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As the development of nanotechnology, the use of composite resins which containing nanofillers becomes popular. The purpose of this study was to test the degree of polymerization of nanofillercontaining composite resins. For the study, three different nanofiller-containing composite resins and two different light-curing units were used. To evaluate the degree of polymerization, the maximum polymerization shrinkage taking place during the light curing, and the microhardness, after the light curing, were measured. As results, two light-curing units exhibited a similar emission spectrum to that of the included photoinitiator, camphorquinone. The only difference between the light-curing units were the width of the emission spectrum. Three different composite resins showed different microhardness values. Among them, Grandio showed the greatest microhardness value. However, there was less microhardness difference on the top and bottom surfaces due to the difference of the light-curing units. The maximum polymerization shrinkage values were also similar in the tested specimens regardless of the difference of the light-curing units. However, Grandio showed the least polymerization shrinkage. According to the manufacturers' data, Grandio showed the highest filler content(vol%).

This study was conducted to research into the recognition level of employment and overseas employment on 173 students majoring in dental technology at two colleges in Daegu metropolitan city and Jeju self-governing island through questionnaires which are recorded individually. The results are as follows. 1. About 31.8% students chose dental technician department taking their aptitude into consideration when they entered college. 52% students gained information about dental technology through internet, and 57.3% students among them, which was the highest level, were under age 20. 2. 48.6% students responded that they thought the level of satisfaction with major was average and there was a difference according to their ages among the level of satisfaction or dissatisfaction with their major and the previous knowledge of major they had gained before entering college. 75.1% students said they wouldn’t transfer to other major even if they were given the chance, which was much higher than the opposite case. And only 2.3% students had dissatisfaction at their major, which means students majoring dental technology evaluate their major positively. 3. Most students(58.4%) wanted to get a job for living cost and 53.2% students took advice from their seniors or elderly people in choosing their jobs. 64.7% students answered they should have professional skills to get a good job, which was different according to their ages. In addition, 51.4% students of dental technology department regarded the opportunities to exert their abilities as the most important element in choosing their jobs. That means students value self-decision and selfrealization when they choose their jobs. 4. The majority of students(32.9%) preferred to work at the dental laboratory in dental college hospital as their workplace. Moreover, seniors over age 21 wanted to work in the field of porcelain and juniors under age 20 preferred to work in the implant part concerning the field which students wants to work. 5. About 91.3% students have ever heard about overseas employment and wanted to work abroad if given the opportunities(77.5%). This points out students have much interest in overseas employment and positive attitude. And there was a difference according to age and grade in case of the preferred country when they work abroad 6. The main barrier to overseas employment was a lack of communication ability(63.0%), therefore, students thought foreign language education should be activated to improve overseas employment(26.0%). To show this more specifically, juniors thought foreign language education and internship are most important factors(both are 21.4% alike), while seniors thought foreign language education is essential(24.6%) as a way to improve overseas employment. Students also thought that participation in language study club helps to prepare for overseas employment(69.4%). When putting all these survey results together, it’s very important to develop people in advance who have job ability and language ability necessary for overseas employment as well as to improve job awareness in the field of dental technology. Consequently, it’s needed to seek for various ways to get a overseas job through foreign language education and overseas internship.

The aim of this study was to make dental technicians recognize the importance of their professional self-concept, and to provide basic data to devise the educational programs and policies of establishing their positive professional self-concept. In addition, the investigator tried to present some improvement measures for dental technicians’ actual services by examining their job satisfaction. Study findings are as follows: First, the score of study subjects’ self-concept is 3.41( .58) (perfect score=5), middle or high in rank. As for the mean score of professional self-concept by realms, the self-concept of communication is 3.59( .67), the highest; the self-concept of leadership in the realm of professional service is 3.54( .75); the self-concept of skills is 3.50( .75); the self-concept of adaptability is 3.47( .69); and the recognizant level of satisfactory self-concept is 2.95( .81), below the normal. Second, as for the difference of professional self-concept according to general characteristics, such variables as age, marital states, and the length of one’s service have a significant influence upon the recognition of self-concept. First, the self-concept of those whose age is between 31 and 35 is the highest (3.64 .49), and it is followed by that of those whose age is 36 and above (3.57 .77) and then that of those whose age is between 26 and 30 (3.31 .56)). And that of those whose age is below 25 is the lowest. The obove results show us that the professional self-concept of older study subjects is higher than that of younger ones in general(p<.01). As for marital states, that of married persons(3.54 .64) is higher than that of unmarried ones(3.35 .55)(p<.05). As for the length of one’s service, that of longtime employees is higher than that of short-period workers(p<.01). In relation to positions, a manager’s professional self-concept is the highest(3.89 .55) and that of an assistant technician is the lowest(3.17 .58). Study findings show that the professional self-concept of higher ranking technicians is higher than that of lower ones in general (p<.001). Based on the study findings, the investigator suggests followings: First, studies on the professional self-concept that is appropriate to the characteristics of dental technicians must be carried out with a new point of view. Second, a tool must be researched and developed in order for the professional self-concept of dental technicians to be measured. Third, if a new professional self-concept is established and a measuring tool is developed, a study on the relationship between dental technicians’ professional self-concept and practice performance can be carried out again.

