In the 21^st century, a new material called Mineral Trioxide Aggregate (MTA) has been introduced in dentistry. Its chemical basis is hydraulic calcium silicate, and it has three major characteristics: sealability, antibacterial effect, and bioactivity. In introduction, SEM study result will be presented about sealability, antibacterial effect and bioactivity. Many researchers’ view will be briefly referred.

In the clinical case report, multifaceted use of MTA and its rationale will be discussed.

In the Department of Oral and Maxillofacial Surgery, Gunma University Hospital, extensive radicular cysts are treated with a combination of complete excision, endodontic microsurgery , whereby favorable outcomes have been achieved. The purpose of this report is to describe our surgical procedure and discuss the therapeutic outcomes. We achieved markedly favorable outcomes: 100% and 84.6% in the treatment of mandibular and maxillary radicular cysts, respectively.

Incisor on cone beam computed tomography (CBCT), a surgical endodontic operation using a surgical operating microscope (SOM) was performed. On dental radiographic examination, CBCT showed the presence of a supernumerary root, and the disto-eccentric projection showed a sinus tract on the mesio-labial side. The tooth itself showed signs of life, although there was a periodontal pocket on the labial side 5-mm deep only near the sinus tract. An X-ray with a gutta-percha point inserted into the sinus tract showed that it went to the apex of the supernumerary root. This showed that the main root canal was not connected to the supernumerary root, and that only the supernumerary root was dead. Therefore, using the SOM, it was possible to resect and remove only the dead supernumerary root and to keep the living tooth in good condition for five years even without a pulpectomy. When used together in surgical endodontic treatment, CBCT and SOM are therefore shown to be effective for examination, diagnosis, and treatment.

The aim of this study was to investigate and analyze various factors, associated with a tooth crack. The subjects’ gender, age, chief complaint, type of tooth, result of percussion, pulp vitality, restoration material and cavity classification, position and direction of the crack, depth of periodontal probing, nature of opposing tooth, and evaluation of occlusion were recorded. In total, 140 vital cracked teeth were diagnosed in 100 patients. Forty-four cases were diagnosed with craze lines, 55 with enamel crack with enamel defect, 18 with a fractured cusp, 44 with a cracked tooth, and 3 with a split tooth. Regarding the tooth type, a significant number of cases occurred in the mandibular molars compared to the maxillary molars in the nonworking-side interference group (NWI, 118 teeth). Thirty teeth were non-restorations, and 110 teeth were treated with restorations. Seventy-seven teeth were restored with metal inlay, 21 teeth with composite resin, and 12 teeth with amalgam. Regarding the final treatment, 86 teeth were covered by a full metal crown, 11 teeth by a four-fifths crown, and 1 tooth by a temporary crown. Thus, cracked teeth, particularly those originating due to occlusal interference, should be protected with the coverage-type restorations.