Earticle

Purpose: This study was to assess the effect of surface and heat treatment on the bond strength of veneering ceramics to zirconia. Methods: The specimens were divided into 7 groups according to surface treatment and heat treatment conditions prior to porcelain application. ten specimens from each group were subjected to a 3-point flexural test. In addition the influence of surface and heat treatment on surface roughness values and phase transformation of zirconia was evaluated. Statistical analysis was performed with one-way ANOVA and post hoc Tukey’s test. Results: Bond strength ranged from 20.67 3.13 to 32.69 4.52. Bond strength of surface treatment group was lower than that of control group but only Al2O3 sandblasting group was significant difference. Bond strength of heat treatment group was higher than that of surface treatment group but there was no statistical significance. Conclusion: Bond strength of veneering ceramics to zirconia was affected by surface and heat treatment.

Purpose: Surface modification is important techniques in modern dental and orthopedic implants. This study was performed to try embedding of bioactive materials in porous Ti implants. Methods: Porous Ti implant samples were fabricated by sintering of spherical Ti powders in a high vacuum furnace. It’s diameter and height were 4 and 20 . Embedding process was used to suction and vacuum chamber. Loading properties of porous Ti implants were evaluated by scanning electron microscope(SEM), confocal laser scanning microscope(CLSM), and UV-Vis-NIR spectrophotometer. Results: Internal pore structure was formed fully open pore. Average pore size and porosity were 10.253 and 17.506%. Conclusion: Porous Ti implant was fabricated successfully by sintering method. Particles are necking strongly each other and others portions were vacancy. This porous structure can be embedded to bioactive materials. Therefore bioactive materials will be able to embedding to porous Ti implants. Bioactive materials embedding in the porous Ti implant will induced new bone faster.

Purpose: This study is to provide basic data of the dental acrylic denture base resin in the mechanical property difference investigation according to the monomer composition weight ratio of the acrylic denture base resin. Methods: The monomer composition of the acrylic denture base resin and weight ratio makes the different specimen. It measured the mechanical property with the specimens through Hardness Test, Tensile Test, Flexural Test, Flexural Modulus, FT-IR Test. Results: The control group Vertex was 18.4 Hv and the experimental group MED was 14.46~19.07Hv in the hardness test. Vertex was 364N, MED-3 was lowest in the tensile strength test and the Head of a family cursor declination was big. The result declination of the experimental specimens showed. Vertex and MED-2 was the highestest in the flexural test and after coming MED-6, MED-5, MED-1, MED-3, MED-4. Vertex and MED-2, as to a spectrum for 500~1800 -1 peak can show the excellent degree of polymerization in the FT-IR Test. Conclusion: The ideal weight ratio of the monomer of the acrylic denture base resin of which the mechanical property is the highestest was MMA 100g, EDGMA 5g, DMA 0.2g, of MED-2.

Purpose: The grindability of Ti-10%Zr-X%Cr(X=0,1,3) alloys in order to develop Ti alloys for dental applications with better machinability than unalloyed titanium has been evaluated. Methods: Experimental Ti-10%Zr-X%Cr(X=0,1,3) alloys were made in an argon-arc melting furnace. Slabs of experimental alloys were ground using a SiC abrasive wheel on an electric handpiece at one of the four rotational speeds of the wheel (12000, 18000, 25000 or 30000rpm) by applying a force(100gf ). Grindability was evaluated by measuring the amount of metal volume removed per minute(grinding rate) and the volume ratio of metal removed compared to the wheel material lost, which was calculated from the diameter loss (grinding ratio). Experimental datas were compared the results with those of cp-Ti (commercially pure titanium)Results: It was observed that the grindability of Ti-10%Zr-X%Cr(X=0,1,3) alloys increased with an increase in the Cr concentration. More, they are higher than cp-Ti, particularly the Ti- 10%Zr-3%Cr alloy exhibited the highest grindability at all rotational speeds except 12000rpm. There was significant difference in the grinding rate and grinding ratio between Ti-10%Zr-3%Cr alloy and cp-Ti at all rotational speeds(p<0.05). Conclusion: The Ti-10%Zr-3%Cr alloy exhibited better grindability at high rotational speeds, great potential for use as a dental machining alloy.

