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Effect of various abutment systems on the removal torque and the abutment settling in the conical connection implant systems (원추형 연결 임플란트에서 지대주 종류에 따른 나사풀림과 침하현상에 관한 연구)

  • Lee, Jin-Seon;Lee, Joon-Seok
    • The Journal of Korean Academy of Prosthodontics
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    • v.50 no.2
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    • pp.92-98
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    • 2012
  • Purpose: The aim of this study was to evaluate the effects of different abutment materials on abutment screw loosening and settling-down effect in conical connection type implant system. Materials and methods: Three types of abutment, cementation, gold UCLA, and metal UCLA abutment were used. Two UCLA groups were fabricated in a similar pattern to cementation abutment. Type III gold alloy and Nickel-Chromium alloy was used for casting gold UCLA abutment and metal UCLA abutment, respectively. Fixture and abutment were tightened to 30 Ncm by using digital torque controller and re-tightening was conducted with same force after 10 minutes. Digital torque gauge was used to measure loosening torque and fixture/abutment length was measured by digital micrometer. Dynamic loads between 25 N and 250 N were applied with $0^{\circ}$ angle to the abutment axis. After loading, fixture/abutment length was re-measured and amount of settlement was calculated. Loosening torque value was also measured for comparison Results: All three groups showed significant differences of length when comparing before and after loading, but there was no significant difference of settling amount in all groups. Loosening torque values were significantly decreased when comparing before and after loading in all groups($P$<.05). However, there was no significant difference in loss of loosening torque values when compared to groups. Conclusion: In internal conical connection type implants, dynamic load affected on settlement and loosening torque of implant, but there was no differences between abutments materials. Likewise gold UCLA abutment, metal UCLA abutment might be able to withstand functional load.

Retention of CAD/CAM Metal Copings Cemented on Short Titanium Abutments with Different Cements (짧은 티타늄 지대주에 합착된 CAD/CAM 금속 코핑의 시멘트 종류에 따른 유지력 비교)

  • Kim, Hyo-Jung;Song, Eun-Young;Yoon, Ji-Young;Lee, Si-Ho;Lee, Yong-Keun;Oh, Nam-Sik
    • Journal of Dental Rehabilitation and Applied Science
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    • v.28 no.2
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    • pp.119-126
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    • 2012
  • State of problem: Cement-retained implant-supported prostheses are routinely used in dentistry. The use of high strength cements has become more popular with the increasing confidence in the stability of the implant-abutment screw connection and the high survival rates of osseointegrated implants. No clinical data on retention of metal copings using CAD/CAM. To evaluate retention of metal copings using CAD/CAM system bonded to short titanium abutment with four different cements and compare retentive strength of metal copings with sandblasting or without sandblasting before cementation. Forty titanium abutment blocks were fabricated and divided into 4 groups of 10 samples each. Forty metal copings with occlusal hole to allow for retention testing were fabricated using CAD/CAM technology. The four cements were Fujicem(Fuji, Japan), Maxcem Elite(Kerr, USA), Panavia F2.0(Kurarary, Japan) and Superbond C&B(Sunmedical, Japan). The copings were cemented on the titanium abutment according to manufacture's recommendation. All samples were stored for 24h at 37oC in 100% humidity and tested for retention using universal testing machine(Instron) at a crosshead speed of 1.0mm/min. Force at retentive failure was recorded in Newton. The mode of failure was also recorded. Means and standard deviations of loads at failure were analyzed using ANOVA and Paired t-test. Statistical significance was set at P<0.05. Panavia F2.0 provided significantly higher retentive strength than Fujicem, Maxcem Elite(P<0.05). Sandblasting significantly increased bond strength(P<0.05). The mode of failure was cement remaining principally on metal copings. Within the limitation of this study, Panavia F2.0 showed significantly stronger retentive strength than Fujicem, Maxcem Elite(p<0.05). The Ranking order of the cements to retain the copings was Panavia F2.0, Fujicem = Maxcem Elite. Sandblasting significantly increased bond strength(P<0.05). The retentive strength of metal copings on implant abutment were influenced by surface roughness and type of cements.

Effect of Implant Types and Bone Resorption on the Fatigue Life and Fracture Characteristics of Dental Implants (임플란트 형태와 골흡수가 임플란트 피로 수명 및 파절 특성에 미치는 효과에 관한 연구)

  • Won, Ho-Yeon;Choi, Yu-Sung;Cho, In-Ho
    • Journal of Dental Rehabilitation and Applied Science
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    • v.26 no.2
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    • pp.121-143
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    • 2010
  • To investigate the effect of implant types and bone resorption on the fracture characteristics. 4 types of Osstem$^{(R)}$Implant were chosen and classified into external parallel, internal parallel, external taper, internal taper groups. Finite elements analysis was conducted with ANSYS Multi Physics software. Fatigue fracture test was performed by connecting the mold to the dynamic load fatigue testing machine with maximum load of 600N and minimum load of 60N. The entire fatigue test was performed with frequency of 14Hz and fractured specimens were observed with Hitachi S-3000 H scanning electron microscope. The results were as follows: 1. In the fatigue test of 2 mm exposed implants group, Tapered type and external connected type had higher fatigue life. 2. In the fatigue test of 4 mm exposed implants group, Parallel type and external connected types had higher fatigue life. 3. The fracture patterns of all 4 mm exposed implant system appeared transversely near the dead space of the fixture. With a exposing level of 2 mm, all internally connected implant systems were fractured transversely at the platform of fixture facing the abutment. but externally connected ones were fractured at the fillet of abutment body and hexa of fixture or near the dead space of the fixture. 4. Many fatigue striations were observed near the crack initiation and propagation sites. The cleavage with facet or dimple fractures appeared at the final fracture sites. 5. Effective stress of buccal site with compressive stress is higher than that of lingual site with tensile stress, and effective stress acting on the fixture is higher than that of the abutment screw. Also, maximum effective stress acting on the parallel type fixtures is higher. It is careful to use the internal type implant system in posterior area.

Three-Dimensional Finite Element Analysis of Internal Connection Implant System (Gsii$^{(R)}$) According to Three Different Abutments and Prosthetic Design (국산 내부연결형 임플란트시스템(GS II$^{(R)}$)에서 지대주 연결방식에 따른 응력분석에 관한 연구)

  • Jang, Mi-Ra;Kwak, Ju-Hee;Kim, Myung-Rae;Park, Eun-Jin;Park, Ji-Marn;Kim, Sun-Jong
    • Journal of Dental Rehabilitation and Applied Science
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    • v.26 no.2
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    • pp.179-195
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    • 2010
  • In the internal connection system, the loading transfer mechanism within the inner surface of the implant and also the stress distribution occuring to the mandible can be changed according to the abutment form. Therefore it is thought to be imperative to study the difference of the stress distribution occuring at the mandible according to the abutment form. The purpose of this study was to assess the loading distributing characteristics of three different abutments for GS II$^{(R)}$ implant fixture(Osstem, Korea) under vertical and inclined loading using finite element analysis. Three finite element models were designed according to three abutments; 2-piece Transfer$^{TM}$ abutment made of pure titanium(GST), 2-piece GoldCast$^{TM}$ abutment made of gold alloy(GSG), 3-piece Convertible$^{TM}$ abutment with external connection(GSC). This study simulated loads of 100N in a vertical direction on the central pit(load 1), on the buccal cusp tip(load 2) and $30^{\circ}$ inward inclined direction on the central pit(load 3), and on the buccal cusp tip(load 4). The following results were obtained. 1. Without regard to the loading condition, greater stress was concentrated at the cortical bone contacting the upper part of the implant fixture and lower stress was taken at the cancellous bone. 2. When off-axis loading was applied, high stress concentration observed in cervical area. 3. GSG showed even stress distribution in crown, abutment and fixture. GST showed high stress concentration in fixture and abutment screw. GSC showed high stress concentration in fixture and abutment. 4. Maximum von Mises stress in the surrounding bone had no difference among three abutment type. In GS II$^{(R)}$ conical implant system, different stress distribution pattern was showed according to the abutment type and the stress-induced pattern at the supporting bone according to the abutment type had no difference among them.

