Biomedical subjects

N J Wang

Publications and source records attributed to N J Wang.

At least 19 recordsLinked to original sources

PubMed2006

Caries increment and prediction from 12 to 18 years of age: a follow-up study.

AIM: This was to determine the increment of caries from 12 to 18 years of age and to explore the possibility of predicting caries increment in this period based on the caries experience at age 12 years. STUDY DESIGN: Prospective longitudinal survey. METHODS: A sample of 12-year-old children (n =159) were examined in 1993 and 70% of them re-examined at 18 years of age. Bitewing radiographs were taken and a diagnostic system using five caries grades (D(1) to D D(5)) was used at both ages. Children at risk were defined as those who developed manifest caries lesions (D(3-5)FS) on approximal surfaces during the follow-up period. Possible predictors were analysed by calculation of sensitivity, specificity, efficiency of the test, proportion that tested positive and actual proportion of the population at risk. RESULTS: The mean caries increment (D(1-5)MFS) from 12 to 18 years of age was 4.2 (SD +/- 9.1). The percentage of caries-free adolescents at 12 and 18 years of age was 10% and 1% respectively; 25% had either a reversal or no increment in caries experience while the D(1-5)MFS increased in 65% of the adolescents. Of the increment of manifest lesions (D(3-5)FS), 18% were located in incisors/canines, 40% in premolars, 26% in first molars and 16% in second molars. Premolars had the largest proportion of the approximal surfaces with manifest caries increment. The best predictors of children at risk of approximal caries increment (D(3-5)FS) were caries experience (D(1-5)FS) on the approximal surfaces of premolars and second molars at the age of 12 years. The individuals that developed four or more manifest lesions on approximal surfaces between 12 and 18 years were the easiest to predict (sensitivity + specificity = 175%). CONCLUSIONS: There was a considerable increment of manifest caries lesions from 12 to 18 years of age in all tooth groups. The best predictors for increment of manifest caries on approximal surfaces during the age period were approximal caries in premolars and second molars at the age of 12 years.

Adolescent↗

PubMed2005

Dental caries and associated factors in 12-year-old schoolchildren in Thiruvananthapuram, Kerala, India.

OBJECTIVES: The aims of the present study were to describe the dental health status of 12-year-old schoolchildren in Thiruvananthapuram, Kerala, India, and to identify sociodemographic factors, oral health behaviours, attitudes and knowledge related to dental caries experience. METHODS: The study took the form of a cross-sectional survey of 838 children in upper primary schools. A two-stage cluster sampling technique was used. Dental caries was measured using World Health Organization criteria. Sociodemographic factors, oral health behaviours, attitudes and knowledge were assessed by a self-administered questionnaire. RESULTS: The prevalence of dental caries in the permanent dentition was 27%. The mean number of decayed, missing and filled teeth was 0.5 (SD=0.9). The decayed component (D) constituted 91% of the total number of decayed, missing and filled teeth (DMFT). Multiple logistic regression analysis showed that children had a higher risk of having dental caries if they lived in urban area [OR=1.5, 95% confidence interval (CI)=1.1-2.1], had visited a dentist (OR=1.6, 95% CI=1.2-2.2), did not use a toothbrush (OR=1.9, 95% CI=1.2-2.9), consumed sweets (OR=1.4, 95% CI=1.0-1.9) or performed poorly in school (OR=1.7, 95% CI=1.0-2.3). CONCLUSIONS: The prevalence of caries in this sample of 12-year-old schoolchildren was low compared to that in other developing countries. The present study indicated that urban living conditions were associated with more dental caries. Since urbanization is rapid in India, oral health promotion at the present time would be valuable to prevent increased caries prevalence.

Analysis of Variance↗

PubMed2004

Supernumerary tricentric derivative chromosome 15 in two boys with intractable epilepsy: another mechanism for partial hexasomy.

