光線力学療法，Er,Cr:YSGGおよびNd:YAGレーザーの根面に対するファイバーポストのプッシュアウトボンド強度に及ぼす影響

Effect of Photodynamic Therapy, Er,Cr:YSGG, and Nd:YAG Laser on the Push-Out Bond Strength of Fiber Post to Root Dentin.

抄録

光線力学療法（PDT），Er,Cr:YSGG，Nd:YAGレーザー，および従来のクリーニング＆シェイピング（CCS）を用いて，ファイバーポストの根面象牙質への押出し接着強度と破壊様式を評価する． 80本の前歯をセメントエナメル質接合部まで2mm切開して水平に切断し，根管にポストスペースを作製した．ポストスペースを形成した後，根管内にファイバーポストを留置した．ファイバーポストは，PDT，Er,Cr:YSGGレーザー，Nd:YAGレーザー，CSS（Cleaning and Shaping）を各群20検体ずつ施行した．試験体から頸部および頂部切片を得た．押し出し試験の実施には，万能試験機を用いた．押出し接着強さの算出式は，σ=N/mmとした． PDT群（8.16±2.19MPa）が最も高く，Er，Cr：YSGG群（7.24±1.27MPa）は最も低い値であった．ANOVA検定では，各実験群の間に統計的な差異が認められた（=0.481）．頚椎セグメントでは，すべての実験グループにおいて，平均押出し接着強さが高いことが示された．頚部では，PDT，Er,Cr:YSGG，Nd:YAG，CSSの各群で，先端部よりも高い平均押し出し接着強度が独立検定で示された（<0.05）．接着剤と象牙質表面との界面レベルでは，20件の破損が認められた．また，接着剤とポストとの混合界面では，それぞれ7回の破損が認められた． PDT，Er,Cr:YSGG，Nd:YAG レーザーの根管象牙質に対するプッシュアウト接着強さは，CCSと比較して影響を受けなかった．しかし，PDTは破壊モードの数が最も少なく，根面象牙質に対するプッシュアウト接着強さがわずかに高かった．PDTとEr,Cr:YSGGを用いたレーザー治療は臨床的に有効であり，ファイバーポストのプッシュアウトボンド強度は良好で，根面象牙質の異なる領域で破損の発生が少ないと考えられた．

To evaluate the push-out bond strength and modes of failure of fiber post to root dentin by using photodynamic therapy (PDT), Er,Cr:YSGG, Nd:YAG laser, and conventional cleaning and shaping (CCS). Eighty anterior teeth were sectioned in a horizontal manner being 2 mm incisal to the cementoenamel junction, and root canal was prepared for post space. After post space was made, fiber posts were placed inside the root canal system. The fiber posts were subjected to PDT, Er,Cr:YSGG laser, Nd:YAG laser, and conventional cleaning and shaping (CSS) with 20 specimens in each group. Cervical and apical sections were obtained from the specimens. For performing the push-out test, the universal testing machine was used. The formula used for calculating the push-out bond strength was σ = N/mm. PDT group (8.16 ± 2.19 MPa) achieved the highest mean push-out bond strength, whereas Er,Cr:YSGG (7.24 ± 1.27 MPa) reported the lowest value in the specimens. Among the experimental groups, the ANOVA test expressed statistical difference ( = 0.481). In the cervical segments, the mean push-out bond strength was found to be higher in all of the experimental groups. For the cervical segments, the independent -test results showed higher mean push-out bond strength values than the apical segments in PDT, Er,Cr:YSGG, Nd:YAG, and CSS groups, respectively ( < 0.05). Twenty failures were observed at the interface level between the adhesive and surface of dentin. Seven failures were found at the interface between mixed and the adhesive and post, respectively. Push-out bond strength to root canal dentin was not affected by PDT, Er,Cr:YSGG, and Nd:YAG laser compared with CCS. However, PDT produced the smallest number of failure modes and slightly higher push-out bond strength to root dentin. Laser treatment using PDT and Er,Cr:YSGG appeared to be clinically efficient showing acceptable push-out bond strength of fiber post with less number of failures at different regions of the root dentin.