Sequential prevalence estimation with pooling and continuous test outcomes

Prevalence estimation is crucial for controlling the spread of infections and diseases and for planning of health care services. Prevalence estimation is typically conducted via pooled, or group, testing due to limited testing budgets. We study a sequential estimation procedure that uses continuous pool readings and considers the dilution effect of pooling so as to efficiently estimate an unknown prevalence rate. Embedded into the sequential estimation procedure is an optimization model that determines the optimal pooling design (number of pools and pool sizes) under a limited testing budget, considering the trade‐off between testing cost and estimation accuracy. Our numerical study indicates that the proposed sequential estimation procedure outperforms single‐stage procedures, or procedures that use binary test outcomes. Further, the sequential procedure provides robust prevalence estimates in cases where the initial estimate of the unknown prevalence rate is poor, or the assumed distribution of the biomarker load in infected subjects is inaccurate. Thus, when limited and unreliable information is available about the current status of, or biomarker dynamics related to, an infection, the sequential procedure becomes an attractive estimation strategy, due to its ability to mitigate the initial bias.     

Prediction of caries activity in children with today''s low caries incidence

One hundred 14-yr-old children were observed over 1 yr to find out if caries incidence and caries progression could be predicted in a low prevalence child population by means of well-known caries related factors. The mean caries incidence was low (0.45, SD 0.70) but, on the other hand, 32% of the children developed at least one new lesion during the test period. In only eight out of 35 children progressing lesions were demonstrated. Independent variables at baseline examination were caries prevalence, sucrose intake, fluoride exposure, oral hygiene, saliva secretion rate, and salivary concentrations of mutans streptococci and lactobacilli. A weak but statistically significant correlation was demonstrated between caries incidence and caries prevalence. No other significant correlations were shown. It was concluded that caries activity could not be predicted in this population. Low disease prevalence was a major reason for the weak correlations.     

Recurrent oral ulcerations associated with recurrent herpes labialis – two distinct entities?

We investigated the prevalence of recurrent aphthous ulcerations (RAU) and recurrent herpes labialis (RHL) in a young adult population. The study group consisted of 20,689 soldiers (aged 18-21 years, mean 19.8 +/- 1 years). There were 14,991 men and 5,698 women. Every patient was asked to complete a self-report health questionnaire which requested information about the occurrence of either RAU or RHL. Data were analyzed using the chi-square test, and the odds ratio was also determined. The prevalence of RAU and RHL was 6.2% and 5.4%, respectively. The prevalence among women was significantly higher (P<0.001), than among men for both RAU (7.1% and 5.8%, respectively) and RHL (6.8% and 4.9%, respectively). Among women, the chance of having RAU for those who were RHL positive was 6.88 greater than for those RHL negative. Among men, the chance of having RAU for those who were RHL positive was 12.37 greater than for those RHL negative. In women, the chance of having RHL for those who were RAU positive was 6.88 greater than for those who were RAU negative. In men, the chance of having RHL for those who were RAU positive was 12.37 greater than for those who were RAU negative. It is concluded that a similar underlying pathological process or unknown cofactor may be involved in both RAU and RHL.     

A study of dental staining among competitive swimmers

OBJECTIVE: To estimate the prevalence of dental stains (DS) in competitive swimmers and quantify the risk of these stains compared with sportsmen in a non-swimmers group in Castellón, Spain. METHODS: Cross-sectional and case-control designs. Between July 1996 and March 1997, 404 subjects, (171 enrolled in two clubs of competitive swimming and 233 sportsmen from two schools), were examined in order to detect and classify yellowish-brown or dark-brown stains on the facial surface of the eight incisors. Participation rates were 88.6% for swimmers, and 95.7% for sportsmen. Mean of participants' age was 12 years, range 7-22 years. Castellón has three public competition swimming pools, two of which are indoors. Two of the pools used chloride products, and the third bromine for the disinfection of water. The recommended hygiene regulations were adhered to. RESULTS: Prevalence of DS was 60.2% in swimmers and 12.9% in sportsmen (P= 0.0001). Risk factors for DS included: use of competition swimming pools, age, gender, years of competition, daily consumption of coffee, red wine, and iron supplement during the last year. Professional dental cleanliness was a protective factor. In a logistic regression analysis, the use of competition swimming pools maintained a high risk of DS, odds ratio (OR)=9.28; 95% confidence interval (CI) 5.21-16.5, adjusted by the other variables. Amongst swimmers, more than 6 h of training a week increased the risk of these stains (OR=3.51; 95% CI 1.35-9.10). CONCLUSION: The study indicated a high risk of DS in competitive swimmers.     

