Abstract
The purpose of this study was to observe the growth and development of the palatal ruga longitudinally in children.
140 dental casts were obtained from 20 children,10 boys and 10 girls, with normal occlusion. Impressions were taken at one year interval from 4 years of age to 10 years of age.
The outline of the primary ruga and all teeth from the occlusal views of the casts were traced using five magnification by Nikon V16A profile projector, and were measured and analysed by computor.
The results were as follows:
1. The distance between two points on the ruga.
1) The distance between terminations of the right and left ruga increased noticeably (1.6-2.3 mm). The more anterior the position of ruga, the more the increase was influenced by the emergence of permanent central and lateral incisors.
2) The length of each left ruga increased longitudinally (0.6-1.2 mm), as the distance between the termination of the right and left ruga but the not so evident.
3)The distance between the origins and between the terminations of each left ruga increase gradually (0.3-0.9 mm), therefore each ruga separated longitudinally.
2. The distance between ruga and reference line.
1) The distance between the first ruga and the distal line of the deciduous canine decreased about 0.7-1.2 mm from 4 years of age to 7-8 years of age, and then increased about 0.4-0.7 mm. With the ruga as a point of reference, it seemed that the deciduous canine moved mesially and distally.
2) The distance between the third ruga and the distal line of the deciduous second moler decreased about 2.1-2.4 mm from 4 years of age to 8 years of age, and then revealed almost no change.
