Research Concerning the Sizes of the Primary Tooth Crown, Primary Dental Arch and the Condition of Primary Occlusions of the Japanese
1993 Volume 31 Issue 3 Pages 375-388
Details
1993 Volume 31 Issue 3 Pages 375-388
Measurements and observations were conducted to study the sizes of the Primary tooth crowns and primary dental arches of the Japanese and the standard. values and frequency distribution of the primary occlusion. Maxilla and mandible dentition models were collected for the study, with the cooperation of departments of pediatric dentistry by dental colleges university in Japan, from a total 158 children - 83 boys and 75 girls - with normal primary occlusion. The following conclusions were obtained:
1. The values shown in Table were obtained for the mediodistral width of the primary crowns of each tooth. The values were significantly larger for boys than for girls in all tooth types except upper second primary molars.
2. The values shown in Table were obtained for the width, length and height of the primary dental arch, these being the standard clinical values for the two groups - one comprising children less than five years old and the other, children exactry five years or older - with the sex-difference factors added.
3. The figures shown in Table were obtained regarding spaces between the teeth. With regard to the types of spaces, primate and growth spaces were found together in 91.8% of The cases in the maxilla and 70.9% of The cases in the mandible.
4. The frequency of terminal planes was 85.4% in the vertical type,8.6% in the distal-step type and 6.0% in the mesial-step type.
5. Regarding primary canines in the maxilla and mandible,83.2% were Type I,13.0% Type II and 3.8% III.
