title: Comparison of apical and coronal extrusions using reciprocating and rotary instrumentation systems.
abstract: BACKGROUND
  The aim of this study was to compare the apical and coronal extrusions by using two reciprocating and two rotary instrumentation systems.
  
  
  METHODS
  Eighty extracted human single-rooted anterior teeth were randomly assigned to four groups. Four different root canal instrumentation systems were used according to the manufacturers instructions, including two reciprocating single-file systems, Reciproc and WaveOne, and two full-sequence rotary BLX and ProTaper instruments. Debris collected from the coronal by the instruments and apical extrusions were quantified respectively. After drying the collections, the mean weight of debris collected from apical and coronal extrusions was assessed using an electronic balance and analyzed using the Kruskal-Wallis H and Mann-Whitney U tests.
  
  
  RESULTS
  Statistically significant differences in the apical extrusion were observed among the four groups. Reciproc and WaveOne instruments produced significantly less debris than BLX and ProTaper instruments (P < 0.05).
  
  
  CONCLUSIONS
  All of the systems produced apical extrusion of debris. However, reciprocating single-file systems produced less apical extrusion than full-sequence rotary systems. No relationship was observed between apical and coronal extrusions.
authors.affiliation: Department of Endodontics and restorative dentistry, School of Stomatology, Tianjin Medical University, Tianjin, 300070, China. dentist_luyan@163.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Department of Endodontics and restorative dentistry, School of Stomatology, Tianjin Medical University, Tianjin, 300070, China. chenmin881112@163.com.
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.affiliation: Department of Maxillofacial Surgery, School of Stomatology, Tianjin Medical University, Tianjin, 300070, China. 1036537600@qq.com.
authors.forename: Feng
authors.initials: F
authors.lastname: Qiao
authors.affiliation: Department of Endodontics and restorative dentistry, School of Stomatology, Tianjin Medical University, Tianjin, 300070, China. zbwlg5647@sina.com.
authors.forename: Ligeng
authors.initials: L
authors.lastname: Wu
mesh_terms: D003722:Dental Alloys / Q000737:chemistry; D004867:Equipment Design; D005119:Extravasation of Diagnostic and Therapeutic Materials / Q000473:pathology; D006801:Humans; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry; D011897:Random Allocation; D012388:Root Canal Irrigants / Q000737:chemistry; D018915:Root Canal Preparation / Q000295:instrumentation*; D012399:Rotation; D016369:Smear Layer / Q000473:pathology*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry; D019227:Tooth Apex / Q000473:pathology*; D019228:Tooth Crown / Q000473:pathology*
chemical_list: D003722:Dental Alloys; D012388:Root Canal Irrigants; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium