The aim of this study is to grasp the oral traits of deciduous dental arches in Chinese children in Hong Kong. Plaster models were taken from 277 children aged 5-year-old, 165 boys and 112 girls. Observations and measurements were carried out on these models. Sixty-six percent of the boys have normal occlusion and this value was slightly lower than that of the girls (73.2%). In types of malocclusion, upper protrusion was most frequent (11.9%) in both boys and girls, followed in order by anterior cross bite (7.6%), edge to edge bite (4.7%), over bite (4.0%), open bite (2.5%), and cross bite (0.4%). Results for boys and girls were similar, except for anterior cross bite which was significantly higher (p<0.05) in the boys. Combined primate space and developmental space type was most frequently observed in both boys and girls. The value of this type was 72.7% in the boys and 67.9% in the girls in upper jaw, and was 65.5% and 51.8%, respectively, in lower jaw. In both boys and girls, frequency of only developmental space in upper jaw and only primate space in lower jaw was lowest. In lower jaw, the boys having both primate space and developmental space were significantly more (p<0.05) than the girls. The percentage of children having bilateral vertical type of terminal plane was highest, 58.8% in the boys and 66.1% in the girls, followed in order by bilateral mesial step type, bilateral distal step type, vertical-mesial step type, and vertical-distal step type. No one had mesial-distal step type. There were no significant differences between boys and girls in each type of terminal plane. Both upper and lower anterior dental arch lengths were similar between the boys and the girls. Posterior dental arch lengths of the boys were 22.79 mm and 19.46 mm in upper and lower jaw, respectively, and were significantly longer (p<0.05) than those of the girls (22.39 mm in upper and 19.08 mm in lower). The dental arch breadth measurements, in all aspects, were significantly greater (p<0.01) in boys than in girls. All the indices, excluding lower anterior-posterior dental arch length index and anterior dental arch index, tended to be higher in girls than in boys. Especially, significant differences (p<0.05) were observed in upper anterior-posterior dental arch length index and upper anterior dental arch index. When compared with Taiwan Chinese and Okinawa Japanese, the length of dental arch in Hong Kong Chinese was longer than that in Taiwan Chinese, but shorter than that in Okinawa Japanese. And the breadth of Hong Kong Chinese was smaller than that in Taiwan Chinese, and smaller in anterior region than but similar in posterior region to that in Okinawa Japanese. In conclusion, when the characteristics observed and the values measured were compared among these populations and combined with the results of dental arch indices, the oral traits of Hong Kong Chinese were close to those of Taiwan Chinese.

View full abstract

Cyclosporin A (CsA), an immunosuppressant which inhibits T lymphocytes in an apparently selective manner, and OK-432, an immunoactivator which strengthens the defense mechanism of the host, were tested for their effects on metastasis in a Syrian hamster cheek pouch carcinoma/excision system. The purpose of the present study is to describe the effects of systemically administered immunomodulators on the metastasis of hamster cheek pouch carcinomas after primary tumor excision, and to show that this model has considerable potential for study of the role of immune responses against metastatic tumors. The results obtained were as follows : 1. Lymph node metastasis was found in the left cervical lymph nodes only, the contralateral nodes of all animals showing no metastases. Metastasis to the lung was observed in one animal only, concomitant with lymph node metastasis in the excision with CsA 25 mg group. The incidence of metastasis is summerized as follows : in the excision with CsA 50 mg group, 14 out of 15 animals (93%) showed metastasis. In the excision with CsA 25 mg group, 7 out of 16 animals (44%) showed metastasis. In the excision with OK-432 group, 1 out of 14 animals (7%) showed metastasis. In the excision only group, 6 out of 15 animals (40%) showed metastasis. The difference between the incidence of lymph node metastasis for the excision with CsA 50 mg group and that of the excision only group, as well as for the excision with OK-432 group and that of the excision only group were found to be significant at the p<0.05 level (Fisher's Exact Probability Test), while the incidence for the excision with CsA 25 mg group was similar to that of the excision only group. These results indicate that the incidence of metastasis of this system may be regulated by the immune system of the host, as well as by the tumors themselves. 2. To assess the influence of CsA and OK-432 on the rate of growth of tumors in the lymph node, the metastasis was classified according to five categories by the degree of invasion. The relation between the extent of invasion and the interval after excision may be summarized as follows : in the excision with CsA 50 mg group, 3 animals with stage 1 metastasis were sacrificed between 3 and 5 days after excision, 6 animals with stage 2 were sacrificed between days 7 and 10, and 5 animals with stage 3 were sacrificed between days 17 and 28. In the excision with CsA 25 mg group, 1 animal having stage 1 metastasis was sacrificed on the 6th day, 5 animals with stage 3 were sacrificed between the 15th and the 28th day, and 1 animal with stage 4 was sacrificed on the 26th day. In the excision with OK-432 group, 1 animal with stage 3 was sacrificed on the 28th day. In the excision only group, 6 animals showing metastasis all fell into stage 3 and were all sacrificed on the 28th day after excision. From the above, it appears that both CsA and OK-432 had no effect on the growth of metastasized tumor cells in the lymph node. This data also showed that the arrest and onset of growth of metastatic tumor cells in this system occurs within 6 days after excision.

