Root canal treatment has advanced in recent years with the spread of microscopes. However, treating complex root canal systems remains difficult. Through an examination of examples from the literature and clinical practice, this paper discusses methods for isthmus and fin root canal enlargement and preparation design and root canal filling on the basis of the three areas of “anatomical complexity,” “root canal enlargement, preparation, and cleaning”, and “root canal filling.” Anatomical complexity: Isthmuses and fins have a high incidence and are present in more than 50% of mandibular molar mesial roots. However, the incidence drops as the root canal system matures with age, which means that age must also be taken into account during treatment. Root canal enlargement, preparation, and cleaning: Appropriate enlargement of the upper part of the root canal is necessary to enlarge and prepare isthmuses and other structures. Ultrasonic tip selection is also important during enlargement and preparation and the combined use of ultrasonic waves during root canal cleaning can enhance the cleaning effect. Root canal filling: The method of root canal filling needs to be chosen based on the site where an isthmus or fin has developed. Conclusions: No clear standards exist for the mechanical root canal enlargement, preparation, and root canal filling of anatomically complex sites, such as isthmuses and fins, and success largely depends on the surgeon’s knowledge and experience. Even if a microscope is used, appropriate treatment will not be possible without anatomical knowledge, techniques, and suitable tools. Treatment must be performed using a microscope and with the appropriate knowledge.

Various methods are available for crown restorations, including direct restoration with composite resin or indirect restoration with ceramic or metal. However, there can be problems with the strength of the material or with marginal secondary caries due to poor fit along the restoration margin, so that the risk-benefit balance is therefore an issue. The author has achieved favorable clinical outcomes with long-term stability through the use of the resin coating method using a microscope and new polymeric materials. Here, I present this technique and report a clinical case.

A patient with a history of persistent pain following endodontic therapy, presented for a second opinion following the recommendation for extraction from endodontists she had consulted with. A diagnosis of Previous Endodontic Therapy with Symptomatic Periradicular Periodontitis was confirmed. Pre-operative radiography revealed the unusually close proximity of the root apex to the mental foramen. Diagnostic protocol and laser-assisted micro-surgical management of the case are discussed.

Although the alveolar crest approach for maxillary sinus bone grafts can be easily used by clinicians, the procedure is blinded and thus has disadvantages. Furthermore, the lateral approach is associated with issues such as being time consuming as well as causes postoperative swelling and pain. The author was able to perform safe, reliable, and minimally invasive maxillary sinus bone grafting using the advantages of microscope magnification and illumination to achieve good clinical outcomes.

A patient was referred by his general dentist following suspicion of periradicular pathosis on tooth #15. Pre-operative assessment disclosed the presence of a periradicular radiolucency around an endodontic instrument fragment. A diagnosis of Previous Endodontic Therapy with Asymptomatic Periradicular Periodontitis was formulated. Optimal management of the case through the combination of modern technology is presented in this case report.

Six-week-old male Wistar rats were placed under general anesthesia and rubber dam isolation technique was applied using a custom-made rubber dam clamp. Under a dental microscope, pulpectomy of the mesial root of the bilateral maxillary first molars was performed and the root canal was prepared with a Ni-Ti rotary file, after which the root canal was filled. Histological observations were made after 4 weeks. The results showed that root canal treatment can be effectively carried out in a microenvironment with no procedural accidents, and the safety and usefulness of medical treatment under a dental microscope was confirmed. Here we report the operative procedure.