title: The influence of different angles and reciprocation on the shaping ability of two nickel-titanium rotary root canal instruments.
abstract: OBJECTIVE
  The purpose of the present study was to investigate and compare the effect of different reciprocating movements and angles on the shaping ability of the WaveOne and the single-fle ProTaper F2 using cone beam computed tomography (CBCT).
  
  
  METHODS
  The mesiobuccal canals of 40 extracted maxillary molars, with curvatures of 20 to 45° were coded and randomly divided into 4 equal experimental groups according to the instrument used (ProTaper F2 fle and Wa-veOne) and the reciprocation range, for both instruments, a 150° angle was used for cutting and a 30° angle was used for release. Group 1 - WaveOne primary 150° CCW rotation angle and 30° CW rotation angle; Group 2 - WaveOne 90° CCW rotation angle and 30° CW rotation angle; Group 3 - ProTaper F2 150° CW rotation angle and 30° CCW rotation angle; Group 4 - ProTaper F2 90° CW rotation angle and 30° CCW rotation angle. Canals were scanned before and after preparation using CBCT to evaluate the volumetric change, canal transportation and the canal centering ability at 2.6, 5.2 and 7.8 mm from the apex. The mean ± standard deviation (SD) values were analyzed, and the significance level was set at p ≤ 0.05.
  
  
  RESULTS
  There was no significant difference in the amount of dentin removed among the experimental groups, except that WaveOne 150°CCW 30°CW significantly showed the least volume of dentin removed (0.40 ± 0.9) at 7.8 mm. All rotary systems tested in the different groups resulted in canal transportation in different directions at all examined levels. WaveOne 150°CCW 30°CW, demonstrated the lowest mean value of root canal transportation in both the mesial and furcal directions and in both the coronal and apical directions compared to the other groups. At the 7.8 level, WaveOne 150°CCW 30°CW yielded the highest mean centering ratio, whereas ProTaper F2 CW 150° CCW 30° yielded the lowest, statistically significant at p ≤ 0.05.
  
  
  CONCLUSIONS
  The results of the present study demonstrated that differences among various reciprocating motions and angles could affect the shaping ability of a single-fle Nickel-titanium (NiTi) instrument.
authors.affiliation: Associate Professor and Consultant, Department of Restorative Dental Sciences, College of Dentistry, King Saud University, Riyadh, Kingdom of Saudi Arabia, e-mail: dinaalsudani@gmail.com.
authors.forename: Dina
authors.initials: D
authors.lastname: Al-Sudani
authors.affiliation: Demonstrator, College of Dentistry, King Saud University, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Hassan
authors.initials: H
authors.lastname: Kaabi
authors.affiliation: Consultant, Department of Endodontics, Security Force Hospital, Riyadh Kingdom of Saudi Arabia.
authors.forename: Abdulrahman
authors.initials: A
authors.lastname: Al Gamdi
authors.affiliation: Specialist, Advanced General Dentistry, Deparment of Restorative Dental Sciences, Riyadh Military Hospital, Riyadh, Kingdom of Saudi Arabia.
authors.forename: Abdulla
authors.initials: A
authors.lastname: Al Dakheel
mesh_terms: D054893:Cone-Beam Computed Tomography / Q000379:methods; D003722:Dental Alloys / Q000737:chemistry*; D003786:Dental Pulp Cavity / Q000000981:diagnostic imaging*; D003804:Dentin / Q000000981:diagnostic imaging; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008422:Materials Testing; D008963:Molar / Q000000981:diagnostic imaging; D009532:Nickel / Q000737:chemistry*; D011897:Random Allocation; D018915:Root Canal Preparation / Q000295:instrumentation*; D012399:Rotation; D014025:Titanium / Q000737:chemistry*; D019227:Tooth Apex / Q000000981:diagnostic imaging
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium