今回はスメアー層除去方法に関する文献です。

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感染除去の為には機械的拡大が不可欠ですが

これにより根管壁表層にスメアー層が形成され

感染を象牙質内に封じ込めてしまう恐れがあります。

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この研究ではヒト新鮮抜去歯を対象とし

以下の3種類の根管洗浄を用いてスメアー層の効果的な除去方法を検討しています。

①6%次亜塩素酸ナトリウム溶液単独

②6%次亜塩素酸ナトリウム溶液と3％過酸化水素水による交互洗浄

③17％EDTA(REDTA)による洗浄

Endodontically treated root canals were examined by scanning electron microscopy. Three separate in vitro studies were conducted to demonstrate the effects of different instrumentation techniques, different irrigating solutions, and various chemical treatments used after instrumentation. The results indicated that most standard instrumentation techniques produced a canal wall that was smeared and often packed with debris. Some of the irrigants commonly used in endodontic practice were no more effective than water in removing debris. These included the combination irrigating procedure using sodium hypochlorite and hydrogen peroxide. The use of a commercial liquid ethylenediaminetetraacetic acid (EDTA) preparation (REDTA) as an irrigant or as a chemical treatment produced the cleanest canal walls. The most effective cleaning procedure was the use of REDTA sealed in the canal for 24 hours. Canals treated in this way were free of a smeared layer and superficial debris.

①の洗浄後の根管壁面の走査電顕像の模式図

③の洗浄後の根管壁面の走査電顕像の模式図

つまり・・・

上図の様にEDTAを用いた群で最も効果的に

スメアー層を除去出来たということです。

肉眼やルーペで術中にスメアー層の残存を確認することは難しいですが

電子顕微鏡を用いればスメアー層の有無により根管壁表層の状態が

視覚的に明瞭に異なることが分かりました。

引用文献

Dorothy McComb, Dennis C. Smith

A preliminary scanning electron microscopic study of root canals after endodontic procedures

Journal of Endodontics 1975;1(7):238-242.