Myeloid deletion of SIRT1 suppresses collagen-induced arthritis in mice by modulating dendritic cell maturation

The type III histone deacetylase silent information regulator 1 (SIRT1) is an enzyme that is critical for the modulation of immune and inflammatory responses. However, the data on its role in rheumatoid arthritis (RA) are limited and controversial. To better understand how SIRT1 regulates adaptive immune responses in RA, we evaluated collagen-induced arthritis (CIA) in myeloid cell-specific SIRT1 knockout (mSIRT1 KO) and wild-type (WT) mice. Arthritis severity was gauged on the basis of clinical, radiographic and pathologic scores. Compared with their WT counterparts, the mSIRT1 KO mice exhibited less severe arthritis, which was less destructive to the joints. The expression levels of inflammatory cytokines, matrix metalloproteinases and ROR-γT were also reduced in the mSIRT1 KO mice compared with the WT mice and were paralleled by reductions in the numbers of Th1 and Th17 cells and CD80- or CD86-positive dendritic cells (DCs). In addition, impaired DC maturation and decreases in the Th1/Th17 immune response were observed in the mSIRT1 KO mice. T-cell proliferation was also investigated in co-cultures with antigen-pulsed DCs. In the co-cultures, the DCs from the mSIRT1 KO mice showed decreases in T-cell proliferation and the Th1/Th17 immune response. In this study, myeloid cell-specific deletion of SIRT1 appeared to suppress CIA by modulating DC maturation. Thus, a careful investigation of DC-specific SIRT1 downregulation is needed to gauge the therapeutic utility of agents targeting SIRT1 in RA.

Inhibitory Effects for Rheumatoid Arthritis of Dietary Supplementation with Resveratrol in Collagen-induced Arthritis

OBJECTIVE: Resveratrol is well-known for its anti-inflammatory, anti-oxidant effects on several diseases. We investigated whether dietary supplementation with resveratrol may suppress joint inflammation and destruction in a mouse model of collagen-induced arthritis (CIA). METHODS: Mice were randomly divided into two groups; CIA mice with normal diet-fed and CIA mice fed a 0.05% resveratrol diet. The effect of resveratrol on arthritis was assessed by clinical scoring system. The plain radiographs of paws were obtained to evaluate the effects on preventing bone destruction. Joint inflammation, cartilage damage, and osteoclastic bone resorption were checked by staining with H&E, Safranin-O, and tartrate resistant acid phosphatase (TRAP). Levels of pro-inflammatory cytokines were checked by enzyme-linked immunosorbent assay. The level of expression of nuclear factor (NF)-kappaB was measured by electrophoretic mobility shift assay (EMSA). RESULTS: Dietary supplementation with resveratrol led to mitigated severity of arthritis compared to the normal diet group (6.7+/-0.8 vs. 2.7+/-0.6, p<0.01). Resveratrol-fed mice showed decreased bone destruction on radiograph (3.4+/-0.3 vs. 2.0+/-0.2, p<0.01), and showed significantly inhibited pathological changes (inflammation 2.0+/-0.3 vs.3.2+/-0.2, p<0.01; cartilage damage 1.5+/-0.3 vs. 3.2+/-0.2, p<0.01; pannus formation 1.4+/-0.3 vs. 3.0+/-0.3, p<0.01; erosion; 1.4+/-0.2 vs. 3.3+/-0.3, p<0.01). Generation of TRAP-positive osteoclasts was inhibited in the resveratrol-fed mice (55.3+/-12.7 vs. 3.27+/-0.8, p<0.01). Resveratrol-fed mice showed decreased levels of tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-6,monocyte chemoattractant protein 1, and the soluble receptor activator of NF-kappaB ligand in joint tissues and sera. Expression of NF-kappaB, measured by EMSA, was decreased in resveratrol-fed mice. CONCLUSION: Dietary supplementation with resveratrol mitigates inflammation and bone destruction in CIA mice.

COMP-Angiopoietin-1 Stimulates Synovial Proliferation but Suppresses Osteoclast by Enhancing Angiogenesis and Osteoblast Maturation in Collagen-Induced Arthritis

