Tissue conditioner를 이용한 dynamic impression

정재현,장두익,김희중 조선대학교 구강생물학연구소 2003 口腔生物學硏究 Vol.27 No.1

Recently, it is frequently accepted for impression of complete denture that alginate (irreversible hydrocolloid) is used for primary impression and special tray is used for secondary impression. But, most standard textbooks recognize the variation in academic opinion and each offers various materials and techniques for functional(secondary) impression. The variety of recommendations in standard textbooks suggests no one technique is satisfactory for all clinical situations. Especially, impression taking is more difficult in mandible that has many muscle movement than in maxilla. The possibilities of overcoming treatment difficulties of patients with advanced mandibular residual ridge resorption by means of a dynamic impression method was stressed in a previous article Numerous presentations of dynamic impression methods include those of Schrott, Momme, Skogsborg, Greene, Loos, Hromatka, and Matthews, At the beginning, this method was applied tentatively for special patients after variations of conventional method was failed. The results were encouraging and, eventually, the dynamic impression became the impressicn of choice in the treatment of patients with a questionable prognosis with conventional dentures. Recently, dynamic impression has been used for treatment of patients with extreme resorption of the mandibular residual ridge. The shape of the osseous structures in these patients offers little possibility of retention and stability of complete dentures. Furthermore, muscle attachments are located near the crest of the residual ridge and, consequently, the dislocating effect of the muscles on the denture is great. For these reasons, the range of muscle action, as well as spaces into which the denture can be extended without dislocation, must be accurately recorded in the impression. Such impressions can be made by means of dynamic method.

Dentacolor Resin System의 물성에 관한 연구

정재헌,고영무 대한치과기재학회 1996 대한치과재료학회지 Vol.23 No.1

The aim of this study was to evaluate the physical properties on Dentacolor resin system. Fifteen specimens(20mm in diameter, 1mm in height) of Dentacolor resin were prepared according to American Dental Association Specification No.27 and the color parameters of L*, a*, b* were measured with a computerized colorimeter(Hunter Associated Laboratory Inc., USA) in the transmittance mode. To measre the amount of water sorption and solubility, fifteen specimens were immersed in distilled water at 37±1℃ and then stored extended up to 20 weeks. Microhardness test were made on fifteen Dentacolor resin specimens using microhardness tester(Shimadzu, Japan) at a cross head speed 50μm/sec., loading time of fifteen seconds, and 50gm of load applied. To measure the shear bond strength between Dentacolor resin and three kinds of dental casting alloys, that is, Neocast 4(Au alloy), Novopal 3(Ag-Pd alloy), and Verabond(Ni-Cr alloy), fifteen specimens were cast into square paddles(15 mm ×15 mm ×1mm) according to the manufacturer's recommendation. Fifteen specimens were prepared in cylindric molds(6mm in height, 3mm in diameter) for the compressive strength measurements. Fifteen specimens were prepared in cylindric molds(3mm in diameter) for the compressive strength Measurements. Fifteen specimens were prepared in cylindric molds(3mm in height, 6mm in diameter) for the diametral tensile strength measurements. The specimens were tested on a universal testing machine(Model No. AGS 110-A, Shimadzu, Japan) at a crosshead speed of 0.1 inch/min, for the shear bond strength, compressive strength and diametral tensile strength. The abtained results were as follows: 1. Dentacolor resin system showed significant total color change(△E value:3.641 ±1.278) after 16 weeks and the range of total color change(△E) of that was between 0.5∼3.641 for 20 weeks. 2. The amount of water sorption of Dentacolor resin system for 1 week was 0.30±0.119mg/㎠, and the amount of mean water sorption was 0.36mg/㎠ for 20 weeks. 3. The amount of solubility of Dentacolor resin system for 1 week was 0.060 ±0.018mg/㎠, and the amount of mean water sorption was 0.044mg/㎠ for 20 weeks. 4. The shear bond strength between Dentacolor resin system and Neocast 4, Novopal 3, and Verabond were 21.029 ±3.743 MPa, 20.242 ±2.548 MPa, and 19.889±4.032 MPa and the differences of shear bond strength of Dentacolor resin system according the kinds of alloys were showed significantly(p<0.05). 5. The compressive strength of Dentacolor resin system was 116.15 ±23.02 MPa, and Diametral tensile strength of that was 48.59 ±5.95 MPa. 6. The microhardness value(V.H.N.) of Dentacolor resin system was 35.28 ±2.53 after specimens were made immediately, and that was 33.15 ±2.15 after 20 weeks. The results of microhardness value showed decrease as elapsed of time, but the differences of that were not significant as a function of time(p>0.05).

