Takakazu Yoshida

Clinical evaluation of the efficacy of EDTA solution as an endodontic irrigant

The effect of eliminating the smear layer by means of 15% EDTA solution as a root canal irrigant was studied in 189 single-rooted infected teeth. Each tooth was treated at two appointments, and the root canal bacteriological examination was studied on the first (pretreatment, and after enlargement and irrigation) and second (pretreatment) visits. The root canals were irrigated with 15% EDTA solution with ultrasonics agitation. No antibacterial intracanal medications were used between the appointment. When 15% EDTA solution was used, no bacteria could be recovered from 93 of 129 root canals at the sampling stage on second visit. No bacteria were found in 21 of 60 root canals when saline solution was used as an irrigant. These results suggest that 15% EDTA solution is more effective than saline solution as a root canal irrigant.

An experimental study of the removal of cemented dowel-retained cast cores by ultrasonic vibration

A technique for the removal of cemented post-cores by means of ultrasonic vibration was studied clinically and histologically. The removal time was measured for 80 extracted human teeth, including 40 single-rooted teeth and 40 multiple rooted ones and then statistically analyzed. The periapical tissue reaction to the ultrasonic vibration was also examined histologically in dogs. The best result was achieved when lateral vibration was simultaneously given by 2 removal tips using 2 ultrasonic generators. There was little harmful influence on the periodontal tissue, excluding a transient reversible reaction.

Histopathological study of the use of freeze-dried allogenic dentin powder and true bone ceramic as apical barrier materials

The biocompatibility of freeze-dried allogenic dentin powder and True Bone Ceramics (TBC), the latter prepared by incineration of bovine bone, as apical barrier materials was evaluated histopathologically in dogs. After pulpectomy, 80 root canals of 53 dog premolar teeth were prepared, and each material was tightly packed to the apical stop area. The remainder of the canal was filled with guttapercha by the lateral condensation method. Control teeth were filled by the lateral condensation method using gutta-percha without constructing apical barriers. In both the teeth filled with the dentin powder and those filled with TBC, multinucleate giant cells appeared on the bone resorption surface and the surface of the root canal wall, and marked bone resorption and positive tartrate-resistant acid phosphate staining were observed. Hard tissue had formed on the root canal wall and the filling material after 3 months. These findings suggest that the test materials are nonirritative and compatible with periapical tissue, and that they may be useful and clinically applicable as apical barrier materials.

The Development of Carbonate-containing Apatite/Collagen Composite for Osteoconductive Apical Barrier Material

The current report describes the properties of a new apical barrier material formulated from carbonate-containing apatite (CAp) and collagen. CAp particles of around 50 nm were deposited on reconstituted collagen fibers. CAp/col with about 60 wt % CAp (corresponding to apatite content of bone) was obtained after 1 day of calcification. CAp content increased up to about 80 wt % in a 15-day calcification reaction. CAp/col was composed of fine calcified collagen fibers. The crystallinity and Ca/PO(4) ratio of CAp were comparable to those of bone apatite. The mixture of CAp/col and saline reached a pH of about 9. The optimum powder-to-liquid ratio (P/L) to set into a root canal was determined to be 1.2. Furthermore, the mixture (P/L = 1.2) condensed in a root canal was liquid permeable. Thus, the CAp/col was expected as an apical barrier material with osteoconductivity.

Inflammatory Myofibroblastic Tumor Mimicking Apical Periodontitis

Inflammatory myofibroblastic tumors (IMTs) are rare. IMTs of the head and neck occur in all age groups, from neonates to old age, with the highest incidence occurring in childhood and early adulthood. An IMT has been defined as a histologically distinctive lesion of uncertain behavior. This article describes an unusual case of IMT mimicking apical periodontitis in the mandible of a 42-year-old man. At first presentation, the patient showed spontaneous pain and percussion pain at teeth #28 to 30, which continued after initial endodontic treatment. Panoramic radiography revealed a radiolucent lesion at the site. Cone-beam computed tomographic imaging showed osteolytic lesions, suggesting an aggressive neoplasm requiring incisional biopsy. Histopathological examination indicated an IMT. The lesion was removed en bloc under general anesthesia, and the patient manifested no clinical evidence of recurrence for 24 months. Lesions of nonendodontic origin should be included in the differential diagnosis of apical periodontitis. Every available diagnostic tool should be used to confirm the diagnosis. Cone-beam computed tomographic imaging is very helpful for differential diagnosis in IMTs mimicking apical periodontitis.