Dr Denzil Albuquerque and Dr Jojo Kottoor discuss the management and prevention of endodontic perforations to increase the success rate of root canal treatment.
Tooth perforation is an artificial communication between the root canal system and the supporting tissues of teeth or to the oral cavity. They can either occur accidentally or due to pathologic causes like resorptions or caries. Accidental root perforations do occur in approximately 2–12% of endodontically treated teeth that might have serious implications.
Perforations occurring during root canal therapy may account for as many as 10% of all failed endodontic cases. In multi-rooted teeth, furcation perforations may occur whilst searching for the canal orifices, as dentin is removed from the pulpal floor. Misidentification of orifices or canals and routine endodontic causes (47%) along with over-zealous post space preparation (53%) are other common causes.
The biologic response of a perforated tooth is inflammatory and can cause a breakdown of the osseous and peri-radicular tissues. This perforation acts as an open channel encouraging bacterial entry either from root canal or periodontal tissues or both eliciting inflammatory response that results in fistula including bone resorptive processes may follow. When perforation occurs laterally or in furcation area there might be over growth of gingival epithelium towards the perforation site.
There are only two options in managing perforations, repair via a coronal approach or surgically, or else extraction. If a tooth is restorable, then visibility and access to the perforation site determine treatment success.
A 40-year-old patient was referred by a dentist who encountered a bleeding point in a previously root canal treated tooth. The patient complained of mild, intermittent pain with her right mandibular first molar.
Clinically, the tooth had a temporary occlusal filling and was tender to percussion and palpation. The gingiva had mild recession with furcal probing on the buccal. A pre-operative x-ray and clinical exploration showed a bur-hole size furcal perforation along with thinning of the dentin on the pulpal floor. The radiograph confirmed an inadequate previously done root canal treatment and persistent apical periodontitis with both roots apices.
Root canal retreatment was completed in a single visit. Key emphasis was placed on irrigation with 5% sodium hypochlorite and passive ultrasonic activation (PUI) followed by heated obturation to obtain a hermetic seal up to working length.
The furcal perforation was cleaned of any inflamed or granulation tissue, the dentin defect was smoothened out using slow speed burs and then filled with white mineral trioxide aggregate (MTA), (ProRoot MTA, DentsplySirona). The MTA was then immediately covered with a layer of resin-modified glass ionomer cement (Fuji, GC) followed by composite resin (Empress, Ivoclar). The patient was then referred back to the referring dentist for a bonded coronal restoration and was advised regular follow-up.
The best treatment for any complication is prevention. For instance, hasty and impatient work or inappropriate patient scheduling is avoidable. Sound knowledge and understanding of the internal and external tooth anatomy along with multiple angulated pre-operative radiographs add clarity and allow for improved planning before the procedure.
Possessing the right tools and equipment and using them appropriately; like accurate bur orientation, slower speed, safe ended burs, measured depth of penetration are important factors in uneventful endodontics. Recognising change in handpiece angulation and thus access orientation due to restricted mouth opening or by the bow of rubber dam clamps is crucial.
Use of magnification, adequate illumination, ultrasonics and long shank burs provide enhanced visualisation and thus better control. Negotiating calcified pulp chambers should be done with caution especially for completely attached pulp stones. Visualising the pulpal floor aided with magnification will prevent misidentification of orifices or canals. Using non-diamond rotary drills at slow speed and respecting canal and root dimensions will prevent perforations during post space preparation.
The first sign of a perforation is sudden, profuse uncontrolled bleeding possibly accompanied with pain. Bleeding can be controlled by pressure or hypochlorite-soaked cotton pellets on the pulpal floor, or paper points or calcium hydroxide within canals.
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