Gilbert 증후군에서 열량 제한 시험과 Phenobarbital 자극 시험의 의의(14예)

이헌영,채경훈,정재훈,강윤세,김연수,문희석,박기오,이엄석,김선문,김석현,성재규,이병석,이강욱 충남대학교 의학연구소 2003 충남의대잡지 Vol.30 No.2

Gilbert 증후군은 인구의 7%에서까지 나타날 수 있는 매우 흔한 증후군으로서 비진행성인 양성의 만성적 경과를 치하며, 간질환의 증상과 징후가 없는 경한 비포합형 고빌리루빈혈증이 특징인 일종의 체질적인 증상으로서 혈장 빌리루빈 농도에 대한 사춘기의 영향 때문에 10대와 20대에 자주 진단이 된다. 따라서 임상적인 중요성은 미약하지만 높은 빈도가 예상되는 점에 그 중요성이 부여되어야 할 것이다. 따라서 적정한 임상적 진단법으로 기왕에 소개된 열량제한 시험과 phenobarbital 유도 시험을 시행하고 이들의 진단적 가치를 알아보기 위하여 본 연구를 시행하였다. 1990년 7월부터 1999년 4월까지 충남대학교병원에 내원하여 HBsAg, IgG anti-HBc 및 anti-HCV가 음성이고, 간 초음파 스캔에서 이상이 없으며, 혈청 AST, ALT 및 AP가 정상인 비음주자에서 경한 비포합형 고빌리루빈혈증이 있는 14예의 환자들을 대상으로 ^(99m)Tc-DISID 스캔을 시행하였으며, 기저 치 총빌리루빈 및 포합형 빌리루빈 치를 측정한 다음에 하루에 400Kcal로 48시간동안 제한한 열량 제한 시험을 시행하였고, phenobarbital을 하루 60mg씩 5일간 투여한 후에도 각각 총빌리루빈과 포합형 빌리루빈 치를 검사하여 비포합형을 구하였다. 대상 환자들은 모두 14예로서 남자가 11예(78.6%)였고 여자가 3예(21.4%)여서 3.7:1로 남자에서 많았으며, 20대가 6예(42.9%), 30대가 역시 6예(42.9%) 및 40대가 2예(14.2%)로서 2,30대가 대부분(85.8%)이었다. 열량 제한 시험 후의 총빌리루빈 치, 비포합형 및 포합형 빌리루빈 치들은 평균 각각 5.5±2.7, 4.2±2.3 및 1.3±10mg/dL 로서, 시험 전 치들인 3.0±0.8, 2.2±0.8 및 0.7±0.4mg/dL 보다 유의하게(p=0.001, p=0.001, p=0.023) 상승하였다. 포합형 빌리루빈 치도 유의하게 상승하였으나 비포합형의 상승보다는 훨씬 낮아서 주로 비포합형이 증가하였다. phenobarbital 투여 중 설사가 발생하여 중단한 1예를 제외한 13예에서 열량 제한 시험 후에 상승하였던 총, 비포합형 및 포합형 빌리루빈 치가 phenobarbital 유도 시험후에는 2.0±1.1, 1.5±0.8 및 0.5±0.4mg/dL로서 열량 제한 시험 결과보다 유의하게 낮아졌고(p=0.00, p=0.000, p=0.001), 열량 제한 시험 전의 기초치들인 3.0±0.8, 2.2±0.8 및 0.7±0.4mg.dL 보다도 더욱 낮아졌으며 유의한 차이(p=0.001, p=0.02, p=0.005)를 나타내었다. 14예에서 시행한 ^(99m)-Tc DISIDA 스캔에서 9예(64.3%)가 정상이었고, 5예(35.7%)에서는 심장 및 신장으로의 간외 섭취가 3예였고, 60분까지 소장 배출이 없는 배설 지연 예와 담낭 수축 불량 예가 각각 1예 씩 발견되었다. Phenobarbital 투여시험에서 민감도가 열량제한시험에 비해 더 높았다(92.3%와 50.0%). Gilbert 증후군에서 1일 400 Kcal로 48시간의 열량제한 시험과 1일 60mg의 phenobarbital을 5일간 투여하는 유도 시험은 편리하고 유용한 임상적인 진단법으로 이용할 수 있다고 생각된다. 