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June 2003 – No Room for Error
A 75 year old male patient arrived in my office with a history percussion sensitivity in this mandibular right first molar. The tooth had been restored with a very old crown restoration that was still serviceable. It also appeared to be periodontally involved. The furca was completely open from buccal to lingual ( no soft tissue coverage at all) but the patient was doing an excellent job of hygiene in the area with a Proxabrush. The tooth was not mobile and the patient wanted to keep the tooth as is. Therefore, rather than doing a hemisection and new separate crown restorations, we decide to keep the crown and try to do endo through it. Fig.1
Before starting, I was a bit concerned about the “leeway” I had to try to find the mesial orifices. Making access through the crown one or two mms in the wrong direction could easily result in a furca perforation or perforation out the mesial crown margin. This case would have been almost impossible to do without a surgical operating microscope.
I find the distal canal easily. (Fig.2) Initially there is some drainage but not much. I finish shaping it with Protapers to size 30. 45 minutes later I finally find the ML canal but can only access it part of the way. At that point ( even with a scope) I can’t locate the MB orifice. Fatigue sets in, I decide I need a “new pair of eyes” and I place CaOH in the D canal and ML canal access – I close the tooth . KaBOOM! The tooth blows up 24 hrs later. I surmise that I must have pushed stuff out the distal canal during instrumentation. Patient is placed on Clindamycin 150 mg tid and responds well. After a weekend, his swelling comes down.
He arrived a few days later, asymptomatic with no swelling. I placed the dam and looked further for the MB. I traced the groove running from the ML under high magnification. With a Carr Diamond tip I detect just a hint of a MB canal orifice. I attempt to place couple of size .06s in the mesial canals and they are tight but they seem to be fairly close to working length.(Fig.3) They appear to join at the apex. The canal constriction is at the coronal aspect so I decide to work the body first. This will allow less obstructed access to the apex. However, I must be careful not to enlarge the mesialfurcal midroot too much, as strip perforation can occur fairly quickly, even with minimal attempts at instrumentation.
I finish shaping the mesial canals conservatively ( Minimal or No GGs on those canals !!) Protapers are used in sequence with final instruments of F1 to apex and F2 and F3 short of WL. Now its time to obturate with System "S" ! Careful canal drying, Minimal sealer, Obtura injected Schwed Normal Flow Gutta Percha applied with vertical plugger pressure and voila!
Fig. 5 - Mesial Shift Shot
Composite is placed in the access and I’m done. Dentin conserved. Crown salvaged and I have one happy patient.