복합레진의 중합 수축력과 수복물의 결합양상에 관한 연구 제 2 편 결합강도

박남수,우이형,최부병,임호남,최대균 大韓齒科器材學會 1993 대한치과재료학회지 Vol.20 No.2

Failure of bond between resinous restorative materials and tooth can be occured by the polymerization contraction forces larger than bond strengths. This study was planned to confirmed that the bond strengths between composite resin and acid etched enamel will be influenced by the polymerization contraction forces altered with filler contents and diameter of attached resin specimens. Ten kinds of experimental composite resins were prepared and bonded to bovine tooth enamel which were acid-etched. The diameter of resin specimens attached were 4 mm and 6 mm. The following conclusions were drawn : 1. Shear bond strengths were increased and then decreased with rise of filler contents, maximum shear bond strength was obtained by the 40% filled composite resin. 2. Unit shear bond strengths of resin specimens bonded with large area were lower than that of narrow area bonding. It was concluded that shear bond strengths to acid etched enamel can be influenced by the polymerization contraction forces.

실시간 홀로그램간섭계를 이용한 In-Ceram과 금속 하부구조의 변형에 관한 비교 연구

장현주,우이형,이성복 慶熙大學校 齒科大學 1995 慶熙齒大論文集 Vol.17 No.2

Porcelain jacket crown and metal ceramic crown are representative esthetic restorations for full veneer crowns. Genarally, Porcelain jacket crown is more esthetic and closer to natural tooth appearance. However it is brittle and subject especially to tensile stress. Recently, a new reinforced porcelain for substructure, In-Ceram(VITA Zahnfabrik, Germany) was developed. This new reinforced porcelain is stronger than all other existing porcelain material and, can be widely used as one of the substructure materials. This study compared the deformation of In-Ceram and metal substructures for the stress of 5, 7 9, 11, 13, 15kg forced to the each lingual slope with 30 degree angle. Metal substructure was casted with 3 kinds of metals precious(Degudent H, Degussa, Germany), semiprecious(Degupal U, Degussa, Germany), nonprecious(Rexillum IQ, Rexillium, U.S.A.). Real time holographic interferometry was used for analysing the stress of these samples. This holographic interferometric analysis can evaluate the whole aspect of deformation without any morphological limitations and analyze finite deformation of samples by um and can be used on the idential samples not on computer model nor any other simulations. The results obtained were as follows 1. When the load by Max. 15kg was added to the lingual slope of each samples, in all cases of In-Ceram, Degudent H, Degupal U, Rexillium III substructures, tensile deformation on the labial aspect and compressive deformation on the lingual aspect were increaced from the cervical to incisal region. 2. When the surface deformation of each substructure was compared , In-Ceram showed uniform stress distribution without any flexion of its surface. In the metal substructures, Rexillium III on the labial aspect, Degupal U on the lingual aspect showed uniform surface deformation without any flexion. 3. In the case of Degudent H, severe changes of fringe patterns appeared at the incisal resion of labial aspect & whole lingual aspect, therfore interpretation of interferogram was not possible in this study: 4. When compared the Max. deformation of labial surfaces, In-Ceram showed least deformation in the load of 5,7,9kg and also in the load of 11,13,15kg except Rexillium M. When compared the Max. deformation of lingual surfaces, In-Ceram showed greatest deformation in all loading condition. 5. In the respect of stress distribution, In-Ceram was not disadvantageous. Holographic interferometry has a few methodological limit for the small dental restoration anlysis relatively great dynamic force condition. But as noncontact and nondestructive stress analyzing method, it is valuable to analyze 'finite deformation and more studies needed to apply it.