그러나 열량 제한 시험에서는 증가 기준의 통일이 필요하다고 유추되며 phenobarbital 유도 시험이 민감도가 더 높은 것으로 생각된다. Gilbert's syndrome is very frequent and benign chronic process characterized by mild, intermittent, unconjugated hyperbilirubinemia without any symptom and sign of liver disease. Previously intoduced caloric restriction test and phenobarbital stimulation test as two appropriate clinical tests had been examined and their diagnostic values were reevaluated. Fourteen patients with mild, persistent, unconjugated hyperbilirubinemia were included. Subsequently caloric restriction has been applicated by 400 Kcal/day for 48 hours and phenobarbital has been prescribed by 60 mg/day for 5 days. Therafter serum levels of total and direct bilirubin were measured. Most of the patients were third and fourth decade(85.8%) and male predominant. Each basal serum levels of total, indirect and direct bilirubin were 3.0±0.8, 2.2±0.8 and 0.7±0.4 mg/dL. After caloric restriction test, each levels were increased significantly to 5.5±2.7, 4.2±2.3 and 1.3±1.0 mg/dL(p=0.001, p=0.001, p=0.023). After phenobarbital stimulation test for 13 patients had been practiced, increased levels of each bilirubin after caloric restriction test were decreased significantly to 2.0±1.0, 1.5±0.8 and 0.5±0.4 mg/dL(p=0.000, p=0.000, p=0.001) and these levels were significantly lower than basal levels(p=0.001, p=0.02, p=0.005). The sensitivities of caloric restriction test were 85.7%, 50.0%, and 71.4%, 35.7%(1.0, 1.5 mg increase of total bilirubin and 1.0, 1.5 mg/dL increase of indirect bilirubin). The sensitivities of phenobarbital stimulation test were 93.2% and 92.3% at criteria of 1.5 mg/dL increase of total bilirubin and indirect bilirubin. On the diagnosis of Gilbert syndrome, caloric restriction test and phenobarbital stimulation test are convenient and useful diagnostic tools in clinical face. And also phenobarbital stimulation test has higher sensitivity than caloric restriction test. Furthermore, standardization of bilirubin increment would be necessary in caloric restriction test.

