2,581人の小児における乳歯の萌出パターンに関する横断的調査

[A cross-sectional survey on the patterns of primary teeth eruption in 2 581 children].

• R X Li
• Y Hu

抄録

重慶市の生後0～40ヶ月の子供を対象とした横断的調査により、原始的な歯の萌出のパターンを調査し、一般的な身体的成長評価に実用的な歯の萌出の正常な時間割を提供すること。 2014年1月から2016年1月まで、重慶医科大学小児病院で生後0～40ヶ月の健康な子供2,581人のデータを収集した。年齢、性別、妊娠年齢、出生体重、最初の一次歯の萌出時期と順序、歯の数、完全な一次歯の萌出時期などの一般的な情報を主治医が記録した。歯の萌出年齢と各年齢における萌出特性を記述する際には、中央値と構成比を用いた。さらに、独立標本検定、分散分析、ピアソン積モーメント相関、ロジスティック回帰もデータ分析に用いた。 この調査には、0～6ヶ月の乳児506名、7～12ヶ月の乳児600名、13～24ヶ月の幼児730名、25～40ヶ月の子供745名、合計2,581名の子供が参加した。最初の歯が生えた年齢は生後2～15ヶ月（中央値：生後8ヶ月、95％2.7～12.7）、最後の歯が生えた年齢は生後23～35ヶ月（中央値：生後31ヶ月、95％24.7～36.7）であった。最初の歯の萌出時期は総歯の萌出時期と正の相関があった（=0.879、<0.05）。歯の萌出情報に応じて，性別の異なるデンタルチャート（年齢に対する歯の本数）を作成した．第一次萌出歯は下顎の切歯が95.3%(1,743/1,829)、上顎の切歯が4.6%(84/1,829)であった．歯が活発に生えてくる時期（歯数≦16本）には，歯数＝年齢（月齢）-初発年齢（月齢）＋1で計算することができる．実際の歯の数と本式で計算した歯の数には統計的に有意な差はなかった(=-2.957, =0.05)。 第1次原始歯萌出年齢の中央値は生後8ヶ月、総歯萌出年齢の中央値は生後31ヶ月であった。この式（歯の数＝月齢-月齢＋１）を用いて、乳幼児の歯の数を推定することができます。歯科用チャートは、子供の身体的成長を評価するための正常なデータセットと補足データセットを提供することができるかもしれません。

To investigate the patterns of primary teeth eruption by a cross-sectional survey in 0-40 months old children in Chongqing and to provide normal timetables of tooth eruption that are practical in general physical growth assessment. Data of 2 581 0-40 months old healthy children were collected from January 2014 to January 2016 at Children's Hospital of Chongqing Medical University. General information was recorded by primary child health care doctors, including age, gender, gestation age, birth weight, time and sequence of first primary tooth eruption, number of teeth and age of totally primary teeth emergence. Median and constituent ratio were used in describing the age of tooth eruption and eruption characteristics at different age. Moreover, independent-sample test, variance analysis, Pearson product-moment correlation and Logistic regression were also involved in data analysis. Totally 2 581 children were involved in this survey, including 506 infants of 0-6 months old, 600 infants of 7-12 months old, 730 toddlers of 13-24 months old and 745 children of 25-40 months old. There were 1 473 boys and 1 108 girls, 89 preterm babies and 2 492 full term babies, 1 829 children with tooth erupted and 626 children with all primary teeth erupted.The age of the first primary tooth eruption was between 2-15 months old ( median age: 8 months old, 95% 2.7-12.7)and for the last primary tooth emergence was between 23-35 months of age (median age: 31 months, 95%: 24.7-36.7). The time of first tooth eruption was positively correlated with that of total teeth emergence (=0.879, <0.05). Dental charts (number of tooth for age) of different gender were drawn according to teeth eruption information. The first primary tooth eruption was the incisor of mandible in 95.3% (1 743/1 829)infants and was the incisor of maxilla in 4.6% (84/1 829)infants. During the period of tooth emerging actively (number of teeth ≤16), the number of primary teeth might be calculated by formula: number of teeth=chronological age in months-age of first eruption in months+ 1. There was no statistically significant difference between the number of actual teeth and calculated by the present formula(=-2.957, =0.05). The median age of first primary tooth eruption and total teeth emergence was 8 and 31 months of age respectively. The first primary tooth eruption is incisor of mandible in most infants.The formula (number of teeth=chronological age in months-age of first eruption in months+ 1 )can be used to estimate the number of primary teeth. Dental charts might provide normal and supplement datasets for evaluating child physical growth.