudinal DMF values with the statistical cross-sectional means. Patient records for two cohorts (1970 and 1980) were collected from three Finnish towns. The study population comprised 1910 children. The eruption times of the permanent teeth, DMFT and DMFS curves (excluding F due to fractures and M due to orthodontic reasons) were investigated for the year of examination in different study locations. The cross-sectional DMF values were compared to longitudinally calculated data. Tooth eruption was earlier in girls than in boys. However, girls did not have significantly higher DMF values than boys. In all towns, dental health was significantly better in the 1980 cohort than in the 1970 cohort. Comparison of the cross-sectional DMF values in the municipal health center statistics showed that the mean statistics gave considerably higher values than the measured values did after 15 years of age. The inconsistency between measured longitudinal DMF values and the cross-sectional statistical DMF values indicates the importance of creating computer programs for analyzing data longitudinally from normal dental records.