Purpose: In this research, non-linear three dimensional finite element models with contact elements were constructed. For the investigations of the distributions of contact stresses, 3 units fixed partial dentures model were studied, especially on the interface of the gold screw and cylinder, abutment screw. Methods: 3 types of models were constructed ; the basic fixed partial denture in molar region with 3 units and 3implants, the intermediate pontic fixed partial denture model with 3 units and 2 implants, and the extension pontic fixed partial denture model with 3 units and 2 implants. For all types, the external loading due to chewing was simulated by applying 45 linguo-buccal loading of 300 N to the medial crown. For the simulation of the clamping force which clinically occurs due to the torque, thermal expansion was provided to the cylinder as a preload. Results: Under 300 N concentrated loading to the medial crown, the maximum contact stress between abutment screw and gold screw was 86.85~175.86 without preload, while the maximum contact stress on the same area was 25.59~57.84 with preload. Conclusion: The preloading affected the outcomes of the finite element stress analysis. Reflecting the clinical conditions, the preloading conditions should be considered for other practical study utilizing FEA. For the study of the contact stresses and related motions, various conditions, such as frictional coefficient changes, gap between contact surfaces, were also varied and analyzed.

Purpose: The purpose of this study was to know the physical properties of UDMA dental composite resins containing two photosensitizers, PD, DA, as a photosensitizer instead of CQ. We want to know Remaining Double Bond(RDB) of UDMA unfilled resin and diametral tensile strength and flexural strength of composite resin containing PD and DA were compared with those of CQ, most widely used photosensitizer for dental composite resins. Methods: The RDB of UDMA studied by FT-IR spectroscopy increased with irradiation time. The composite resins were tested for their physical properties. The dental composite resins were made with UDMA as a monomer,silanized silica as filler, N,N-dimethylaminoethyl methacrylate (DAEM) as amine initiator, and one of the two kinds of new photosensitizers. Results: The relative RDB of UDMA was in the order: DA > CQ > PD but the physical properties of the composite resins show PD and DA with higher results compared with that containing CQ. The reason for the results is that PD and DA serve not only as a photosensitizer but also as a photo-crosslinking agent. Conclusion: PD and DA show as effective photosensizers, suitable for UDMA dental composite resin compare with a higher efficiency than CQ.

Purpose: This study was examined the characteristics of bacteria isolated from the dental stone that is made ??inthe dental laboratory. Methods: 104 dental stones samples were collected from the 4 dental laboratory. Characteristics of bacteria wereinvestigated by microorganism isolation culture method using a Blood Tryptic Soy Agar(TSA) medium. Results: The detected various bacteria was confirmed as pathogenic bacteria, non-pathogenic bacteria and naturalbacteria. The isolated bacterial number was confirmed 2.9 103CFU and maxium bacterial number of 3.0 104CFU. Conclusion: Therefore, infection prevention education is required, it must be to live up the hand-washing andwear protective clothing to protect themselves when working in a dental laboratory.

Purpose: The purpose of this study was to evaluate the flexural strength of indirect composite resins with differentpolymerization conditions. Methods: Ten specimens (2 2 25 ) of each composite resins (Tescera (T), Gradia (S) and Sinfony (S)) were fabricated by two polymerization methods : manufacturers’s and light heat pressure. Composite resinspolymerized by manufacturers’s method and light heat pressure served as control (TS, GS and SS) andexperimental groups (TE, GE and SE), respectively. The composite resins were tested for flexural strength and thesurface of composite resins were observed with scanning electron microscope (SEM) under X1,000 magnification. Results: The flexural strength values of cured composite resin decreased in the following order: TE (195.4 ), TS(179.8 ), GE (169.9 ), SE (137.7 ), SS (111.1 ) and GS (100.9 ) groups. Conclusion: The flexural strength values between the control and the experimental groups were not significantlydifferent although experimental groups showed higher flexural strength values than control groups.

Purpose: The purpose of this study was to investigate to effect of the ZrN coated on corrosion resistance and physical property of dental Co-Cr alloys using various instruments. Methods: The specimens were used, respectively, for experiment, Arc Ion plating was carried out for dental casting alloys using ZrN coated materials with nitrogen gas. ZrN coated surface of each specimen was observed with field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), vickers hardness tester, and electrochemical tester. Results: The current density of ZrN coated specimen was smaller than that of non-coated specimen in 0.9% NaCl solution. Pit nucleated at scratch of specimen. The pitting corrosion resistant Emax- Erep increased in order of ZrN coated (110 mV), and non-coated wire (100 mV). Conclusion: The corrosion potential of the ZrN coated specimen was comparatively high. the surface of ZrN coated specimen was more smooth than that of other kinds of non-coated specimen. ZrN coated surface showed higher hardness than that of non-coated surface.