Effect on bone healing by the application of low intensity pulsed ultrasound after injection of adipose tissue-derived stem cells at the implantation of titanium implant in the tibia of diabetes-induced rat (당뇨유도 백서 경골에 티타늄 임플란트 매식 시 지방조직 유래 줄기세포 주입 후 저출력 초음파 적용이 골치유에 미치는 영향)

  • Jung, Tae-Young;Park, Sang-Jun;Hwang, Dae-Suk;Kim, Yong-Deok;Lee, Soo-Woon;Kim, Uk-Kyu
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.37 no.4
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    • pp.301-311
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    • 2011
  • Introduction: This study examined the effect of the application of low intensity pulsed ultrasound on bone healing after an injection of adipose tissue-derived stem cells (ADSCs) during the implantation of a titanium implant in the tibia of diabetes-induced rats. Materials and Methods: Twelve Sprague-Dawely rats were used. After inducing diabetes, the ADSCs were injected into the hole for the implant. Customized screw type implants, 2.0 mm in diameter and 3.5 mm in length, were implanted in both the tibia of the diabetes-induced rats. After implantation, LIPUS was applied with parameters of 3 MHz, 40 mW/$cm^2$, and 10 minutes for 7 days to the left tibiae (experimental group) of the diabetesinduced rats. The right tibiae in each rat were used in the control group. At 1, 2 and 4 week rats were sacrificed, and the bone tissues of both tibia were harvested. The bone tissues of the three rats in each week were used for bone-to-implant contact (BIC) and bone area (BA) analyses and the bone tissues of one rat were used to make sagittal serial sections. Results: In histomorphometric analyses, the BIC in the experimental and control group were respectively, $39.00{\pm}18.17%$ and $42.87{\pm}9.27%$ at 1 week, $43.74{\pm}6.83%$ and $32.27{\pm}6.00%$ at 2 weeks, and $32.62{\pm}11.02%$ and $47.10{\pm}9.77%$ at 4 weeks. The BA in experimental and control group were respectively, $37.28{\pm}3.68%$ and $31.90{\pm}2.84%$ at 1 week, $20.62{\pm}2.47%$ and $15.64{\pm}2.69%$ at 2 weeks, and $11.37{\pm}4.54%$ and $17.69{\pm}8.77%$ at 4 weeks. In immunohistochemistry analyses, Osteoprotegerin expression was strong at 1 and 2 weeks in the experimental group than the control group. Receptor activator of nuclear factor kB ligand expression showed similar staining at each week in the experimental and control group. Conclusion: These results suggest that the application of low intensity pulsed ultrasound after an injection of adipose tissue-derived stem cells during the implantation of titanium implants in the tibia of diabetes-induced rats provided some positive effect on bone regeneration at the early stage after implantation. On the other hand, this method is unable to increase the level of osseointegration and bone regeneration of the implant in an uncontrolled diabetic patient.

The influence of magnet on tissue healing after immediate implantation in fresh extraction sites in dogs (성견에서 발치 후 즉시 식립 임플란트에 설치한 자석이 주위 조직에 미치는 영향)

  • Yu, Seok-Min;Cho, In-Ho;Shin, Soo-Yeon
    • The Journal of Korean Academy of Prosthodontics
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    • v.47 no.4
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    • pp.435-444
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    • 2009
  • Statement of problem: The clinical use of electric and electomagnetic fields for fracture healing applications began in the early 1970s. Since then, several technologies have been developed and shown to promote healing of fractures. Developments of these devices have been aided in recent years by basic research and several well controlled clinical trials not only in the medical field but in dentistry. Purpose: The purpose of this study was to compare alveolar bone reduction following immediate implantation using implants onto which magnets were attached in fresh extracted sockets. Material and methods: Four mongrel dogs were involved. Full buccal and lingual mucoperiosteal flaps were elevated and third and fourth premolars of the mandible were removed. Implants with magnets and implants without magnets were installed in the fresh extracted sockets and after 3 months of healing the animals were sacrificed. The mandibles were dissected and each implant sites were sampled and processed for histological examination. Results: The marginal gaps that were present between the implant and walls of the sockets at the implantation stage disappeared in both groups as a result of bone fill and resorption of the bone crest. The buccal bone crests were located apical of its lingual counterparts. At the 12 week interval the mean of marginal bone resorption in the control group was significantly higher than that of the magnet group. The majority of specimens in magnet group presented early bone formation and less resorption of the buccal marginal bone compared to the control group. Conclusion: Within the limitations of this study, it could be concluded that implants with magnets attached in the early stages of implantation may provide more favorable conditions for early bone formation and reduce resorption and remodeling of marginal bone.

