title: Effects of NiTi rotary and reciprocating instruments on debris and smear layer scores: an SEM evaluation.
abstract: OBJECTIVE
  The purpose of the present study was to investigate the cleaning efficacy of 2 different nickel-titanium (NiTi) rotary systems: a new single system Reciproc compared with the rotary full sequence Mtwo. The amount of debris and the morphology of smear layer were the parameters for the evaluation of the cleanliness of root canals. The null hypothesis of the study was that there would be no significant difference in debris scores and smear layer scores between the 2 systems.
  
  
  METHODS
  Forty single-rooted freshly extracted teeth were selected and divided into 2 groups. For each group, all root canals were shaped with 2 different NiTi instruments (Mtwo and Reciproc) and irrigated with 5.25% NaOCl and 17% ethylenediaminetetraacetic acid (EDTA) solutions by 3 trained operators. Specimens were fractured longitudinally and prepared for scanning electron microscopy (SEM) analysis at a standard magnification of ×5,000. The presence/absence of smear layer and the presence/absence of debris at the coronal, middle and apical third of each canal were evaluated using two 5-step scales for scores. Numeric data were analyzed using the Kruskal-Wallis and Mann-Whitney U statistical tests, and significance was set at a P value <0.05.
  
  
  RESULTS
  This study revealed significant differences among the various groups. The Mtwo group presented significantly lower smear layer scores than the Reciproc group (P<0.01) in the middle and apical third of the canal.
  
  
  CONCLUSIONS
  Conventional continuous rotary NiTi instruments associated with 5.25% NaOCl and 17% EDTA solutions seem to be better for obtaining clean dentinal canal walls. Reciprocating instruments leave a higher quantity of smear layer which covers dentinal walls and dentinal tubules.
authors.affiliation: Department of Endodontics, University of Pavia, Pavia - Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Poggio
authors.forename: Alberto
authors.initials: A
authors.lastname: Dagna
authors.forename: Marco
authors.initials: M
authors.lastname: Chiesa
authors.forename: Andrea
authors.initials: A
authors.lastname: Scribante
authors.forename: Riccardo
authors.initials: R
authors.lastname: Beltrami
authors.forename: Marco
authors.initials: M
authors.lastname: Colombo
mesh_terms: D003786:Dental Pulp Cavity / Q000601:surgery / Q000648:ultrastructure*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D066298:In Vitro Techniques; D009532:Nickel; D018915:Root Canal Preparation / Q000009:adverse effects* / Q000295:instrumentation* / Q000379:methods; D012399:Rotation; D016369:Smear Layer / Q000209:etiology* / Q000648:ultrastructure*; D014025:Titanium; D016896:Treatment Outcome
chemical_list: C040654:titanium nickelide; D009532:Nickel; D014025:Titanium