The EndoExperience - Not What You Expected

Case of the Month

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September 2002 – A Tricky Mandibular Molar Treated with Ni-Ti Rotary

Fig. 1 - Prior to access	September's case of the month (Fig. 1) shows a mandibular first molar that had presented with symptoms of irreversible pulpitis. The referring dentist made access to the pulp chamber and removed some of the tissue in the distal canal . He insisted that the case was vital upon access.

Fig. 2 - Tooth as it presented for treatment	Two months later, the patient presented in my office with buccal gingival; swelling and a probeable Cl 2 (+) furca involvement. The root anatomy was also unusual in that the apical portion of the mesial root was severely curved while the furca portion of the root was extremely thin. There was some question as to whether the furca involvement was as a result of a subsequent mesial- distal fracture. Instrumentation of the mesial root would be challenging.

Fig. 3 - mesial Working Lengths	After negotiating the apex with small files, copious irrigation and patience, two #15 stainless steel S files confirmed working length had been achieved. The challenge at this point was to maintain apical patency while not straightening the canal or stripping the furca through excess removal of dentin on the distal side of the mesial root. This was accomplished by using Ni-Ti rotary instrumentation ( Tulsa GT ProFiles .20 mm - tapers .1,.08, .06 and .04.

Fig 4. - Gutta Percha Cone Fit/Sealer	Figure 4 shows the gutta cone fits ( Kerr AutoFit GP) with a very small amount of sealer, only at the very tip of the cones. Since the Gutta Percha cones match the taper of the instruments, it is possible to get very good adaptation of the cones to the prepared canal space, with a minimum of voids. This allows for better compression during obturation.

Fig. 5 - Final Film	Figure 5 shows the final result. Not only did we fill to the apical foramen, we also filled an important accessory canal in the furca area. Once this accessory canal was filled, the story behind the furcal involvement became clearer. The referring dentist had originally made access into a vital pulp. During the next two months, the mesial canal contents became necrotic and leaked out of the accessory canal into the furca. This created the CL II furca involvement that was caused by a lesion of endodontic origin .

Over the next few months we can expect the furcal radiolucency to resolve and with it retrun of the attachment apparatus to normal. Bone fill should occur. I suggested to the restoring dentist that an interim restoration should be placed that allows us to monitor the area for 6 months while at the same time protecting the tooth against fracture or recontamination of the canal space.

It is unlikely that this kind of case could have been properly treated without the use of Ni-Ti rotary instruments. By using these flexible instruments, we preserved the dentin of the mesial root while at the same time properly shaping the case. Attempting to negotiate this canal with a "Push Pull file technique or a serial hand file reaming technique, it is likely that the canal would have either been straightened or the canal walls thinned. In order for us to use LESS flexible stainless steel instruments in the deeper portions of the canal space, it is likely that thinning or stripping of the mesial root would have occurred, causing a strip perforation.