Dentacolor Resin System의 색안정성 및 물흡수도에 관한 연구

고영무,정재헌,최유석 大韓齒科器材學會 1995 대한치과재료학회지 Vol.22 No.2

The purpose of this study was to measure the color stability and water sorption of Dentacolor resin system at various time intervals over 6 week period. Ten, 20 x 1mm discs of the resin specimen were prepared according to ADA specification No.27 and cured with a photo-polymerization equipment(Dentacolor XS and Unilux AC). The color parameters of L*, a*, b* were measured with a computerized colorimeter(Hunter Associates Laboratory Inc., USA) in the transmittance mode. The total color change(ΔE) occurred during two different time periods was calculated using the following equation: ?? The amount of water sorption measurements was done in accordance with ADA specification No.27 for one week in distilled water at 37 ±1℃ and then stored extended up to 6 weeks. The obtained results were as follows : l. At first week, total color difference(ΔE) value of Dentacolor resin system was 1.430 ±0.664. 2. It was found that the range of total color difference(ΔE) of Dentacolor resin system was between 0.5∼1.430 for 6 weeks. 3, The amount of water sorption for one week was 0.30 ±0.119mg/cm²and it was lower than the 0.7mg/cm²/week for type Ⅱ composites in ADA specification No.27. 4. The amount of water sorption of Dentacolor resin system after 6 weeks was much more than its amount of water sorption of the first week, but it was not significant difference(p>0.05).

치과용 자성 어태치먼트의 내구성에 관한 연구

이상훈,정재헌,고영무 대한치과기재학회 1997 대한치과재료학회지 Vol.24 No.1

The purpose of this study was to evaluate the compare the endurance of the commonly used dental magnetic attachments using potentiodynamic polarization method. For this study, 2 kinds of Sm-Co based; Magfit 600 and Magfit 400(G.C.) and 4 kinds of Nd-Fe-B based dental magnetic attachments ; Hicolex Super J(Morita Co.), Magfit EX 600(G.C.), Magfit EX 400(G.C.) and Neomagnet(Preat Corp.) were chosen as a specimen and performed electrochemical corrosion test in 4 electrolyte solutions ; 0.9% NaCl, 1% lactic acid, 0.05% HCI, modified Fusayama's artificial saliva solution. In 4 kinds of electrolyte solutions, the potential scanning was performed starting from -1000mV(SCE) to 1300mV and scan rate was 1.25mV/sec. From this study, we calculated the values of corrosion potential(Ecorr), corrosion rate, pitting potential(Epit), and passivation current density resulted from anodic polarization curves and then obtained physical properties such as changing rate of magnetic flux density, amount of metal ion released, mean average surface roughness values, the changing of surface microhardness values, weight loss of dental magnetic attachments and observed surface of dental magnetic attachments using metallurgical microscope after electrochemical corrosion test. The obtained results were as follows : 1. In potentiodynamic polarization curves, SNM showed the lowest values of pitting potential and the most fast corrosion rate. 2. The amount of released metal was reduced in the order of ME6, SNM, MG4, MG6, ME4 and HSJ and was the greatest in applying the 0.9% NaCl solution and was the least in applying the modified Fusayama's artificial saliva. 3. The order of magnetic flux density was HSJ, MG6, ME6, MG4, ME4, and SNM before corrosion. The decreasing rate of magnetic flux density was the least in case of MG4 and was the greatest in case of SNM after first and second corrosion. The decreasing rate of magnetic flux density of 6 kinds of all magnetic attachments was the least in applying the 1% lactic acid solution. 4. The order of average surface roughness values(Ra) was SNM, MG6, MG4, ME4, ME6 and HSJ before corrosion. Average surface roughness values(Ra) was the greatest in case of SNM and was the least in case of HSJ after first corrosion. ME6 and ME4 showed the greatest increasing rate of average surface roughness values(Ra). 5. The order of average surface microhardness values(V.H.N.) was the least in case of HSJ and was the greatest in case of SNM after first and second corrosion. The decreasing rate of average surface microhardness values of 6 kinds of all magnetic attachments was the least in applying the 1% lactic acid solution. 6. The decreasing rate of weight loss was reduced in the order of ME6, SNM and ME4 after first corrosion and was reduced in the order of ME4, SNM, ME6 after second corrosion. The decreasing rate of weight change showed the greatest in applying the 0.9% NaCl solution and the least in applying the 1% lactic acid after second corrosion. In conclusion, all 6 kinds of dental magnetic attachments showed great decreasing of endurance and much more corrosion resulted in increased the amount of metal ion released, decreased the magnetic flux density, increased the surface roughness values, and highly decreased surface microhardness values and increased the weight loss of dental magnetic attachments. it should be considered that the choice of the commercial dental magnetic attachments was needed properly because their endurance showed differences among each king of products.

