Summary

Despite the high rate of success in the treatment of peri-apical disease with conventional endodontics, failures may occur. Such unfavourable results may be reversed by standard retreatment, tooth extraction or microsur-gery. With a rate of positive outcomes of above 90%, endodontic microsurgery is a therapeutic alternative to be considered for the functional and aesthetic preserva-tion of teeth with recurrent periapical disease.

Introduction

Endodontic treatment has a high success rate. However, failure occurs. Conventional retreatment is commonly selected to deal with persistent periapical periodontitis and has an 83% success rate. However, with the growing use of microscopy associated with ultrasound and MTA (mineral trioxide aggregate), endodontic micro-surgery has evolved significantly and became a viable  alternative to conventional retreatment. The evolution of technique has improved the success rate from less than 60%5–8 to 90%.6, 7, 9–12 A success rate of less than 60% for the macro-surgical technique (no microscope and no ultrasound) does not define it as a viable option  for treating the complexity of periapical periodontitis.

Case presentation

A female patient, aged 64 and with an ASA I physical status (healthy), blood pressure of 125/85 mmHg, a heart rate of 61 bpm, oxygen saturation of 98%, a temperature of 36.5 °C and a weight of 69 kg, presented to the clinic on 28 November 2017 complaining about pain and swell-ing around teeth #26 and 27.

During examination, a buccal acute abscess was ob-served between these teeth, in the apical region. The patient reacted with light pain to tests of apical palpation and vertical percussion. The response to horizontal per-cussion was negative. Thermal and electrical pulp test results were negative for both teeth.

Radiographically, two porcelain-fused-to-gold crowns and two intra-radicular posts (probably glass fibre) pre-sented with correct adaptation. Endodontic treatment of both teeth was deficient, and periapical pathology could be observed (Fig. 1). Preoperative tomography revealed a buccal cortical bone rupture at the distobuccal root of tooth #26 and periapical disease in teeth #26 and 27 (Figs. 2 & 3).

Fig. 1: Radiographic view during first emergency consultation.

Fig. 2: Tomogram of the distobuccal root of tooth #26.

Fig. 3: Tomogram of the periapical lesion of tooth #27.

After careful analysis of all clinical and imaging data, the diagnosis was chronic periapical periodontitis of teeth #26 and 27 probably because of unsatisfactory root canal ther-apy. As an emergency procedure, the abscess was drained.

Two alternatives were considered to solve the case. The first would have involved removal of the crowns and posts with the purpose of providing access for standard re-treatment. Consequently, after root canal intervention, the posts and crowns would have had to have been re-built. The second was a microsurgical approach aimed at root canal retro-filling of both teeth. One major benefit of the latter would have been that the posts and crowns would not have had to have been removed. After detailed explanation of all advantages and compromises of the two options, endodontic microsurgery was selected. For personal reasons, the patient did not return until 8 April 2018 (Fig. 4), and surgery was scheduled for 4 June 2018.

Fig. 4: Pre-op radiograph.

Preoperative medication was 4 mg of oral dexamethasone for pre-emptive analgesics,13 1 hour before the procedure. Local anaesthesia was administered with 3.6 ml of 4% artic-aine and 1:100,000 adrenaline: palatal infiltration of 0.9 ml and 2.7 ml at the site between the attached gingiva and buccal oral mucosa. After anaesthesia, two intrasulcular incisions were followed by a vertical releasing incision. Piezo-syndes-motomy was performed with an ultrasonic tip (PR1, mectron).

Because of the infection, the buccal cortical bone had already ruptured, which facilitated finding the apex of the distobuccal root of tooth #26. However, osteotomy was required to reach the apices of the buccal roots of tooth #27 and mesiobuccal root of tooth #26. Piezo-osteotomy was performed with the ultrasonic tips OT12 and OP7 (mectron) and exposed the entire lesion. For the api-cectomies, the ultrasonic piezoelectric system was also used (OT12 tip). All apices were cut perpendicular to the long axis of the roots to completely remove any possi-ble ramifications and branching of the root canal system.

With ultrasonic tips P1 and P1T (Helse Ultrasonic), the retro- preparation was performed. The root canals were retro-filled with Bio-C Repair (Angelus). Material insertion at the retro- cavity was facilitated by product consistency and its ready-to-use, premixed presentation. There was no need for specific instruments or applicators to fill the retro-cavity. With this step done, to avoid connective tissue growth into the osseous defect, the apical bone cavity was filled with surgical calcium sulphate (New Osteo, GMReis; Fig. 5). Postoperative images were obtained at baseline and at four months, when it was possible to observe complete bone repair (Figs. 6–12).

Fig. 5: Immediate post-op radiograph.

Fig. 6: Four-month post-op radiograph.

Fig. 7: Four-month post-op tomogram of tooth #27.

Fig. 8: Four-month post-op tomogram of the mesiobuccal root of tooth #27.

Fig. 9: Four-month post-op tomogram of the distobuccal root of tooth #27.

Fig. 10: Four-month post-op tomogram of tooth #26.

Fig. 11: Four-month post-op tomogram of the mesiobuccal root of tooth #26.

Fig. 12: Four-month post-op tomogram of the distobuccal root of tooth #26.

Discussion

The operating microscope, ultrasonic inserts and bio-active retro-filling materials, associated with technological and scientific advances, increased the positive outcomes of this type of treatment from 60% to over 90%.

Selection of the retro-filling material is essential for  success.14 Besides filling the site, the substance must protect the surgical wound, be radiopaque, bioco m-patible, impermeable, antimicrobial and osteocon-ductive, and behave optimally in moist environments. Products such as Cavit (3M ESPE), zinc oxide eugenol,  calcium hydroxide, amalgam, gutta-percha, tricalcium  phosphate and hydroxyapatite have been used to seal retro-cavities.15 However, none of them was able to re-establish the original architecture of the affected sites.

The introduction of bioactive sealers, such as MTA (the precursor of the bioceramic group), brought great prog-ress regarding sealing properties and biocompatibility. MTA presents the most desired features of a reparative substance: it is biocompatible with tissue and stimulates new formation of cementum, has outstanding behaviour in moist conditions, induces biomineralisation and pro-motes greater sealing than all other materials.

However, MTA has two inconveniences: handling and tooth staining. Both are no longer any trouble with the launch of a new generation of bioceramic products. These offer all the biological characteristics of MTA, but improved consistency and presentation too. Bio-C Repair  is an example of these new products that facilitate  clinical handling. It is premixed and ready to use, and its consistency enables easy shaping with a spatula, facil-itating cavity insertion. The other relevant feature is that Bio-C Repair does not stain the tooth or the surround-ing tissue.

Conclusion

The synergy of clinical microscopy and ultrasonic devices enables the execution of extremely precise treatments. Endodontic microsurgery, when performed according to modern concepts, is a remarkable therapeutic alterna-tive, being predictable and viable for the conservation of teeth with secondary or persistent periapical periodon-titis. A new generation of premixed bioceramic products simplifies retro-filling procedures and may elicit quicker and complete apical bone repair.