ポスト除去のための異なる超音波振動モードの比較

Comparison of different ultrasonic vibration modes for post removal.

抄録

このin vitro研究では，歯頸部内鋳造ポスト除去のための異なる超音波振動モードを比較した．24本の上顎犬歯の歯冠を除去し，歯根をアクリル樹脂ブロックに埋入し，歯内療法を行った．ポスト孔を作製し，セルフキュアレジンアクリルで根管印象の採得を行った．鋳造後，リン酸亜鉛セメントでポストを固化した．試料は無作為に3群（n=8）に分配した．G1：超音波振動なし（コントロール），G2：超音波装置の先端をコア表面に対して垂直かつ切縁に近い位置に配置，G3：超音波装置の先端をコア表面に対して垂直かつ歯頚部でセメンテーション線に近い位置に配置．超音波診断装置Enac OE-5とST-09チップを使用した．すべてのサンプルは，万能試験機を用いてクロスヘッド速度1 mm/minで引張試験を行った．データは，一元配置分散分析およびTukeyのポストホック検定にかけた（α=0.05）．ポストが外れる荷重の平均値（MPa）は次の通りであった．したがって，装置先端を歯頸部に近づけて超音波振動させた方が，根管への鋳造ポストの保持力を低下させる効果が高いことが示された．

This in vitro study compared different ultrasonic vibration modes for intraradicular cast post removal. The crowns of 24 maxillary canines were removed, the roots were embedded in acrylic resin blocks, and the canals were treated endodontically. The post holes were prepared and root canal impressions were taken with self-cured resin acrylic. After casting, the posts were cemented with zinc phosphate cement. The samples were randomly distributed into 3 groups (n=8): G1: no ultrasonic vibration (control); G2: tip of the ultrasonic device positioned perpendicularly to core surface and close to the incisal edge; and G3: tip of the ultrasonic device positioned perpendicularly to core surface at cervical region, close to the line of cementation. An Enac OE-5 ultrasound unit with an ST-09 tip was used. All samples were submitted to the tensile test using an universal testing machine at a crosshead speed of 1 mm/min. Data were subjected to one-way ANOVA and Tukey's post-hoc tests (α=0.05). Mean values of the load to dislodge the posts (MPa) were: G1 = 4.6 (± 1.4) A; G2 = 2.8 (± 0.9) B, and G3= 0.9 (± 0.3) C. Therefore, the ultrasonic vibration applied with the tip of device close to the core's cervical area showed higher ability to reduce the retention of cast post to root canal.