Clinical Evaluation of Implant-Supported Fixed Prostheses (임플란트-지지 고정성 보철물의 임상적 상태에 대한 평가)

  • Park, Chan-Yong;Yun, Mi-Jung;Huh, Jung-Bo;Jeong, Chang-Mo;Jeon, Yeong-Chan
    • Journal of Dental Rehabilitation and Applied Science
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    • v.29 no.4
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    • pp.317-326
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    • 2013
  • This study was to compare the cumulative survival rate of implant-supported fixed prostheses and to analyze association between risk factors and cumulative survival rate of implant-supported fixed prostheses. In order to assess the clinical status of implant-supported fixed prostheses, individuals who treated in the Department of Prosthodontics, Pusan National University Dental Hospital, between 2000 to 2007 were examined. The results of this study were as follows: 1. Length of service of implant-supported fixed prostheses was $6.6{\pm}32.0$ years (mean), 11.7 years (median). 2. Age and sex of patient was found to have no statistically significant influence on longevity of implant-supported fixed prostheses (P>.05). 3. Reason of tooth extraction wax found to have statistically significant influence on implant-supported fixed prostheses (P<.05). The longevity of fixed prostheses was low in tooth extraction case due to periodontal disease (median:9.0 years). 4. Location of implant-supported fixed prostheses was found to have statistically significant influence on longevity of fixed prostheses (P<.05). The longevity of fixed prostheses was low in molar region (median:8.8 years). 5. Number of units in implant-supported fixed prostheses was found to have no statistically significant influence on longevity of fixed prostheses (P>.05). 6. Condition of opposing dentition was found to have no statistically significant influence on longevity of implant-supported fixed prostheses (P>.05). 7. Food impaction (40.5%), porcelain fracture (25.8%), screw loosening (23.6%) were frequent complications.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.12
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

The Crystal Structure of Cholesteryl Carbonates (콜레스테롤 카보네이트 결정구조에 관한 연구)

  • 박영자;신정미
    • Korean Journal of Crystallography
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    • v.7 no.1
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    • pp.8-19
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    • 1996
  • Cholestryl Methyl and Propyl Carbonate(CH3OCOOC27H45, C3H7OCOOC27H45) are monoclinic, space group P21, with a=17.014(1), b=7.682(1), c=10.612(1)Å, β=103.05(1)°, Z=2, V=1351.16Å3, Dc=1.09 g/cm3 for methyl carbonate, and with a=13.683(1), b=11.864(2), c=18.904(2)Å, β=106.30(1)°, Z=4, V=2945.4Å3, Dc=1.06 g/cm3, Dm=1.06 g/cm3 for propyl carbonate. The intensity data were collected on an Enraf-Nonius CAD-4 diffractometer with a graphite monochromated Cu-Kα radiation. The structure was solved by direct methods and refined by full matrix least-squares methods. The final R factor was 0.051 for 2323 observed reflections for methyl carbonate and 0.074 for 3323 observed reflections for propyl carbonate. Compared with other cholesteryl derivatives, the cholesteryl ring and tail region of the molecules are normal. The molecules are stacked in clearly separated layers. At center of the layer, there are cholesteryl-C(17) side chain interactions. The interface region between layers is occupied by the loosely packed methyl carbonate chains. The structure of cholesteryl propyl carbonates have two propyl carbonates have two molecules(A, B) that are not related by crystal symmetry and have their tetracyclic system almost parallel to each other. Cholesteryl-cholesteryl interactions between symmetry related A-molecules, and cholesteryl-C(17) side chain interactions between symmetry related B-molecules occur at the center of the layers and these molecules stack along 2₁ screw axes. There are also C(17)chain-carbonate chain and C(17)chain-C(17)chain interactions in the interface region between layers. There is efficient packing between cholesteryl ring systems in propyl carbonates. Temperature ranges of cholesteric mesophases of cholesteryl alkyl cargonates are narrow for methyl, pentyl and hexyl carbonates, and rather broader for ethyl and propyl carbonates. Cholesteryl-isotropic transitions change very little with chain length.

