ミニスクリューを用いた上顎の歯牙移動傾向の3次元有限要素解析と歯牙スペース閉鎖のための上部強調曲線

[Three dimensional finite element analysis of tooth movement tendency in maxilla using mini-screw cooperated with upper accentuated-curve to close tooth space].

抄録

研究目的:

臼歯部突出の原因究明と臼歯部突出回避のため、上方アクセントカーブの角度やフリートラクションフックの高さを変化させ、歯の移動傾向を解析した。

OBJECTIVE: In order to find out the cause of molar intrusion and how to avoid molar intrusion, we analyze the movement tendency of tooth by changing the angles of upper accentuated-curve and the height of free traction hook.

方法:

本研究では，スパイラルCTスキャンとMimics 10.0ソフトウェアを用いて，上顎歯，歯根膜，歯槽骨の3次元有限要素モデルを構築し，角度の異なるインチステンレス製上方アクセントカーブアーチワイヤー（5度，10度，15度，20度，25度）と高さの異なる自由牽引フック（2.1 mm，4.0 mm，5.5 mm）を製作した．1.5Nの後方荷重を加え，上顎歯の変位傾向を分析した．

METHODS: Spiral CT scanning and Mimics 10.0 software were employed in this study to construct the three dimensional finite element model of maxillary teeth, periodontal ligaments and alveolar bone as well as the inch stainless steel upper accentuated-curve archwires with different angles (5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees) and the free traction hook with different height (2.1, 4.0, 5.5 mm). By exerting 1.5 N backward force to analysis the displacement trend of maxillary tooth.

結果:

上方アクセントカーブアーチワイヤーは，切歯の唇側先端，内寄せ，遠位起立，中内転位，犬歯の唇側先端，外寄せ，中内転位，第二小臼歯および第一大臼歯の頬側先端，内寄せ，遠位起立，中内転位に作用した．また，アーチワイヤーの角度を大きくすると，すべての歯の移動傾向が大きくなり，フリートラクションフックの高さを大きくすると，すべての歯の移動傾向が小さくなった．

RESULTS: Upper accentuated-curve archwires made the incisors labially tip, intruse, distally upright and mesilabially torsion; made the canines labially tip, prolong, mesial-tipped and mesi-labially torsion; made the second premolars and the first molars buccal tip, intruse, distal upright and mesi-labially torsion. With the angle of upper accentuated-curve archwires increased, all tooth movement tendency increased; while with the height of free traction hook increased, all tooth movement tendency decreased.

結論:

上方アクセント曲線アーチワイヤーの角度が大きくなると，臼歯部の侵入の程度が大きくなるが，free traction hookの高さが大きくなると，臼歯部の侵入の程度は小さくなった．5度アーチワイヤーと5.5mmフリートラクションフックを併用した場合，臼歯部侵入の程度は最小であった．

CONCLUSION: When the angle of upper accentuated-curve archwires increased, the extent of molar intrusion increased, but when the height of free traction hook increased, the degree of molar intrusion decreased. The degree of molar intrusion was minimum using 5 degrees upper accentuated-curve archwires cooperated with 5.5 mm free traction hook.