• The Journal of Korean Academy of Prosthodontics
• /
• v.35 no.4
• /
• pp.719-741
• /
• 1997

This study was undertaken to compare by Atomic Force Microscope the effects of various finishing and polishing instruments on surface roughness of filling and veneering composite resins. Seven composite resins were studied : Silux Plus (3M Dental Products, U.S.A.), Charisma (Heraeus Kulzer, Germany), Prisma THP (L.D.Caulk, Dentsply, U.S.A.), Photoclearfil (Kuraray, Japan), Cesead (Kuraray, Japan), Thermoresin LC (GC, Japan), Artglass (Heraeus Kulzer, Germany). Samples were placed and polymerized in holes (2mm thick and 8.5mm in diameter) machined in Teflon mold under glass plate, ensuring excess of material and moulded to shape with polyester matrix strip. Except control group (Polyester matrix strip), all experimental groups were finished and polishied under manufacturer's instructions. The finishing and polishing procedure were : carbide bur (E.T carbide set 4159, Komet, Germany), diamond bur (composite resin polishing bur set, GC, Japan), aluminum-oxide disc (Sof-Lex Pop-On, 3M Dental Products, U.S.A.), diamond-particle disc (Dia-Finish, Renfert Germany), white stone bur & rubber point( composite finishing kit, EDENTA, Swiss), respectively. Each specimens were evaluated for the surface roughness with Atomic Force Microscope (AutoProbe CP, Park Scientific Instruments, U.S.A.) under contact mode and constant height mode. The results as follows : 1. Except Thermoresin LC, all experimental composite resin groups showed more rougher than control group after finishing and polishing(p<0.1). 2. A surface as smooth as control group was obtained by $Al_{2}O_{3}$ disc all filling composite resin groups except Charisma and all veneering composite resin groups except Thermoresin LC(p<0.05). 3. In case of Thermoresin LC, there were no statistically significant differences before and after finishing and polishing(p>0.1). 4. Carbide bur, diamond bur showed rough surfaces in all composite resin groups, so these were inappropriate for the final polishing instruments.

• Applied Microscopy
• /
• v.34 no.3
• /
• pp.185-197
• /
• 2004

To investigate the effect of the squalene against the lead toxicity and recovery of renal failure. Healthy male ICR mice were used for experiment. The activity of nitric oxide (NO) was observed after the intraperitoneal injection in mice. The ultrastructural changes of the kidney were observed after the intraperitoneal injection of lead acetate in mice. The experimental groups were divided into three groups. Group 1 was normal mouse. Group 2 was not treatment with squalene after intraperitoneal contamination of lead acetate (30 mg/kg). And, Group 3 was injected squalene (180 mg/kg) after intraperitoneal contamination of lead acetate. All groups were used to 10 mice. The results were as follow: In the case of the group 2, swelling of the outer membrane and destruction of the inner membrane (cristae) of the mitochondria, dripping of the ribosomes from the rough endoplasmic reticulum were happened at 24 hours and 48 hour. These were gradually reparied after 72 hours. In the case of the group 3, damages of the mitochondria and the rough endoplasmic reticulum were showed less than the group 2 at 24 hours. Especially, after 48 hours, these were almost same as the group 1. In the case of group 2, the level of NO was decreased. However, In the case of group 3, the level of NO was increased more than normal as well as repaired the decreased NO level by Pb (P<0.05). It was concluded that the squalene was the protective and recovery effects for the toxicity of the lead in the renal proximal tubules.

• Applied Microscopy
• /
• v.32 no.3
• /
• pp.205-211
• /
• 2002

The purpose of this study was to evaluate the effect the lead toxicity of chitosan on the rats. A healthy male of Wistar rat was used for experiment. The lead acetate (30 mg/kg, Pb) was injected two times per a week into the abdomen. 0.1% chitosan solution (1 mg/ml) was supplied by feeding ad libitum. After 4 or 8 weeks, we was observed kidney by electron microscope. The experimental groups were divided into two groups. Group 1 was control group which was not treated with chitosan solution after contaminatation of lead acetate. Group 2 was experimental group which was treated with chitosan solution after contamination of lead acetate. All groups were used to 10 rats. The results were as follow: On the proximal convoluted tubules of the group with only Pb, the number of microvillis were decreased and the number of lysosomes were increased on the cytoplasm. The mitochondria and rough endoplasmic reticulum were extended and ribosomes dropped from the rough endoplasmic reticulum. On the proximal convoluted tubules of the group with Pb-chitosan, the shapes and number of microvilli were not changed and the number of lysosomes were decreased. The shapes of mitochondria and endoplasmic reticulum observed not changes. We concluded that chitosan has effect on reducing toxicity of lead in the rat kidney.

• The Journal of Korean Academy of Prosthodontics
• /
• v.46 no.2
• /
• pp.169-174
• /
• 2008

Statement of problem: Changes of the marginal bone around dental implants have significance not only for the functional maintenance but also for the esthetic success of the implant. It was proposed that bone-retention elements such as microthreads at the coronal part of implant might help maintain the marginal bone level. Purpose: This study was designed to evaluate the effect of microthread configuration within the marginal coronal portion of the implant fixture at the marginal bone changes after loading around two different external hex implants. Material and methods: Twenty-four patients were included and randomly assigned to treatment with $Br{{\aa}}nemark$ system implants (Group 1, rough-surfaced implants, n=20) and Oneplant system implants (Group 2, rough-surfaced neck with microthreads, n=20). Clinical and radiographic examinations were conducted at baseline (implant loading) and 1 year postloading. Data analysis was performed by the SAS statistical package version 9.1.3 (SAS Institute, Cary, NC, USA) and the final model was calculated by the MIXED procedure (three-level ANCOVA) for marginal bone change of each test group at baseline and 1 year follow-up. Results: Comparing to baseline, significant differences were noted in marginal bone level changes for the 2 groups at 1 year follow-up (P<0.05). Group 1 had a mean crestal bone level changes of $0.83{\pm}0.31mm$; Group 2 had a mean crestal bone level changes of $0.44{\pm}0.36mm$. Rough-surfaced with microthreads implants showed significantly less marginal bone loss than rough surfaced neck without microthread implants. Conclusion: A rough surface with microthreads at the implant was beneficial design to maintain the marginal bone level against functional loading.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.18 no.1
• /
• pp.32-38
• /
• 1993

In this paper a effective classification method for character recognition is proposed. The existing classification methods select candidates by comparing an unknown input character, with all the standard patterns based on the similarity measur. The proposed method, however, groups similiar characters together and uses their average distance as representative value of the group. We divided the character region into several sub-region and applied ISODATA algorithm to partial vectors of each sub-region to anstruct appropriate number of groups. After computing the distance between partial feature vector and its mapping group, we could collect all the information of input character ultimately. The proposed method showed improvement in the processing speed and certainty in classification than the existing methods.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.23 no.5
• /
• pp.396-405
• /
• 2001

Osseointegrated implants are used for the fixation of dental prosthesis with good long-term clinical results. In an attempt to improve the quantity and quality of the bone-implant interface, numerous implant modification have been used. Implants surface modifications have been used such as titanium-plasma sprayed, hydroxyapatite-coating, sandblasted, sandblasted and acid-etched, acid-etched. Rough surface implants have greater implant surface area and enhance the bone-implant interface and improve stabilization. The purpose of present study was to evaluate light microscopic and scanning microscopic examinations and removal torque value of newly developed calcium phosphate blast and acid-etched implant in the femur of rabbits. Titanium plasma sprayed(TPS) implant served as controls. After 12 weeks of healing of the femurs of 12 rabitts, the implant-containing segments of femur were removed on bloc and bone block including sections. Histologic examination and histomorphometric and removal torque values comparision were made for two implants. Obtained results are follows: 1. Newly developed calcium phosphate blasted and acid-etched implants were in close contact with bone under light microscopic examinations. 2. New implants showed mean bone-to implant contact 59.8%, whereas TPS implants showed mean bone-to implant contact 54.5% (statistically no difference p<0.05). 3. New implants showed mean bone density 56.7%, whereas TPS implants showed mean bone density 49.2% (statistically difference p<0.05). 4. New implants demonstrated mean removal torque values 40.5Ncm, whereas the mean removal torque values of TPS implants ranged 39.3Ncm. No statistical differences(p<0.05) were observed between two groups of implants nor was there any difference between the two implants at the clinical level.

• Journal of Periodontal and Implant Science
• /
• v.38 no.sup2
• /
• pp.309-316
• /
• 2008

Purpose: The aim of this study was to determine the survival rates of implants placed in grafted maxillary sinuses and compare the results obtained with graft materials, implant surfaces and timing of implant placement. Materials and Methods: Between January 1996 and December 2005, 391 implants were placed in 161 patients who underwent sinus grafting treatment simultaneously or separately at Ewha Womans University Hospital. According to inclusion criteria, 272 implants were placed in 102 patients with 112 sinus grafts (30 females, 72 males), aged 26 to 88 years (mean age $49.0{\pm}9.7$). The follow-up period ranged from 12 to 134 months (mean F/U $47{\pm}32$). Survival rates were evaluated according to graft material, implant surface and timing of implant placement. The Kaplan-Meier procedure and the log rank (Mantel-Cox) test were used to estimate survival rates and test for equality of survival rates between different groups of patients. Results: Ten-year cumulative survival rate for implants placed in the grafted sinuses was 90.1%. The survival rates for autogenous bone, combination and bone substitutes were 94.6%, 85.9% and 100%, respectively (p > 0.05). According to implant surface, survival rates were 84.8% in machined group and 97.5% in rough group (p < 0.05). The survival rates were 92.9% in delayed group and 86.0% in simultaneous group (p > 0.05). Conclusion: Ten-year cumulative survival rate for implants placed in the grafted sinuses was 90.1%. Rough-surfaced implants have a higher survival rate than machined-surfaced implants when placed in grafted sinuses (p < 0.05).

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.15 no.1
• /
• pp.27-40
• /
• 1985

This study was undertaken to observe the histopathologic changes in salivary gland of the white rats when exposed to megavoltage fractionated dose of cobalt-60 irradiation and 78 female white rats, weighing approximately 180gm, were divided into control and 3 experimental groups. Irradiation on experimental groups was delivered by using 6000 curies MeV ALCYON cobalt-60 teletherapy unit with exposure rate 183 rads per minute, in source skin distance 80cm, 600 rads every 3 days. In experimental groups, Group Ⅰwas irradiated of total dose 1200 rads for a period of 6 days, Group Ⅱ was irradiated of total dose 2400 rads for a period of 12 days and Group Ⅲ was irradiated of total dose of 4800 rads for a period of 24 days. The animals were sacrificed serially at 3 hours, 6 hours, 10 hours, 1st day, 4th day, 7th day after each completion of irradiation exposure. At sacrifice, salivary glands were excised and examined microscopically and electromicroscopically. The results were as follows: 1. The acinar cells of parotid and submaxillary gland showed damage varied with dose, 1200 rads resulted in very mild injury while 4800 rads caused most extensive injury. 2. The acinar cells of parotid and submandibular gland showed similar ultrastructural alterations, appeared as pleomorphic nucleus, decreased numbers and pleomorphism of secretory granules, distention of rough endplasmic reticulum, expansion and pallor appearance of mitochondria, and hypertrophy of Golgi complex. 3. Parotid serous cells were the most sensitive components, displaying morphological alterations of radiation damage as early as 3 hours, followed by submandibular seromucinous cells and secretory tubular cells. 4. The mucous cells of sublingual gland, as well as the whole ductal lining cells of each salivary gland, displayed no significant alterations. No evidence of microvascular injury through whole experimental groups indicated that microvascular impairment does not contribute to early salivary gland injury.

• Applied Microscopy
• /
• v.24 no.1
• /
• pp.1-10
• /
• 1994

The integumental secretory structure is exocrine unicellular gland located in the epidermis of goldfish, Carassius auratus, and divided into two groups, mucous and granular cells. By the histochemical studies of integumental secretions the mucos cells reacted for acidic polysaccharides, and the granular cells for neutral glycoprotein. According to concentration of the secretion the integumental mucous are gradually sulphated. The mucous cells are typical form of goblet cell located in the upper region of the epidermis, and membrane bounded vesicles of the mucous are observed several size and electron densities by the cellular differentiation. The granular cells in middle and lower epidermis are present syncitial forms occasionally, and contain electron dense granules sized $1.0{\mu}m$ which are accumulated in cytoplasmic process held the cells to the basal lamina. The precursors of the integumental secretory materials are originated from the rough endoplasmic reticulum and next transported through the Golgi apparatus as a form of membrane bounded vesicles. After accomplish this process mature secretions are extruded to integumental surface by the mechanism of merocrine secretion in response to nerve stimulations respectively.

• Korean journal of food and cookery science
• /
• v.22 no.1 s.91
• /
• pp.30-36
• /
• 2006

Tofu samples with added herbs (green tea, rosemary, lavender and thyme) were prepared. The yield of the herb tofus was higher than that of the control tofu. The L value of the control tofu was higher than that of the herb tofus, whereas the b values were lower. The herb tofus had generally lower pH than the control tofu. Especially, lavender tofu showed the lowest pH. Under SEM examination, the control tofu showed a rough folding surface, whereas the green tea and lavender tofus had small air cell size and smooth surface. Most textural characteristics did not show significant difference among the tofu groups. However, chewiness and hardness of the thyme tofu were the lowest. In the sensory evaluation, the herb tofus had low scores in air cell size and a beany smell, but high scores in herb smell and hardness.