View full abstract

This paper deals with the adhesiveness of the osteoclasts disaggregated from femora of 5-day-rat and the condition and factors affecting the adhesiveness during the incubation. The purpose is to show that the increase in osteoclastic adhesiveness is the first step of bone resorption. Results are as follows : 1. The cells disaggregated from femora of 5-day-old rats were sedimented for 15 min and incubated for 1 day on the slices of bovine cortical bone. Osteoclasts were identified as tartrate resistant acid phosphatase (TRAP)-positive cells. Many osteoclast adhered on the slices and many resorption pits occurred after incubation for 1 day. In the case of the bone slices washed after 15 min-sedimentation and incubated for 1 day, few osteoclasts adhered on the slices and no resorption pits occurred on the surface. These results show that the femora from 5-day-old rats contained many low adhesive osteoclasts which were removed by washing, and that the cells from 5-day-old rats increased the adhesiveness during the incubation. 2. Incubation media affected the adhesiveness of osteoclasts. After 1-day-incubation with medium 199 or with a-minimum essential medium, numbers of adhered osteoclast were higher than those with the other culture media. 3. Number of adhered osteoclast in the culture containing rat serum was very high in comparison with that in the culture without serum. Among sera from the other animals, only fetal bovine serum increased the adhered osteoclast number which was similar to that in the case of rat serum. 4. Parathyroid hormone (PTH) increased the number of adhered osteoclast, and the effect was a maximum at 10 ng per ml. Interleukin 1 (IL-1) also increased the number of adhered osteoclast at 10 U. The result that the increase in the adhesiveness by bone resorption activators PTH and IL-1 suggests that the increase in the adhesiveness is one of the activation process of the osteoclastic bone resorption. Thus it was shown that the many osteoclasts from 5-day-old rats were low adhesiveness and the adhesiveness was increased by some factor (s) in serum such as PTH and IL-1.

