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12 Dental Tribune United Kingdom Edition | 7/2016 TRENDS & APPLICATIONS Use of operating microscopy, ultrasound and MTA in periapical microsurgery Treatment of a persistent endodontic infection By Prof. Leandro A.P. Pereira, Brazil In most cases, pulpal and periapical pathologies are caused by intra- canal infections and their initial treatment is by conventional en- dodontic treatment. In cases of teeth without apical periodontitis, the success rate is approximately 98 per cent. If apical periodontitis and primary infections (which may be of bacterial or non-bacterial ori- gin)1 occur, this rate is reduced to 86 per cent.2 Endodontic failure is usually associated with technical limitations that prevent adequate intra-canal microbial control in the complex internal microanatomy of the root canal system.3 The treatment recommended for cases of primary endodontic infections is endodontic retreat- ment, which has a success rate of approximately 83 per cent.4 Thus, even after the endodontic retreat- ment, owing to the factors of complex internal microanatomy, the failure may persist. In these clinical situations, apical micro- surgery has been proven to be an alternative for the clinical treat- ment of these infections. Various technological ad- vances in the area of apical micro- surgery have occurred in recent years. A very important triad has been established for achieving high success rates, consisting of the use of operating microscopy, ultrasound and mineral trioxide aggregate (MTA). When periapical microsurgery is performed tradi- tionally, without the use of mi- croscopy, ultrasound and MTA— that is, in the macro-surgical form—its success rate does not ex- ceed60percent.5–8 However,when performed with the contempo- rary technique of microsurgery, its success rate is over 90 per cent.6, 9–13 This evolution has made microsurgical endodontic treat- ment a more viable clinical proce- dure with greater predictability. Clinical case A 42-year-old female patient presented at our clinic with spon- taneous pain resulting from api- cal periodontitis around tooth #36. The last endodontic re- treatment had been performed 19 months before. During the semio-technical examination, a negative response to pain was ob- served in the palpation, and verti- cal and horizontal percussion tests. Thermal and electric pulpal tests of tooth #36 obtained no response. Responses of the neigh- bouring teeth were normal. On the radiograph, we detected a metal–ceramic prosthetic crown functioning within acceptable standards, as well as a cast metal intra-radicular retainer. Overall, this was a satisfactory endodontic treatment with good shaping and good obturation. However, tooth #36 showed apical periodontitis (Figs. 1–3) and the preoperative CBCT scan showed fracture of the vestibular cortical bone (Fig. 4). The proposed treatment was endodontic micro- surgery aimed at endodontic ret- rograde retreatment. In this thera- peutic situation, the prosthetic crown and the intra-radicular re- tainer would be kept; there was no need for new prosthetic rehab- ilitation. After the evaluation of all the advantages, disadvantages and risks, the endodontic micro- surgical treatment was per- formed. One hour before the micro- surgical procedure, 4 mg of dexa- methasone was administered orally for the purpose of pre- emptive analgesia.14 The control of peroperative anxiety was accom- plished through conscious inhala- tion sedation with a nitrous oxide and oxygen mixture at a ratio of 65 per cent to 35 per cent and a minute volume of 6.5 l/min. As anaesthetic solution, 5.4 ml of 2percentlidocainewith1:100,000 epinephrine was used, with 1.8 ml each of the solution administered through the traditional technique toblocktheinferioralveolarnerve and the buccal nerve. Another 1.8 ml of the same solution was in- filtrated between the gingivae and mucosa. After anaesthesia was estab- lished, the papillae-based incision was made, followed by a vertical relaxing incision. Using a micro- syndesmotome, the syndesmot- omy was performed smoothly to prevent damage to the soft-tissue structures (Fig. 5). The fracture of the vestibular cortical bone was treated using piezo-osteotomy with an ultrasonic tip (ST3 Bone Surgery Tip, Vista Dental) at full power. The osteo- tomy exposed the entire periapical lesion (Fig. 6). Subsequently, apical curettage was performed (Fig. 7). The apicectomy was also per- formed using a piezo-electric ul- trasonic system with a W7 ultra- sonic tip (CVDentus) at a power of 80 per cent and under copious irri- gation with a sterile saline solution (Fig. 8). The apex was cut at an angle perpendicular to the long axis of the root to allow for removal of possible ramifications of canals lo- cated to both the vestibular and lingual directions. After the api- cectomy of the medial root, it was possible to observe an infected api- cal region of the mesial canal, which had not been cleaned and shaped (Fig. 9). With a retro-mirror, an isthmus was found connecting the vestibular mesial canal to the lingual mesial (Fig. 10). This isth- mus had not been shaped and dis- infected by the conventional endo- dontic preparation owing to the limitations inherent in the kine- matics and design of the endodon- tic instruments and the auxiliary irrigant chemicals. These poorly cleaned and shaped areas of the ca- nals were identified as the possible cause of the apical periodontitis. Using JETip JT-1 ultrasonic tips (B&LBiotech),theretrogradeprepa- ration was performed, adjusting the ultrasonic power to 30 per cent and under irrigation with a sterile saline solution. The quality of the retrograde preparation was evaluated with a surgical mi- cro-mirror (Fig. 11). The isthmus of the medial root was cleaned using these ultrasonic tips with move- ments in the vestibular-lingual ” Page 14 1 2 4 3 5 6 7 9 10 8 11 Fig. 1: Initial radiograph.—Fig. 2: Initial radiograph.—Fig. 3: Pre-op clinical photograph.—Fig. 4: Pre-op CBCT scan.—Fig. 5: Flap design.—Fig. 6: Piezo-osteotomy.— Fig. 7: Osteotomy.—Fig. 8: Apical resection.—Fig. 9: Missed anatomy.—Fig. 10: Isthmus.—Fig. 11: Retrograde preparation. 12 67 910