치과용 자성 어태치먼트 재료의 안정성 개선에 관한 연구 : II.질화티타늄 코팅이 치과용 자성재의 내식성에 미치는 영향 Ⅱ.Effect of TiN Coating on Corrosion Resistance of Dental Magnetic Materials

최한철,고영무,정재헌,신종연,김일선,최성욱,정효수 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.4

Dental magnetic materials have been applied to removable prosthetic appliances, maxillofacial prostheses, obturator and dental implant but they still have some problems such as low corrosion resistance in oral environments. To increase the corrosion resistance of dental magnetic materials, surfaces of Sm-Co and Nd-Fe-B based magnetic materials were plated with TiN and then electrochemical corrosion test were performed in 4 kinds of electrolyte solutions(0.9% NaCl. 1% lactic acid, 0.05% HCl and modified Fusayama's artificial saliva). From this study, corrosion behavior, amount of elements released, mean average surface roughness values and the changing of mean surface microhardness values were measured comparing with control group of non-sputtered plating magnetic materials. The results were as follows: 1. TiN layer coated on magnet grows into preferred direction with lamellar structure and its thickness is 3.0㎛. 2. Sm-Co base magnetic materials coated with TiN have good corrosion resistance in 1% lactic acid and their pitting corrosion can not be seen. 3. Nd-Fe-B base magnetic materials coated with TiN showed good tendency of corrosion resistance in 0.05% HCl solution. 4. The amount of elements released from both Sm-Co and Nd-Fe-B base magnetic materials coated with TiN were more significantly decreased than that of uncoated magnetic materials. 5. The mean surface roughness values of both Sm-Co and Nd-Fe-B base magnetic materials coated with TiN were smooth than that of uncoated magnetic materials after corrosion test. 6. The decreasing rate of microhardness of both Sm-Co and Nd-Fe-B base magnetic materials coated with TiN were lower than that of uncoated magnetic materials after corrosion test. 7. Dental magnetic materials coated with TiN produced various corrosion products such as TiO, TiO₂, Ti₂O₃on the surface and resulted in better corrosion resistance than uncoated magnetic materials. In conclusion, it is considered that the corrosion problem of dental magnetic materials could be solved to some extent by EB-PVD with TiN on the surface of dental magnetic materials.

치과용 콘빔CT영상에서 총의치 장착 후 하악과두의 위치변화

이봉호,김재덕,정재헌 대한구강악안면방사선학회 2008 Imaging Science in Dentistry Vol.38 No.1

Purpose : The aim of this study was to evaluate the change in the position of the mandibular condyle within articular fossa by a CBCT after wearing complete denture (CD). Materials and Methods : CBCT of 34 temporomandibular joints were taken from 9 male and 8 female patients with CB Mercuray (Hitachi, Japan) before and after wearing a CD for rehabilitation. Position of mandibular condyle within articular fossa at centric occlusion was evaluated with Vimplant2.0(CyberMed, Korea) on the central parasagittal view and curved panoramic coronal view of the condylar head. A statistical evaluation was done with SPSS. Results : The range of anteroposterior positional rate (AP) of condylar head within articular fossa was -16-5 and -10-12 respectively on the right and left sides. Before wearing CD, the AP rate showed discrepancy between right and left sides (p<0.05). After wearing CD, both condyles showed a tendency to decrease in posterior condylar position (right side; p<0.05). The average discrepancy between right and left side in mediolateral positional rate (MD) was 15.5 and 4.5 respectively before and after wearing CD. The improvement was observed in mediolateral relationship of both condylar heads after wearing CD (p<0.01). Before wearing CD, the average horizontal angle of long axis of condylar head was 79.6±2.7˚and 80.1±5.7˚ respectively on the right and left sides. After wearing CD, both condyles were rotated in the same direction in average on axial plane. Conclusion : We observed with CBCT the significant clinical evidence in case of positional change of mandibular condyle after wearing complete denture.

