A second maxillary premolar with three root canals are extremely unusual to encounter such teeth in clinical practice. Here, we report a case in the right maxillary second premolar in which we carried out root canal treatment using a surgical microscope. Before treatment, CBCT was taken and the diagnosis was maxillary second premolar with three root canals. The patient received verbal and written explanations of the procedures in advance, and she consented to the procedures and for details of her case to be published. Rubber dam isolation was carried out before the start of the root canal treatment. On the first visit, microscopic observation revealed DB2 in addition to the three root canals. At the second visit, the canal was filled. A follow-up examination was conducted at 1 year after the end of prosthetic treatment. The patient’s condition was therefore considered to be cured. The use of a microscope in the present case to search for and treat the root canals allowed predictive treatment to be performed and a favorable result was obtained.

Apical root lesions are usually treated with infected root canal therapy, although teeth with previous root canal therapy may be treated with surgical endodontic procedures such as root-end resection. However, such treatment may be difficult in cases where the affected tooth has a calcified root canal. The present case involved a female dentist in her 40s who was aware of forceful bruxism. The occlusion was canine-guided, and craze lines on the upper and lower canines suggested occlusal trauma. Preoperative dental X-rays showed that the pulp chamber had almost disappeared. The author suspected that forceful bruxism may have been connected to the craze lines and calcification and the disappearance of the pulp chamber. The author performed infected root canal treatment as usual, but were unable to penetrate the root canal. Dental cone beam computed tomography revealed a narrowed root canal near the root apex, and microendodontic surgery was performed. Two years after surgery, bone regeneration was observed at the root apex and the patient showed satisfactory progress.

In the present case, a patient noticed some discomfort around a maxillary right lateral incisor, external root resorption (ERR) was identified radiographically, periapical infection coming from within the tooth was located, and all those problems were remedied by performing non-surgical root canal therapy (NSRCT), which is cleaning the root canal both mechanically and chemically, and then sealing it with a bioactive root canal sealer called Canal Sealer BG (CS-BG) that not only has excellent adhesion to dentin, but also has been shown to promote regeneration of both hard tissues and soft tissues. The treatment was very successful, and therefore needs to be recommended to all practitioners of dentistry.

The author developed a technique for opening periodontal pockets using an absorbent paper point (micro-retraction technique) to treat periodontal pockets under a microscope. This report describes the characteristics and progress in development of the technique. This technique allowed for widening of the treatment area, maintenance of clarity, biological debridement, and reduction of invasion.

Two cases of intractable apical periodontitis in an anterior maxillary tooth are reported, in which the cause appeared to be a lateral branch during periradicular surgery. The lateral branch opened on the labial root surface and was difficult to identify on plain radiographs. It had been the cause of discomfort in the affected tooth for a long time. Microscopic examination showed a lateral branch, which was treated, and the discomfort disappeared. The incidence and location of lateral branches in maxillary anterior teeth should be considered in surgical endodontic treatment, and the usefulness of the microscope was confirmed.

A patient was referred to the endodontic expert for evaluation of tooth #36. The patient had pain on biting and sought recommendations to save her tooth. The tooth had originally been endodontically treated almost 20 years earlier. Pre-operative assessment disclosed a peri-apical radio-lucency at the distal root apex. A diagnosis of Previous Endodontic Therapy with Symptomatic Periradicular Periodontitis was formulated. Optimal management of the case and use of modern technology is presented in this case report.

A patient was evaluated by an endodontic expert for evaluation of tooth #36. The patient complained of a draining sinus tract in spite of receiving non-surgical endodontic therapy. Pre-operative assessment disclosed a large peri-radicular radiolucency around the root. A diagnosis of Previous Endodontic Therapy with Chronic Periradicular Abcess was formulated. Optimal management of the case and use of modern technology is presented in this case report.