Objective: The aim of this study was to investigate the relapse tendency in the maxillary dental arch widths in unilateral cleft lip and palate patients with different types of maxillary arch form. Subjects: Thirty-two unilateral cleft lip and palate patients treated by one-stage surgical palatal closure were included. The subjects were divided into three groups according to the types of the maxillary arch forms: group A, symmetrical arch form; group B, collapse of minor segment; group C, collapse of both segments. Methods: Using dental casts obtained at three different times, relapse in the intercanine, interpremolar, and intermolar widths in each group was assessed and differences between groups were investigated. Results: Patients in group A showed stable results in all measurements. Patients in group B showed posttreatment relapse in the intercanine width only, whereas patients in group C demonstrated significant posttreatment relapses in the interpremolar and intermolar widths. Comparison between groups showed more significant relapse in the interpremolar and intermolar widths of group C than in those of group B. Conclusion: The types of the maxillary arch forms in unilateral cleft lip and palate patients might play a stronger role in the stability of the maxillary dental arch widths after orthodontic treatment in patients with collapse of both segments and a severe degree of maxillary narrowness.

The aim of this study was to develop a method for quantitative measurement of urinary metabolites of pyrethroid (PYR) insecticides, trans-chrysanthemumdicarboxylic acid (CDCA) and 3-phenoxybenzoic acid (3-PBA), extracted from disposable diapers. This study was approved by the university ethics committees, and informed consent was obtained from all the parents for their children and from adult volunteers. After extraction of PYR metabolites in the absorber of diapers with 5 ml acetone, the metabolites in the eluents were extracted with tert-butyl methyl ether, derivatized with 1,1,1,3,3,3-hexafluoroisopropanol and analyzed by gas chromatography–mass spectrometry. The limits of quantitation (LOQs) were 0.55 μg/l for CDCA and 0.09 μg/l for 3-PBA in 2 ml urine extracted from diapers. Within-series and between-day precisions were <14% (CV%) over the concentration range of metabolites from 0.4 to 20.4 μg/l urine. When concentrations of each metabolite were measured with the developed method after pouring 2 ml urine, which was obtained from adults both in a general population and pest control operators, on diapers, good correlations were shown between the measured results and the concentrations measured directly for the respective urine with the conventional method (Spearman’s rank correlation coefficient 0.889 for CDCA and 0.989 for 3-PBA; n=27–28). The developed method would be applicable to epidemiological studies.