Abstract:
The purpose of this study were to determine the correlation of sum of canine and premolars width in both arches to the width of first molar and sum of the incisor widths in both orches in a group of Thai. A sample of 400 Thai children, 200 boys and 200 girls were selected from Dedsirin School and Stimahaprutaram girls school. All of them, ages 13-15 years, were taken impression, their study models were measured and calculated statistically. The resulted were concluded that 1. SUm of canine premolars width in upper arch had a highest correlation with upper first molar width, r=0.67 for boys, r=0.66 for girls and r=0.69 for all. 2. Sum of canine and premolars width in lower arch had a highest correlation with lower first molar width, r=0.64 for boys, r=0.64 for girls and r=0.68 for all. 3. Prediction equation for sum of canine and permolars width in upper arch from upper first molar width. Boys Y = 7.26 + 1.47 X Girls Y = 9.86 + 1.20 X All Y = 8.19 + 1.37 x 4. Predicyion equation for sum of canine and premolars width in lower arch form lower first molar width Boy Y = 6.70 - 1.34 X Girls Y = 7.90 + 1.20 X All Y = 6.05 + 1.38 X