Permalink : http://hdl.handle.net/2115/58235

KEYWORDS : vertical root fracture;intra-oral bonding treatment;sealability;垂直歯根破折;口腔内接着法;封鎖性

The basic conservative treatment of a vertical root fracture is bonding and sealing the gap of the root fracture. It is difficult to seal the gap completely from the root canal side. Grinding the gap wall using an ultrasonic endodontic file from the root canal side improves sealability of the gap However, there may be excessive and insufficient grinding. It is possible that dissolving the root canal wall with 10% citric acid 3% ferric chloride solutions （10-3） and 10% sodium hypochlorite （NC） enlarge a region that is difficult for mechanical expansion. The purpose of this study was to evaluate the sealability after enlarging the gap of a root fracture with a chemical method and together with an ultrasonic endodontic filing and chemical agents. In the first experiment, 1 millimeter thick dentin pieces were cut out from extracted human teeth, fractured in the direction of tooth axis, restored to the original position, and held. The gaps were treated by 10-3 for five minutes and NC for two minutes one time （one time group）, three times （three time group） and no time （control group）. In all groups, gaps were bonded using 4META/MMA-TBB resin （Super Bond） to seal the fractured gaps. All pieces were then tested by dye penetration tests and the gaps were microscopically measured. In the second experiment, extracted human teeth were fractured vertically and restored. The gaps were treated by the following methods. 1） not treated （control group）, 2） ground from the root canal wall side with an ultrasonic endodontic file, until the Root ZX reading showed 1.0 （grinding group）, 3） treated by 10-3 for 5 minutes and NC for 2 minutes three times （chemical group）, 4） treated by 3rd method after grinding by 4th method （combination group）. In all groups, gaps were sealed using Super Bond, tested by dye leakage tests, and microscopically measured. In the first experiment, enlarged width was significantly larger in the three times group than in the control and one time group. The rate of dye penetration was significantly smaller in the three times group than in the control and one time group. In the second experiment, the rate of dye penetration was significantly statistically smaller in the combination group than the other groups. These findings indicate that the combination of a chemical method and a mechanical method with the ultrasonic endodontic file in the gap of root fractures is effective to enhance the sealability of the fractured gap while preventing over grinding.
垂直歯根破折に対する保存治療の基本は，破折間隙を接着し，封鎖することである．超音波エンドファイルを用い，根管内から破折線を切削すると，破折間隙の封鎖性は向上するが，過剰切削や切削不足が生じることが課題である．一方，化学的な根管壁の溶解によって，機械的拡大が困難な部位の根管拡大が可能であるので，本研究では破折間隙の切削と化学的拡大を併用することで，接着後の封鎖性が向上するかを検討した． 　実験１．ヒト抜去歯から厚さ１mmの象牙質片を作製して破折，復位固定した．破折間隙に対して，処理群は10％クエン酸/ ３％塩化第二鉄溶液（10-３溶液）５分，10％次亜塩素酸ナトリウム溶液（NC）２分の処理を１回あるいは３回行った．未処理群では破折間隙の処理は行わなかった．３群ともスーパーボンドで破折間隙を接着し，色素侵入試験を行うとともに破折間隙幅を計測した．その結果，間隙幅は３回処理群が他の２群より有意に広く（p＜0.05），色素侵入率は３回処理群が他の２群より有意に小さかった（p＜0.05）． 　実験２．ヒト抜去歯を垂直破折させて復位固定し，破折間隙に対して以下の処置を行った．①未処理群：処理なし．②形成群：ソルフィーZXのオートストップ値を1.0に設定して超音波エンドファイルで破折間隙を切削．③化学的拡大群：10-３溶液５分，NC2分の処理を３回．④併用群：②の後に③の処理．４群ともスーパーボンドで破折間隙を接着後，色素侵入試験を行った．その結果，併用群においては歯根表面に切削が達している試料はなく，その色素侵入率は他の３群と比較して有意に小さかった（p＜0.05）． 　以上の結果から，超音波エンドファイルによる破折間隙の切削と化学的な拡大を併用することは，過剰な切削を防止して封鎖性を向上するのに有効である．