永久歯の萌出と不正咬合との関連性の評価

Evaluation of the eruption of permanent teeth and their association with malocclusion.

抄録

目的:

本研究は、男女別の永久歯萌出時期および年齢別の永久歯萌出本数を明らかにし、不正咬合との関連を評価することを目的とした。

OBJECTIVES: This study was done to determine the timing of eruption of permanent teeth by sex and the number of permanent teeth erupted at different ages and to assess its association with malocclusion.

材料と方法:

本研究の対象は、5.0～15.0歳の健常者633名（男子317名、女子316名）である。対象者は1歳間隔でサブグループに分けられた。

MATERIAL AND METHODS: The sample for this study consisted of 633 healthy subjects (317 boys and 316 girls) aged between 5.0 and 15.0 years. The subjects were divided into subgroups considering an age interval of 1 year.

結果:

上顎と下顎の第二小臼歯と第二大臼歯を除き、女子の平均萌出期間は男子に比べて短く、男子の方が早く萌出することがわかった。第二小臼歯を除くすべての下顎永久歯は、男女ともに上顎永久歯よりも早く萌出する傾向があった。上顎犬歯と上顎第二小臼歯の萌出順序は、女子と男子で異なっていた。III級不正咬合では、すべての下顎永久歯が上顎対合歯よりも早く萌出している。全標本において、萌出歯数と年齢の相関は強かったが（p<.05）、男女間の差は有意ではなかった。

RESULTS: The mean eruption times were lower for girls compared with boys except for the maxillary and mandibular second premolars and second molars, which were found to erupt earlier in boys. All the permanent mandibular teeth, except the second premolars, tended to erupt earlier than their maxillary antagonists in both sexes. The sequence of eruption differs between girls and boys in the maxillary canine and maxillary second premolars. In Class III malocclusion, all the permanent mandibular teeth erupt earlier than their maxillary antagonists. In the entire sample, the correlation between the number of erupted teeth and age was strong (p < .05), but the differences between sexes were not significant.

結論:

小児歯科および矯正歯科における診断およびより良い治療計画のために、集団における永久歯の正常な萌出時期を知ることは重要である。

CONCLUSIONS: It is important to know the normal eruption time of permanent teeth in the population due to diagnosis and better treatment planning in pediatric dentistry and orthodontics.