小児の前歯部埋伏歯は、適切な時期に治療を行うことで歯根の発育が促進される

Appropriate timing of treatment contributes to better root development of impacted anterior teeth in children.

抄録

はじめに:

本研究では、小児の前歯部埋伏歯の歯根発育に及ぼす矯正治療のタイミングの違いによる影響について検討した。

INTRODUCTION: This study investigated the effects of different timings of orthodontic treatment on the root development of impacted anterior teeth in children.

方法:

前歯部に衝撃を受けた小児45名のコーンビームCT（CBCT）データを未形成歯根（UR）群と基本形成歯根（BFR）群に分け、治療前と治療後の衝撃を受けた歯と反対側の非衝撃歯の歯根長（RL）と歯根成長長（RGL）を評価した。さらに、歯冠-歯根角度と歯根発育段階がRLとRGLに及ぼす影響を評価するために、衝撃歯拡張症患者22名を選択した。統計学的評価には、Student t検定、Wilcoxon検定、分散分析、重回帰分析を用いた。

METHODS: The cone-beam computed tomography (CBCT) data of 45 children with impacted anterior teeth were divided into unformed root (UR) group or basically formed root (BFR) group to evaluate root length (RL) and root growth length (RGL) of impacted teeth and contralateral nonimpacted teeth pretreatment and posttreatment. In addition, 22 patients with impacted dilaceration were selected to assess the effects of the crown-root angle and root development stage on RL and RGL. The Student t test, Wilcoxon test, analysis of variance, and multiple linear regression analysis were used for statistical evaluations.

結果:

治療前および治療後の咬耗した歯のRLは、対側の咬耗していない歯の値よりも有意に短かった(P<0.05)。治療後、UR群の衝撃歯のRLとRGLはBFR群のそれよりも有意に大きかった(P<0.05)。UR群では、BFR群に比べ、拡張した歯根のRGLがかなり高かった（P<0.05）。歯冠根尖角度が大きい群では、治療後のRLが長かった（P<0.05）。重回帰分析の結果、治療前の衝撃歯のノーラステージと対合歯のRLが治療後の衝撃歯のRLに有意に影響することが明らかになった。

RESULTS: The RL of treated impacted teeth pretreatment and posttreatment was significantly shorter than contralateral nonimpacted teeth values (P <0.05). Posttreatment, the RL and RGL of impacted teeth of the UR group were significantly greater than those of the BFR group (P <0.05). The RGL of the dilacerated root in the UR group was considerably higher than in the BFR group (P <0.05). The larger crown-root angle group had a longer posttreatment RL (P <0.05). Multiple linear regression analysis revealed that the Nolla stage of impacted teeth and RL of contralateral teeth pretreatment significantly influenced the RL of impacted teeth posttreatment.

結論:

前歯部に衝撃を受けた小児に対しては，衝撃状態を解除し，より良好な歯根発育を得るために迅速な矯正治療が必要である．しかし，歯冠-歯根角が歯根長を制限していた．

CONCLUSIONS: Prompt orthodontic treatment is necessary for children with impacted anterior teeth to release the impacted state and achieve better root development. The root length of dilacerated tooth continued to develop under treatment, but the crown-root angle partly constrained it.