OBJECTIVE: Angiopoietin-1 (Ang1) is a potent angiogenic factor that can increase synovial angiogenesis and also enhance osteoblast maturation and bone formation. However, its role in rheumatoid arthritis (RA) has not been well documented. Thus, we investigated roles of Ang1 in collagen-induced arthritis (CIA). METHODS: A recombinant adenovirus carrying the gene that encodes either cartilage oligomeric matrix protein (AdCOMP)-Ang1 (a modified form of Ang1) or LacZ (AdLacZ) was injected intravenously into CIA mice. Clinical, radiological, histopathological, and immunofluorescent analyses were performed. Serum levels of receptor activators of nuclear factor kappaB ligand (RANKL) and osteoprotegerin (OPG) and expression of osteoblast maturation genes were analyzed. RESULTS: AdCOMP-Ang1-injected mice developed more severe inflammation than the AdLacZ-injected mice. However, there were no significant differences in cartilage damage and bone erosion. More PECAM-1-positive blood vessels were seen in the synovium of the AdCOMP-Ang1-injected mice than in those injected with AdLacZ. Interestingly, a lower number of TRAP-positive osteoclasts were observed in AdCOMP-Ang1-injected CIA mice than in the AdLacZ group when comparing sections obtained from joints showing similar synovial proliferation. The serum OPG/RANKL ratio and expression of osteoblast maturation genes, such as runt-related transcription factor 2, bone sialoprotein, type 1 collagen, osteopontin, and osterix, were significantly upregulated in the AdCOMP-Ang1 group. CONCLUSION: COMP-Ang1 facilitates arthritis onset and increases synovial inflammation, but enhances osteoblast maturation, which in turn inhibits osteoclastogenesis by increasing the OPG/RANKL ratio in CIA. Our results suggest that careful investigation is necessary to delineate the possible therapeutic use of COMP-Ang1 as an adjunctive agent, in combination with anti-inflammatory therapies, for the prevention of bone destruction in RA.

Experience of a Performing Alternative Assessment Procedure for Tests without External Proficiency Test Program / 대한수혈학회지

BACKGROUND: Proficiency testing is part of a total quality management program that provides objective evidence of clinical laboratory testing competence for customers, accrediting bodies, and regulatory agencies. Performing alternative assessment procedures for clinical tests, without proficiency testing, is recommended by Clinical and Laboratory Standards Institute (CLSI) guideline. In our study, an alternative assessment procedure was performed for blood bank tests that do not have an external proficiency program. METHODS: The laboratory for development and an evaluation center, supervised the program. Proficiency testing by seven institutions was performed 3 times at 6 month intervals by evaluating isoagglutinin and anti-D titers, and Weak D, Rh C and E typing, using ID-Internal Quality Control (Bio-Rad Laboratories) kits. RESULTS: Isoagglutinin and anti-D titer results were within one fold dilution range for all seven participating institutions, and Weak D, Rh C and E typing results all demonstrated identical antigenic reference patterns. CONCLUSION: An alternative assessment procedure was successfully performed without a proficiency testing program. Commercially manufactured reference materials could be an alternative method to support commutable, external, proficiency testing program.

The effect of different surface treatment on the osseointegration and stability of implants / 대한치과보철학회지

PURPOSE: This experiment examined the effect of different surface treatment on the osseointegration and stability of implants. MATERIAL AND METHODS: In this study, 40 each of machined, SLA and RBM implants, which are the most commonly used implants, were implanted into the tibia of 20 normal rabbits using OsseoCareTM. The rabbits were sacrificed after 1 week, 4 weeks, 8 weeks and 12 weeks for implant stability analysis, removal torque analysis, histologic and histomorphometric analysis. RESULT: ISQ showed significant difference between Machined and RBM at first week and at 4 weeks. There was significant difference between Machined and both SLA and RBM(p<0.05) but after 8 weeks there were no significant difference between each group. In the removal torque, RBM showd significantly higher values than SLA and Machined surface at 1st week. At 4th and 12th week, there was significant difference between Machined and SLA, RBM(p<0.05). In the bone to implant contact variable, there was no significant difference between each surface treatment method. In the Machined surface group, there was no significant difference between each time interval, but in SLA group, there were significant differences between the 1st week and 12th week. and in RBM group, there were significant differences between the 1st week and 8th, 12th week and between 4th and 12th week(p<0.05). The bone area showed significantly higher values in SLA and RBM compared to Machined surface 1st and 8th week and significantly higher values in SLA than Machined surface at the 4th week(p<0.05). CONCLUSION: The roughened surface of implants showed positive effect in the early stages of implantation and assisted in bone formation. After the bone formation stage, there was no statistical difference between Machined and roughened surface groups. In dental implantation, where initial stability is critical to the success of implants, the use of roughened surface implants should assist in reducing the healing period after implantation.

