根管治療的失誤(endodontic mishaps)或治療過程中的意外是牙齒治療中最不希望發生的情況。根管平台(ledge formation)的形成是在根管治療過程中發現工作長度(working length)無法保持暢通或原本根管路徑(pathway of canal)無法維持情況。一般認為，只要將根管開口（窩洞）(access cavity)以直線開口(straight-line access)的觀念作適當開展以減少修形器械的阻礙，並配合彎曲的器械尖端，被動階梯式後退(passive step-back)與力量平衡(balance-force)根管修形技術等方法，便可以容易保持修形器械在根管內的正確工作長度，間接可減低根管平台形成的機會。如果修形過程真的發生平台的錯誤，應選擇使用容易操控的小號根管銼針，將尖端依平台位置處彎曲後，以緩慢旋轉(rotation)及輕啄(picking)的動作嘗試繞道(bypass)的方式重新尋找根管路徑並深入暢通。本篇文章除了針對根管平台形成的原因，預防及處理的方法詳細的探討瞭解外，同時以臨床病例輔助說明。

Endodontic mishaps or procedural accidents are unfortunate occurrences that are occur during treatment. A ledge is created when the working length can no longer be negotiated and the original pathway of the canal has been lost during root canal instrumentation. Extension of the access cavity according to straight-line access concepts to provide unobstructed access to the root canals, precurving and not forcing instruments, using NiTi files, using passive step-back and balanced force techniques, and instrumenting the canal to its full length will all help to prevent ledge formation. Initial negotiation and bypassing the ledge can be achieved using a small file with a distinct curve at the tip, whereas a slight rotation motion of the file combined with a "picking" motion can often help advance the instrument. A review of the literature and case discussion of the options for prevention, recognition and managing the ledge during canal cleaning and shaping are presented in the article.