title: Technical quality of a matching-taper single-cone filling technique following rotary instrumentation compared with lateral compaction after manual preparation: a retrospective study.
abstract: OBJECTIVE
  The objectives of the study were to evaluate the radiographic technical quality of root canal treatment before and after the implementation of a nickel-titanium rotary (NiTiR) preparation followed by a matching-taper single-cone (mSC) obturation and to detect the procedural errors associated with this technique.
  
  
  METHODS
  A random sample of 535 patients received root canal treatment at the Department of Conservative Dentistry and Periodontology at the University of Würzburg: 254 teeth were treated in 2002-2003 by using stainless steel instruments (SSI) for preparation and a lateral compaction (LC) technique (classic group (CG)). Two hundred eighty-one teeth were root filled in 2012-2013 employing NiTiR instruments for the root canal shaping and a mSC technique (advanced group (AG)). The quality assessments were based on the radiographic criteria of the European Society of Endodontology. The presence of voids was recorded separately for the apical, central and cervical thirds of the root canals. Procedural errors, such as ledges, apical transportations, perforations and fractured instruments, were detected. The root canal fillings in the CG and AG were compared using chi-squared and Fisher's exact tests. Multivariable logistic regression was performed to investigate the association between the independent variables (patient age, tooth type and type of treatment) and the dependent variables (density and length).
  
  
  RESULTS
  Adequate length was achieved significantly more often in the AG compared to the CG for molars (p = 0.017), mandibular teeth (p = 0.013) and primary root canal treatments (p = 0.024). No significant difference was detected between the AG and CG regarding adequate length in general (p = 0.051) or adequate overall quality of root canal filling (p = 0.1). In the AG, a significant decrease in procedural errors was evident (p = 0.019) and decreases in the densities of the root canal fillings in the cervical (p = 0.01) and central (p = 0.01) thirds of the root canals were also observed. Moreover, root canals in elderly patients exhibited fewer voids (p = 0.009).
  
  
  CONCLUSIONS
  Rotary root canal preparation followed by a matching-taper single-cone filling technique provides a reliable shaping of the root canal, with fewer procedural errors and a more acceptable filling quality in terms of length and homogeneity in the apical third. Less favourable results were achieved in the central and cervical parts of the root canals.
  
  
  CONCLUSIONS
  The matching-taper single-cone technique seems to effectively obturate well-tapered root canals after adequate rotary instrumentation. Irregularly shaped canals require additional lateral or warm vertical condensation to avoid voids.
authors: Department of Conservative Dentistry and Periodontology, University of Würzburg, Pleicherwall 2, 97070, Würzburg, Germany. ralf_krug@web.de.
authors: R
authors: R
authors: Krug
authors: Department of Conservative Dentistry and Periodontology, University of Würzburg, Pleicherwall 2, 97070, Würzburg, Germany.
authors: G
authors: G
authors: Krastl
authors: Department of Conservative Dentistry and Periodontology, University of Würzburg, Pleicherwall 2, 97070, Würzburg, Germany.
authors: M
authors: M
authors: Jahreis
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009532:Nickel; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012389:Root Canal Obturation / Q000295:instrumentation; D018915:Root Canal Preparation / Q000295:instrumentation*; D013193:Stainless Steel; D014025:Titanium; D016896:Treatment Outcome
chemical_list: C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium
keywords: NiTi rotary; Root canal treatment; Single-cone technique; Technical quality