Early bone healing onto implant surface treated by fibronectin/oxysterol for cell adhesion/osteogenic differentiation: in vivo experimental study in dogs

PURPOSE: This study aimed to evaluate the effects of fibronectin and oxysterol immobilized on machined-surface dental implants for the enhancement of cell attachment and osteogenic differentiation, on peri-implant bone healing in the early healing phase using an experimental model in dogs. METHODS: Five types of dental implants were installed at a healed alveolar ridge in five dogs: a machined-surface implant (MI), apatite-coated MI (AMI), fibronectin-loaded AMI (FAMI), oxysterol-loaded AMI (OAMI), and sand-blasted, large-grit, acid-etched surface implant (SLAI). A randomly selected unilateral ridge was observed for 2 weeks, and the contralateral ridge for a 4-week period. Histologic and histometric analyses were performed for the bone-to-implant contact proportion (BIC) and bone density around the dental implant surface. RESULTS: Different bone healing patterns were observed according to the type of implant surface 2 weeks after installation; newly formed bone continuously lined the entire surfaces in specimens of the FAMI and SLAI groups, whereas bony trabecula from adjacent bone tissue appeared with minimal new bone lining onto the surface in the MI, AMI, and OAMI groups. Histometric results revealed a significant reduction in the BIC in MI, AMI, and OAMI compared to SLAI, but FAMI demonstrated a comparable BIC with SLAI. Although both the BIC and bone density increased from a 2- to 4-week healing period, bone density showed no significant difference among any of the experimental and control groups. CONCLUSIONS: A fibronectin-coated implant surface designed for cell adhesion could increase contact osteogenesis in the early bone healing phase, but an oxysterol-coated implant surface designed for osteoinductivity could not modify early bone healing around implants in normal bone physiology.

Dissolution behavior and early bone apposition of calcium phosphate-coated machined implants

PURPOSE: Calcium phosphate (CaP)-coated implants promote osseointegration and survival rate. The aim of this study was to (1) analyze the dissolution behavior of the residual CaP particles of removed implants and (2) evaluate bone apposition of CaP-coated machined surface implants at the early healing phase. METHODS: Mandibular premolars were extracted from five dogs. After eight weeks, the implants were placed according to drilling protocols: a nonmobile implant (NI) group and rotational implant (RI) group. For CaP dissolution behavior analysis, 8 implants were removed after 0, 1, 2, and 4 weeks. The surface morphology and deposition of the coatings were observed. For bone apposition analysis, block sections were obtained after 1-, 2-, and 4-week healing periods and the specimens were analyzed. RESULTS: Calcium and phosphorus were detected in the implants that were removed immediately after insertion, and the other implants were composed mainly of titanium. There were no notable differences between the NI and RI groups in terms of the healing process. The bone-to-implant contact and bone density in the RI group showed a remarkable increase after 2 weeks of healing. CONCLUSIONS: It can be speculated that the CaP coating dissolves early in the healing phase and chemically induces early bone formation regardless of the primary stability.

Bone apposition on implants coated with calcium phosphate by ion beam assisted deposition in oversized drilled sockets: a histologic and histometric analysis in dogs

PURPOSE: The purpose of this study was to evaluate the osseointegration of calcium phosphate (CaP)-coated implants by ion beam assisted deposition with a lack of primary stability. METHODS: A total of 20 CaP-coated implants were bilaterally placed in the mandible of five dogs. In the rotational implant group, the implants were inserted in oversized drilled sockets without mechanical engagement, while the conventional surgical protocol was followed in the control group. Each group was allowed to heal for 4 and 8 weeks. The bone-to-implant contact (BIC, %) was measured by a histometric analysis. RESULTS: All of the implants were well-maintained and healing was uneventful. In the histologic observation, all of the implants tested were successfully osseointegrated with a high level of BIC at both observation intervals. There was no significant difference in BIC among any of the groups. CONCLUSIONS: Within the limitation of this study, successful osseointegration of CaP-coated implants could be achieved in unfavorable conditions without primary stability.

Exposure to Volatile Organic Compounds and Possibility of Exposure to By-product Volatile Organic Compounds in Photolithography Processes in Semiconductor Manufacturing Factories

OBJECTIVES: The purpose of this study was to measure the concentration of volatile organic compound (VOC)s originated from the chemicals used and/or derived from the original parental chemicals in the photolithography processes of semiconductor manufacturing factories. METHODS: A total of four photolithography processes in 4 Fabs at three different semiconductor manufacturing factories in Korea were selected for this study. This study investigated the types of chemicals used and generated during the photolithography process of each Fab, and the concentration levels of VOCs for each Fab. RESULTS: A variety of organic compounds such as ketone, alcohol, and acetate compounds as well as aromatic compounds were used as solvents and developing agents in the processes. Also, the generation of by-products, such as toluene and phenol, was identified through a thermal decomposition experiment performed on a photoresist. The VOC concentration levels in the processes were lower than 5% of the threshold limit value (TLV)s. However, the air contaminated with chemical substances generated during the processes was re-circulated through the ventilation system, thereby affecting the airborne VOC concentrations in the photolithography processes. CONCLUSION: Tens of organic compounds were being used in the photolithography processes, though the types of chemical used varied with the factory. Also, by-products, such as aromatic compounds, could be generated during photoresist patterning by exposure to light. Although the airborne VOC concentrations resulting from the processes were lower than 5% of the TLVs, employees still could be exposed directly or indirectly to various types of VOCs.

The effect of fibronectin-coated implant on canine osseointegration

PURPOSE: The purpose of this study was to characterize the osseointegration of the fibronectin-coated implant surface. METHODS: Sand-blasted, large-grit, acid-etched (SLA) surface implants, with or without a thin calcium phosphate and fibronectin coating, were placed in edentulous mandibles of dogs 8 weeks after extraction. All dogs were sacrificed forhistological and histomorphometric evaluation after 4- and 8-week healing periods. RESULTS: All types of implants were clinically stable without any mobility. Although the bone-to-implant contact and bone density of the SLA implants coated with calcium phosphate (CaP)/fibronectin were lower than the uncoated SLA implants, there were no significant differences between the uncoated SLA surface group and the SLA surface coated with CaP/fibronectin group. CONCLUSIONS: Within the limits of this study, SLA surfaces coated with CaP/fibronectin were shown to have comparable bone-to-implant contact and bone density to uncoated SLA surfaces.

Characteristics of Occupational Exposure to Benzene during Turnaround in the Petrochemical Industries

OBJECTIVES: The level of benzene exposure in the petrochemical industry during regular operation has been well established, but not in turnaround (TA), where high exposure may occur. In this study, the characteristics of occupational exposure to benzene during TA in the petrochemical companies were investigated in order to determine the best management strategies and improve the working environment. This was accomplished by evaluating the exposure level for the workers working in environments where benzene was being produced or used as an ingredient during the unit process. METHODS: From 2003 to 2008, a total of 705 workers in three petrochemical companies in Korea were studied. Long- and short-term (< 1 hr) samples were taken during TAs. TA was classified into three stages: shut-down, maintenance and start-up. All works were classified into 12 occupation categories. RESULTS: The long-term geometric mean (GM) benzene exposure level was 0.025 (5.82) ppm (0.005-42.120 ppm) and the short-term exposure concentration during TA was 0.020 (17.42) ppm (0.005-61.855 ppm). The proportions of TA samples exceeding the time-weighted average, occupational exposure level (TWA-OEL in Korea, 1 ppm) and the short-term exposure limit (STEL-OEL, 5 ppm) were 4.1% (20 samples of 488) and 6.0% (13 samples of 217), respectively. The results for the benzene exposure levels and the rates of exceeding the OEL were both statistically significant (p < 0.05). Among the 12 job categories of petrochemical workers, mechanical engineers, plumbers, welders, fieldman and scaffolding workers exhibited long-term samples that exceeded the OEL of benzene, and the rate of exceeding the OEL was statistically significant for the first two occupations (p < 0.05). CONCLUSION: These findings suggest that the periodic work environment must be assessed during non-routine works such as TA.

Characteristics of Occupational Exposure to Benzene during Turnaround in the Petrochemical Industries

OBJECTIVES: The level of benzene exposure in the petrochemical industry during regular operation has been well established, but not in turnaround (TA), where high exposure may occur. In this study, the characteristics of occupational exposure to benzene during TA in the petrochemical companies were investigated in order to determine the best management strategies and improve the working environment. This was accomplished by evaluating the exposure level for the workers working in environments where benzene was being produced or used as an ingredient during the unit process. METHODS: From 2003 to 2008, a total of 705 workers in three petrochemical companies in Korea were studied. Long- and short-term (< 1 hr) samples were taken during TAs. TA was classified into three stages: shut-down, maintenance and start-up. All works were classified into 12 occupation categories. RESULTS: The long-term geometric mean (GM) benzene exposure level was 0.025 (5.82) ppm (0.005-42.120 ppm) and the short-term exposure concentration during TA was 0.020 (17.42) ppm (0.005-61.855 ppm). The proportions of TA samples exceeding the time-weighted average, occupational exposure level (TWA-OEL in Korea, 1 ppm) and the short-term exposure limit (STEL-OEL, 5 ppm) were 4.1% (20 samples of 488) and 6.0% (13 samples of 217), respectively. The results for the benzene exposure levels and the rates of exceeding the OEL were both statistically significant (p < 0.05). Among the 12 job categories of petrochemical workers, mechanical engineers, plumbers, welders, fieldman and scaffolding workers exhibited long-term samples that exceeded the OEL of benzene, and the rate of exceeding the OEL was statistically significant for the first two occupations (p < 0.05). CONCLUSION: These findings suggest that the periodic work environment must be assessed during non-routine works such as TA.

A Study for Health Hazard Evaluation of Methylene Chloride Evaporated from the Tear Gas Mixture

This study explored the health hazard of those exposed to methylene chloride by assessing its atmospheric concentration when a tear gas mixture was aerially dispersed. The concentration of methylene chloride ranged from 311.1-980.3 ppm (geometric mean, 555.8 ppm), 30 seconds after the dispersion started. However, the concentration fell rapidly to below 10 ppm after dispersion was completed. The concentration during the dispersion did not surpass the National Institute for Occupational Safety and Health 'immediately dangerous to life or health' value of 2,300 ppm, but did exceed the American Conference of Governmental Industrial Hygienists excursion limit of 250 ppm. Since methylene chloride is highly volatile (vapor pressure, 349 mmHg at 20degrees C), the postdispersion atmospheric concentration can rise instantaneously. Moreover, the o-chlorobenzylidenemalononitrile formulation of tear gas (CS gas) is an acute upper respiratory tract irritant. Therefore, tear gas mixtures should be handled with delicate care.

Bone formation following dental implant placement with augmentation materials at dehiscence defects in dogs : pilot study / 대한치주과학회지

PURPOSE: Guided bone regeneration(GBR) has emerged as a treatment in the management of osseous defects associated with dental implants. But several studies have reported different degrees of success of guided bone regeneration, depending upon the type of barrier selected, presence or absence of an underlying graft material, types of graft material, feasibility of technique, and clinician's preference. The aim of the present study was to evaluate bone formation following dental implant placement with augmentation materials at dehiscence defects in dogs. MATERIAL AND METHODS: Standardized buccal dehiscence defects(3x5 mm) were surgically 2 Mongrel dog's mandibles, each 8 SLA surface, 8 anodizing surface implants. Each buccal dehiscence defect received flap surgery only(no treatment, control), Cytoflex(R) membrane only, Resolut XT(R) membrane only, Resolut XT(R)+Osteon(TM). Animals were sacrificed at 8 weeks postsurgery and block sections were harvested for histologic analysis. RESULTS: All experimental group resulted in higher bone formation than control. Resolut XT(R)+Osteon(TM) group resulted appeared highest defect resolution. There was no difference between SLA and anodizing surface, nonresorbable and resorbable membrane. CONCLUSION: GBR results in rapid and clinically relevant bone closure on dehiscence defects of the dental implants.

A Study on the Fitness of Adjustable Dental Impression Trays on the Chinese and Japanese / 대한치과보철학회지

PURPOSE: This study was designed to investigate the fitness of adjustable dental impression trays on the Chinese and the Japanese. MATERIAL AND METHODS: Initial design of the adjustable dental trays was developed from the results of the dental arch size of Korean adults. This design was applied to the CAD-CAM process in order to create tray model samples. Simple silicon-base molds were then replicated based on these sample models. Polyurethane injection into the silicon-base molds completed the process of creating a large number of test products. 60 Chinese dental students (male:30, female:30) from the Shanghai Second Medical University and 60 Japanese alumni from the Kumamoto high school (male:30, female:30) were selected for taking irreversible hydrocolloid impression with these trays. The width and length of the impression body were measured on several measuring points by Vernier caliper. The results were analyzed statistically to evaluate the fitness of the trays. RESULTS: 1. Uniform impression material thickness was achieved on the Chinese and Japanese by controlling the width of the tray using stops and beveled guides. The material thickness was generally within the range of 3 mm to 6 mm. 2. In the maxillary tray of the Chinese, average thickness of the impression material of the labial vestibule of the incisal teeth was 6.2 mm, the canine was 5.9 mm and the midpalatal part 10.5 mm and the posterior palatal part 9.7 mm. These were relatively large values. 3. In the mandibular tray of the Chinese, average length of the impression material of the lingual vestibule of first, second premolar contact point was 8.9 mm, the incisal teeth was 7.8 mm and thickness of the labial part of canine was 6.8 mm and premolars 7.0 mm. These were relatively large values. 4. In the maxillary tray of the Japanese, average thickness of the impression material of the labial vestibule of the incisal teeth was 7.4 mm, the canine was 7.7 mm and the midpalatal part 9.1 mm. These were relatively large values. 5. In the mandibular tray of the Japanese, average thickness of the impression material of the labial vestibule of first, second premolar contact point was 8.4 mm, and thickness of the labial part of canine was 7.4 mm. These were relatively large values. CONCLUSION: This adjustable dental tray shows good accuracy to Korean because it was designed by the analysis of the dental arch size of Korean adult model. With this result, it can be applied to Chinese and Japanese, we can take more easy and accurate dental impressions.

