The effects of Mtwo, R-Endo, and D-RaCe retreatment instruments on the incidence of dentinal defects during the removal of root canal filling material.
BACKGROUND
The aim of this study was to compare the incidence of dentinal defects after retreatment procedures with different nickel-titanium rotary retreatment files.


METHODS
One hundred-eighty mandibular premolars were randomly assigned to 6 groups (n = 30 teeth per group). One group was left unprepared, and the remaining 5 groups were prepared with K-files (Dentsply Maillefer, Ballaigues, Switzerland) and filled with gutta-percha and AH plus sealer (Dentsply Maillefer, Ballaigues, Switzerland). Of these 5 groups, 1 group was left filled and received no further treatments; in the other groups, removal of the filling material was performed with Mtwo R (VDW, Munich, Germany), D-RaCe (FKG Dentaire, La Chaux-de-Fonds, Switzerland), R-Endo instruments (Micro-Mega, Besançon, France), or Hedström files (Dentsply Maillefer). Roots were then sectioned 3, 6, and 9 mm from the apex and observed under a microscope. The presence of dentinal defects was noted. Chi-square tests were performed to compare the incidence of dentinal defects between the groups. A Pearson correlation test was performed to check the correlation between defects and root level or remaining dentin thickness.


RESULTS
No defects were observed in the unprepared group. Dentinal defects were detected in all retreatment groups. Retreatment groups showed significantly more defects than the filled but no retreatment group (P < .05). There was no significant difference in the occurrence of defects between retreatment groups (P > .05). There was no correlation between the appearance of defects and level of the root or remaining dentin thickness.


CONCLUSIONS
Under the experimental conditions, all retreatment techniques used in this study created defects in the root dentin.
Department of Endodontics, Faculty of Dentistry, Erciyes University, Kayseri, Turkey. Electronic address: topcuogluhs@hotmail.com.
Hüseyin Sinan
HS
Topçuoğlu
Department of Restorative Dentistry, Faculty of Dentistry, Erciyes University, Kayseri, Turkey.
Sezer
S
Demirbuga
Department of Endodontics, Faculty of Dentistry, Erciyes University, Kayseri, Turkey.
Öznur
Ö
Tuncay
Department of Restorative Dentistry, Faculty of Dentistry, Erciyes University, Kayseri, Turkey.
Kanşad
K
Pala
Department of Endodontics, Faculty of Dentistry, Katip Çelebi University, Izmir, Turkey.
Hakan
H
Arslan
Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey.
Ertuğrul
E
Karataş
D001641:Bicuspid / Q000293:injuries / Q000473:pathology; D003722:Dental Alloys / Q000737:chemistry*; D003786:Dental Pulp Cavity / Q000293:injuries* / Q000473:pathology; D003804:Dentin / Q000293:injuries* / Q000473:pathology; D004853:Epoxy Resins / Q000737:chemistry; D004867:Equipment Design; D006171:Gutta-Percha / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry*; D019233:Retreatment; D012387:Root Canal Filling Materials / Q000737:chemistry*; D018915:Root Canal Preparation / Q000009:adverse effects / Q000295:instrumentation*; D014025:Titanium / Q000737:chemistry*; D019227:Tooth Apex / Q000293:injuries / Q000473:pathology; D014082:Tooth Fractures / Q000209:etiology; D019415:Torque
D003722:Dental Alloys; D004853:Epoxy Resins; D012387:Root Canal Filling Materials; C534916:epoxy resin-based root canal sealer; C040654:titanium nickelide; D009532:Nickel; D006171:Gutta-Percha; D014025:Titanium
Defect; retreatment; root canal