矯正歯科保定中の下顎第三大臼歯のインパクションによる第二大臼歯の外歯根吸収

External Root Resorption of Second Molars Due to Impacted Mandibular Third Molars during Orthodontic Retention.

抄録

第三大臼歯の埋伏と叢生の発症に関係があるかどうかは未だ解明されておらず、矯正治療後の第三大臼歯の抜歯は開業医の判断に委ねられている。本報告では、矯正治療後に第三大臼歯が下顎第二大臼歯の外歯根吸収（ERR）を引き起こした症例について述べる。非抜歯矯正治療後に下顎第二大臼歯のERRが認められたため、患歯を抜歯し第三大臼歯に置き換えた。矯正治療終了時のパノラマX線写真で第三大臼歯の状態を観察し，低リスクと判断したにもかかわらず第二大臼歯の外歯根吸収が発生した．今回の結果から，下顎第三大臼歯が存在し，コーパス長が短く，非抜歯治療を行った場合，第二大臼歯のERRを回避するためには，定期的にX線画像を取得するか，予防的に第三大臼歯を抜歯する必要があることが示唆された．

Whether there is a relationship between impaction of the third molars and the onset of crowding remains to be determined, and extraction of third molars after orthodontic treatment is left to the judgement of the practitioner. This report describes a case where a third molar caused external root resorption (ERR) of the mandibular second molar after orthodontic treatment. As ERR of the mandibular second molar was detected after non-extraction orthodontic treatment, the affected tooth was extracted and substituted with the third molar. External root resorption of the second molar occurred despite being determined as low risk given the state of the impacted third molar as observed on a panoramic radiograph obtained at the end of active treatment. The present results indicate that in cases where the mandibular third molar is present, the corpus length is short, and non-extraction treatment has been performed, it is necessary to obtain X-ray images on a regular basis or preventively extract the third molar to avoid ERR of the second molars.