Fitness of Adjustable Dental Impression Trays on the Caucasian and African American / 대한치과보철학회지

PURPOSE: This study was designed to investigate the fitness of adjustable dental impression trays on the Caucasian and African American. MATERIAL AND METHODS: The size and shape of these trays were designed from the results of the dental arch size of Korean adults. Tray samples were made by CAD-CAM working. Sixty Caucasian (male: 30, female: 30) and sixty African American (male: 30, female: 30) were selected for taking irreversible hydrocolloid impression using these trays. The author measured the width and length of impression material on the several measuring points. RESULTS: 1. Uniform impression material width was achieved by controling the width of the tray using stops and beveled guides. 2. In the maxillary tray on the Caucasian, the impression material thickness was measured to be rather great showing thickness of the midpalatal part 13.0 mm. 3. In the maxillary tray on the African American, the impression material thickness was measured to be rather great showing thickness of the midpalatal part 12.0 mm, posterior palatal part 11.0 mm and the labial frenum width was 11.0 mm. 4. In the maxillary tray on the African American, the impression material width of posterior border (0.8 mm) was measured to be small. 5. In the mandibular tray on the Caucasian, the impression material width was measured (2.7-6.7 mm) and posterior border width (2.1 mm) was measured small. The impression material length was measured (2.8-6.7 mm). 6. In the mandibular tray on the African American, the impression material width was measured to be rather great showing width of the labial frenum 9.2 mm and the width of posterior border was measured too small (0.3 mm). CONCLUSION: This adjustable dental tray shows good accuracy to Korean because it was designed by the analysis of the dental arch size of Korean adult model. With this result, it can be applied to Caucasian and African American, we can take more easy and accurate dental impressions.

The histometric analysis of osseointegration in hydroxyapatite surface dental implants by ion beam-assisted deposition / 대한치주과학회지

PURPOSE: This study compared the effects of coating implants with hydroxyapatite (HA) using an ion beam-assisted deposition (IBAD) method prepared with machined, anodized, sandblasted and large-grit acid etched (SLA) surfaces in minipigs, and verified the excellency of coating method with HA using IBAD. MATERIAL AND METHODS: 4 male Minipigs(Prestige World Genetics, Korea), 18 to 24 months old and weighing approximately 35 to 40 kg, were chosen. All premolars and first molars of the maxilla were carefully extracted on each side. The implants were placed on the right side after an 8 week healing period. The implant stability was assessed by resonance frequency analysis (RFA) at the time of placement. 40 implants were divided into 5 groups; machined, anodized, anodized plus IBAD, SLA, and SLA plus IBAD surface implants. 4 weeks after implantation on the right side, the same surface implants were placed on the left side. After 4 weeks of healing, the minipigs were sacrificed and the implants were analyzed by RFA, histology and histometric. RESULTS: RFA showed a mean implant stability quotient (ISQ) of 75.625+/-5.021, 76.125+/- 3.739 ISQ and 77.941+/-2.947 at placement, after 4 weeks healing and after 8 weeks, respectively. Histological analysis of the implants demonstrated newly formed, compact, mature cortical bone with a nearby marrow spaces. HA coating was not separated from the HA coated implant surfaces using IBAD. In particular, the SLA implants coated with HA using IBAD showed better contact osteogenesis. Statistical and histometric analysis showed no significant differences in the bone to implant contact and bone density among 5 tested surfaces. CONCLUSION: We can conclude that rough surface implants coated with HA by IBAD are more biocompatible, and clinical, histological, and histometric analysis showed no differences when compared with the other established implant surfaces in normal bone.

