Hitoshi Oguchi

Long-term histological evaluation of hydroxyapatite ceramics in humans

We have investigated the interface between bone and hydroxyapatite (HA) chronically implanted in man. By light microscopy, HA appeared to bind directly to bone without intervening fibrous tissue. By transmission electron microscopy, two patterns were noted: (1) HA either bound directly to bone; or (2) electron-dense material intervened between HA and bone. The orientation of bone collagen fibres likewise showed two patterns: (1) collagen fibres were oriented parallel to the HA; or (2) the fibres were aligned perpendicularly. We have observed similar binding properties of HA to the jaw bone of humans in vivo and in vitro.

Evaluation of a high-velocity flame-spraying technique for hydroxyapatite

Titanium alloy sprayed with hydroxyapatite (HA) was developed by a high-velocity flame-spraying technique (HVFST). Biocompatible responses of bony tissues to high-velocity flame-sprayed HA (HVFS-HA) implanted into tibias of adult male rabbits was investigated 4 and 18 months after implantation by light and electron microscopy. Both light and electron microscope features in histological sections showed that inflammatory responses of tissues in situ were completely cleared and the interface between the bone and the implant was filled with newly formed bony substrate. This suggests that the HVFS-HA was sufficiently biocompatible to be adapted to the bone in situ.

Growth of Normal Human Osteoblast Cells on Hydroxyapatite/Titanium Alloy Composites Formed by Implantation of Hydroxyapatite Granules into Titanium Alloy

On the hydroxyapatite/titanium alloy composite disks, the normal human osteoblast cells were cultured. As a result, the samples were covered with normal human osteoblast cells after 2 hours. Moreover, we did not observe cracks in any of the HA granules, and the normal human osteoblast cells extended between the HA granules and the titanium alloy. From these results, we have concluded that this material has good biocompatibility.

Endodontic-Endosseos Anchoring Method using Hydroxyapatite Sprayed Titanium Sticks

ABSTRACT 23 patients involving 29 anchored teeth were treated between April 1990 and April 1991 using a hydroxyapatite sprayed titanium sticks. Clinical diagnosis were radicular cysts (13 patients; 17 teeth), marginal periodontitis (4 patients; 6 teeth), root fractures (3 patients; 3 teeth) and tooth luxation (3 patients; 3 teeth). The complications were fistula on account of infection (4 patients; 4 teeth), tooth dislocation during operation (3 patients; 3 teeth) and removal of the stick because of a root fracture (1 patient; 1 tooth). As a result, we were able to save 28 teeth by applying these implants. The success rate of this method was 97%.

Observing the Responses of the Interface Between New Bioactive Glasses and Human Osteoblast Cells (HOCs) by TEM

The purpose of this study was to investigate differences in the interface between new bioactive glasses (RKKP, RBP1, RBP2) and mirror-polished titanium alloys in the evaluation of human osteoblast cells (HOCs) by TEM. Mirror-polished titanium alloy (MTi), bioactive glass (RKKP, RBP1, RBP2), and plastic culture dishes (Falcon [F]; used as a control) were used in this study. 1.0×105 HOCs were plated on each of the materials and cultured for 1 week. For TEM, HOCs were fixed in 2.5% glutaraldehyde, post-fixed in 1% osmium tetroxide, dehydrated, and embedded in Epon 812. After polymerization for 48 hours, the sample was removed with liquid nitrogen, and the specimen was re-embedded in Epon 812, sliced into 200-nm-thick semithin sections, and stained with a mixture of 1% toluidine blue, 1% Azur II, and 1% borax. After confirming the presence of cells, the specimens were sliced at a thickness of approximately 78 nm, double-stained with uranyl acetate and lead citrate, and examined under a TEM. As results, In Falcon, we found an extremer on the material side, focal contact, and close contact in parts of the plate. In M-Ti, we observed a non-structured homogeneous layer. In RBP1 and RBP2, an intervening layer with a gel like condition of approximately 100 nm in thickness was observed. In RKKP the collagen fibers bonded directly, indicating the presence of a bone matrix of HOCs at all sites. In conclusion, the interface between the different bioactive materials and the bio-inactive material showed completely different phenomena. Furthermore, even the same bioactive materials showed different patterns because of their different composition. From these results, we concluded that RKKP might be the best biomaterial because it bonded directly to human osteoblast cells without an intervening layer.

Occlusal Dysesthesia: A Clinical Report on the Psychosomatic Management of a Japanese Patient Cohort.

PURPOSE A cohort of Japanese patients diagnosed with occlusal dysesthesia (OD) was clinically analyzed for psychosomatic background, management, and treatment outcome. MATERIALS AND METHODS The study group comprised 61 patients (17 men and 44 women) who met the OD criteria. Treatment outcomes were categorized as improvement, interruption, and transfer to another department. RESULTS The diagnosed OD was resolved in 25 patients (41%), 20 patients (33%) discontinued treatment, 13 (21%) were referred or transferred to other specialties such as psychiatry, and 3 (5%) continued to receive treatment following an engagement period of 3 months, 2 years, and 5 years, respectively. Among the 20 patients who discontinued treatment, complaints persisted for 10 and they did not comply with treatment, 1 had immodithymia characterized by adherence to symptoms, 3 had depressive states, 2 were suspected to have schizophrenia, and 2 were suspected to have so-called phantom bite syndrome. CONCLUSION This study suggests that OD treatment should take into account the underlying psychiatric disorder manifesting as physical complaints.

A case of tooth fracture occurred upon medicating bisphosphonate for an elderly person: Preservation therapy and responses for Stage 0 of bisphosphonate-related osteonecrosis of jaw

This case report aimed to report the progress of preservation therapy and response of symptoms and signs for Stage 0 of bisphosphonate-related osteonecrosis of jaw (BRONJ). A 68-year-old female was recognized having a tooth at the left upper first molar fracture upon medicating bisphosphonate (BP) in 2007. At that time, the extraction of the tooth was an absolute contraindication. Therefore, we performed preservation therapy. We observed the symptoms and signs every month. After 5 months, swelling and redness in the entire first molar tooth were seen and fistula formed partly. Bone exposure was not seen. We administrated antibiotics immediately. As a result, symptoms disappeared. On April 10, 2009, the patient visited us as she felt a sense of incongruity in the lower left first and second molar teeth. Clinically, there were no symptoms of pain. However, we observed the radiolucent finding in about 5 mm diameter at apical position by X-ray photography; we considered a possibility of Stage 0 for BRONJ. We immediately administered medicine for 5 days and the symptoms disappeared. At present, no inflammation with signs and symptoms at the upper left first molar and lower left first, second molar parts is shown. We performed preservation therapy for tooth fracture case medicating of BP. Immediate responses for inflammation and symptoms of the Stage 0 of BRONJ have led to success. Hence, dentists should perform regular clinical observation, and enough education to the patient for BRONJ is necessary.