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AN EXPERIMENTAL STUDY OF NEWLY DESIGNED IMPLANT WITH RBM SURFACE IN THE RABBIT TIBIA : RESONANCE FREQUENCY ANALYSIS AND REMOVAL TORQUE STUDY

  • Won Mi-Kyoung;Park Chan-Jin;Chang Kyoung-Soo;Kim Chang-Whe;Kim Yung-Soo;Isa Zakiahbt Mohd;Ariffin Yusnidar Tajul
    • The Journal of Korean Academy of Prosthodontics
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    • v.41 no.6
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    • pp.720-731
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    • 2003
  • Statement of problem. The importance of fixture design and surface treatment. Purpose. The clinical success of dental in plants is affected by many factors such like as degree of osseointegration, the effective load dispersion for the prostheses, and a lot of attempts have been made to overcome the difficulties. In this study, efforts were made to find the possibility of clinical acceptance of the dental implants of newly designed surface and resorbable blast media surcace. Materials and methods. In this study, two groups of custom-made, screw-shaped implants were prepared. The first with the consisting of Branemark clone design and the other with the new design. These implants were divided into four groups according to the kinds of surface treatment. Four implants($AVANA^{(R)}$, Osstem, Busan, Korea)of each group were installed in twenty rabbits. Group A was consisted of Branemark done implant left as machined, Group B with Branemark clone implants with RBM(Resorbable blast media) surface, Group C with newly designed implants left as machined and Group D with newly designed implants with RBM surface. One of the twenty rabbits died from inflammation and the observation was made for six weeks. Specimens from four groups were observed using scanning electron microscopy with 40, 100, 1000 magnification power and microsurface structures were measured by white-light scanning interferometry for three dimensional surface roughness measurements(Accura $2000^{(R)}$, Intek-Plus, Korea.). Removal torque was measured in 17 rabbits using digital torque gauge(MGT 12R, Mark-10 corp., NY, U.S.A.) immediately after the sacrifice and two rabbits were used for the histologic preparation(EXAKT $310^{(R)}$, Heraeus Kulzer, wehrheim, Germany) of specimens and observed under light microscope. Resonance frequency measurement($Osstell^{(R)}$) was taken with the 19 rabbits at the beginning of the implant fixation and immediately after the sacrifice. Results. Following results were taken from the experiment. 1. The surface of the RBM implants as seen with SEM had rough and irregular pattern with reticular formation compared to that of fumed specimens showing different surface topographies. 2. The newly designed implant with RBM surface had high removal torque value among four groups with no statistical significance. The average removal torque was $49.95{\pm}6.70Ncm$ in Group A, $51.15{\pm}4.40Ncm$ in Group B, $50.78{\pm}9.37Ncm$ in Group C, $51.09{\pm}4.69Ncm$ in Group D. 3. The RFA values were $70.8{\pm}4.3Hz$ in Group A, $71.8{\pm}3.1Hz$ in Group B, $70.9{\pm}2.5Hz$, $72.7{\pm}2.5Hz$ in Group D. Higher values were noted in the groups which had surface treatment compared to the untreated groups with no statistical significance. 4. The results from the histomorphometric evaluation showed a mean percentage of bone-to-implant contact of $45{\pm}0.5%$ in Group A, $55{\pm}3%$ in Group B, $49.5{\pm}0.5%$ in Group C, and $55{\pm}3%$ in Group D. Quite amount of newly formed bone were observed at the surface RBM-treated implants in bone marrow space.