Purpose: This study was observation shear bonding strength by compositional change and firing step of a Ni-Cralloy for porcelain fused metal crown. The aim of study was to suggest the material for firing step of Ni71-Cr14alloy to development of alloy for porcelain fused to metal crown. Methods: The test was on the two kinds of Ni-Cr alloy specimens. The surfaces of two alloys were analyzed byEDX in order to observe oxide characteristic. And the shear test was performed by MTS. Results: The surface property and oxide characteristic analysis of oxide layer, weight percentage of Element Owithin Ni71Cr14 alloy measured 23.32wt%, and Ni59Cr24 alloy was measured 23.03wt%. And the maximum shearbonding strength was measured 58.02 between Ni59Cr24 alloy and vintage halo(H4 group). Conclusion: The surface property and oxide characteristic three kind of Ni-Cr alloy was similar. and shearbonding strength showed the highest bonding strength in H4 specimens.

Purpose: This study was to observe characteristic of metal oxidation and bonding strength according tocomposition of Ni-Cr alloy for porcelain fused to metal crown. The three kinds of Ni-Cr alloy with differentcomposition ratio of parent metal were observed general properties and chemical properties of each alloy surface andmeasured the shear bonding strength between ceramic and each alloys. The aim of study was to suggest the materialfor design of parent metal’s composition ratio to development of alloy for porcelain fused to metal crown. Methods: The three kinds of alloy as test specimen was Ni(59wt%)-Cr(24wt%), Ni(67wt.%)-Cr(16wt.%) alloyand Ni(71wt%)-Cr(12wt%)alloy. The oxide on surface was observed by EDX. And the shear test was performed byMTS. Results: The surface property and oxide characteristic analysis of oxide layer, weight percentage of Element Owithin Ni59Cr24 alloy measured 23.03wt%, Ni67Cr16 alloy measured 21.13wt% and Ni71Cr12 alloy was measured48.55wt%. And the maximum shear bonding strength was measured 58.02Mpa between Ni59Cr24 alloy and vintagehalo(H2 group). Conclusion: The surface property and oxide characteristic three kind of Ni-Cr alloy was similar. and shearbonding strength showed the highest bonding strength in H2 specimens.

Purpose: The purpose of this study is to investigate self management and subjective chewing ability and providethe basic information to research of healthy life of old people from development of education and method fordental health of denture patient. Methods: From 15th or August to 15th of September in Daegu and Gyeong-buk, denture patients were targetedfor a survey. Data from 295 people were analyzed. Results: Adjusted R2 of oral health and denture satisfaction of an object of study increased to 24.9% (F=20.460,p<.001). Adjusted R2 of denture custody and method of sterilization was 37.8% and Adjusted R2 of recognitiondenture satisfaction of chewing effect was 14.4% which affect to most(F=9.274, p<.001). Conclusion: In conclusion denture condition, denture custody, method of sterilization, chewing effect influenceoral health, healthy life of patients who have denture.

Purpose: This research conducted by using Department of Dental Laboratory Technology students investigatesinterpersonal and emotional intelligence impact on psychological happiness. Methods: Study was conducted in the Daegu-Gyeongbuk area Department of Dental Laboratory Technologystudents, based on 132 people who were enrolled college students. Data analysis, frequency analysis, factor analysis,reliability test, correlation analysis, multiple regression analysis was carried out and SPSS/WIN 18.0 was used. Results: Interpersonal factors utilize emotions, emotional self-control and emotional awareness. Others turnedpositive (+) was found to affect the psychological, emotional factors utilized in euphoria, emotional adjustment andwere found to have positive effects. Conclusion: Looking at the above results gathered from dental engineering students, improvement ininterpersonal relationships, and psychological welfare have improve more effectively through utilizing andcontrolling emotions, including the ability to set their own goals for the future. Motivational training programs forstrengthening study habits is more important than what can be based in dental college engineering students. Inconjunction with an active lifestyle, future professional dental health services for patients and clinicians care aboutthe improvement of his own psychological happiness was inspire by the care received from home and school and theresulting map is considered to require constant attention.

Purpose: This aim of this paper is to research the influence of customer satisfaction and reutilization on Dentalhospitals and clinics of medical service quality. Methods: The study examines 140 Patients who received treatment in Daegu from 1 July 2012 to 30 July 2012. The methods of research were used to factor analysis, reliability test using Cronbach’s factor, correlation analysis,multiple regression analysis and spss/win18.0. Results: The factor of quality of care has the highest impact on customer satisfaction. the influence of reutilizationdepends on the highest reliability and the physical environment was significant. Conclusion: To improve customer satisfaction and reutilization is required to maintenance of hospital facilities,medical services mind and quality of care. The medical service providers are important to develop patient educationprograms, self-development and customer satisfaction training techniques.