This research collected the curriculum for Dental Technology from a total of 20 schools -3-year colleges and 4-year colleges- all in Korea. And we analyzed the average credits of subjects from students. As a result of this analysis, we get the conclusion below: 1. In a distribution which students answered about each subjects; Seminar, Dental morphology , Dental morphology practice , and Dental devices & instruments don’t have many credits and mostly have a converged tendency in high points, according to the arithmetic mean of the major basis subjects. 2. In an analysis of the correlation which is based on the distinction of sex: Complete denture prosthodontics , Dental orthodontics , Dental orthodontics practice , and Dental orthodontics & practice have a meaningful difference. ( < 0.05 ) 3. In an analysis of the correlation which is based on an age The major basis subjects -Introduction to dental technology, Dental esthetic, and Dental casting procedure-, and the major application subjects -Crown and bridge prosthodontics practice, Complete denture prosthodontics, Dental orthodontics, Dental orthodontics practice, and Operative dentistry laboratory technology- have meaningful difference. ( < 0.05 ) 4. In a correlation coefficient between subjects; The correlation coefficient of the major application subjects is higher than the major basis subjects. According to the student - t, we found that the level of significance is < 0.001, which is meaningful. We feel the lack of a limitation which we didn’t survey all students who are major in Department of Dental Technology. And we also feel that we’d better to consider not only students who being in college but also graduated students.

This study is for the purpose of studying the validity of the construction of items and grading of the evaluation table at clinical practice used as the method of evaluation when clinical practice of Dept. of Dental Technology. 205 dental technicians in 4 cities were questioned to analyze the relation between items of the evaluation table at clinical practice and its grading. The collected materials were inspected by SAS V8 for Windows. The results are as follows: 1. Making up all the items and grading seem to be appropriate because they had the marks more than midium(more than 3.28). 2. Making up detailed items and grading seem to be trusted because they had the marks more than 3.30. 3.The significance level of the relation between items of the evaluation at clinical practice and its grading by t-inspection is p<0.0001 and so it appears to be meaningful. 4. It proved to be meaningful in result of regression analysis of the influence on the construction of the evaluation at clinical practice and its grading. With this result, further study is needed for the better methods of the evaluation in its adjustment and graduated grading among the items.

In this study, We tried to find out the fracture strength of zirconia coping all ceramic crown and collarless porcelain fused gold alloy crown as the compared group. Each of the collarless porcelain fused gold crown and zirconia all ceramic crown has been produced specimen 10 each. And after pasting them on the steel jig, it had load given at porcelain incisal edge by 130 and measured fracture strength by Universal Testing Machine and then We have results from that. 1. The average value of fracture strength suggested 950.49 N at collarless porcelain fused gold alloy crown, 656.81 N at zirconia coping all ceramic crown. 2. Fractured pattern showed that the whole of labial part was exposed in collarless porcelain fused gold crown, but porcelain of margin part did not show fracture in advance. In the practice, the concern that collarless might cause fracture strength to be weaken does not matter, we concluded zirconia all ceramic crown made fracture that only a part of labial porcelain was fractured. The combination of zirconia all ceramic crown and turned out to be excellent.

The purpose of this study is to widen the subject of research to the whole social activity, which is divided into the following four categories in the previous study on “Reality of social activity of senior citizen”: 1. work 2. social participation and volunteer activity 3. learning activity 4. individual activity, and to clarify which category is most related to the masticatory ability. There were 57korean subjects in the survey: aged 65 through 85 (73.8 5.5), 81 women: aged 65 through 85 (74.3 5.3), a total of 138: aged 65 through 85 (74.1 5.4), in College for senior citizen of A city, Buddhist College for senior citizen of A city and senior citizen’s welfare facility of A city who gave consent to the research The Japanese subject were 38 men: aged 65 through 85(75.3 5.4), 54 women: aged 65 through 85(75.5 5.2), a total of 92: aged 65 through 85(75.4 5.2) in women’s division of F city Federation of Senior Citizens’ Club, Otsuka division of B ward Federation of Senior Citizens’ Club and S ward Federation of Senior Citizens’ Club who gave consent to the research. The major findings were as follows: A social activity, individual activity were active in a social activity domain on a day so that people of Japanese advanced age had you, and writing ability was high, and, as for freezing, learning activity was active for people of Korean advanced age in a social activity domain so that writing ability was high.