Rearrangements of chromosome 15q, including isodicentric 15 chromosomes and interstitial duplications and triplications, have been previously reported in association with autism spectrum disorders. We have identified two boys with exceptionally large der(15) chromosomes that are tricentric and contain four copies of the proximal long arm, including the Prader Willi/Angelman critical region, and leading to hexasomy of the involved segment. Biallelic inheritance of maternal alleles and methylation analysis indicate that the markers are maternally derived. Clinical assessment of the boys indicated severe cognitive impairment associated with marked delays in gross and fine motor skills. Social and language deficits were present in both, although the severity of the mental retardation precluded diagnosis of autism (both were considered to have pervasive developmental disorder-not otherwise specified). Neurologic manifestations included infantile spasms evolving into intractable early-onset myoclonic seizures, psychomotor regression, and profound diffuse hypotonia. These patients represent the most severe end of the spectrum of phenotypes associated with segmental aneuploidy for chromosome 15q11-q13.

Abnormalities, Multiple↗

PubMed2000

Determinants of atherosclerosis susceptibility in the C3H and C57BL/6 mouse model: evidence for involvement of endothelial cells but not blood cells or cholesterol metabolism.

Lipids, monocytes, and arterial wall cells are primary components involved in atherogenesis. Using the inbred mouse strains C57BL/6J (B6) and C3H/HeJ (C3H), which have been extensively studied as models of the genetic control of diet-induced atherosclerosis, we examined which of these components determine genetic susceptibility. To test whether dietary responsiveness is involved, a congenic strain of C3H carrying an apoE-null allele (apoE(-/-)) was constructed. Although C3H.apoE(-/-) mice had higher plasma cholesterol levels, they developed much smaller lesions than their B6.apoE(-/-) counterpart on either chow or Western diets. Reciprocal bone marrow transplantation between the strains, with congenics carrying the same H-2 haplotype, was performed to examine the role of monocytes. The atherosclerosis susceptibility was not altered in the recipient mice, indicating that variations in monocyte function were not involved. Endothelial cells isolated from the aorta of B6 mice exhibited a dramatic induction of monocyte chemotactic protein-1, macrophage colony-stimulating factor, vascular cell adhesion molecule-1, and heme oxygenase-1 in response to minimally modified LDL, whereas endothelial cells from C3H mice showed little or no induction. In a set of recombinant inbred strains derived from the B6 and C3H parental strains, endothelial responses to minimally modified LDL cosegregated with aortic lesion size. These data provide strong evidence that endothelial cells, but not monocytes or plasma lipid levels, account for the difference in susceptibility to atherosclerosis between the 2 mouse strains.

Animals↗

PubMed2000

Effect of macrophage-derived apolipoprotein E on established atherosclerosis in apolipoprotein E-deficient mice.

Apolipoprotein E-deficient (apoE(-/-)) mice have hyperlipidemia and develop spontaneous atherosclerosis in a time-dependent manner. Although macrophage-derived apoE has been shown to prevent the development of atherosclerosis in apoE(-/-) mice, whether it would induce regression of established atherosclerosis is unknown. To determine this, 8-week-old apoE(-/-) mice were transplanted with apoE(+/+) bone marrow. Four weeks after transplantation, when plasma cholesterol levels had reached normal levels, a group of mice (n=12) were killed and their aortic lesions were measured and used as a baseline to judge regression. Twelve and 20 weeks after transplantation, aortic lesion areas of the mice were 9340+/-2184 micrometer(2) (mean+/-SEM, n=8) and 12 211+/-1433 micrometer(2) (n=9), respectively, values not significantly different from the lesion areas of the baseline mice (12 347+/-2487 micrometer(2); n=12, P>0.05). In contrast, apoE(-/-) mice reconstituted with apoE(-/-) bone marrow developed severe atherosclerotic lesions (453 036+/-29 767 micrometer(2), n=7) 20 weeks after transplantation. These data suggest that macrophage-derived apoE was insufficient to induce significant regression of established atherosclerotic lesions in apoE(-/-) mice, although it was sufficient to eliminate hypercholesterolemia and prevent progression of aortic lesions.

Animals↗

PubMed2000

Is amalgam in child dental care on its way out? Restorative materials used in children and adolescents in 1978 and 1995 in Norway.

