The intriguing tale of an iatrogenic perforation

INTRODUCTION

Endodontic therapy or root canal therapy is a sequence of treatment for the pulp of a tooth which results in the elimination of infection and protection of the decontaminated tooth from future microbial invasion. Poveda et al has said thatin satisfactory obturation of the root canal, the filling material and the endodontic instruments should not extend to periapical tissues or other neighbouring structures.¹ Although more than a half of the overfilled teeth heal satisfactorily after proper endodontic therapy, in some cases, it can lead to foreign body reaction in the connective tissue. One of the complications of root canal therapy, which has a negative effect on prognosis for the endodontically treated teeth is the accidental perforations of the root canal Perforations are one of the most detrimental consequences of root canal therapy, because it may result in recurrent pain, sinus tract formation, foreign body reaction to the material extruded through the perforation and in some instances, the development of endoperio lesions due to the formation of an iatrogenic pathway of communication between the pulp and periodontium. The simultaneous involvement of periodontal tissues can complicate diagnosis and treatment planning. Pulpal and periodontal problems are responsible for more than 50% of tooth mortality.²

A careful approach will help in prevention of these complications during the endodontic procedures and a systematic approach must be undertaken to manage the complications, should the endodontic therapy produce an injury.

The first step in the management of an endodontic mishap and the subsequent complications is the identification of the problem. Visual examination, fistula tracking in the presence of a sinus tract, palpation, percussion, probing and radiographic examinations are some of the modalities that help in diagnosis. Based on the diagnosis, the treatment protocol would be decided. If an endodontic retreatment is required, it will be done as the first measure to allow for healing to take place. In the presence of involvement of the tissues of periodontium, the periodontal measures would be undertaken on the basis of the clinical and radiographic findings.

This case report gives an account of a lateral perforation on a canine tooth and the management strategy under the circumstances. It also gives an overview of some of possible approaches to prevent iatrogenic perforations.

CASE REPORT

A 26-year-old female patient reported to the Department of Conservative Dentistry and Endodontics, DAPMRV Dental College, Bangalore, with a complaint of intermittent pain in an endodontically treated tooth in the upper front region. The patient had been experiencing the symptoms intermittently ever since the endodontic therapy was completed, which was 1 year prior to the time the patient reported to the Department.

Clinical examination revealed an endodontically treated upper right canine tooth. There was tenderness on palpating the mucosa covering the roots and apices. The tooth was tender on percussion. Radiograph of the tooth showed a rarefaction on the mesial aspect of the tooth suggestive of a bone loss in the area.

A re-treatment of the root canal was decided and initiated. The endodontic access was reopened through the existing post endodontic restoration. Previous gutta percha filling was removed using Hedstrom files in conjunction with Endosolv-E. A radiograph taken to ensure complete removal of gutta percha showed the complete outline of prepared root canal However, on the mesial aspect, the outline of the root canal was uneven in the region of the junction of the cervical third and the middle third of the root and the outline extended till the lamina dura. It was suggestive of an over preparation in the area and probable perforation.Working length was determined radiographically and canal preparation was accomplished in a circumferential filing motion using H files while irrigating with copious amount of 1% sodium hypochlorite. This was followed by irrigation with normal saline to remove any remnants of hypochlorite. The canal was dried with absorbent paper points and obturated using the TP guttapercha (Calamus). Care was taken to avoid undue pressure during the lateral condensation. Post procedure radiograph showed adequate root fill with no extrusion of the material through the perforation (Fig 1).

Following the endodontic re-treatment, it was deemed prudent to reflect a full thickness mucoperiosteal flap in the region to confirm and explore the extent of the perforation and to treat the bone defect, if present, by using an appropriate technique. After administration of LA, a sulcular incision was given extending from the distal line angle of 12 to the mesial line angle of 14. Vertical incisions were then given at the end points of the sulcular incision extending into the alveolar mucosa and a full thickness mucoperiosteal flap was reflected. It was seen that, approximately in the region of the junction of the cervical and middle third of the mesial aspect of the root of the canine, the buccal cortical plate and the underlying cancellous bone had been resorbed and replaced with granulation tissue. The granulation tissue was curetted out to reveal the bone defect (Fig 2). The defect was then filled with Novabone® putty graft material (Fig 3, Fig 4). The flap was repositioned and stabilized with direct interrupted sutures (Fig 5). After 10 days, the sutures were removed. The patient was given oral hygiene instructions and was advised to maintain good oral hygiene.