Holographic Interferometry를 이용한 탄성 고무 인상재의 체적변화에 관한 연구

하치양,이성복,우이형 慶熙大學校 齒科大學 1995 慶熙齒大論文集 Vol.17 No.1

This study investigated the time-dependent dimensional changes of elastomeric impression materials using holographic interferometry. Six commercial impression materials, Permlastic(polysulfide), Xantopren VI, (condensation silicone), low and medium viscosity of Exafine, Provil (addition silicone), and Impregum( polyether), were selected. Steel plate was used as custom tray, and each impression specimen was 20 mm in width, 15 mm in length and 3 mm in thickness. Each impression material was evaluated at 30 minutes, 1, 2 4, 6, 8 and 12 hours after setting using real-time holography. The results were as follow 1. Xantopren VL and Permlastic showed relatively severe and continuous dimensional changes after setting. Low viscosity of Exafine, Provil, Impregum showed relatively slight dimensional changes with function of time and medium viscosity of Exafine showed almost no dimensional change from 2 hours after setting to 6 hours. 2. On initial dimensional changes within 1 hour, the amount of change in low viscosity of Exafine was the least and Xantopren VL was the largest. 3. On dimensional changes at 4 hours after setting, the amount 'of change in medium viscosity of Exafine was the least and the change of Xantopren VL was the largest. 4. In overall dimensional stability during 12 hours, medium viscosity of Exafine was the most stable and Xantopren VL and Permlastic were least stable.

금속면의 표면처리 방법에 따른 금합금과 전장레진간의 전단결합강도에 관한 연구

박동원,임호남,우이형,최부병 慶熙大學校 齒科大學 1994 慶熙齒大論文集 Vol.16 No.1

The effect of five different surface treatments on the shear bond strength of the resin bond to Type IV Gold alloy was studied by bonding resin to metal. The metal surface was subjected to one of the following treatments and bonded ; (1) air abraded with 50?m alumina particles, (2) beads (3) beads and tin-plated at current density of 300mA/cm2, (4) tin-plated at current density of 300mA1cm (5)silicacoating with Sililink, and bonded with an MDP Opaque primer, CESEAD resin system. The bonded specimens were immersed in water for 23 hours after 1 hour resin curing and shear bond strength were recorded On the basis of this study, the following conclusions can be drawn; 1. Difference were found in the shear bond strength among all experimental groups. and bead group exihibited the highest shear bond strength and sand blasting group exhibited the lowest shear bond strength on five groups. 2. Bead group, mechanical bonding was significantly higher than that obtained with the samples, tinplating, silicacoating, and chemical bonding. 3. No statistically significant difference was found between the shear bond strengths obtained with bead and bead tinplating, and between tinplating and silicacoating.

Holographic Interferometry를 이용한 하악 구치부 도재소부 전장관용 금속 구조물의 굴곡성향에 대한 연구

최진웅,우이형,최부병 慶熙大學校 齒科大學 1995 慶熙齒大論文集 Vol.17 No.1

Flexion of a metal/ceramic fixed partial denture(FPD) frameworks under function can cause fracture of porcelain or deterioration of the cement seal. This study evaluated the flexion characteristics of three-unit mandibular FPI) frameworks, replacing the second premolar under compressive load(200g, 400g). Testing was accomplished with real-time holographic interferorrmetry, using 6 porcelain fused-to metal frameworks. Tested alloys were non-precious alloy(Heracles, Holland), semi-precious alloy(Degudent U, Germany) and precious alloy(Degudent H, Germany). Changes of the fringe patterns according to the heat treatment (porcelain firing cycle), various loads (200g, 400g), occlusal forms (occlusal porcelain veneering, facial porcelain veneering), various alloys and post-soldering units were compared. Dental study model (Nissan dental products, Inc. D51DP-500A, Japan) and six 3-unit metal/ceramic fixed partial denture frameworks were used as experimental materials. 36 holograms were taken on fixed dental study model b using the 10mW He-Ne laser and real-time holographic interferometry. On the basis of this study, the following conclusions can be drawn : 1. In the frameworks for facial porcelain veneering, the semi-precious alloy framework was least deformed and precious alloy framework, non-precious alloy framework orderly before heat treatment, and the deformation was not shown great difference among three alloys after heat treatment and post-soldering. 2. In the frameworks for occlusal porcelain veneering, the precious alloy framework was greatest deformed and the deformation was not difference between semi-precious alloy framework and non-precious alloy framework before, after heat treatment, and the deformation was not shown great difference among three alloys after post soldering. 3: In the non-precious alloy frameworks for facial porcelain veneering and occlusal porcelain veneering, the deformation was greatly decreased after heat treatment and conversely increased after post-soldering. 4. In the semi-precious alloy framework for facial porcelain veneering, the deformation was not detectable after heat treatment and increased after post-solder. And in the framework for occlusal porcelain veneering, the deformation was slightly decreased after heat treatment and increased after post-soldering. 5. In the precious alloy framework for facial porcelain veneering, the deformation was greatly decreased after heat treatment and increased after post-soldering. And in the framework for occlusal porcelain veneering, the deformation was greatly decreased after heat treatment and decreased after post-soldering.