Periodontal Attachment Loss in Independently Living Older Adults in Ontario, Canada

This paper describes the periodontal disease experience of a community-dwelling population aged 50 years and older, living in four communities in Ontario, Canada. The periodontal status of this population was assessed using attachment loss and the extent and severity index. Attachment loss was measured at two sites on each tooth using a pressure-sensitive periodontal probe. Complete periodontal data were obtained on 624 subjects. The mean number of sites per subject was 37.9. In line with recent US studies, the diagnostic threshold for a diseased or previously diseased site was set at 2 mm of loss. The overall mean attachment loss was 2.95 mm, with 19.7 percent of subjects having an overall mean attachment loss of 4.00 mm or more. The proportion of sites examined with loss of attachment of 2 mm or more was 77 percent. The severity of disease, defined as the average distance between the base of the sulcus or pocket and a point 1.00 mm apical to the cemento-enamel junction in sites with loss of 2 mm or more was 2.44 mm. These data indicate that the extent and severity of disease in this population were greater than that reported by some recent studies in the US. Taken together, the results of these studies suggest that there is some variation in the periodontal disease experience of population subgroups across North America.     

Dental caries and its relationship to bacterial infection, hypoplasia, diet, and oral hygiene in 6- to 36-month-old children

Caufield et al. (1) have suggested that the acquisition of mutans streptococci in young children most likely takes place during a "window of infectivity" from 19 to 31 months of age. OBJECTIVES AND METHODS: This study determined the prevalence of dental caries and bacterial infection in a randomly selected sample of 199 children 6 to 36 months old from the island of Saipan in the Common-wealth of the Northern Mariana Islands, USA. The relationships between caries and Streptococcus mutans infection, hypoplasia, diet and oral hygiene behavior were investigated. RESULTS AND CONCLUSIONS: The overall estimated prevalence of caries was high: 46.8% of the children had white spot lesions and 39.1% had enamel cavitation. Colonization was seen in very young children; S. mutans was detected in 25% of the predentate children. The results of multi-variable modeling support the hypothesis that bacterial infection, diet, and hypoplasia are important in the etiology of dental caries in this population. Adjusted for age and ethnicity, children with a high level of S. mutans detected were 5 times more likely to have dental caries than children with a lower level of S. mutans detected. Hypoplasia and a high cariogenicity score (diet) were also significant independent predictors. The odds of having any white spot lesions or enamel cavitation were 9.6 times greater for children with any hypoplasia, and 7.8 times greater for children with high cariogenicity scores relative to those with lower scores after adjusting for level of S. mutans, age and ethnicity. Sleeping with a bottle, maternal sharing of utensils, and high snacking frequency were not significant predictors of caries in this population.     

Relationship between smoking and dental status in 35-, 50-, 65-, and 75-year-old individuals

