Steven Lipner

NE OF THE CHALLENGES in root canal therapy is the severely curved canal. Cases involving these canals present the practitioner with many possible iatrogenic complications, including canal transportation, canal perforation, and instrument separation. If not handled with the utmost care and finesse, these cases can quickly transform from difficult to nearly impossible—necessitating surgical intervention in the form of an apicoectomy or extraction.
    A sixty-year-old female patient presented to the office with the chief complaint of severe pain on tooth #19. Root canal therapy had been performed on tooth #19 approximately thirty years earlier. The root canal therapy was poorly done, yet the tooth had remained asymptomatic until presently. The patient currently stated that she had not slept in two days and was in agony.
    The first step in negotiating a highly curved canal is paying close attention to the pre-op radiograph. In this case, the radiograph was highly suggestive of a c-shaped canal system. As I discussed in “C-Shaped Canals” (Endo-Mail January–March 2009), when the clinician encounters a c-shaped canal system, aberrant apical anatomy should always be presumed to exist. When one expects these sharp apical curvatures, blocking oneself out or ledging becomes much less likely.
    Upon accessing the tooth, I noted the c-shaped anatomy. I removed the old gutta percha fillings, using Gates Glidden drills. Once I had flared the coronal two-thirds of the canal, getting a feel for the apical anatomy became much easier. The reamer does not bind in the coronal dentin, making tactile perception of the apical anatomy more reliable. In this particular case, I placed varying bends on #10 reamers in an attempt to detect a “catch.” Once I had identified a “catch” with the #10 reamer, I pushed the reamer 1 mm past the constriction and attached it to the reciprocating handpiece. I ran the handpiece for about 10 seconds, and gradually increased the amplitude of the coronal-to-apical motion. I repeated this sequence up to a #25 SafeSiders® reamer. I then placed a bend on a 25/.06 NiTi reamer. Because nickel titanium has shape memory, retaining a curve on the reamer is more difficult. As a result, the clinician must use more force than is customary when bending stainless steel. After negotiating the 25/.06 NiTi reamer to the severe distal curvature of the mesial canal, I employed a series of short push-pull strokes. I applied a calcium hydroxide paste to the canals between visits.
    When the patient presented a week later for the second visit, her symptoms had subsided and she was feeling great. A large portion of this visit was spent in ultrasonic activation of irrigants. I will post the six-month follow-up when the patient returns.
 

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