グラスファイバーポストの象牙質に対する接着強さに及ぼす合着用セメント厚さの影響

Effect of luting cement thickness on the bond strength of glass fiber posts to dentin.

抄録

本研究の目的は，グラスファイバーポスト（GFP）の根面象牙質に対するプッシュアウト接着強さに及ぼすセメント厚さと合着セメントタイプの影響を検討することである．ヒト上顎歯根充填犬歯または小臼歯の単直根60本を，GFPの形態（従来型またはコンポジットレジンによるリライン）と使用セメント（RelyX U200，Ketac Cem，Allcem Core）によってランダムに6群（n＝10）に分類した．歯内療法およびGFPセメント充填後，全根を長軸方向に切断し，1.0mm厚のスライスを得た（各群n=6）．このデータ（試験前の破損のため，各群45〜51個）を2元配置分散分析（ANOVA）およびTukey検定（α＝0.05）により分析した。破損の種類は実体顕微鏡で判定し，代表的な試験片は走査型電子顕微鏡で観察した．セメントとGFPの配置の間に有意な相互作用が冠状3分の1と頂端3分の1で検出された（P < 0.05；2-way ANOVA）．コロナルサードでは，RelyX U200セメントを用いたグループが最も高いプッシュアウト接着強さを示したが，Allcem Coreを用いたグループとの有意差は認められなかった．中顎では，セメントとGFPの組み合わせによる有意な相互作用は認められなかった（P = 0.232; 2-way ANOVA）．象牙質とセメント層の接着不良が最も高頻度に観察される不良形態であった．GFPではコンポジットレジンが添加されているため，セメント層が薄くなることが予想された．使用したセメントの種類は，プッシュアウト接着強さに重要な役割を果たした．

The objective of this study was to evaluate the effect of cement thickness and luting cement type on the push-out bond strength of glass fiber posts (GFPs) to root dentin. Sixty human maxillary root-filled canines or premolars with single straight roots were randomly divided into 6 groups (n = 10) according to the GFP configuration (conventional or relined with composite resin) and the cement used (RelyX U200, Ketac Cem, or Allcem Core). After endodontic treatment and GFP cementation, all of the roots were sectioned perpendicular to their long axis to obtain 1.0-mm-thick slices (n = 6 per group), which were mounted on a universal testing machine and submitted to a push-out test. The data (n = 45 to 51 specimens per group because of pretest failures) were analyzed by means of 2-way analysis of variance (ANOVA) and Tukey tests (α = 0.05). The type of failure was determined under a stereomicroscope, and representative specimens were observed with scanning electron microscopy. Significant interactions between the cements and GFP configurations were detected in the coronal and apical thirds (P < 0.05; 2-way ANOVA). For the coronal third, both RelyX U200 cement groups exhibited the greatest push-out bond strengths but were not significantly different from the Allcem Core relined group. For the middle third, no statistically significant interactions were observed between the cements and GFP configurations (P = 0.232; 2-way ANOVA). Adhesive failure between the dentin and cement layer was the most frequently observed failure mode. As expected, because of the composite resin added to relined GFPs, the cement layer was thinner in those groups. The type of cement used played an important role in the push-out bond strength.