The large variations observed in dentists' management of periapical lesions in endodontically treated teeth suggest that disease concepts used in clinical practice should be investigated. In the present study it was hypothesized that dentists regard various periapical conditions as different stages on a health continuum. Variations could then be regarded as the result of the individuals selection of differing cut-off points for prescribing retreatment. The hypothesized decision-making model was tested using dental students in Amsterdam (Holland), Gothenburg (Sweden) and Pavia (Italy). The students were shown six simulated cases among which the quality of root filling seal and presence of post and crown were systematically varied. For each case, management of five periapical conditions was assessed. Five options were offered: no therapy, wait-and-see, nonsurgical retreatment, surgical retreatment, and extraction. For each examiner and case a 'retreatment preference score (RPS)' was established. The investigation showed large interindividual variations in RPS. A statistically significant higher mean RPS was seen among students in Pavia compared with students in Amsterdam and Gothenburg. Among all observers and cases it was found that if retreatment was proposed for a certain size of lesion, retreatment was subsequently selected for all larger lesions. The experiment gave evidence in support of the proposed hypothesis. The data also suggest that the choice of retreatment criterion is affected by values, costs of retreatment and technical quality of the original treatment.

TULLDAHL, JENNY, KJELL PETTERSSON, SUSAN W. ANDERSSON, AND LENA HULTHEN. Mode of infant feeding and achieved growth in adolescence: Early feeding patterns in relation to growth and body composition in adolescence. Obes Res. 1999;7:43 1-437. Objective: Feeding mode in infancy and differences in childhood growth have been studied in several longitudinal studies, but few studies have followed children up to adolescent age. There is evidence that formula-fed infants weigh more and are taller than their breast-fed counterparts, and indications that this difference may sustain. Research Methods and Procedures:We have studied the relations between length of breast-feeding, growth, and body composition in a group of 781 representatively chosen adolescents. Data on feeding pattern in infancy and on weight and height from birth up to 18 years were collected. We studied the relation between high body mass index (BMI) (defined as 5 8 S h percentile) in adolescence and length of breast-feeding. Results: Girls who were not breast-fed or breast-fed for less than 3 months had a significantly higher height curve than girls exclusively breast-fed for more then 3 months. There were tendencies towards higher values of adipose tissue measured by skinfolds in girls breast-fed for 3 months or less. Short duration of exclusive breast-feeding was associated with higher BMI (p<0.04). In a subgroup of 194 adolescents, body composition was measured with dual energy X-ray. Both boys and girls who were exclusively breast-fed for more than 3 months were leaner and showed a trend towards lower skinfold values. Conclusion: These results are important to include in the debate about optimal feeding in infancy. Regarding breastfeeding as a standard, our results imply that formula fed infants may be at risk for overfeeding, which might lead to overweight, even up to adolescent age.

A regression may be constant for small values of the independent variable (for example time), but then a monotonic increase starts. Such an "outbreak" regression is of interest for example in the study of the outbreak of an epidemic disease. We give the least square estimators for this outbreak regression without assumption of a parametric regression function. It is shown that the least squares estimators are also the maximum likelihood estimators for distributions in the regular exponential family such as the Gaussian or Poisson distribution. The approach is thus semiparametric. The method is applied to Swedish data on influenza, and the properties are demonstrated by a simulation study. The consistency of the estimator is proved.

In a case-control study asbestos exposure in 64 consecutive men with idiopathic pleural effusion and 129 randomly sampled age matched male controls was compared. Furthermore, seven women and 64 men with idiopathic pleural effusion were studied, including a three year re-examination, in an attempt to identify characteristics that might distinguish asbestos exposed from non-exposed patients. Asbestos exposure was significantly (p < 0-01) more frequent in men with idiopathic effusions than in controls. The idiopathic effusions seen in asbestos exposed patients were compatible with the diagnosis "asbestos pleural effusion." Two features were characteristic of patients with asbestos pleural effusion: a chest radiograph at the initial examination showing converging pleural linear structures or rounded atelectasis or a history of recurrent pleural effusion, or both.