치과용 자성재의 안정성 개선에 관한 연구 : I. 치과용 자성재의 전기화학적 부식에 대한 스퍼터링 도금의 효과 I. Effects of Sputtered Film Deposition on the Electrochemical Corrosion of Dental Magnetic Materials

고영무,최한철,정재헌,정효수,최성욱 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.4

In order to investigate the various properties of dental magnetic materials studies on corrosion behavior, decreasing rate of magnetic flux density, amount of elements released, mean average surface roughness values and the changing of mean surface microhardness values for dental application were done. To increasing the corrosion resistance of dental magnetic materials, surfaces of Sm-Co and Nd-Fe-B based magnetic materials were plated with gold(Au), platinum(Pt), titanium(Ti), chromium(Cr) and cobalt(Co), and then electrochemical corrosion test were performed in 4 kinds of electrolyte solution(0.9% NaCl, 1% lactic acid, 0.05% HCl and modified Fusayama's artificial saliva). The results were as follows: 1. In Sm-Co and Nd-Fe-B based magnetic materials, the pitting corrosion of experimental group was higher than that of the control group, the experimental group was less corrosive than control hroup. 2. The amount of elements released from experimental group was more significantly decreased than that of control group. 3. Decreasing rate of magnetic flux density of experimental groups was significantly lower than that of control group after corrosion test. 4. The mean average surface roughness value of one(Sm-Co based magnetic materials not plated) of the control group was much increased in modified Fusayama's artificial saliva after first corrosion but that of the other(Nd-Fe-B based magnetic materials not plated) was much increased in 0.05% HCl solution. 5. The decreasing rate of surface microhardness values of experimental groups were lower than that of control group after corrosion, 6. Intergranular corrosion started first from the grain boundary of the control group and they advanced gradually to general corrosion, and the pitting corrosion occurred locally at area of existing pits in experimental group.

