In order to clarify an anthropological position of the Chaoxian based on Mongoloid dental variations, 19 tooth crown traits of the Chaoxian were examined and compared with 22 East Asian populations. In the 8 traits which show considerable difference between Sinodonty and Sundadonty, Shoveling, Double-shovel and Y-groove pattern of the Chaoxian were similar to those of Sinodonty, while Winging, Carabelli's trait, Deflecting wrinkle and 4-cusp of the Chaoxian were similar to those of Sundadonty. Cusp 5 of the Chaoxian lay midway between Sinodonty and Sundadonty. From a cluster analysis among 23 East Asian populations, the Chaoxian was included in the Sinodonty cluster. Furthermore, the multidimensional scaling analysis showed that the Chaoxian was the closest to the Man in Sinodonty. Judging from the above analyses, it was proved that the dentition of the Chaoxian was characteristic of both Sinodonty and Sundadonty, and the Chaoxian is the closest to the Man in the East Asian Mongoloid populations.

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Apoptosis is an important and well-controlled form of self-regulated cell death that differs from necrosit. This process has been recognized to be of major importance for embryonic development, tissue homeostasis, neurodegeneration, autoimmune disease, carcinogenesis, cancer progression, and the killing of cancer cells induced by chemotherapeutic drugs. Apoptosis is induced by radiation, heat, chemical agents, anticancer drugs, or some kinds of divalent metals. However, the effects of anticancer agents on cultured malignant cell lines are still obscure. The role of the anticancer drugs in induction of apoptosis in cultured malignant tumor cell lines also is not known. To investigate a possible relationship between anticancer reagents and apoptosis in oral malignant tumor cells, the effects of Carboplatin, Cisplatin, Mitomycin C, Peplomycin sulfate, and Doxorubicin hydrochloride on malignant tumor cell lines including human squamous carcinoma cell line, SCC-25 cells, human submandibular gland cell line, HSG cells, and human osteosarcoma cell line, Saos-2 cells were examined. Subconfluent cells were exposed to varying concentrations of these anticancer drugs. All the anticancer drugs used induced cell death in these cell lines in dose- and time-dependent fashions as determined by WST-1 assay and phase-contrast microscopy. By using the Hoechst 33342 staining, marked nuclear condensation and fragmentation of chromatin were observed in these cells treated with the anticancer agents. DNA ladder formation, a hallmark of apoptosis, also was detected in the anticancer drug-treated cells. The induced-DNA fragmentation and DNA ladder formation were dose and time dependent. The present results suggest the decreasing of tumor mass by the anticancer agents may be in part regulated by apoptosis.

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Five-week-old rats, corresponding to childhood in humans, were used and divided into 4 groups : the control group, the zinc-deficient diet group, the low-zinc diet group and the high-zinc diet group. After 4 weeks of feeding, the rats were sacrificed and their mandibular alveolar bone was removed, then the formation of bone matrix was examined. 1. Body weight There was a significant difference in body weight between the control group and the zinc-deficient diet group and the latter showed the lower value. During the second week, the value of the control group was significantly different to that of the high-zinc diet group and the latter was high. 2. Bone mineral content There was a significant difference between the control group and the low-zinc diet group or the zinc-deficient diet group, and the former showed the high value. There was also a significant difference between the low-zinc diet group and the high-zinc diet group or the zinc-deficient diet group, and the high-zinc diet group showed the high value while the zinc-deficient diet group showed the low value. 3. Hematological test 1) Ca in serum : The value of the control group was significantly different to that of the zinc-deficient diet group or the high-zinc diet group, and the zinc-deficient diet group showed the low value while the high-zinc diet group showed the high value. 2) P in serum : The value of the control group was significantly different to that of the zinc-deficient group, and the latter was a little lower. 3) Ratio of Ca to P in serum : The value of the control group was significantly different to that of the high-zinc diet group, and the latter was a little higher. 4) ALP : The value of the control group was significantly different to that of the zinc-deficient diet group, and the latter was a little lower. 4. X-ray findings The high-zinc diet group showed almost the same X-ray findings as the control group. Compared with the high-zinc diet group and the control group, both the zinc-deficient diet group and the low-zinc diet group showed a decrease in thickness and quantity of trabeculae. 5. Histopathological findings Compared with the control group, the zinc-deficient diet group showed the decreased bone remodeling. The bone modeling in the low-zinc diet group was more sufficient than that in the zinc-deficient diet group but worse than that in the control group showing a decrease in bone matrix formation. The bone modeling in the high-zinc diet group was more sufficient than that in the control group, but there is no significant difference in bone modeling between the two groups. It was determined that zinc deficiency might inhibit bone modeling in the growing rats, which was possible to result from the decrease of the metal enzymes containing zinc. It was also understood that excess zinc intake had no remarkable effect on bone modeling but the increased calcium concentration in blood played an important role in the improvement of bone modeling in spite that the mechanism was unclear.

