Success Rates for Removing or Bypassing Fractured Instruments: A Prospective Clinical Study
Giselle Nevares, DDS, MSc,* Rodrigo Sanches Cunha, DDS, MSc, PhD,†
Ma rio Luis Zuolo, DDS, MSc,‡ and Carlos Eduardo da Silveira Bueno, DDS, MSc, PhD§
Introduction: The objective of this study was to eval-
uate the success rates of standardized techniques for
removing or bypassing fractured instruments from root
canals and determine whether visualization of the
fractured instrument with the aid of an operating micro-
scope has any impact on the success rates. Methods: In
this prospective study, attempts were made to visualize
112 fractured instruments under a dental operating
microscope after creating a straight-line access to the
fragment. By using ultrasonic tips alone or associated
with bypassing, the Ruddle technique was attempted
to remove the 68 visible instruments. Bypassing was
performed for the 44 nonvisible fragments. The c2 test
was performed to assess whether any significant differ-
ence occurred between the success rates observed for
the visible and nonvisible fractured instrument groups.
Results: The overall success rate (removal and by-
passing) was 70.5% (n = 79). In the visible fragment
group, the success rate was 85.3% (n = 58), and in
the nonvisible fragment group it was 47.7% (n = 21).
Success rates were significantly higher when the frag-
ment was visible (P = .0009). Conclusions: The stan-
dardized techniques used in this study for removing or
bypassing fractured instruments were effective, and
approximately 2 times greater success rate was ob-
tained when the fragment was visible inside the root
canal compared with when it was non visible.
(J Endod
2012;38:442–444)
Key Words
Bypassing, fractured instrument, instrument removal,
operating microscope, ultrasonics
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