CASE REPORT/CLINICAL TECHNIQUESEvaluation of an Ultrasonic Technique to Remove Fractured Rotary Nickel-Titanium Endodontic Instruments from Root Canals: Clinical Cases
Section snippets
Instrument Removal Procedure
The technique used to attempt removal of the fractured instrument segment in each of these cases is an adaptation of the ultrasonic technique described by Ruddle (6) and reported in our previous study (7). This technique is recommended by the instructional video accompanying the Spartan piezoelectric ultrasonic unit.
Case 1
A 44-yr-old female was referred to the Endodontic Unit, Royal Dental Hospital of Melbourne, for the orthograde endodontic retreatment of her maxillary right first molar and endodontic assessment of the second premolar in the same quadrant. The first molar was asymptomatic with the radiograph showing root-filling material in only the distobuccal canal (Fig. 1A). On examination, the second premolar had a deficient distal restoration with recurrent caries. Extraction of the premolar was
DISCUSSION
Several studies have evaluated the influence of various factors on the fatigue life and resulting fracture of rotary nickel-titanium endodontic instruments. Instrument design, rotational speed, torque, operator proficiency, and the angle and radius of canal curvature all have been shown to influence failure of rotary nickel-titanium instruments (8, 9, 10).
Management of a case with a broken instrument may involve an orthograde or a surgical approach. The three orthograde approaches are: (a)
CONCLUSION
An ultrasonic technique using CPR tips combined with the creation of a “staging platform” using Gates Glidden instruments and the use of the dental operating microscope was consistently successful at removing fractured rotary nickel-titanium instruments from narrow, curved root canals when some part of the fractured instrument segment was located in the straight portion of the canal. When the fractured instrument segment was located entirely around the curve, care must be taken because the
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2021, Journal of EndodonticsCitation Excerpt :However, the individual time frame to remove an instrument will still vary greatly depending on various factors, such as tooth type and root, the location of the fragment in relation to the length and curvature of the canal, the patient’s mouth opening, and the operator’s experience and skills. Visualization and illumination of a fragment with a microscope plays a significant role for accurate placement of a vibrating tip using the BP preparation.19,20,27 A limitation of the BP technique is the inability to retrieve fragments that remain invisible beyond a curvature.9,36
Factors Affecting the Removal Time of Separated Instruments
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This study was supported by a grant from the School of Dental Science, The University of Melbourne, Australia.
The authors thank Mr. Lindsay Forrest (J. Morita Corporation, Pacific agents for Obtura-Spartan Corporation) for the use of the Spartan ultrasonic unit and a supply of CPR tips.