OBJECTIVE: Improvements in dental health in children and adolescents and development of dental materials influence the selection of restorative materials. The purpose of this study was to obtain information on the amount and type of restorative materials used in children and adolescents in Norway in 1995 and compare this with the materials placed in 1978. DESIGN DATA: on numbers of restored surfaces and the use of amalgam and other restorative materials were collected from the dental records of 7,278 children aged 5, 9, 12, 15 and 18 years in 1995. Data from 1978 on 9,224 children were collected from the reports of the public dental services. RESULTS: From 1978 to 1995, the number of permanent surfaces restored was reduced by 69, 68, 64 and 52% for 9-, 12-, 15- and 18-year-old children respectively, and the number of primary surfaces restored declined by 64 and 59% in 5- and 9-year-old children. The proportion of restored surfaces that were filled with amalgam was reduced in all age groups and in both primary and permanent teeth. In 1995 most of the surfaces restored were filled with glass ionomer. The number of surfaces restored with amalgam decreased in all age groups. The reduction varied from 73% in the oldest age group to 97% among 5-year-old children. CONCLUSIONS: The study shows that the use of amalgam has decreased dramatically in children and adolescents and that with the present low caries rates the amount of amalgam inserted is small.

Adolescent↗

PubMed1999

Government policies on fluoride utilization in the Nordic countries.

In most but not all the Nordic countries, the National Boards of Health have issued guidelines governing the utilization of fluoride. The purpose of this paper is to outline the process of policy formation, describe the current fluoride guidelines in the Nordic countries, and discuss compliance with and appropriateness of the guidelines. The fluoride guidelines summarize current knowledge and make recommendations on choice of fluoride preparations (supplements, toothpaste, and varnish) and doses. Fluoride policies in the Nordic countries in the late 1990s state that use of fluoride toothpaste twice a day is the preferred and sufficient source of fluoride for the majority of the population. The policies of the Nordic countries are similar, but there are differences, some of them self-explanatory others not so obvious. In the case of supplements, for example, there are differences in the recommended dosage schedules. In the case of toothpaste, it is unclear what concentrations of fluoride are recommended both for children and for adults. Starting time for the use of fluoride, whether toothpaste or supplements, varies between countries. The clinicians' compliance with fluoride guidelines has not been systematically evaluated. Comparing the advice and treatments offered by dentists in the Nordic countries with current guidelines suggests that national policies influence the practice of clinicians. For government policy to be appropriate, it is imperative that the guidelines are based on sound scientific evidence. It is thus concluded that if nonevidence-based elements are included in national guidelines, this should be clearly stated to prevent confusion and enhance compliance from professionals and the public.

Adult↗

PubMed1999

Fluoride supplements and caries in a non-fluoridated child population.

In Norway, there is no water fluoridation and little naturally occurring fluoride in drinking water. Fluoride toothpaste is used by 95% of the population and there is a long tradition of use of fluoride supplements. The purpose of this study was to analyse whether children who used fluoride toothpaste regularly and complied with the recommendations for use of fluoride supplements had less caries than other children at the age of 8 years. Most fluoride supplements sold in Norway are lozenge-type tablets, which allow for extended enamel exposure to fluoride. All children (n = 551) born in 1988 living in a suburban community in Norway were invited to participate. In those who participated (n = 470), caries was registered clinically and radiographically and parents provided data on use of supplements. Thirty-eight percent of the children had used fluoride supplements regularly during the period 0.5 to 4.0 years of age and 66% used supplements regularly at the age of 6 to 8 years. Multivariate analyses showed that the children complying with the recommendations for use of fluoride supplements during the period 0.5 to 4.0 years of age had lower caries experience (dmfs) and fewer decayed surfaces (ds) in primary teeth than other children. No significant associations were found between supplement use in childhood and caries prevalence (DMFS) or number of decayed surfaces (DS) in permanent teeth at the age of 8 years. Supplement use from 6 to 8 years of age was not associated with caries occurrence either in primary or in permanent teeth. Both mother's education and the quality of dental hygiene were inversely associated with caries occurrence.

Analysis of Variance↗

PubMed1999

Caries-preventive methods used for children and adolescents in Denmark, Iceland, Norway and Sweden.