Abstract. The aim of the present study was to examine the dental status and smoking habits in randomized samples of 35-, 50-, 65-, and 75-year-old subjects (n= 1093), recruited for a cross-sectional epidemiological study in the County of Värmland, Sweden. The following clinical variables were recorded by 4 well-calibrated dentists: number of edentuolous subjects, number of missing teeth, probing attachment level, furcation involvement, CPITN scores, DMF surfaces, plaque and.stimulated salivary secretion rate (SSSR). In addition, the subjects reported in a questionnaire their tobacco habits, oral hygiene habits, dietary habits etc. The percentage of smokers in 35-, 50-, 65-, and 75-year-olds was 35%, 35%, 24% and 12%, respectively. In 75-year-olds, 41% of the smokers were edentulous compared to 35% of non-smokers. The difference in number of missing teeth between smokers and non-smokers was 0.6 (p=0.15), 1.5 (p=0.013), 3.5 (p=0.0007) and 5.8 (p=0.005) in the 4 age groups. Smokers had the largest mean probing attachment loss in all age groups. The differences between smokers and non-smokers in mean attachment level were 0.37 (p=0.001), 0.88 (p=0.001), 0.85 (P=0.001) and 1.33 mm (p=0.003) in the 35-, 50-, 65-, and 75-year-olds, respectively. Treatment need assessed by CPITN was in all age groups greatest among smokers. The number of intact tooth surfaces was fewer in 35-, 50-, and 75-year-old smokers than in non-smokers. The number of missing surfaces (MS) was higher in 50-, 65-, and 75-year-old smokers than in non-smokers. In addition, 35-year-old smokers exhibited a significantly larger number of decayed and filled tooth surfaces (DFS) than non-smokers. Male smokers had significantly higher SSSR than non-smoking males (p=0.012). Plaque index and oral hygiene were similar in smokers and non-smokers. Smokers reported a more frequent intake of sugar containing soft drinks (p=0.000) and snacks (p=0.003) than non-smokers. The opposite was reported for consumption of fruit (p=0.003). It was concluded that smoking is a significant risk indicator for tooth loss, probing attachment loss and dental caries.     

Prevalence, phenotype and genotype of oral enterococci

This study investigated the prevalence, phenotype and genotype of oral enterococci. Enterococci were detected in oral rinse samples from 11% of 100 patients receiving endodontic treatment and 1% of 100 dental students with no history of endodontic treatment ( P  = 0.0027). All enterococcal isolates were identified as Enterococcus faecalis . Viable counts ranged from 1 × 10 to 6 × 10³ colony forming units per mL of oral rinse sample. Potential virulence traits expressed by oral E. faecalis strains included production of hemolysin ( n  = 4) and gelatinase ( n  = 4), and response to pheromones in E. faecalis culture filtrate ( n  = 1). Six strains produced bacteriocin. All strains were susceptible to ampicillin, benzylpenicillin, gentamicin and vancomycin. There was no evidence of metal-ion resistance. One isolate produced hemolysin, gelatinase and bacteriocin, was resistant to several antibiotics, and responded to the pheromone cPD1. Pulsed-field gel electrophoresis and plasmid analysis showed that oral E. faecalis exhibited widespread genetic polymorphism, with plasmids detected in seven strains.     

北京市怀柔区儿童口腔健康状况的调查与分析--怀柔区调节水氟浓度预防龋齿可行性研究

目的 :通过对北京市怀柔区儿童的口腔健康流行病学调查 ,为该区开展调节水氟浓度预防龋齿提供可行性依据。方法 :采用随机、整群抽样方法调查 3～ 15岁 6个年龄组儿童共 15 62人 ,调查内容包括龋病患病状况、12岁和 15岁组氟牙症患病状况。结果 :怀柔区儿童 5岁乳牙患龋率 87.2 % ,龋均 5 .93 ,12岁恒牙患龋率67.7% ,龋均 1.73 ,均高于全国和北京市平均患龋水平。 12岁儿童氟牙症指数为 0 .0 2 ,15岁组氟牙症指数为 0。讨论 :怀柔区自来水覆盖区属于龋病较严重地区 ,氟牙症非流行区。已知所调查地区水氟浓度 <0 .2 ppm ,因此 ,从流行病学研究方面可以认为该地区适合于调节水氟浓度预防龋齿。     

Orthodontic treatment needs in Westmead Hospital Dental Clinical School

One hundred and fifty-four adolescents, 76 female and 78 male consented to take part in this survey. The two authors examined and assessed them for dental aesthetics, malocclusion related features and TMJ related signs. The patients were also questioned about their opinion of dental aesthetics, their interest in having orthodontic treatment and their TMJ symptoms. Only 63 per cent of the adolescents who were considered suitable for orthodontic treatment expressed an interest in wanting treatment. Twenty-seven per cent of patients had signs and/or symptoms of TMJ disturbance. No association was found between individual malocclusion problems and TMJ signs and symptoms. The authors considered 56.5 per cent of the total group for orthodontic treatment, the majority for aesthetic reasons, and placed them into high, medium and low priority groups. Fixed appliance therapy for both arches was the recommended type of treatment for most patients.