Root canal preparations, including the cleaning and shaping of the root canal, are a key step in the root canal treatment process. Advanced equipment and new materials have continuously emerged to better achieve this step. From standard stainless steel files to the use of nickel-titanium rotary file systems, the quality and efficiency of root canal preparation have greatly improved. However, while the resulting root canal filling radiographs are impressive, the third dimension of the root canal is commonly ignored. A new nickel–titanium instrument, the self-adjusting file(SAF), was recently developed. This tool is a breakthrough in root canal preparation technology because its unique design overcomes the lack of flexibility and plasticity of traditional files. As the file features its own washing device, the synchronous operation of root canal cleaning and shaping may be realized, thereby achieving more efficient root canal preparations. This study discusses research progress on the characteristics, mechanical properties, and clinical applications of SAF.
