[PERSON]  
2 Department of Physical Sciences, University of Turin, 10126 Turin, Italy;  
[EMAIL_ADDRESS] (N.S. ); alle.comb@yahooit (A.C.); [EMAIL_ADDRESS] (O.P.) [PERSON]  
1 Department of Surgical Sciences, Dental School, Endodontics, University of Turin, 10126 Turin, Italy;  
[EMAIL_ADDRESS] (M.A. ); [EMAIL_ADDRESS] (H.B. ); [EMAIL_ADDRESS] (G.C. ); [EMAIL_ADDRESS] (N.S. ); alle.comb@yahooit (A.C.); [EMAIL_ADDRESS] (O.P.) [PERSON]
2 Department of Biomedical, Surgical and Dental Science, Universita degli Studi di Milano, 20122 Milan, Italy;  
[EMAIL_ADDRESS] (N.S. ); [EMAIL_ADDRESS] (N.S. ); alle.comb@yahooit (A.C.); [EMAIL_ADDRESS] (O.P.) [PERSON]
2 Department of Biomedical, Surgical and Dental Science, Universita degli Studi di Milano, 20122 Milan, Italy;  
[EMAIL_ADDRESS] (N.S. ); [EMAIL_ADDRESS] (N.S. ); alle.comb@yahooit (A.C.); [EMAIL_ADDRESS] (N.S. ); alle.comb@yahooit (A.C.); [EMAIL_ADDRESS] (O.P.) [PERSON]  
2 Department of Physical Sciences, University of Turin, 10126 Turin, Italy;  
[EMAIL_ADDRESS] (N.S. ); alle.comb@yahooit (A.C.); [EMAIL_ADDRESS] (O.P.) [PERSON]  
2 Department of Biomedical, Surgical and Dental Science, Universita degli Studi di Milano, 20122 Milan, Italy;  
[EMAIL_ADDRESS] (N.S. ); [EMAIL_ADDRESS] (N.S. ); alle.comb@yahooit (A.C.); [EMAIL_ADDRESS] (N.S. ); alle.comb@yahooit (A.C.); [EMAIL_ADDRESS] (O.P.) [PERSON]  
2 Department of Physical Sciences, University of Turin, 10126 Turin, Italy;  
[EMAIL_ADDRESS] (N.S. ); alle.comb@yahooit (A.C.); [EMAIL_ADDRESS] (O.P.) eating, sleeping, speaking, carrying out daily functions, and relating with other people as well as perceived pain [5; 6]. Previous studies evaluated the relationship between the root canal treatment and patient QoL and showed that several patients perceive it as a negative event, being frequently associated with pain [3; 7]. There is a growing interest in patients' treatment perceptions, and postoperative QoL could be considered as an indicator of the overall quality of the endodontic therapy [4; 5]. Root canal treatment aims to resolve pulpal and periradicular diseases and to improve long-term tooth prognosis [8]. However, postoperative pain is a possible complication, and it can worsen patient QoL [9]. Pain can be caused by a phlogistic reaction following the root canal shaping [10; 11; 12; 13] and can be influenced by operator experience, preoperative status, and shaping techniques [14]. In particular, the postoperative pain is frequently caused by debris extrusion beyond the apex during root canal shaping, such as dental chips, pulp debris, bacteria, and irrigants [9; 15; 16] and it has a great impact on patients' QoL [9]. The Nickel-Titanium (NiTi) reciprocating shaping instruments are associated with high cyclic fatigue resistance and respect of the canal anatomy [17; 18; 19]. However, they are claimed to promote greater debris extrusion and postoperative pain prevalence compared to rotary systems, negatively affecting patients' QoL [20; 21; 22]. Recently, the reciprocating WaveOne Gold (WOG) system was introduced with substantial improvements in alloy, taper, and section. The gold NiTi alloy is thermically treated in order to enhance flexibility and shape memory. Moreover, a reduced variable taper compared to WaveOne Classics (WOC) and an off-centered, parallelogram cross-section provides one single contact point between the instrument and the canal walls, leaving more space for debris removal. The new features are supposed to lead to an improved conservative shaping, with a consequent less debris extrusion and a better postoperative trend, if compared to other reciprocating mechanical files. Several studies reported that rotary shaping is associated to better postoperative quality of life, probably due to a lesser amount of debris extrusion beyond the apex during the canal instrumentation [22; 23]. However, there are no studies considering instruments with the same type of motion but different design and alloy properties.