복합레진의 중합 수축력과 수복물의 결합양상에 관한 연구 제 3 편 변연누출과 틈새

박남수,최대균,임호남,최부병,우이형 大韓齒科器材學會 1993 대한치과재료학회지 Vol.20 No.2

This study was designed to confirm the influence of the polymerization contraction stress to the marginal leakage and gaps of resin restorations. Ten kinds of experimental composite resins were prepared with varing the filler contents to display the different polymerization contraction stress. A cavity with enamel and dentin margins were prepared on the cervical area of human tooth. Enamel margins were etched with 37% phosphoric acid for 1 minute. Experimental composite resins were filled into the cavities and immersed in water bath of 37±1℃ for 24 hours, and then immersed into dye solution. Tooth were cut through the restoration, and the infiltration of dye was observed. Marginal gaps were measured on the light microscope with 100 magnifications. The following conclusions were drawn : 1. Polymerization contraction stress and gaps showed the corelation between them, gaps were decreased by increase of filler contents. 2. There was not exist the relationships between polymerization contraction stress and marginal leakage. 3. Marginal leakage and gaps were larger at dentinal margins than enamel margins.

복합레진의 중합 수축력과 수복물의 결합양상에 관한 연구 제 1 편 : 중합수축력

박남수,최대균,임호남,최부병,우이형 大韓齒科器材學會 1993 대한치과재료학회지 Vol.20 No.1

The polymerization contraction forces has a relationship with the contents of filler, and if forces surpass the bond strength between restoration and bonded surface, the failure of bond can be occured. This study was designed to evaluate the effects of filler contents on the polymerization contraction forces and to confirm whether the polymerization forces could induce the bond failure of composite resins to enamel or dentin. Low capacity load cell using strain gauge were prepared and used as a measurement system for polymerization contraction forces. Oxidized alloy surfaces, enamel surfaces and dentin surfaces were used as bonded surface. Measurements of the polymerization contraction forces were done for 1 hour, and a stress at 1 hour after was recorded as a polymerization contraction force. It was considered as a bond failure that the polymerization contraction forces increased and then decreased by the time. The following conclusions were drawn : 1. Polymerization contraction forces of composite resins were decreased by the increase of filler contents. 2. Polymerization contraction forces were increased at thickened resin specimens, but it was not significant at over two millimeter thickness. 3. Bond strength of composite resins to the acid etched enamel surfaces exceeded the polymerization contraction forces and the reduced polymerization contraction forces due to the bond failure were not confirmed. 4. Failure of bond and reduced polymerization contraction forces occured on dentin.