View full abstract

Various kinds of diagnostic parameters for periodontitis have been proposed and especially the parameters in gingival crevicular fluid (GCF) have been paid attention of clinical interest in recent years. Alkaline phosphatase (ALPase) activity in GCF is one of those parameters and the activity has been reported to be associated with the progression of periodontitis. Specific gram-negative bacteria which are thought to be etiology and pathogenesis of human periodontitis have been reported to show high ALPase activity. Although ALPase activity in GCF seems to be related to periodontopathic bacteria, previous reports have not shown quantitative comparison of ALPase activity between periodontopathic bacteria and other oral bacteria. Besides the activity might originate from host response against the inflammation. To clarify this, the effect of SDS on each ALPase of periodontopathic bacteria and mammalian species was examined. Furthermore, ALPase in GCF taken from some patients with adult periodontitis was analyzed. The results were as follows : 1. ALPase activity was detected in only 3 kinds of periodontopathic bacteria, A. actinomycetemcomitans, P. gingivalis and P. intermedia and no detectable activity was observed in other oral bacteria. Of 3 kinds of bacteria, P. gingivalis and P. intermedia showed extremely high ALPase activity and the activity of A. actinomycetemcomitans was less than a tenth activity of P. gingivalis or P. intermedia. 2. All ALPases of periodontopathic bacteria were inhibited strongly by 1% SDS. In contrast, 3 types of mammalian ALPases, liver/kidney/bone type, intestinal type and placental type, were not at all inhibited in the presence of 1% SDS. 3. ALPase activity in GCF from the patients consisted of combination of SDS-sensitive and SDS-resistant activities in multiple ratio of two types of the activity. 4. ALPase activity ratio (ALPase activity in the presence of 1% SDS / that in the absence of 1% SDS) in GCF showed a positive relationship with ALPase activity in the absence of 1% SDS in GCF. These results suggest that although ALPase assay in GCF has been proposed for estimation of periodontitis progress, the assay in combination with SDS is useful for establishment of qualitative classification of periodontitis.

View full abstract

The occlusal surface of a complete denture must be formed in harmony with mandibular movement and is adjusted on an articulator. However, occlusal facets are enlarged and their forms change after insertion of the denture, especially for acrylic resin teeth. Recently, artificial hard resin teeth, whose core is made of acrylic resin and surface is covered by composite resin, were developed, and drawing attention of the clinical dentistry. This type of resin teeth is superior in luster and transparency. The surfaces feel hard when they are ground to get balanced occlusion. Observation of complete dentures with this artificial hard resin teeth was made, and changes by abrasion in projected area of occlusal facet to occlusal plane, discoloration of the teeth were examined. The hard resin teeth used in this investigation were Endura by Shofu Co. and Duracross by Nisshin Co. The results were as follows : 1. Projected area indexes of occlusal facets of Endura for 1st, 3rd, 5th month were 108±6, 116±8, 119±10, respectively. Those of Duracross were 105±6, 116±5, 118±6, respectively. 2. There were no significant statistical difference between Endura and Duracross. Long term examination should be performed to evaluate these hard resin teeth. 3. Discoloration to yellow at the cervical area, or dark brown for the whole surface was found for Endura at 1st month, and no discoloration was seen for Duracross.

View full abstract

Bilaterally pulpotomized wounds were made in the maxillary molar of 25 male Wistar rats to compare the effect on mitosis of neurovascular components with different pulp capping materials and methods (Ca(OH)_2 method : CHM and formocresol method : FCM). The rats were sacrificed at various time intervals (postoperative 1, 3, 7, 14 and 28th day) after pulptomy. Also, 3 hours before sacrifice, each animal was given an intraperitoneal injection of 0.3 mg/100 g b.w. of vinblastine sulphate. For histological investigation, serial sections at 8μm were made and stained with hematoxylin and eosin, or only with hematoxylin. All of the mitotic cells arrested in metaphase of neuronal (Schwann cell and fibroblast) and vascular (endothelial cell, smooth muscle cell and pericyte) components in the residual pulp tissue at various time intervals were calculated and evaluated. The results were as follows : 1. The maximum peak on mitotic activity of neurovascular components in the residual pulp was the 3rd day postoperatively in both CHM and FCM throughout the experimental period. 2. The mitotic activity since the postoperative 3rd day decreased faster by CHM than by FCM. 3. The healing process on mitotic activity of neurovascular tissue by CHM seems to be ended, but not by FCM on the postoperative 14th day. 4. The mitotic activity by FCM increased slightly on the postoperative 28th day. The derivating site for regeneration of neurovascular tissue shifted more apically. These chronological differences on mitotic activity of neurovascular components in the residual pulp by both CHM and FCM applied depend on different volume and quality of the necrotic tissue produced by the capping material and method, and the long-standing inflammation in the residual pulp tissue by FCM. The mitosis-arresting method in this study is available one for investigating the effect of various type of pulp capping materials and methods.

View full abstract