At 3 months recall, the patient was asymptomatic. There was no tenderness on palpation at the site and the tooth was no longer tender on percussion.

DISCUSSION

Iatrogenic root perforations are the second most common reason for endodontic failure.³ In a study by Kvinnslandet al, it was shown that the maxillary canine was the most frequently perforated tooth, followed by the lateral incisor, and then with about equal frequency the central incisors, premolars and first molar teeth. However, the reason behind the increased frequency of perforation of canines was difficult to fathom.⁴ Kvinnslandet al4 said that in the maxillary anterior teeth, all perforations occurred on the labial aspect of the roots and were due to deficiencies in access extension.

Underestimation of the palatal inclination of the roots of the teeth in the upper jaw has been considered as another cause of perforation.⁴ The operator should have an in depth knowledge of the anatomy of the tooth in question and its orientation intraorally to prevent inadvertent perforations. This should be supplemented with clear pre-operative radiographs with multiple angled radiographic views of the tooth.⁵

It has been suggested that by taking a more incisal starting point in the access preparation on all anterior teeth, the potential for a buccal perforation will be reduced, more tooth structure will be retained, and it will also facilitate true straight line access, improving the quality of the root treatment and facilitate the post space preparation if and when required.⁵

The use of some form of illumination and magnification would enable the operator to differentiate between the root dentine, the floor of the pulp chamber and calcified deposits within the pulp chamber, thereby reducing the risk of perforation in calcified canals.⁵

The use excessively large instruments to prepare the coronal two thirds of the root system should be avoided and the use of rotary nickel titanium instruments for canal preparation should be advocated.⁵

If a root perforation does occur, meticulous treatment of the defect would help in salvaging the tooth. In the present case report, a retreatment was done using the TP Gutta Percha. The thermoplasticized Gutta Percha has been used to allow for the material to flow into the uneven root canal space. In a study by Michelotto et al, it was seen that the best values of penetration in lateral canals in the middle third occurred in the groups where TP gutta-percha was used.

Following the endodontic re-treatment, the mucoperiosteal flap was reflected; the bone defect was packed with Novabone® putty graft material NovaBone® Putty is an osteoconductive bioactive device used for grafting osseous defects. It is a premixed composite of bioactive calcium-phosphosilicate particulate and a synthetic, absorbable binder. The bioactive particulate is composed solely of elements that exist naturally in normal bone (Ca, P, Na, Si, O). The absorbable binder is a combination of polyethylene glycol and glycerin. The device requires no mixing or preparation prior to application. The non-hardening putty is supplied ready-to-use, to be applied directly to the intended graft site. The binder is then absorbed from the site such that only the bioactive particulate remains. Upon absorption of the binder, the particulate material remaining undergoes a time-dependent kinetic modification of the surface that occurs when implanted in living tissue. Specifically, a series of surface reactions results in the formation of a calcium phosphate layer on the particles that is substantially equivalent in composition and structure to the hydroxyapatite found in bone mineral This apatite layer provides scaffolding onto which the patient’s new bone will grow allowing complete repair of the defect. Studies have shown that Novabone® putty has an excellent potential for osseous tissue formation.⁷ A radiographic examination after 6- 9 months of treatment, might be helpful in assessing the potential of the graft material to form osseous tissue.

CONCLUSION

Although complications during endodontic therapy cannot be completely eliminated, a thorough knowledge of the anatomy of the tooth, combined with the use of appropriate techniques can help in reducing the problem considerably. However, if a problem does occur, a scrupulous management would facilitate rescuing the tooth. Timely diagnosis and fabrication of a specific treatment protocol is the primary requisite. Nevertheless, prevention is always better than cure, and hence care must be taken to perform endodontic therapy uncomplicated by endodontic mishaps.