하악골 충격시 안면 두개골의 응력분산양상에 미치는 구강보호장치의 역할에 관한 유한요소법적 연구

김일한,노관태,노현식,김지연,우이형,Kung-Rock Kwon,최대균 대한치과보철학회 2012 대한치과보철학회지 Vol.50 No.1

연구 목적: 이 연구의 목적은 하악골 충격 시 안면 두개골의 응력 분산양상에 미치는 구강보호장치의 효과에 대해 조사하는 것이다. 연구 재료 및 방법:: 구강보호장치를 제작하고 사람의 머리부위와 치열의 3차원적 유한요소 모델을 컴퓨터 토모그래피를 사용하여 제작하였다. 머리부위의 finite element model은 356,092요소와, 87,099절점으로 이루어져 있다. 그리고 skull과 maxillae, mandible, articular disc, teeth, 그리고 구강보호장치로 구성되었다. 경부의 움직임을 묘사하기 위하여 스프링이 사용되었다. 하악골의 충격점은 gnathion, center of inferior border 와 anterior edge of gonial angle이었다. 충격방향은 수직, 경사방향(45 도), 그리고 수평이다. 충격량은 0.1초당 800 N이었다. 결과: 수직충격을 가한 경우에는 구강보호장치의 장착여부와 무관하게 비슷한 응력과 분산양상이 나타났다(P>.05). 경사충격(45 도)을 가한 경우 구강보호장치를 장착한 모델에서는 응력이 치아와 안면골 및 두개골로 넓게 분산되었으나 이에 비하여 장착하지 않은 모델에서는 치아에 응력이 집중되었다(P<.05). 수평충격을 가한 경우 구강보호 장치를 장착한 모델에서는 응력이 치아와 안면골 및 두개골로 넓게 분산되었으나 이에 비하여 장착하지 않은 모델에서는 치아에 응력이 집중되었다(P<.05). 구강보호장치를 장착하지 않은 모델에서는 상악 치아에 응력이 집중되는 반면, 장착한 모델에서는 모든 충격실험에서 계측된 응력이 매우 낮았으며, 전달된 응력이 상악 치아와 안면골 및 두개골로 넓게 분산되었다. 결론: 구강보호장치는 외부충격 시에 하악에 수직으로 가해지는 충격에는 완충효과가 적었고, 45 도 경사 충격과 수평 충격에는 발생하는 응력을 안면골과 두개골의 넓은 범위로 분산시키고 응력을 감소시켜 응력의 완충 효과가 있었다. PURPOSE. The purpose of this study was to investigate the effects of a mouthguard on stress distribution under mandibular impact. MATERIALS AND METHODS. The FEM model of head consisted of skull, maxilla, mandible, articular disc, teeth, and mouthguard. The impact locations on mandible were gnathion, the center of inferior border, and the anterior edge of gonial angle. And the impact directions were vertical, oblique (45 degrees), and horizontal. The impact load was 800 N for 0.1 sec. RESULTS. When vertical impact was applied, the similar stress and the distribution pattern was occurred without the relation of the mouthguard use (P>.05). The model with mouthguard was dispersed the stress to the teeth, the facial bone and the skull when the oblique (45 degrees) impacts were happened. However, the stress was centralized on the teeth in the model without mouthguard (P<.05). The model with mouthguard was dispersed the stress to the teeth, the facial bone and the skull when the horizontal impacts was occurred. However, the stress was centralized on the teeth without mouthguard (P<.05). For all impact loads, stress concentrated on maxillary anterior teeth in model without mouthguard, on the contrary, the stress was low in the model with mouthguard and distributed broadly on maxillary anterior teeth, facial bone, and skull. CONCLUSION. The mouthguard was less effective at shock absorbing when vertical impact was added. However, it was approved that mouthguard absorbed the shock regarded to the oblique (45 degrees) and horizontal impact by dispersing the shock to the broader areas and decreasing the stress.

Esthetic prosthodontics in relation to tooth enamel

Woo, Yi-Hyung 경희대학교 동서의학연구소 1991 INTERNATIONAL SYMPOSIUM ON EAST-WEST MEDICINE Vol.1991 No.3

The public is bombarded by media extolling the virtures of "the perfect smile." Dental profession is faced with specific esthetic demands and a rapid evolution of new technics. Dental porcelain has become the most widely used material for the construction of crowns in dentistry because of its excellent esthetic properties and its ability to closely duplicate the appearance of natural tooth structure.

Comparison of Osteogenic Differentiation of Bone Marrow Stromal Cells on Zirconia and Titanium

( Yi Hyung Woo ),( Ah Ran Pae ),( Ki Chang Bae ),( Hyeong Seob Kim ),( Hee Su Lee ) 한국조직공학·재생의학회 2009 조직공학과 재생의학 Vol.6 No.14

The ivory color of zirconium oxide, which is similar to the color of natural teeth, makes it useful in esthetically important areas of the oral cavity, and its high biocompatibility with reduced bacterial adhesion and flexural strength render it an excellent material for implant abutments. The purpose of this study is to evaluate the proliferation and osteogenic potential of bone marrow stromal cells on zirconium oxide surfaces using cDNA microarrays. Rat bone marrow stromal cells were harvested and cultured on (1) grade 4 titanium disc (control group) and (2) yttrium-stabilized tetragonal zirconia polycrystal (experimental group). cDNA microarrays were used to monitor expression of 21575 genes in both control and experimental groups. Cell proliferation activity was evaluated through MTT assay and SEM was used to visualize the progression of osteoblast culture. ALP activity was also measured to evaluate cell differentiation rates. The optical densities of blue formazan produced by bone marrow stromal cells on titanium and zirconia surfaces were not significantly different in the results of MTT assays. SEM examination revealed that cells were well spread and attached on both surfaces. Cells cultured on titanium and zirconia showed similar ALP activities, while cDNA microarrays indicated that the expression profiles of cells in control and experimental groups were similar. Zirconia proved comparable to titanium in terms of biological response and as a substrate for the growth of bone marrow stromal cells.