STUDIES ON THE ROOT RESORPTION OF THE MANDIBULAR DECIDUOUS TEETH BY ORTHOPANTOMOGRAPHY

Orthopantomography에 의(依)한 하악(下顎) 유치치근흡수(乳齒齒根吸收)에 관(關)한 연구(硏究)

Surveying the root resorption of the mandibular deciduous teeth in 967 children, (Male 493 Female 474) from 3 to 12 years old by orthopantomography, the author obtained the following results. 1) Female in the root resorption of the deciduous teeth was earlier than male. 2) The stages of initial resorption of the deciduous teeth were as follow. central incisor 4 years lateral incisor 4 years 2 months cuspid 6 years first decid uous molar 6 years second deciduous molar 6 years 5 months 3) The exfoliational stages ($R_5$) of the deciduous teeth were as follow. central incisor 6 years 8 months lateral incisor 7 years 2 months cuspid 9 years 10 months first deciduous molar 10 years 3 months second deciduous molar 11 years.