高度に湾曲した根管の形成における5種類のシングルファイルシステムの比較：ex vivo試験

Comparison of five single-file systems in the preparation of severely curved root canals: an ex vivo study.

抄録

背景:

5種類のニッケルチタンシングルファイルシステム（M3-L, Reciproc Blue, V-Taper 2H, WaveOne Gold, XP-endo Shaper）を用いて、重度に湾曲した臼歯根管の根管形成成績を比較するex vivo研究である．

BACKGROUND: The ex vivo study is to compare the root canal preparation outcomes achieved by five nickel-titanium single-file instrumentation systems (M3-L, Reciproc Blue, V-Taper 2H, WaveOne Gold, XP-endo Shaper) in severely curved molar root canals.

方法:

ヒトの臼歯部抜去歯から曲率25°～50°の根管60本を選び、使用するインスツルメンテーションシステムにより5群に分けた（n=12）。根管形成前後にMicro-CTスキャンを行い，術前術後のデータを解析し，根管容積増加量（VI），未処理根管領域（UTA），根管輸送量（CT）を評価した．また，根管形成の際に，先端から押し出された破片（AD）を回収した．その後，すべての試料を2つに分け，それぞれ走査型電子顕微鏡（SEM）で観察し，清掃性を評価した．データはANOVA（UTA, AD, VI）またはKruskal-Wallis検定（CT, SEM-score）で統計的に分析し、有意水準はα=0.05と設定した。

METHODS: A total of 60 root canals were selected from extracted human molar teeth with curvatures ranging from 25° to 50° and divided into five groups based on the instrumentation system employed (n = 12). Before and after root canal preparation, a Micro-CT scan was taken, and pre- and post-operative data were analyzed to evaluate the following parameters: volume increment of root canals (VI), untouched root canal areas (UTA), and canal transportation (CT). Apically extruded debris (AD) was collected during preparation. After that, all samples were separated into two parts and examined respectively by scanning electron microscope (SEM) to assess cleaning ability. Data were statistically analyzed with ANOVA (UTA, AD, VI) or Kruskal-Wallis test (CT, SEM-score), the level of significance was set at α = 0.05.

結果:

AD、VI、UTAの各パラメーターは、5つのシステム間で有意な差は見られなかった（P>0.05）。CTに関しては，管腔直線部および頂部レベルでは有意差は認められなかったが，XP-endo Shaperは湾曲頂部レベルにおいてM3-Lよりも管腔輸送量が少なく（P＜0.05），V-Taper 2Hは屈曲初期点においてWaveOne Goldよりも有意にセンタリング能力が高かった（P＜0.05）．すべての検体で管壁にデブリとスミア層が存在し，管端3分の1はすべての群で冠状3分の1より高いSEMスコアを示した（P<0.05）．レシプロックブルーおよびXP-エンドシェイパーは，先端3分の1ではウェーブワンゴールドよりもスミアスコアが低く（それぞれP<0.01，P<0.05），中・冠状3分の1では他のグループとの統計的差異は認められなか った．

RESULTS: There were no significant differences between the five systems regarding the AD, VI, and UTA parameters (P > 0.05). In terms of CT, no significant difference was noted at the straight section of canal and apical levels, while XP-endo Shaper showed less canal transportation than M3-L at the level of curved vertex (P < 0.05), and the centering ability of V-Taper 2H was significantly better than WaveOne Gold at the initial point of bending (P < 0.05). Debris and smear layers were present on the canal walls of all specimens, the apical thirds of the canal presented higher SEM scores than the coronal thirds in all groups (P < 0.05). Reciproc Blue and XP-endo Shaper showed fewer smear scores than WaveOne Gold in the apical thirds (P < 0.01 and P < 0.05, respectively), and no statistical difference was found between other groups in the middle and coronal thirds.

結論:

5種類のシングルファイルシステムは，根尖側へのデブリの押し出し，象牙質の除去，根管内の未処理領域において同等であり，XP-endo Shaper，V-Taper 2HはM3-L，WaveOne Goldと比較して根管輸送が少なかった．洗浄性については，レシプロックブルーとXP-endo ShaperはWaveOne Goldに比べ，根尖3分の1のスミア層が少ないことが示された．

CONCLUSION: The five single-file systems evaluated performed equally in apically debris extrusion, dentin removal, and untouched root canal areas, while XP-endo Shaper and V-Taper 2H resulted in less canal transportation compared to M3-L and WaveOne Gold. Regarding cleaning ability, Reciproc Blue and XP-endo Shaper were associated with less smear layer than WaveOne Gold in the apical thirds.