미니 임플란트 직경에 따른 피로파절강도의 비교 연구

허유리,손미경,김희중,최한철,정재헌 大韓齒科補綴學會 2012 대한치과보철학회지 Vol.50 No.3

Purpose: This study was conducted to obtain difference in fracture strength according to the diameter of one-body O-ring-type of mini implant fixture, to determine the resistance of mini implant to masticatory pressure, and to examine whether overdenture using O-ring type mini implant is clinically usable to maxillary and mandibular edentulous patients. Materials and methods: For this study, 13 mm long one body O-ring-type mini implants of different diameters (2.0 mm, 2.5 mm and 3.0 mm) (Dentis, Daegu, Korea) were prepared, 5 for each diameter. The sample was placed at 30 from the horizontal surface on the universal testing machine, and off-axis loading was applied until permanent deformation occurred and the load was taken as maximum compressive strength. The mean value of the 5 samples was calculated, and the compressive strength of implant fixture was compared according to diameter. In addition, we prepared 3 samples for each diameter, and applied loading equal to 80%, 60% and 40% of the compressive strength until fracture occurred. Then, we measured the cycle number on fracture and analyzed fatigue fracture for each diameter. Additionally, we measured the cycle number on fracture that occurred when a load of 43 N, which is the average masticatory force of complete denture, was applied. The difference on compressive strength between each group was tested statistically using one-way ANOVA test. Results: Compressive strength according to the diameter of mini implant was 101.5 ± 14.6 N, 149 ± 6.1 N and 276.0 ± 13.4 N, respectively, for diameters 2.0 mm, 2.5 mm and 3.0 mm. In the results of fatigue fracture test at 43 N, fracture did not occur until 2×106 cycles at diameter 2.0 mm, and until 5×106 cycles at 2.5 mm and 3.0 mm. Conclusion: Compressive strength increased significantly with increasing diameter of mini implant. In the results of fatigue fracture test conducted under the average masticatory force of complete denture, fracture did not occur at any of the three diameters. All of the three diameters are usable for supporting overdenture in maxillary and mandibular edentulous patients, but considering that the highest masticatory force of complete denture is 157 N, caution should be used in case diameter 2.0 mm or 2.5 mm is used. 연구 목적: 일체형의 o-ring type 미니 임플란트 고정체의 직경에 따른 파절강도의 차이를 비교하고자 한다. 연구 재료 및 방법: 길이 13 mm의 one body o-ring type의 미니 임플란트(Dentis, Daegu, Korea)를 직경2.0, 2.5, 3.0 mm 각각 5개씩 준비하였다. Instron universal testing machine 에 수직면에서 30도 각도로 샘플을 위치시키고 off-axis loading을 가하여 영구변형이 일어난 하중 값을 파절강도로 하고 5개의 시편의 평균을 구하여 각 직경에 따른 임플란트의 고정체의 파절강도를 비교하였다. 또한, 각 직경마다 3개의 시편을 준비하고 동적하중 피로 시험기를 이용하여, 파절이 발생할 때까지 파절강도의 80%, 60%, 40%의 loading 을 가하여 파절되는 cycle수를 측정하여 각 직경의 피로 파절을 분석하였다. 추가적으로 총의치의 평균 저작력인 43 N의 하중을 가하여 파절되는 cycle 수를 측정하였다. 각 군간의 차이를 검증하기 위해서 일원분산분석(one-way ANOVA test)을 시행하였고, 통계처리는 SPSS ver.12 (SPSS Inc. Chicago, IL, USA) 을 이용하여 실시하였다. 결과: 직경 3.0 mm 의 미니 임플란트는 평균 276.0 ± 13.4 N의 압축력을 받았을 때 영구 변형이 일어났고 직경 2.5 mm 미니 임플란트가 149.0 ± 6.1 N, 2.0 mm 미니 임플란트가 101.5 ± 14.6 N일 때 영구 변형이 일어났다. 각 군간의 파절강도에는 유의한 차이가 있었다(P<.001). 총의치의 평균 저작력 하중에서 실시한 피로 파절 실험 결과, 세직경 모두 5×106 cycle까지 파절이 일어나지 않았다. 결론: 미니 임플란트의 정적 하중 하에서 최대 압축강도는 직경이 증가할수록 유의적으로 증가하였다. 최대 압축강도는 세 직경 모두 총의치의 평균 저작력 보다는 크나 최대 교합력보다는 직경 3.0 mm에서만 크게 나타났다. 총의치의 평균 저작력 하중에서 실시한 피로 파절 실험 결과, 세 직경 모두 파절이 일어나지 않았다.

Degradation Phenomena of Magnetic Attachments Used Clinically in the Oral Environment

( Chae Heon Chung ),( Han Cheol Choe ),( Jong Ha Kwak ) 대한금속재료학회 ( 구 대한금속학회 ) 2006 METALS AND MATERIALS International Vol.12 No.4

The purpose of this study was to investigate the mechanisms involved in the failure of magnetic attachments used to retain dental prostheses. Dyna magnets were retrieved from dentures that had failed after 34 months of clinical use. These magnetic attachments were prepared and sectioned so as to observe the corrosion surface and layer in order to analyze the corrosion behaviors of the attachments. The corroded surface was observed under a field emission scanning electron microscope (FE-SEM) (JSM 840A, JEOL, Japan). An X-ray diffractometer (XRD) was used to analyze the corrosion product formed due to corrosion in the oral environment. Erosion-corrosion started in the uneven portion of the stainless steel cover in the magnetic attachments composed with Nd-Fe-B alloy. Corrosion was initiated on the worn stainless steel surface, followed by spalling of magnetic material due to corrosive solution. The corrosion rate increased drastically after the corrosion product caused spalling in Nd-Fe-B alloy. Corrosion initiated in the uneven stainless steel surface as well as in the welded zone. In conclusion, the failure of magnetic attachments may occur by either welding failure or breakdown of the encapsulating material. Thus, we believe that treating the surface of magnetic attachments would resolve the corrosion problem seen in magnetic attachments to some extent.