The effects of Hydroxyapatite nano-coating implants on healing of surgically created circumferential gap in dogs / 대한치주과학회지

PURPOSE: The aim of this study is to compare the healing response of various Hydroxyapatite(HA) coated dental implants by Ion-Beam Assisted Deposition(IBAD) placed in the surgically created circumferential gap in dogs. MATERIALS AND METHODS: In four mongrel dogs, all mandibular premolars and the first molar were extracted. After an 8weeks healing period, six submerged type implants were placed and the circumferential cylindrical 2mm coronal defects around the implants were made surgically with customized step drills. Groups were divided into six groups : anodized surface, anodized surface with 150nm HA and heat treatment, anodized surface with 300nm HA and heat treatment, anodized surface with 150nm HA and no heat treatment, and anodized surface with 150nm HA, heat treatment and bone graft, anodized surface with bone graft. The dogs were sacrificed following 12 weeks healing period. Specimens were analyzed histologically and histomorphometrically. RESULTS: During the healing period, healing was uneventful and implants were well maintained. Anodized surface with HA coating and 430degrees C heat treatment showed an improved regenerative characteristics. Most of the gaps were filled with newly regenerated bone. The implant surface was covered with bone layer as base for intensive bone formation and remodeling. In case that graft the alloplastic material to the gaps, most of the coronal gaps were filled with newly formed bone and remaining graft particles. The bone-implant contact and bone density parameters showed similar results with the histological findings. The bone graft group presented the best bone-implant contact value which had statistical significance. CONCLUSION: Within the scope of this study, nano-scale HA coated dental implants appeared to have significant effect on the development of new bone formation. And additional bone graft is an effective method in overcoming the gaps around the implants.

A socio-Psychiatric study on male adolescent delinquency / 신경정신의학

No abstract available.

Three cases of lethal catatonia syndrome / 신경정신의학

No abstract available.

Three cases of lethal catatonia syndrome / 신경정신의학

No abstract available.

Detection of specific proteins in the aqueous humor in primary open-angle glaucoma

To elucidate the mechanism of increased intraocular pressure in primary open-angle glaucoma (POAG), the protein profiles of aqueous humor obtained from POAG patients were compared with those of cataract patients as a control group. Aqueous humor proteins were analyzed by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and detected by the ultrasensitive silver staining technique. In 79% of the samples taken from POAG patients, protein bands of 140,000 or 160,000 daltons were stained, but none were stained from cataract patients. The presence of these protein bands revealed statistically significant differences between the two groups. Protein bands of 140,000 or 160,000 daltons were evenly visible at all ages in POAG patients, and the positivity of bands had no correlation with sex or initial intraocular pressure level. It is possible that the ultrastructural changes of the aqueous outflow pathway in POAG may be related to the changes in the aqueous protein, presence of 140,000 or 160,000 daltons protein bands.

Ocular Rigidity in Korean

The Korean 218 normal eyes, 74 myopic eyes and 42 glaucomatous eyes were examined. The intraocular pressure were measured by Goldmann applanation tonometer and Schiotz indentation tonometer using the 5.5 gm plunger load successively. The occular rigidity was estimated from Friedenwald 1955 nomogram. In normal eyes, the average coefficient of ocular rigidity was 0.0221 (standard deviation 0.0058, range 0.0032~0.0370). There was a statistically significant increase with age. It was higher in males than in females. But there was no statistically significant difference between sex. In myopic eyes. the average coefficient of ocular rigidity was 0.0189. There was an increase with refractive power but it was not statistically significant. In glaucomatous eyes. the average coefficient of ocular rigidity was 0.0181 in the medication-treated group and 0.0163 in the operated group. They were significantly lower than in normal eyes statistically. But there was no significant differance between medication-treated and operated groups.

The Effect of Urokinase on the Hyphema in Rabbits

In 20 eyes of 10 rabbits, total hyphema were produced by injecting human fresh blood into the anterior chamber after aspirating the aquous humor. six hours later, 10 left eyes of them were treated with injection of urokinase into the anterior chamber. A control group of 5 right eyes were treated with normal saline and the other 5 right eyes were left untreated. The eyes treated with urokinase showed the most rapid rate of absorption of blood clot and clearance of corneal opacity among 3 groups. The comparison between the group treated with normal saline and the untreated group about the absorption rate of blood clot and clearance of corneal opacity were made. The former is slightly rapid than the later, but there was no significant differance between them. The observation of ciliary injection and changes of intraocular pressure had not shown a significant differance among 3 groups.