As a dental technician, the aim of the present study on maxillofacial prosthesis was to research its relation with dental technology and further development aspects by looking into its history, kinds, production materials and process. Dental technicians are to expect a great potential to work as maxillofacial prosthetist if having an interest in education of maxillofacial prosthesis field, and developing and operating the education process by expanding the range of dental technology. This article is to present overall history of maxillofacial prosthesis and some background information on the materials which have been used from the past. The maxillofacial field plays essential functions of mastication and speech, as well as performs appearance, which evokes good or bad feelings as an instant and instinctive response. The use of maxillofacial prostheses is not merely the replacement of a missing part of the face, resulted from injuries, but a rehabilitation process to help individuals come back to society. Rehabilitation includes both patient’s physical and psychological recovery, such as self-esteem and selfconfidence. There has been a rapid development in application potentials of maxillofacial prosthesis technology which include implant, which can penetrate skin, and new materials. In order to produce maxillofacial prosthesis, general procedures of maxillofacial laboratory work should be understood first. Maxillofacial prosthesis and the dental prosthesis have many similarities in its academic perspective and originality. Maxillofacial prosthesis should be added into the curriculum for dental technology to achieve co-enhancement of the two fields.

Although there are many different ways that restorations can be made, it can be said that the biocompatibility of abutment and crown is very important in this experiment. When placed in the actual oral cavity, the differences were obvious. Compared to In-ceram Aluminium, the structure that is obtained after firing reveals a particularly homogeneous distribution of the crystal and glass phase. The In-ceram aluminium system had many problems, such as having weak tensile strength, and having low bonding strength due to the shrinking that occurs after firing. Because of the opaque finish of the metal frame, the two may look similar from the outside, but it is evident that there are differences between using a metal frame and In-ceram. VITA VM9 has been designed as a special ceramic featuring a fine structure or stabilized Zro2 substructures, and so the VITA VM9 excels in its light refraction and reflection behavior, which is similar to natural teeth. It also has outstanding chemical balance, which presents advantages such as considerably reduced accumulation of plaque on the ceramic surface.? This ultimately results in easier care and cleaning for the patient.

The purpose of this study was to evaluate the titanium castability (internal porosity) between pressure type casting machine & centrifugal casting machine with air-vent or not. Internal porosity is a well-known problem in dental titanium casting, resulting in inferior mechanical properties of dental restorations. To evaluate the castability, the square plate was chosen. 40 plate patterns(20 20 1.8 )were attached to funnel-shaped sprue. Then 20 plate patterns were attached air-vent. They were invested in titanium investment material and cast in a pressure type casting machine(20castings) and centrifugal casting machine(20castings). Each group were divided with air-vent(10castings) or not(10castings). The titanium castings were evaluated by radiographic photograph for the location of the internal porosities. The percentage porosity of each specimen was determined using standardized digital radiographs. The results were analyzed with analysis of variance and t-test for paired comparison between two groups.

The purpose of this study was to ascertain the bonding durability of self-etching dentin bonding agents to dentin by means of shear bonding strength. Several acid-etching dentin bonding system (ESPE Z100) and self-etching dentin bonding systems (DEN-FIL, GRADIA DIRET) were used. The occlusion surface of human molars were ground flat to expose dentin and treated with the etch bonding system according to manufactures instruction and followed by composite resin application. After 24hours of storage at 37 , the shear bonding strength of the specimens was measured in a universal testing machine with a 1mm/min crosshead speed. An one-way analysis of variance and the scheffe test were performed to identify significant differences (p<0.05). The bonded interfacial surfaces and treated dentin surfaces were examined using a SEM. Through the analysis of shear bond strength data and micro-structures of dentin-resin interfaces, following results are obtained. In dentin group, the shear bond strength of DEN-FIL showed statistical superiority in comparison to the other groups and followed by ESPE Z100 and GRADIA DIRECT (p<0.05).

