Influence of instrument taper on the resistance to fracture of endodontically treated roots.
OBJECTIVE
The aim was to compare the force required to fracture uninstrumented and instrumented canines and to investigate the root-reinforcing capability of AH Plus sealer.


METHODS
In groups 1-3 (n = 24) canals were instrumented with either GT files, FlexMaster, or stainless steel hand instruments. Twelve teeth from each group were obturated with lateral compaction using gutta-percha and AH Plus. Group 4 (n = 12) acted as uninstrumented controls. The force required to fracture the roots was measured. ANOVA, Scheffé, and t test were used for statistical analysis.


RESULTS
The intact roots were significantly stronger than all groups with instrumented and unobturated roots (P < .05). Roots enlarged with GT files were significantly weaker (P < .05) than those instrumented with FlexMaster or hand instruments. Between the obturated and unobturated roots there were no significant differences (P > .05).


CONCLUSIONS
The roots were significantly weakened by the preparation with greater taper instruments. An obturation with AH Plus did not increase the fracture resistance.
Zandbiglari
Tannaz
T
Department of Operative Dentistry, University of Münster, Münster, Germany.
Davids
Hendrik
H
Schäfer
Edgar
E
D003481:Cuspid; D003722:Dental Alloys; D003762:Dental Instruments; D003799:Dental Stress Analysis; D004853:Epoxy Resins; D004867:Equipment Design; D006171:Gutta-Percha; D006801:Humans; D009532:Nickel; D012387:Root Canal Filling Materials; D018915:Root Canal Preparation / Q000009:adverse effects / Q000295:instrumentation*; D013193:Stainless Steel; D014025:Titanium; D014082:Tooth Fractures / Q000209:etiology / Q000517:prevention & control*; D014092:Tooth Root / Q000293:injuries
D003722:Dental Alloys; D004853:Epoxy Resins; D012387:Root Canal Filling Materials; C534916:epoxy resin-based root canal sealer; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D006171:Gutta-Percha; D014025:Titanium