Chin caps have been used for the correction of primary anterior crossbites, but previous studies of the treatment effects have highlighted problems such as pressure on the temporomandibular joint (TMJ). Therefore, to reduce pressure on the TMJ, a functional orthodontic appliance, the Yanagisawa Class III (YC3) shield was developed to improve the overjet in the primary dentition. The aim of this study was to determine the treatment effects of the YC3 in correcting a primary anterior crossbite compared with a chin cap. The pre- and post-treatment lateral cephalograms of 10 patients (5 male, 5 females) and 10 treated with a YC3 (5 males, 5 females) were compared in relation to craniofacial morphology and tongue position [the YC3 was used from 51 months of age +/- 7 months to 74 months of age +/- 12 months (i.e. for 23 +/- 9 months) and the chin cap from 53 months of age +/- 2 months to 75 months of age +/- 1 month (i.e. for 22 +/- 5 months)]. A Mann-Whitney U-test was used to determine any statistical differences. The YC3 group showed significantly higher values for gonial angle and U1 to SN (P < 0.05), and significantly lower values for interincisal and tongue position (P < 0.05), compared with the chin cap group. The results indicate that the use of the YC3 not only improves overjet, but also changes the tongue position. The findings also suggest that the YC3 results in functional effects on the skeletal system during the mid-growth period.
The lack of information on oral health in Laos makes it difficult to estimate the need and methods for preventing oral disease. This study identified problems concerning the oral health of Lao children. The study subjects were 59 school children who lived in Pakkading District. Dental caries, gingivitis malocclusions, temporomandibular joint (TMJ) disorders, dental plaque, and calculus were examined. We observed an average of 1.6 decayed, missing, and filled teeth (DMFT) and 4.1 decayed and filled deciduous teeth (dft) per child. 25.4% had gingivitis scores from 16 to 20 on the papillary, marginal, and attached (PMA) index; 29.6% had one or more occlusal abnormality; and 0% had signs of TMJ disorders. 93.5% of the children had at least one buccal or lingual tooth surface with plaque covering more than two thirds of the surface; 32.6% had dental calculus. Oral health promotion programs for children should prioritise prevention and treatment of caries. It is likely that the high rate of gingivitis in Lao children is due mainly to unsuccessful plaque control in daily life. In addition to descriptive epidemiological studies of dental diseases in other areas, the influence of sociological and behavioural factors on oral health should be analyzed epidemiologically to promote child health.
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