Purpose: This article examined the affecting factors of a malocclusion status of a patient for orthodontic treatment, orthodontics medical expenses and oral health behavior on orthodontic satisfaction. Methods: This paper conducted a survey from the 15th of July to 30th of September 2012 for the patients whowere under orthodontic treatment at three dental clinics where are in Deagu, and distributed a total of 210questionnaires and analyzed 194 questionnaires, excepting for some questionnaires that were answered unfaithfully. Results: This study classified the related factors into a feeling of satisfaction with treatment and mental satisfactionfor finding orthodontic satisfaction. There were the effect of the right tooth-brushing method, a periodic scalingand orthodontics medical expenses on a feeling of satisfaction with treatment, and power of explanation was 16.7%. Conclusion: There were the effect of a malocclusion status, matters that requires attention during orthodontictreatment, a periodic scaling during orthodontic treatment and orthodontics medical expenses on mentalsatisfaction, and power of explanation was 16.9%. Based on the result above, this paper concluded that preventivetreatment and early treatment should be emphasized through developing a program for regular oral examinationsuited to each medical type, including the method for improving the medical treatment condition and care servicefor increasing orthodontic satisfaction, which the dental medical-service providers could consider the patients andsecure trust.

Purpose: The purpose of this study was to examine the relationship of the general characteristics of health-relatedmajors to their life expectancy scale, depression scale, health perception scale, subjective wellbeing scale, somaticsymptom scale and college life stress scale. And it’s also meant to analyze influential factors for their stress aboutcollege life. Methods: The subjects in this study were the students who were in the department of dental laboratorytechnology and the department of dental hygiene at a college located in the region of Iksan, North Jeolla Province. Conclusion: As the worse physical health and worse mental health(life expectancy, depression, health perception,subjective wellbeing and physical symptoms, etc.) of the college students led to heavier stress about college life, howto promote their physical health and mental health should discreetly be considered, and every necessary measureshould be taken to improve their physical and mental health. Data were gathered in November and December, 2012. The life expectancy scale, depression scale, healthperception scale, subjective wellbeing scale, physical symptom scale, somatic symptom scale and college life stressscale of the general characteristics were analyzed by t-test and one way analyses of variance (ANOVA) and theDuncan’s multiple range test at the 95% confidence level to assess the statistical significance. And stepwise multipleregression analysis was conducted to determine what factors would affect the stress of the students about college life. The data were analyzed with the windows ver. 12.0(SPSS GmbH, Germany) statistical software program. Results: Among the general characteristics, there were significant differences according to gender and age in all thevariables that were life expectancy scale, depression scale, health perception scale, subjective wellbeing scale, physicalsymptom scale and college life stress scale. 61.3% of the students responded they slept for six hours or less, and therespondents who slept for six hours or less scored significantly statistically lower in health perception scale,subjective wellbeing scale and physical symptom scale. As for college life stress, the respondents who got depressedmore often, whose subjective peace or happiness was lower, whose life expectancy was lower, who had worse physicalsymptoms, whose living standard was lower and whose academic year was lower were under heavier stress abouttheir college lives.

Purpose: This study is to present a standard value for clinical crown angulation and inclination required inlaboratory process and see if the value can be used for actual laboratory process. Methods: In order to find out a standard value for clinical crown angulation and inclination, this study made astudy model of normal occlusion of 21 females in twenties. The clinical crown angulation and inclination of bothsix-maxillary and six-mandibular anterior teeth are measured by Set-up Model Checker. From the measured valueabove, the mean and standard deviation of the twelve teeth are obtained, and then the mean of the teeth betweenright and left side is calculated. Results: Each clinical crown angulation of maxillary central incisor, lateral incisor, and canine is like this; 1.01.3 , 3.0 1.3 , and 5.0 1.4 . In case of mandibular, each degree is like this; 0.6 1.1 , 1.5 1.1 , and4.1 1.1 . Each clinical crown inclination of maxillary central incisor, lateral incisor, and canine is like this; 6.11.8 , 4.5 1.9 , and -6.2 1.4 . In case of mandibular, each degree is like this; 0.3 1.5 , 0.3 1.8 , and-7.5 1.8 . Conclusion: As the result, the mean value for clinical crown angulation and inclination can be referred to actuallaboratory process. However, the mean value is different from those of the precedent study and an unsatisfied onefor adopting the standard value.