Abstract
The occurrence of malocclusion in the primary dentitions has been established. A few studies have revealed the incidence of malocclusion in incompleted primary dentitions. The purpose of this study is to investigate the change of the occlusion form and the duration of the oral habits in the children from the age of 1 year and 6 months to 2 years.
707 children enrolled in the Dental Health Service Program in Kunitachi City were available for examination. As part of oral health screening, the occlusion of the incompleted primary dentitions was observed for frequency of abnormalities. In addition, the appearance of oral habits and the effects on the occlusion were investigated.
The following results were obtained:
1) The malocclusion in the 2 years old children was 47.2 percent of the 707 children examined.
2) The most frequent malocclusion observed was an open bite, which had a frequency of 15.7 percent among the 707 children. The remaining malocclusions were: anterior cross bite,14.3 percent; deep bite,10.2 percent; edge to edge bite,4.4 percent; crowding,2.0 percent; posterior crossbite,0.7 percent.
3) 88 children who had normal occlusion at 1 year and 6 months of age changed to malocclusion at 2 years of age, and especially to open bite and to deep bite.57 children (anterior cross bite 16, open bite 15, edge to edge bite 11, deep bite 10, crowding 5) who had malocclusion changed to normal occlusion.
4) The appearance of oral habits in children 2 years of age was observed in 227children (32.1%). This frequency decreased about 10 percent in comparison with children 1 year and 6 months of age. The finger sucking habit revealed the greatest percentation (79.8%) among all oral habits.
5) 78.4 percent of the open bite children has the habit of finger sucking.27 out of 38 children who changed to open bite from normal occlusion continued finger sucking until 2 years of age. On the other hand,6 out of 15 children who changed to normal occlusion from open bite stopped finger sucking. In view of these facts, the finger sucking habit appear to have serious effect on the open bite and there seems to be a cause effect relationship between the two.