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Forty 5-week-old Wistar strain male rats, corresponding to childhood in humans, were used to examine the effects of zinc and activated vitamin D_3 on bone formation by intramembranous ossification. 1. Body weight During the whole study the value in the control group was significantly different to that in the low-Zn and VD_3 group, and from the 1st week to the 3rd week the latter showed low (p<0.05) while at the 4th week the latter showed much lower (p<0.01). 2. X-ray findings Compared with the control group, the VD_3 group showed an increase in thickness of the tibial diaphyseal cortex. The low-Zn and VD_3 group showed no change in thickness of the tibial diaphyseal cortex. The high-Zn and VD_3 group showed an increase in width of diaphyseal cortex. 3. Bone mineral content 1) Interosseous marginal cortex There was a significant difference between the high-Zn and VD_3 group and the control group or the low-Zn and VD_3 group, and the former showed the high value (p<0.05). 2) Medial marginal cortex There was a significant difference between the VD_3 group and the control group or the low-Zn and the VD_3 group, and the former showed the high value (p<0.05). There was also a significant difference between the low-Zn and VD_3 group and the high-Zn and VD_3 group, and the latter showed the high value (p<0.01). 4. Hematological test There was no significant difference in electrolytic test, biochemical test or endocrine function test respectively between the control group and the VD_3 group. The value of Ca or P in the control group was significantly different to that in the high-Zn and VD_3 group, and the latter was low (p<0.05) while it was not significantly different to that in the low-Zn and VD_3 group. The value of C-PTH in the control group was significantly different to that in the high-Zn and VD_3 group, and the latter was high (p<0.05). The value of CT in the low-Zn and VD_3 group was significantly different to that in the high-Zn and VD_3 group, and the latter was low (p<0.05). The value of 1, 25(OH)_2D_3 in the control group was significantly different to that in the high-Zn and VD_3 group, and the latter was low (p<0.05). 5. Histopathological findings The VD_3 group, compared with the control group, showed an increase in the bone lacunae between the lateral and the medial basic lamellae, in the Haversian canals and bone lacunae present in Haversian lamellae, and in bone remodeling layer. The low-Zn and VD_3 group, compared with the control group, showed that the density and thickness of bone tissue were decreased, and small bone medullary cavities were obviously seen. The high-Zn and VD_3 group showed that bone tissue was dense and thick. In the interosseous marginal cortical bone, the newly formed trabeculae were obviously seen. The present study suggested that zinc supplementation combined with activated vitamin D_3 could enhance bone formation of the tibial diaphysis in the growing rats and in the conditions of zinc deficiency bone formation could be inhibited in spite of administration of activated vitamin D_3.