Denmark, Iceland, Norway, and Sweden have all had a similar decline in dental caries during the last 20 years, although the decline has come later in Iceland. The purpose of this study was to compare the caries-preventive methods used for children and adolescents in these four countries. Questionnaires were sent to random samples of dentists, dental hygienists, and dental nurses working with children during 1995 and 1996. The results showed that the use of preventive methods was generally consistent between the countries. Nevertheless there were differences between the countries concerning the choice of preventive strategy for risk patients and also in how prevention was implemented. Danish dental care providers chose oral hygiene education as the priority, which they put into practice. Apart from fluoride varnish for some patients, most of them did not use or recommend fluoride except fluoride toothpaste. The Norwegian and Icelandic dental care providers chose both oral hygiene education and the use of fluoride as priorities, while most Swedish dental care providers preferred to provide dietary advice and oral hygiene education, and additional fluoride for risk patients. The differences could not be explained by other variables than nationality, implying that there are differences between the dental cultures in the four countries. The informational basis of decisions on preventive strategies varied between the different dental professionals in each country as well as between the countries, indicating that national professional cultures are being shaped differently. Despite the differences in choice of preventive methods, the dental health of children varies little across the frontiers. This raises the question of the significance of the choice of preventive methods to the decline of dental caries and points towards an urgent need to develop evidence-based preventive strategies.

Adolescent↗

PubMed1998

Preventive dental care of children and adolescents in the 1990s: Denmark, Iceland, Norway, and Sweden.

This article describes the provision of preventive care for children and adolescents in Denmark, Iceland, Norway, and Sweden in the 1990s. It includes information on personnel giving preventive care, administration of the dental care system, strategies and methods used for prevention, and resources allocated for preventive dental care. In all these countries comprehensive and systematic dental care, subsidized or free of charge, has been instituted for children and adolescents. However, comparisons between the countries show significant differences in the organization of the dental care for children, the time used for preventive care, the recall routines, and the implementation of risk-based and population-based preventive strategies. The relative importance of different caries-prevention methods (fluorides, hygiene, and diet) reported by the clinicians varied between Denmark, Iceland, Norway, and Sweden. While variation poses rather than answers questions concerning effectiveness, available data provide evidence of differences in the input of resources. Unless the dental profession addresses the issue of effectiveness of preventive dental care, politicians and administrators in a cost-containment context will easily conclude that least is best.

Adolescent↗

PubMed1998

Caries preventive services for children and adolescents in Denmark, Iceland, Norway and Sweden: strategies and resource allocation.

According to the dental acts of Denmark, Iceland, Norway and Sweden, emphasis is placed on preventive dental care. The purpose of this study was to describe and compare two aspects of the caries preventive services: the strategies and the resource allocation for preventive dental care of children and adolescents in Denmark, Iceland, Norway and Sweden. Questionnaires were sent to samples of dentists and other dental personnel who provided preventive care to children during 1995 and 1996. Comparisons between the countries showed significant differences in recall routines and in implementation of risk-based and population-based preventive strategies. Multivariate analyses showed that the time used for preventive care varied by country and was not associated with the DMFT of the children. More time was allocated for prevention when more operating dental auxiliaries were available at the clinic, when the recall interval was shorter, when the time used for routine examination was longer and when the clinician was an auxiliary rather than a dentist. In conclusion, resource allocation and strategies used for prevention were not consistent between the countries.

Adolescent↗

PubMed1998

Clinical judgement as a basis for choice of recall interval in child dental care?

OBJECTIVE: Extending recall intervals can be an important strategy for making children's dental care more efficient. The purpose of this study was to describe the recall intervals that the clinicians decided were appropriate for children and adolescents when they were instructed to extend and individualise the routines based on clinical judgement. In addition, the effect on recall interval of the profession of the clinician (dentist or dental hygienist), the child's age and the need for fillings were studied. DESIGN: In a four week period in 1995, all dentists and dental hygienists in one county in Norway reported recall intervals for 2,513 children aged 3 to 18 years. RESULTS: The mean current interval since the previous examination was 17.1 months (SD = 4.7 months) and the mean proposed interval until the next examination was 16.4 months (SD = 4.4 months). Approximately 50% of children were evaluated by the clinicians to be suitable for recall intervals of 20 months or more and 10% were assessed as requiring a new examination within 12 months. The length of the current recall interval, the age of the child, whether or not the child received fillings, and whether the decision-maker was a dentist or a dental hygienist were statistically significantly associated with the length of the proposed recall interval. CONCLUSIONS: Basing recall intervals on clinical judgement resulted in intervals longer than 12 months for the majority of the children.

Adolescent↗

PubMed1997

Risk factors associated with fluorosis in a non-fluoridated population in Norway.