To obtain the information of dental arch size and the distance from one tooth center to adjacent tooth center of occlusal surface of each tooth which is perforated by Pindex system on working cast for removable die system, 600 dental casts in Busan were examined. The distance of center of occlusal surface of each tooth and dental arch size were digitized. The results were as follows; 1. Mean values of the distance from center of maxillary central incisor to maxillary lateral incisor(tooth number 11~12, 21~22) is 5,7 , 12~13(22~23) is 5.9 , 13~14(23~24) is 6.9 , 14~15(24~25) is 7.1 , 15~16(25~26) is 8.4 , 16~17(26~27) is 10.2 , 11~21 is 7.30 . Mean values of the distance from center of mandibular central incisor to mandibular lateral incisor(tooth number 31~32, 41~42) is 4.5 , 32~33(42~43) is 4.8 , 33~34(43~44) is 6.3 , 34~35(44~45) is 7.2 , 35~36(45~46) is 9.2 , 36~37(46~47) is 10.7 , 31~41 is 4.7 . 2. Mean values of the distance from the center of maxillary right central incisor to the center of maxillary left central incisor(11~21) is 7.3 , 12~22 is 18.2 , 13~23 is 26.9 , 14~24 is 37.2 , 15~25 is 43.2 , 16~26 is 48.5 , 17~27 is 53.5 . Mean values of the distance from the center of mandibular right central incisor to the center of mandibular left central incisor(31~41) is 4.7 , 32~42 is 13.3 , 33~43 is 21.7 , 34~44 is 31.9 , 35~45 is 38.2 , 36~46 is 44.8 , 37~47 is 50.7 . 3. Mean values of the distance from the line of between 11~21 to 12~22 is 10.9 , 12~22 to 13~23 is 8.7 , 13~23 to 14~24 is 10.3 , 14~24 to 15~25 is 6.0 , 15~25 to 16~26 is 5.3 , 16~26 to 17~27 is 5.0 . 31~41 to 32~42 is 8.6 , 32~42 to 33~43 is 8.4 , 33~43 to 34~44 is 10.2 , 34~44 to 35~45 is 6.3 , 35~45 to 36~46 is 6.6 , 36~46 to 37~47 is 5.9 . 4. We checked the bottom side of cast to verify the position of dowel pin. There is no difference upper side and lower side.

The purpose of this study is comprehension for relationships between job stress and mental health for dental technicians in performing their duties. and this study can make use of opportunity of accumulation of data on dental technician's health care and work environment in future. Job stress for dental technicians served in general hospital dental laboratory were more highly effected than in local dental laboratory. and this result was statistically reliable. There were no meaningful differences in mental health between dental technician in dental laboratory in dental climic dental laboratory and commercial dental laboratory. and this result was not statistically reliable. The analysis of this study could be used by preliminary data to further research of relationships between job stress and mental health for dental technicians in the future. This study was made progress partially under limited members of dental technician in Seoul. so future studies are suggested that the more advanced total figure study for whole dental technicians in Korea.

There was a great problem about the deposition between materials of a different kind at the beginnings of the introduction of porcelains, however, thereafter the deposition efficiency was settlded to the sufficient level of all user thanks to effort to have studied by many scholars and clinical authorities. But in a clinical process, as the difference of designs has an effect on fractures of porcelains, this researcher divided them into 4 groups of A: 1 , B: 2 , C: 3 , and D: 4 , and made 40 pieces to each 10 as the test samples to consider a length axis of tooth for studies in accordance with a position of a finishing line to meet between porcelain and metal at the contact point at the adjacent side to a metal porcelain. The sample materials are those to be use at the open market and the test samples wer completed by the same manufacturing technique to that of existent metal porcelain tube. As a result of the strength test on fractures, the average value is as in the following, A: 1 - 8.5bar, B: 2 - 10.5bar, C: 3 - 14.3bar, and D: 4 - 15.0bar. In case of the metal porcelain tube, the more faraway to process parts of metal and porcelain from the contact point of adjacent side has the stronger strength of fractures, Accordingly, the research shows that it had better to keep off more than 3 to consider a ledngth axis of tooth.