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This pilot study aims at inquiring into Tokumaru's investigation on the abutment tooth movements of the denture with the resilient dental teeth more closely. Various shaped test food were placed on the dental tooth and/or teeth of the unilateral mandibular distal extension removable partial dentures without soft liner (design Ct), ones with resilient silicone layer under the basal seat of dental teeth (design E), and ones with ordinal soft liner over the denture base (design R) which were made on the simulation model of Kennedy class II missing of the right second premolar, first and second molars. And the movements of the abutment tooth (〓) in each design denture when crushing respective shaped test food were measured by using digital laser displacement sensors and the measured values were reciprocally compared through the statistical analysis. The results obtained were as follows : 1. Comparison of the abutment tooth movements of each designed denture : 1) The inclination of the abutment tooth when crushing various shaped test food was the largest of all in design R3 significantly (p<0.001). And there was a significant difference (p<0.05) between those of E3 and Ct while the load was relatively small and the former showed small inclination, but no significance was found between those of E3 and Ct when the load increased. 2) Twist like movement on design E3 was also the smallest of all designs, and Ct and R3 in order. And high significance was detected between those of E3 and Ct, and between Ct and R3, and the most high significance was recognized between those of E3 and R3. 3) Although the depression in Ct showed a extreme variation by crushing various shaped food, that of E3 was not affected very much and exhibited almost constant one, and the smallest depression and the largest one were observed in E3 and in Ct respectively. 4) The parallel movement was the largest of all in design R3 significantly (p<0.001). However, there was no significant diference between those of E3 and Ct while the load was relatively small in contrast with the inclination, but as the load increased, a significant difference between both designs gradually appeared showing larger parallel movement in E3 than that of Ct (p<0.05). 2. Depending on the type of food shape, considerably large difference was recognized in abutment tooth behaviours. Especially food type-b induced larger inclination and depression in the abutment tooth. This fact seems to suggest the neccesity of reexamination on the occlusal treatment of the fixed and removable prostheses which sometimes puts into practice as one of the clinical techniques now. 3. In buccolingual displacement of the denture base, that of R3 was significantly larger than those of E3 and Ct respectively (p<0.01, p<0.05), and that of E3 had a tendency to be smaller than that of Ct, although there was no significant difference between those of E3 and Ct. On the basis of the foregoing findings, the resilient dental tooth has some problems for the complete assembly. However, surely this dental tooth will be one of the excellent component of removable partial dentuters by the above facts that were able to minimize the inclination and the twist like movement of the abutment tooth.

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After radical operation of the maxillary sinus according to the Caldwell-Luc method, the scar tissue invaded into the maxillary sinus from the bone defect. The invaded scar tissue caused some complications. To prevent the invaded scar tissue, in 30 patients, the bone defect was closed by free reimplantation of anterior wall bone. The reimplantated bone remained and the scar tissue had not invaded the maxillary sinus. The drainage window into the lower nasal cavity remained, and the walls of the maxillary sinus had retracted. The reclosure of the bone defect in the anterior wall bone prevented the invasion of the scar tissue and enhanced favorable healing of the maxillary sinus.

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The purpose of this study is to examine the influence of intraglandular nerves during the process of regeneration in the glandular parenchyma, in rat submandibular and sublingual glands. Forty-four adult Wistar rats were used for this study and examined by immunohistochemical and electron-microscopic techniques, from 6 hours to 60 days after proximal duct ligation. The experiments produced the following results : 1. The wet weight of submandibular and sublingual glands, rapidly increased and reached a peak a day after ligation. Then it gradually decreased. 2. Within 3 days after ligation, both intraglandular nerves and glandular parenchyma revealed severe atrophy or destruction. Both the interlobular and the periglandular connective tissue of glands, were severely edematous. All of the nerve fibers and the ganglion cells showed negative NFPstaining from 12 hours to 3 days after ligation. At 5 days after ligation, the regenerative duct epithelium appeared and formed duct-like structure, therafter, the atrophic or destructive region was gradually replaced by granulation tissue and the duct-like structure untill 14 days after ligation. At 21 days after ligation, some acinar cells appeared among these duct-like structures. At 60 days after ligation, histological findings of the gland parencyma were similar to that of control gland, but no granular convoluted tubules were observed in the new lobes. Some of the nerve fibers and ganglion cells in the interlobular region showed positive NFPstaining from 5 days to 60 days after ligation. The NFP-positive nerve fibers, which appeared around duct-like structure at 7 days, were close to the acini at 60 days after ligation. 3. On electron microscopy, degeneration of both nerve fibers and ganglion cells on the hilum were recognized within 3 days after ligation. The cytoplasm of Schwann cell containing with degenerative axons was extremely destroyed. Conversely, new Schwann cells appeared on the endoneurium of nerve bundle at 3 days after ligation, and therafter, they increased in number. Many regenerative axons were observed around the new Schwann cell. These axons and new Schwann cells were seen through the same common basement membrane. Many of sprouted axons ramified into individual fibers at 30 days. From 5 days to 30 days after duct ligation, some of ganglion cells recovered structurely. 4. Nerve fibers and ganglion cells, which have regenerated or recovered, were less than that of the control. From these results, it is concluded that (1) the time of rearrangement of nerves in rat submandibular and sublingual glands may be 21 days after proximal duct ligation, and that (2) intraglandular nerves may play an important role in the process of regeneration of the gland parenchymal cells after proximal duct ligation.

