The design and development of a new fine fiberscope (1.0 mm outer diameter) is described, that includes an irrigation system for endoscopic use. This effectively allows visualisation of fields involved in periodontal disease. This fiberscope has been used in our clinic for seven years to diagnose and treat periapical and periodontal lesions through fistulae and periodontal pockets. The fiberscope has been applied to endodontic surgery for the inspection of root apices and the denuded root surfaces, in addition to the cut root face, rootend cavity and root-end filling after root-end resection. The advantages of endoscopy compared to surgical microscopy are portability and easy adjustment of direct viewing angle to examine around corners without the use of additional mirrors. Furthermore, the fiberscope can be utilised through the sinus tract or a minimal incision without the need for surgical flaps to observe the root surface, periapical tissue and foreign materials before, during and after curettage. The system requires little local anaesthesia, no large incisions, no opening flaps and no sutures. As a result, postoperative symptoms are minimised. Periapical curettage using a fiberscope represents a useful and minimally invasive surgical procedure.