The purpose of this study was to investigate the effects of the polyvinylidene fluoride (PVDF) piezoelectric porous membrane on bone regeneration. The PVDF piezoelectric porous sheet was prepared as a membrane for guided bone regeneration technique, which involved 70% pores 0.45μm in average diameter and was 125μm in thickness and 2.6pC/N in piezoelectric constant. Non piezoelectric PVDF porous membrane was also used for a comparison. For three adult beagles bone cavities 4 mm in diameter reaching the marrow space in bilateral mandibles were prepared three months after the bilateral 2nd, 3rd and 4th premolars and 1st molars had been extracted. Of the four bone cavities, two were covered with the PVDF piezoelectric porous membrane (experimental group), one was covered with the nonpiezoelectric PVDF porous membrane (comparison group), and the remaining one was left as it was without covering (control group). After six weeks from the surgery, the specimen blocks were removed from the defect areas for histopathological evaluation. The four specimens corresponding to the central portion were histopathologically studied by microradiograms, fluorescent labeling observation, and conventional staining observation. The following results were obtained : 1. In the control groups, the new bone tissue grew in a hollow shape. 2. In the comparison groups, the original bone appearance was maintained by the membrane. In 50% of specimens, the superior region of the marrow space was not closed with newly formed bone. No new bone tissue was formed at the crest of the existing alveolar bone in all the specimens. 3. In the experimental groups covered with PVDF piezoelectric porous membrane, most of the bone defects were restored by bone regenerations with the bone contour being kept in original appearance. In 79% of specimens, the bone defects between the bone cavity and the marrow space was covered newly formed bone. At the crest of the existing alveolar bone, the new bone tissue was found in all the specimens. 4. With the PVDF piezoelectric porous membrane, new bone tissue was formed and mineralized faster than with other GBR membranes. The foregoing results suggest that the PVDF piezoelectric porous membrane may be a superior material in bone regeneration and multiplication for GBR technique.

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Recently, bone substitutes, such as hydroxyapatite (HAP) and β-tricalcium phosphate (β-TCP), have been reported. These artificial substances are available for bone augmentation. However, the use of these substances is not without problems ; they are difficult to handle and shape and are not retained well in the host tissue. Chitosan, a naturally occurring high molecular weight polymer stable in vivo like collagen, was mixed with these artificial substances. The use of chitosan paste made the artificial substances much easier to handle and to be retained in the tissue. The osteoconductive properties of a chitosan HAP paste have been assessed in the rabbit. In this study, we evaluated the response to placement of a subperiosteal implant using chitosan β-TCP paste on rat calvaria, and examined the tissue cytohistochemically for evidence of soft tissue infiltration within the chitosan β-TCP paste when it is inserted into living tissue with direct approximation to bone. Male Wistar rats were injected through the jugular vein with horseradish peroxidase (HRP) as a peptide tracer, after various durations of experimental implantation. Dissection of the experimental regions showed that chitosan β-TCP paste was not spread on the calvaria and was firmly incorporated in the connective tissue without mobility. Light microscopically, soft tissue rapidly infiltrated the chitosan β-TCP paste, but no evidence of toxicity for host tissue was noted in any of the specimens. The materials were encapsulated roughly in fibrous connective tissue with few inflammatory cells. Healing formation was observed on the side of the materials. Cytohistochemically, HRP was deposited in the chitosan paste. Macrophages were observed around the chitosan β-TCP paste and had migrated into the materials. Uptake of HRP was detected intracellularly as granular reaction products in most macrophages but was more prominent in macrophages directly in contact with the chitosan β-TCP paste. These peroxidase-positive endocytotic structures were dense bodies, micropinocytotic vesicles and multivesicular bodies. Foreign body giant cells were also seen around the chitosan β-TCP paste. Uptake of HRP was seen in foreign body giant cells as well as macrophages. In newly formed bone HRP was detected throughout the lacunae and intracellularly in most osteocytes. In the calvaria not all of the lacunae was positive for HRP. These findings suggest that endocytosed chitosan is incorporated into the lysosomal system of macrophages and foreign body giant cells and then digested intracellularly by the lysosomal enzymes. Macrophages and foreign body giant cells may play an important part in absorption of chitosan. In conclusion, chitosan β-TCP paste is a resorbable, non-toxic and osteoconductive substance useful as a bone substitute.