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Local anesthetics cause cytotoxicity to various types of mammalian cells. To determine whether local anesthetics can induce apoptosis in osteoblastic cells, the effects of prilocaine were examined on cultured human osteoblastic cell lines, Saos-2 and MG63 cells, and mouse MC3T3-E1 cells. The cells in confluence were exposed to varying concentrations of prilocaine. In Saos-2 cells, prilocaine induced cell damage in a dose- and time-dependent manners up to the concentration of 10mM as determined by phase-contrast microscopy and WST-1 assay. Marked nuclear condensation and fragmentation of chromatin were observed in the prilocaine-treated cells by using Hoechst 33342 staining. Prilocaine-induced DNA ladder formation in agarose gel electrophoresis was dose-dependent with maximal effect at a concentration of 5mM and was time-dependent from 12 h to 48 h. Prilocaine induced also DNA ladder formation in both human osteoblastic MG63 cells and mouse osteoblastic MC3T3-E1 cells. Other local anesthetics, including dibcaine, tetracaine, lidocaine, and procaine, also induced DNA ladder formation in Saos-2 cells. Cycloheximide and Actinomycin D prevented prilocaine-induced apoptosis in Saos-2 cells in a dose-dependent fashion up to 10μM and 40nM, respectively, as determined by WST-1 assay and DNA ladder formation. The present results showed that prilocaine and other local anesthetics caused both morphological and/or biochemical features indicative of apoptosis in osteoblastic cells, and that the synthesis of specific proteins would be involved in prilocaine-induced apoptosis.

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We assessed the usefulness of newly developed biodegradable Poly-L-Lactide (PLLA) bone mini plate and screw system for internal fixation of the fracture of the mandible. Biodegradable PLLA bone mini plate and screw system was performed on 9 patients (8 males and 1 female) in our department during 1.5 years from January, 1998 to June, 1999. The ages of patients were ranged from 13 years old to 33 years old (mean 22 years). In our series, no postoperative complications were found as a result of using bioabsorbable materials. We believe PLLA bone plate and screw system is safer and more effective and more valuable for the fracture of the mandible.

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The purpose of this study is to specify posttreatment changes occurring in the dentofacial complex displaced by orthodontic treatment of patients with complete growth and development. Nineteen patients, completely grown and developed, selected for this study, and treated by the edgewise technique, had a time-elapse of at least two years between posttreatment and postretention. With the use of gnathostatic models and roentgenographic cephalograms, angles and distances were measured and compared pretreatment, posttreatment and postretention. The results were as follows : 1. The changes in skeletal pattern In the case of starting the orthodontic treatment after complete growth and development, the skeletal pattern of ∠SNA, ∠SNB, ∠SN-Mp changed during the orthodontic treatment but almost no relapse was shown. 2. The changes in denture pattern In the case of starting the orthodontic treatment after complete growth and development, the denture pattern of ∠SN-Occ. and lower intermolar width changed significantly during the orthodontic treatment but almost no relapse was shown.

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