In Norway, there is no water fluoridation and little naturally occurring fluoride in drinking water. Fluoride toothpaste is used by 95% of the population and there is a long tradition of fluoride supplement use. The purpose of this study was to record the prevalence and severity of dental fluorosis in 8-year-old children and relate this to systemic fluoride exposure (supplements and toothpaste). All children (n = 551, born 1988) in a municipality in Norway were invited to participate. Dental fluorosis on the buccal surface of the upper permanent incisors was recorded according to the Thylstrup-Fejerskov index (TF). Parents provided data on use of supplements and toothpaste. Complete data were obtained from 383 children. Sixty-seven percent of the children had used fluoride supplements regularly during childhood. At 8 months or earlier, the teeth of 26% of the children, and at age 14 months or earlier the teeth of 82%, were being brushed. Among children who used fluoride supplements regularly, periodically, seldom and not at all, 45%, 21%, 10% and 0%, respectively, had dental fluorosis. The dental fluorosis was mild (TF = 1) in 87% of the cases. Bivariate and multivariate analyses showed that, in addition to use of fluoride supplements, starting toothbrushing at an early age was associated with higher prevalence of dental fluorosis. The child's birth weight and liking for or swallowing of toothpaste did not influence the prevalence of fluorosis. Risk factors for fluorosis were use of toothpaste before the age of 14 months and regular use of fluoride supplements during childhood.

Age Factors↗

PubMed1997

Analysis of transforming growth factor (TGF)-alpha/epidermal growth factor receptor, hepatocyte growth Factor/c-met,TGF-beta receptor type II, and p53 expression in human hepatocellular carcinomas.

Experimental data suggest that dysregulation of growth factors and the cognate receptors may play an important role in hepatocarcinogenesis. The objective of the present study was to characterize the expression of two hepatotrophic growth factor/receptor systems [transforming growth factor-alpha/epidermal growth factor receptor (TGF-alpha/EGFR) and hepatocyte growth factor/c-met receptor (HGF/c-met)], both of which are implicated in the development of human liver tumors. In addition, we have analyzed the expression of transforming growth factor-beta receptor type II (TGF-beta-RII) and p53, genes associated with growth inhibition and tumor suppression, respectively. Surgical biopsy specimens from 86 human hepatocellular carcinomas were analyzed. TGF-alpha was overexpressed in 17%, equally expressed in 21%, and down-regulated in 62% of the hepatocellular carcinomas when compared to the surrounding hepatic tissue. No major changes were found with EGFR expression. HGF was over-expressed in 33% and down-regulated in 21% of the tumors. The c-met receptor was overexpressed in 20%, equally expressed in 48%, and down-regulated in 32% of the neoplasms. In contrast, TGF-beta-RII was overexpressed in only 8%, equal in 42%, and down-regulated in 50% of tumors. Nuclear staining of p53, indicative of a mutation(s), was observed in the great majority of the tumors (80%), whereas no nuclear p53 was detected in peritumoral tissues. Interestingly, simultaneous down-regulation of c-met and TGF-beta-RII was observed in 23% of the hepatocellular carcinomas, 85% of which also showed nuclear p53 staining. Taken together, our data suggest that down-regulation of c-met and TGF-beta-RII may, together with p53 mutations, play a significant role in human liver carcinogenesis.

Adult↗

PubMed1996

Dental caries and resources spent for dental care among immigrant children and adolescents in Norway.

The purpose of this study was to compare dental status and resource requirements in immigrants to Norway, three to 18 years of age, with Norwegians of the same age group. Data on dmft and DMFT, fillings placed and time spent for dental care were registered in the records of 9000 such children in the period 1992-93. Eleven per cent of the children were immigrant children. Immigrant children three to six years of age had fewer sound teeth and more decayed, missing and filled teeth than Norwegian children and the pre-school immigrant children had higher treatment needs. However, the time spent on a pre-school child with an immigrant background was shorter than the time spent on a Norwegian child with the same number of decayed teeth. The differences between immigrants and Norwegians disappeared with higher age. Immigrant children older than six years had dental health and resource requirements similar to those of Norwegian adolescents.

Adolescent↗

PubMed1995

Individualizing recall intervals in child dental care.

