Studies have shown that root canal fillings alone never offer a reliable seal, regardless of the material or technique employed. For this reason, the importance of an effective post-endodontic seal for the long-term prognosis of an endodontically treated tooth is similar to that of the endodontic treatment itself: The success rate of even a good root canal obturation is massively reduced if the seal is poor and insufficient.
If a root canal filling is exposed to the oral environment for more than three months, one must expect it to be infected throughout. This situation is not all that uncommon in everyday practice, as core restorations, fillings or crowns may develop leakage. If the affected teeth are subsequently re-treated, they will often develop apical lesions, or existing apical lesions may fail to heal. Health insurance guidelines that preclude immediate post-endodontic restorative treatment unintentionally aggravate the problem.
The Dentsply Endo-Resto System facilitates cleaning of the endodontic cavity following root canal treatment. The AH Plus Cleaner removes all excess AH Plus sealer. In a second step, the cavity floor and walls are lined with a thin-flowing composite resin (SDR) for a complete anti-bacterial seal. This article describes how this was implemented in a specific clinical re-treatment case.
A 32-year-old man in general good health presented with minor complaints emanating from tooth 46. He had sought emergency dental help the previous weekend due to increasing occlusal pain in the right mandible. The emergency dentist had prescribed an antibiotic and recommended to have the tooth removed or an apicoectomy to be performed.
At the time of presentation, the complaints had largely subsided. The patient reported having noted a sensation of pressure on previous occasions, at times accompanied by a bad taste. The root canal treatment for this tooth had been performed many years previously, while the crown restoration had been delivered only three or four years ago (fig 1).
An intraoral fistula was found at site 46. The tooth was slightly tender to percussion. Pocket depth was between 2-4mm. The tooth was not mobile and showed incipient grade I furcation involvement. Radiographs showed an insufficiently endodontically treated tooth 46 with a pronounced peri-radicular translucency, primarily around the distal root, and in incipient interradicular translucency. In addition to three treated root canals that were underfilled, it was suspected that a fourth canal was present (fig 2).
The patient was advised of the possibilities associated with revision surgery as well as of alternative treatment modes (extraction followed by bridge or implant treatment). The patient was very keen on preserving the tooth and opted for revision surgery.
With the rubber dam placed, the metal-ceramic crown was trephined. The pulp cavity exhibited a greasy gangrenous mass mixed with sealer and excess gutta-percha from the old root canal filling, accompanied by fetor (fig 3). After cleaning and rinsing with NaClO, it was found that four root canal orifices were in fact present. The distal lingual canal had not been treated. The old root canal filling material was removed completely. All four canals could be instrumented up to the apical constriction and were prepared in a hybrid technique using manual files and the ProTaper system (fig 4). This was followed by sonic NaClO rinses and application of a calcium hydroxide medical root canal dressing. The access cavity was adhesively sealed (Cavit, XP Bond, SDR). Six weeks later, the patient, by now pain-free, presented for placement of the new root canal filling. He reported that the fistula had disappeared as soon as three days after the previous treatment.
A rubber dam was once again placed and the adhesive seal removed. This was followed by another extensive sonic rinse (EndoActivator) with NaClO, EDTA and CHX and subsequent drying of the canals. The filling material was introduced thermoplastically using vertical compaction with gutta-percha and AH Plus. During a radiological inspection of the root canal filling (fig 5), it was noted that the periapical and interradicular translucencies had already subsided somewhat.
Following the radiological control of the root canal filling, the gutta-percha in all four canals was cut off slightly below the orifice, making sure that no residual gutta-percha remained on the cavity floor or walls (fig 6).
Using small foam rubber pellets (Roeko Endo Frost Pellets) soaked in AH Plus Cleaner, the entire cavity was cleaned from sealer residue. AH Plus Cleaner was developed specifically for the removal of AH Plus. The cleaning procedure was repeated until the milky-white layer had disappeared, followed by a thorough rinse with water spray. The floor of the pulp cavity and the trephined access cavity were then etched with phosphoric acid (DeTrey Conditioner 36) for 15 seconds. Another rinse was performed to ensure that the etch gel was removed completely. After drying, XP Bond was introduced with an applicator, allowed to soak for 20 seconds and then air-thinned for approximately five seconds. While no excess liquid should remain in the cavity, the dentine should not be excessively dry, either. The XP Bond was then light-cured for 10 seconds. The next step was the application of a thin layer of SDR. The first layer was polymerised with a curing lamp for 20 seconds.
The Endo-Resto System provides a useful match of endodontic and post-endodontic components. From a clinical point of view, I appreciate that the immediate adhesive seal of the endodontic cavity renders reinfection or microleakage less likely. Furcal accessory canals in molars such as those frequently seen in younger patients are also sealed effectively. Finally, tooth stability, which is compromised by the endodontic access cavity and reduced by approximately 60 per cent, is increased because the adhesive chemical bond between the SDR, the capping (composite resin) and the tooth has a stabilising effect. None of these positive effects can be achieved with non-adhesive sealer such as cements.
Cavit is a registered trademark of 3M Espe.
References available on request.