Oral and maxillofacial surgeons acquire specialized skills in mandibulectomy and subsequent reconstruction of oral cancer; both procedures are directed toward restoration of not only aesthetics but also the most basic oral functions. It would be beneficial for the patients if expert physicians conversant with oral and maxillofacial surgery and oral functions are involved in the management of such cases. In cancer treatment, ‘treatment of the cancer itself’ and ‘disability/rehabilitation medicine’ for any resulting impairment are essential, just like a set of wheels, and reconstruction fills the role of an axle connecting these wheels. Reconstructive surgery is a science and an art. To achieve favorable outcomes, surgeons need to select procedures by which they can perform to the best of their ability and demonstrate their skills. Oral and maxillofacial reconstruction must improve both functionality and aesthetics, and despite the technical difficulties involved, due consideration must be given to both aspects.

Here, we report the clinical management of two cases with traumatic injury of immature permanent maxillary anterior teeth. In the first case, a 7.3-year-old girl fell down while riding a bicycle and hit her face. Dental radiographs revealed a coronal fracture of #21 involving the pulp. The need for endodontic treatment of the injured teeth was assessed. In the second case, a 7.5-year-old girl hit her face on a high bar and #21 and #22 were avulsed. After the injury, #21 and #22 were reimplanted and fixed. One month later, a sinus tract was observed, which was diagnosed as chronic apical periodontitis. In both cases, we waited for apex closure by apexification using calcium hydroxide. We replaced the calcium hydroxide regularly. It is difficult for clinicians to determine the timing for root canal filling in conventional endodontic treatment without a microscope as the condition of the apex can not be seen directly. Therefore, we evaluated the condition of the apex using a microscope to decide the timing for root canal filling in these cases. In the first case, 2.1 years after the injury and in the second case, 11 months after the injury, we confirmed that both root canal apices were strongly calcified by microscopic examination. Consequently, we obturated the root canal of #21 by thermoplasticized injection molded technique. Closure of the apex of the root canal and favorable healing were confirmed in both clinical cases using the microscope.

In recent years, dental microscopes are widely used in endodontic and periodontal fields. However, their application is not so common in the field of prosthodontics yet. The superstructure of implants may be damaged or detached by occlusal changes caused by aging, bruxism, an ill-fitting superstructure, overloading, and malfunction. This damage might sometimes lead to implant fractures, damaged abutments, abutment screw fractures and gold-alloy screw fractures. We report a technique for removal of broken segments without damaging the implant using an ultrasonic tip under microscopic vision.

Two common methods for performing sinus lift for implant therapy are the lateral approach and the vertical approach. The vertical approach is more commonly used at present and is considered highly atraumatic, but is essentially performed blindly. As a result, perforations in the mucosa often pass unnoticed. In addition, there is a tendency for beginners to readily use this approach because of its comparative simplicity, resulting in the occasional patient with poor progress. The procedure could be carried out more safely if the mucosa could be viewed during the vertical approach while peeling away the flap, similar to the lateral approach. The field of vision thus needs to be expanded using a microscope. We used a specially developed raspatory and sinus balloons to successfully achieve sufficient elevation of the sinus floor. This technique enables a safe, atraumatic operation, and is potentially applicable to retreatment in patients in whom the initial implant does not survive.

In the Department of Oral and Maxillofacial Surgery, Gunma University Hospital, relatively large radicular cysts extending over 3 or more teeth are treated with a combination of complete excision, endodontic microsurgery and CO₂ laser irradiation, 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 90% in the treatment of maxillary and mandibular radicular cysts, respectively.

Aim: The aim of this study was to improve root canal irrigation by intracanal aspiration technique (IAT), which was designed to minimize extrusion of irrigant from the apical foramen, by using different types of aspiration needles. Materials and Methods: A model which had two lateral canals at the coronal 1/3 and apical 1/3, was irrigated with only injection flow, or injection and aspiration flow for 50 sec at flow rate 0.2 ml/sec. A side-vented needle was used for injection, and aspiration was performed with a side-vented or iNP needle that had one hole at the pointed end, and a thinner tip. Injection and aspiration needles were inserted to a point 3 mm from the root canal orifice (point U) or the apical foramen (point L). In Experiment 1, the percentage of calcium hydroxide paste (CP) remaining in the root canal and lateral canals after irrigation was measured in each method. The x-ray contrast image of the remaining CP in the model was acquired with a digital CCD sensor. The contrast ratio of the root canal and lateral canal areas was calculated. In Experiment 2, extrusion of 0.2% methylene blue (MB) from the apical foramen after irrigation was measured in each method. The amount of MB extrusion was quantified by absorbance. Results: Experiment 1: The remaining CP in the root canal was the least when IAT irrigation was aspirated by an iNP needle at point L. In lateral canals, the remaining CP observed depended on the insertion point of the injection needle. Experiment 2: IAT irrigation aspirated point L group showed the least amount of MB extrusion compared with other groups. Conclusion: The aspiration needle for IAT should be inserted more apically. Furthermore, aspiration using an iNP needle enables more efficient cleaning compared with side-vented needle in IAT.

The effectiveness of ultrasonic instruments has been noted with the increased use of microscopes in the field of endodontics. The optimal EDTA concentration for removing the smear layer (SL) and smear plugs (SP) caused by ultrasonic instruments under various conditions, however, is still unclear. The aim of the present study is to determine the optimal EDTA concentration for removing those SL and SP. Fifty sectioned single-rooted specimens without SL and SP were used. In examination 1, the SL and SP were formed using a diamond tip (DT) with water at power level 3. Specimens with SL and SP were immersed for 2 min in 2 ml solutions of EDTA at different concentrations (1%, 5%, 10%, and 15%; pH = 7.4). The specimens were observed by scanning electron microscopy (SEM) and scored. In examination 2, specimens were shaped by DT with water at power level 3 for making SL and SP. The specimens were then prepared using a stainless steel tip with water for reducing SL. After preparation, specimens were immersed for 2 min in 2 ml solutions of EDTA at different concentrations (1%, 5%, 10%, and 15%; pH = 7.4). The specimens were observed by SEM and scored. Specimens in examination 1 retained SL and SP even when using 15% EDTA solution. SL was not observed when using 10% and 15% EDTA solutions in examination 2, but SP was observed when 1% and 5% EDTA solutions were used. The optimal EDTA concentration differed according to the conditions used to form the SL and SP. In conclusion, 10% EDTA for 2 min can remove the smear layer and smear plugs when the root canal is shaped using a smooth-surface ultrasonic tip, if water is applied and the tip slightly (5–10 gf) contacts the root canal wall.