Self-adjusting file (SAF): managment in pediatric endodontic dentistry

Aim. The aim of this study was to demonstrate the efficacy of a new endodontic system instrumentation through the presentation of clinical cases performed on deciduous elements and immature permanent. Methods. The Self-Adjusting File (ReDent-Nova, Raanana, Israel) is a new system of cleaning, shaping and irrigation in the root canals treatment. The SAF is the first hollow file cylindrical, made of a nickel-titanium lattice with a rough external surface, compressible, that adapts itself to the shape of the canal. The SAF is used as a single instrument to achieve complete 3D root canal cleaning and shaping in a minimally invasive way. Its hollow shape allows for the continuous flow of irrigant through its lumen to achieve superior disinfection. The SAF compresses to adapt to the root canal anatomy. Its attempt to re-expand shapes the canal by applying light continuous pressure along the entire circumference of the root canal wall. Thanks to a vibration in the vertical direction associated with a rotation without torque allows us to obtain uniform removal of a layer of dentine from the surface of canal. The SAF’s abrasive surface acts similarly to sandpaper by scrubbing uniformly and gradually enlarging the root canal circumferentially. The SAF is extremely flexible and compressible. It does not impose its shape on the canal, but rather adapts to the canal’s original shape. This is true both circumferentially and longitudinally, thus keeping the long axis of the canal in its original position. In our study we selected elements of the series deciduous and permanent with a wide open apex. In all cases, the elements presented periapical lesion. After making an preoperative x-ray, an endodontic access cavity was prepared in each tooth, was determined the working length and the root canal was negotiated using a size 15 K-file. A glide path was established by manual instrumentation up to a size 20 K-file using 5.25% sodium hypochlorite. In our study SAFs (diameters of 1.5mm and 2.0 mm) was used for cleaning and shaping the root canal using an in-and-out vibrating handpiece. The hollow SAF allowed for continuous irrigation throughout the procedure. After treatment clinical and radiographic controls were obtained. Results. The use of this innovative system guarantees the three-dimensional cleaning and shaping of oval and curved canals, an effective disinfection, uniform layer dentin removal without varying the thickness of the remaining walls and respecting the physiological root canal anatomy, the three-dimensional obturation of canals. Clinical and radiographic controls showed a regression of the periapical lesion and a progressive closure of the root apex. Conclusion. When SAFs are used in root canals which are substantially narrower than the thickness of the SAF, the file is compressed and the attempt of the file to get back to its original, non-compressed form generate the light pressure that allows the removal of a thin uniform layer of dentin all around the perimeter of the canal. When the SAF is inserted into a wide canal the compression of the file is smaller and the pressure on the walls is limited. Consequently, removal of dentin stops to be effective, even when the SAF is intimately adapted to and touching the canal walls. This phenomenon may be useful in cleaning the walls of immature teeth.