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OBJECTIVES: The aim of this study was to evaluate the geometry and the quality of bristle tip-rounding using 14 different heads from powered toothbrushes. MATERIAL AND METHODS: Six powered toothbrushes for children and eight for juveniles and adults were included. Five replaceable heads of each product were randomly selected. Of each sample, 35 bristles were used for examination. This resulted in 175 bristles from each product being evaluated. The quality of end-rounding was assessed by scanning electron microscopy at an original magnification x 80 in two categories of acceptable and five categories of unacceptable rounding according to Silverstone & Featherstone (1988). RESULTS: The portion of acceptable end-rounding varied strongly between the products (18.9-94.3%). There were significant differences regarding the products for children (p<0.001) and for adults (p<0.001) with respect to end-rounding quality. Only one product achieved more than 90% and eight products had between 68% and 86% acceptable end-rounding. Two products for children and one for adults had less than 25% acceptable end-rounding. CONCLUSION: A high standard of bristle tip-rounding is an important feature with respect to the safety of powered toothbrushes. Those products with a greater portion of unacceptably rounded bristles might cause more harm to oral soft tissues during use. The end-rounding quality of some of the products should be improved. [ABSTRACT FROM AUTHOR]

Sister chromatid exchanges (SCE) and lymphocyte subsets of children with acute lymphoblastic leukemia (ALL) were investigated in children with ALL during chemotherapy and at least 5 years after chemotherapy. The treatment of the new admitted patients followed protocol ALL-BFM-90. Children with ALL at the time of diagnosis showed statistically significant higher SCE frequencies (4.9 +/- 0.77) than healthy controls (3.6 +/- 0.93; p = 0.002). The in vivo effects of cyclophosphamide (CP) resulted in a dramatic increase of the SCE frequency (20.5 +/- 3.76). This increased SCE level of lymphocytes might reflect an instability of DNA or a deficiency of DNA repair capacity. However, immediately one week after the administration of CP, the SCE rate decreased. This decline of SCE frequency correlates with a severe reduction of the absolute numbers of T lymphocytes. The observed reduction of SCE frequency may be due to a depletion of T lymphocytes, or a repair of DNA. The patients in long term remission ( > 5 years) have had the therapy according BFM-83 (9 pat.) and modified 'Pinkel-regime' (2 pat.). No difference was found between the SCE-rate of the patients in remission and of the age-dependent control group. These results might correlate with the low risk for future development of relaps or second malignancy.

Sister chromatid exchanges (SCE) and lymphocyte subsets of children with acute lymphoblastic leukemia (ALL) were investigated during chemotherapy. The treatment followed protocol ALL-BFM-90. Children with ALL at the time of diagnosis showed statistically significant higher SCE frequencies (4.9 +/- 0.77) than healthy controls (3.6 +/- 0.93; P = 0.002). The in vivo effects of cyclophosphamide (CP) resulted in a dramatic increase of the SCE frequency (20.5 +/- 3.76). This increased SCE level of lymphocytes might reflect an instability of DNA or a deficiency of DNA repair. One could suggest that lymphocytes of children with ALL might have a higher susceptibility to harmful influences; and this could be a co-factor towards the development of the malignant disease. However, immediately 1 week after the administration of CP, the SCE rate decreased. This decline of SCE frequency correlated with a severe reduction of the absolute number of T lymphocytes. The observed reduction of SCE frequency may be due to a loss of T lymphocytes, or SCE became repaired during 1 week.