The purpose of this study is to investigate relations between the organizational culture and job satisfaction of ordinary dental technicians who are serving at dental laboratories. Findings of the study are summarized as follows. Ordinary dental technicians’ job satisfaction as a whole was measured 3.40 in average score. In detail, those dental technicians were highest in satisfaction about their work, followed by their work conditions, organizational relations and occupation itself in order, but showed some dissatisfaction in terms of their self-realization. Regarding relations between the organizational culture and job satisfaction of ordinary dental technicians, the former was found significantly affecting the latter. Those dental technicians' job satisfaction was being most positively influenced by innovation-orientation as one of their organizational culture styles, followed by task-orientation. In regard to relations between sub-areas of the satisfaction and styles of the culture, ordinary dental technicians’ organizational relations were being significantly, positively affected by such styles of their organizational culture as relation-orientation and task-orientation. Those technicians' occupational satisfaction, self-realization and work conditions were being strongly influenced by one of their organizational culture styles, that is, innovation-orientation. Originary dental technicians’ work satisfaction was not being significantly affected by any of the organizational culture styles. The more relation- or task-orienting ordinary dental technicians were in organizational culture, the stronger their organizational relations were. The more innovation-orienting ordinary dental technicians were in organizational culture, the more those dental technicians’ satisfaction regarding their occupation, self-realization and work conditions is likely to positively change. These findings indicate that ordinary dental technicians are even more orienting both relation and task in organizational culture, while being afraid of innovation and that their organizational culture as a whole is somewhat strict hierarchically.

With the development of orthodontics and increasing concerns on physical appearance, the number of patients has been steadily increasing. It is quite important not only to make effective cure plans and accurate diagnoses but also to have a thorough grasp of patients’ malocclusion types and their occurrence frequency, in addition to patients' personality in order to cure the patients appropriately. This study is based on 946 malocclusion patients who had visited Chong-A Dental Hospital from 1999 to 2004 and investigated their aspects of malocclusion and characteristics of their gender, age and residence. The results are as follows. 1. The number of patients per year had been decreased until 2001, after which year the number had fluctuated. The number was the largest in 1999, 169 and the smallest in 2001, 140. Female occupied 68.0% of the total, twice as many as male, 32.0%) 2. Based on the Angle’s classification, 19 or over year - old group was the largest of the total, 59.3% and 6 or younger year - old group, the smallest, 0.5%. The 19 or over year old group was less than a half of the total (47.4%) in 2003 and there were no patients who belonged to the 6 or younger year - old group in 2003 and 2004. 3. Distributions on the types of malocclusion have shown that 39.9 % of the total are in the Class I, the largest, 31.0% in the Class and 29.2 in the Class , the smallest. 1) The number of the ClassI was 73, the largest, that of the Class being 35, the smallest in 1999. On the whole, the number of the Class accounted for the largest part of the total. 2) The number of male patients in the Class was the smallest, generally being the largest in the Class . In case of female, that of the Class was the smallest. 3) Based on the age, the Class was the highest in between 7 and 13 age group, the Class the lowest. The Class occupied the largest around 40%. 4) In the shape of physiognomy, the meso occupied the largest part among all the Class, of which the Class was the highest, 64.2%. The bracy was the largest in the Class , and the dolicho in the Class. 5) In the profile, the convex shape was the largest in the Class and , and especially in the Class , over 3/4 of the total, 75.4%. In contrast, the direct shape was the largest in the Class and the sunken shape occupied 33.3%, which was nearly ten times more than the case of the Class and. 6) In the asymmetry of physiognomy, the number of patients of the Class was the largest, 34.1% and that of the Class , the smallest, 19.5%. It was found that about one fourth of the malocclusion patients were under the asymmetry of physiognomy. 4. In the distribution of patients’ residence, 81.4% were from the Seoul Metropolis and 48.2% from Gangnam-Gu where Chong-A Dental Hospital is located and Seocho-Gu and Songpa-Gu which are adjacent to Gangnam-Gu.

The success of a porcelain fused to metal (PFM) restoration depends upon the quality of the porcelain-metal bond. The adhesion between metal substructure and dental porcelain is related to the diffusion of oxygen to the reaction layer formed on cast-metal surface during firing. The purposed of this investigation was to study the effects of gold based bonding agent on Ni-Cr alloy-ceramic adhesion between porcelain matrix, gold based bonding agent and metal substructure interface. gold based bonding agent have been applied as an intermediate layer between a metal substructure and a ceramic coating. gold based bonding agent(Aurofilm NP, Metalor, Swiss) was applied on Ni-Cr alloy surface by four method. Surfaces only air abraded with 110ß≠ Al2O3 particles were used as control. metal ceramic adhesion was evaluated by a biaxial flexure test(N=5) and volume fraction of adherent porcelain was determined by SEM/EDS analysis. Result of this study suggest that the layering sequence of gold based bonding agent is very important and can improve porcelain adherence to PFM.