Individualizing and extending recall intervals for children have been recommended in Norway to target resources efficiently. Recall intervals were changed for children aged 3-18 years in Drammen from 1991. Clinical time spent by dentists and dental hygienists, dental health status and length of recall intervals were registered from 1990 to 1993. For the child population, the mean recall interval changed from 12.5 to 13.7 months and the annual time spent per child was reduced by 14% from 1990-91 to 1992-93. Adjusted for the decline in number of new decayed teeth, the reduction in time spent was 11%. Children with intervals of 17 to 20 months had fewer new decayed teeth and their care required less personnel time than other children. For children with new decayed teeth, time spent for dental care was not associated with recall interval, while for children without new decayed teeth, longer recall intervals were associated with shorter time for dental care. The variation in number of decayed teeth and time spent for dental care was substantial at all intervals. Individualizing and extending recall intervals to some extent targeted resources at children with more dental disease. However, in the short run, inequality in dental health persisted. Limited extension of recall intervals did not interrupt the long-term trend toward better dental health in the children and substantial resources were saved in the dental services.

Adolescent↗

PubMed1995

Recall intervals, dental hygienists and quality in child dental care.

Decline in dental disease and the need to provide dental care efficiently suggest changes in clinical and administrative routines in public dental care provision for children. A field project in Norway demonstrated productivity gains after the introduction of individualized recall intervals and using dental hygienists to conduct recall examinations. The purpose of the present study was to assess changes in the quality of dental health outcome and changes in the quality of the process of dental care provision. Recall intervals were increased from a target of 12 months to 16 and 18 months in two districts. Dental hygienists undertook all recall examinations and referred to dentists those patients who required operative care. Bitewing radiographs were inspected for all 18-yr-olds who were examined in 1989, 1990 and 1991 (n = 956) and for those who were examined before the changes were implemented in 1987 (n = 300). For each child, approximal caries on 24 surfaces was scored according to a 4-point severity scale. Clinical records were examined to determine what treatment had been provided. For each year after the changes were implemented, the quality of health outcome was assessed by comparing the radiographic caries prevalence and the number of sound surfaces with 1987 data. Quality in the process of care provision was indicated by the treatment decisions for approximal caries and by the proportion of uninterpretable surfaces on radiographs for each study year. The mean number of sound surfaces increased over time. A declining proportion of sound surfaces was restored over the study period, and almost all caries lesions extending deep into dentine were restored. Radiographic quality improved during the project period.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

Alterations of tumor suppressor genes and allelic losses in human hepatocellular carcinomas in China.

Aflatoxin B1 has been suggested as a causative agent for a G to T mutation at codon 249 in the p53 gene in human hepatocellular carcinomas (HCC) from southern Africa and Qidong in China. The objective of the present work was to test the hypothesis that exposure to aflatoxin B1 either alone or coincident with other environmental carcinogens might be associated with allelic losses occurring during development of human hepatocarcinogenesis in China. The HCCs were obtained from two different areas in China: Qidong, where exposure to hepatitis B virus (HBV) and aflatoxin B1 is high; and Beijing, where exposure to HBV is high but that of aflatoxin B1 is low. We analyzed the tumors for mutations in the p53 gene and loss of heterozygosity for the p53, Rb, and APC genes and at marker loci on chromosomes 4, 13, and 16. Frequencies of mutation, loss, and aberration (mutation and loss) of the p53 gene in 25 HCCs from Qidong were 60, 58, and 80%, respectively. The frequencies in 9 HCCs from Beijing were 56, 57, and 78%. However, the frequency of a G to T transversion at codon 249 in HCCs from Qidong and Beijing were 52 and 0%, respectively. These data indicate that mutation and/or loss of heterozygosity in the p53 gene, independent of the 249 mutation, play a critical role in the development of hepatitis B virus-associated HCCs in China. Loss of the Rb and APC genes was observed in 44 and 7% of HCCs from Qidong, respectively. Allelic losses on chromosome 4 and especially on chromosome 16 were frequent in HCCs from Qidong but were not observed in HCCs from Beijing, while loss of heterozygosity on chromosome 13 occurred at similar frequency in both Qidong and Beijing. These results show a distinct difference in the pattern of allelic losses between HCCs in Qidong and Beijing and suggest that aflatoxin B1 and/or other environmental carcinogens may contribute to this difference.

Base Sequence↗