They informed there is no difference between the applications after 1 month. Besides, Boutsioukis et al26 reported that MTA was difficult to be removed when it was used along the whole root canal. Bortoluzzi et al27 also informed that grey MTA applied in the coronal customer review region of the root canal caused discoloration. Consequently, it seems it may be more appropriate to fill the only apical part of the root canal with MTA. When the MTA is filled as 5 mm apically, if the treatment goes to failure and root-end resection had to be performed after the treatment, no retrograde filling would have to be placed at the time of surgery.28 Healing of periapical lesions is a dynamic event and its duration changes from case to case.

Longterm observation, especially a length of six years, is an important time for the assessment of the quality and reliability of materials or techniques. There have been studies that have been followed for up to 27 years.29 However, Ingle30 based a follow-up period of 2 years for evaluating whether a treatment is successful or not. The follow-up period in the literature for MTA applications were generally applied only one or two years in different studies.31,32 We observed the patients for six years. The present case report is the first of its kind in which MTA is used clinically and followed up for six years using an apical filling material for root canal treatment of teeth with large periapical lesions. CONCLUSIONS The use of MTA in the treatment of large periapical lesion is not a routine application; however, MTA positively affected the healing of the teeth with the lesion after 6 years so it may be concluded that it can be used clinically in the treatment of the teeth with large periapical lesion.

These results may lead the way for further studies in this field. Further researches are needed to evaluate the use of MTA in the root canal.
Periodontitis, an oral infectious disease, is characterized by clinical attachment loss, alveolar bone resorption, periodontal pocket formation, and gingival inflammation.1,2 One of the main objectives of periodontal therapy is regeneration of the periodontium, including restoration of the alveolar bone, cementum, and periodontal ligament lost because of periodontitis.

3,4 Periodontal regeneration can be achieved by guided tissue regeneration (GTR),4 which delays the apical migration of the gingival epithelium by excluding Batimastat the gingival connective tissue and allows granulation tissue derived from the periodontal ligament and osseous tissues to repopulate the space adjacent to the denuded root surface through the use of barrier membranes.5 New connective tissue attachment and bone fill, and improved clinical parameters have been documented in human biopsy6,7 and clinical GTR studies,8,9 respectively. Bone grafting procedures with autogenous bone grafts, allografts, xenografts, and alloplasts are also used to promote periodontal regeneration.