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We investigated the incidence of the worse change in diabetic control after a surgery under a general anestesia without following intravenous feeding among 49 diabetic patients hospitalized in the First or Second Depatmentof Oral and Maxillofacial Surgery division of Kyushu Dental Collage Hospital. The worse change in diabetic control was diagnosed from an increase in the fasting blood glucose level of more than 30 mg/dl, and/or a need for the more intensive therapy for diabetic control after the surgery. The relationship was evaluated between the worse change in diabetic control and the cause of surgery, preoperative diabetic therapy, age, body-mass index, operation time, total perioperative steroid administration, and hemoglobin Alc (n=33), serum fructosamine, fasting blood glucose, CRP levels measured just before surgery. The worse change in diabetic control was observed in 53%, and continued more than 3 days after surgery in 33% of the patients. The patients with inflammatory disease or malignant tumor showed higher incidence of the worse change than the others (78%, 69%, and 30%, respectively, p=0.0011). Although there was no correlation between the worse change in diabetic control and preoperative diabetic therapy, and age, significant correlation was observed in body-mass index (p=0.0036), operation time (p=0.0088), total perioperative steroid administration (p=0.0213), hemoglobin Alc (p=0.0282), serum fructosamine (p=0.0005), fasting blood glucose (p=0.0120), and CRP (p=0.0015) levels. In the patients with slender build, long operation time, perioperative steroid administraion, poor preoperative diabetic control (high levels of hemoglobin Alc, serum fructosamine, and fasting blood glucose), and with inflammation (positive CRP level), high incidence of the worse change in diabetic control after surgery is expected, and blood glucose level should be checked repeatedly in order to achieve good diabetic control after surgery. On the other hand, good preoperative diabetic control also is desirable so as not to worsen the postoperative diabetic control.

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Anterior interdental space and dental rotation are of great importance, as far as bite injury or dental mark as criminal evidences on site are concerned, and different interracially. Here is presented the interracial comparative study of anterior interdental space and Winging status with impression taken in Ghana in March 1996. The subjects comprised 197 male and 187 female inhabitants in Ghana between 15-39 years of age. Interdental space was taken to be that more than 1 mm by inspection. Winging was determined by Dahlberg's classification. Of 384, interdental spaces were identified in 182 (47.4 %), more than 36.5 % in the Japanese. As for region, maxillary intercentral incisor spaces were most frequently revealed (28.9 %), and bilateral spaces between mandibular lateral incisor and canine amounted to 26.1%. Median mandibular spaces were found in 11.5%, more than 1.3% in the Japanese. One space per one jaw amounted to 12.5% in maxilla and 7.6% in mandible, both were the most frequent. With interdental space existing, both the length and width of anterior dental arch were increased in the Ghanaian, as oppose to only length increment in the Japanese. Bilateral Winging was shown to be 13.8% more than 3.0% in the American White and 9.7% in the Japanese.

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Intrathecal (i.t.) injection of strychnine (STR : glycine antagonist) or bicuculline (BIC : GABA-A receptor antagonist) results in tactile-allodynia that can be blocked by N-methyl D-aspartate (NMDA) receptor antagonists. These glycine and GABA-A receptors tonically regulate activity in spinal glutamatergic terminals and i.t. STR and BIC enhance the spinal release of amino acids (AAs). Under halothane (1.5 %) anesthesia Sprague-Dawley rats were implanted with a lumber i.t. loop dialysis catheter and an i.t. injection catheters. Four days after implantation, rats were randomized to receive an i.t. injection of STR (3μg) or BIC (10μg). Before and after injections the touch-evoked agitation (TEA) was scored and dialysate samples were collected periodically and analyzed for glutamate (Glu) and taurine (Tau) concentration by HPLC with EC detector. To assess the contribution of NMDA receptors which themvelves exert an excitatory effect upon spinal glutamatergic neuron, the effects of i.t. NMDA (3μg) on spinal AAs release and TEA scores were also examined. Interthecal NMDA and BIC evoked a transient spinal release of Glu and Tau in the 0-10 min sample and prominent allodynia, whereas STR did not affect spinal transmitter release at any time. These results suggest that the development of allodynia may result from either a loss of GABA-A or glycine inhibition. The spinal mechanisms underlying these two actions appear to differ, the former facilitating spinal glutamate release, the latter not.

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A 59-year-old man was admitted to our department complaining of a right neck swelling. The preoperative diagnosis was lipoma based on clinical findings as well as the image findings of CT scan and MRI. The tumor was excised through a cervical skin incision under general anesthesia. It lay between the platysma and the superficial layer of the cervical facia. Because it was difficult to separate the tumor from the parotid gland, we had to excise the tumor with a part of the parotid grand. The extirpated yellow and soft specimen weighed 92g and was 15×7×5cm in size. Histologically, mature adipose cells were arranged like the meshes of a net and there was no finding of malignancy, but some tumor cells infiltrated into the palotid grand. Although lipomas are common cervical benign tumors, such a case of lipoma infiltrating into the parotid grand has not been reported. In this patient, the postoperative course was good and there has been no recurrence.

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We performed pathological and immunohistochemical examination of diffuse invasive type squamous cell carcinoma (SCC) transformed from leukoplakia of the tongue. Expression of the proliferating cell nuclear antigen (PCNA) at the region of tumor-host borderline revealed high immunoreactivity. By using the TUNEL method, preoperative chemotherapy had no effect on the tumor cell apoptosis at the same region. Generally, SCCs transformed from oral leukoplakias reveal low malignancy. In the present case report, we demonstrated that the tumor which had been transformed from leukoplakia showed high malignancy of its nature.

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