A study on the solubility and the water sorption of various resin cements / 대한치과보철학회지

STATEMENT OF PROBLEM: Among the physical properties of adhesion luting cement, the aspect that requires the most important factor is the degree of solubility and water sorption. Dissolution or an inadequate due to excessive water sorption inside the oral cavity compromises the while concurrently increasing the susceptibility to secondary dental caries. Susceptibility to dissolution and difficulty of removing remnant cement from the gingival sulcus have hindered the use of dental resin cement in the clinical practice, but the improved characteristics of newer generation resin cements have interest in and enabled resin cements to be widely used in adhesion of fixed prosthesis, such as laminate veneers and all-ceramic crowns. PURPOSE: The purpose of this study is to compare and analyze the degrees of solubility and water sorption of a variety of resin cements widely used for clinical purposes with different curing methods. MATERIALS AND METHODS: Self-curing resin cements, Avanto(R), CandB(TM) CEMENT and Superbond CandB cements comprised group 1, 2 and 3. The dual-curing resin cements Panavia(TM) F, Calibra(R) and Variolink(R) II were divided into groups 4, 5, and 6, respectively. The investigation was carried out using disc-shaped specimens as specified by ANSI/ADA Specification No. 27. The degree of water sorption, water solubility and lactic acid solubility of each test group was analyzed statistically leading to the following conclusion. RESULTS: The degree of water sorption was shown to increase in the following order : group 6, 5, 4, 2, 1 and 3. There were significant differences between the water sorption of each group. Results of the degree of water solubility were shown to increase in the following order : group 6, 5, 4, 2, 1 and 3. Statistically significant differences were found between each group, with the exception of groups 1 and 3. Finally, the degree of lactic acid solubility was found to increase in the following order : group 6, 5, 4, 2, 3 and 1. Significant differences were found between each group. In general dual-curing resin cements displayed substantially lower values than self-curing resin cements with regard to water sorption, water solubility, and lactic acid solubility. CONCLUSIONS: From the results of this study, dual-curing resin cements show a significantly lower degree of water sorption and solubility than their self-curing counterparts. Clinically, when selecting resin cements, the product with a lower degree of water sorption and solubility are preferred. The results of this study indicate that the use-of dual-curing resin cements is preferable to self-curing cements.

A study on the marginal fidelity and the fracture strength of ceromers / 대한치과보철학회지

STATEMENT OF PROBLEM: The use of Ceromer is increasing in dentistry. But, the research of Ceromer has not been conducted much. Purpose: This study was to evaluate the marginal fidelity and internal adaptation according to marginal position. MATERIALS AND METHODS: In this study 60 resin crowns were fabricated. The measurements of the marginal fidelity were carried out using stereomicroscope SZ-40(R)(Olympus, Japan) and the measurements of fracture strength were done using Instron 8871(R)(Instron Co., U.S.A.) at a cross head speed of 1mm/min. All of the measurements were statistically analyzed by ANOVA test, multiple range test and Weibull analysis. Statistical significance was set in advance at the probability level of less than 0.05. All of the measurements were analyzed with Window SPSS(R) Version 10.0 soft ware for the personal computer. RESULTS: 1. There were no statistical differences of the marginal fidelity between Targis(R) and Tescera(R), but difference between these two and BelleGlass(R) according to materials. 2. There were no statistical differences of the marginal fidelity between no fiber group and fiber group. There were no interactions between each maerial and with/without fiber group in the marginal fidelity. 3. There were statistical differences of the fracture strength between Tescera. and BelleGlass(R), but no statistical differences of the fracture strength between Targis(R) and Tescera(R), Targis(R) and BelleGlass(R) according to materials. 4. There were statistical differences of the fracture strength between no fiber group and fiber group. There were no interactions between each material and with/without fiber group in the fracture strength. 5. When comparing the fracture surface, no fiber group showed the resin which were fractured at the labial surface and separated from the adhesion surface. In fiber group, the fractures took a place in resin compartments. CONCLUSION: The marginal fidelity and the fracture strength were clinically acceptable. From these results, Targis(R) and Tescera(R) were superior than BelleGlass(R) in the marginal fidelity. But, when applying these resin crowns in clinic, more careful consideration is needed and further study is recommended.

The effect of fermented foods on the color and hardness change of denture base acrylic resins / 대한치과보철학회지

STATEMENT OF PROBLEM: For a long time, many of denture base acrylic resins have been used for edentulous and partial edentulous patients because of easy manipulation and good mechanical properties, but its esthetic aspect has not been commented enough. Denture base acrylic resins also has caused esthetic problems due to discoloration or staining as in esthetic restoration. Many researches and reports have treated the problems and accomplished esthetic improvement. But these researches and reports dealt with general food colors or beverages, not with fermented foods. PURPOSE: This study is designed to assess what fermented foods, such as soy sauce, gochujang, and toenjang that many of Koreans have taken in, influence on the color and hardness variation of denture base acrylic resins. MATERIALS AND METHODS: For the procedure, twelve disks per 4 denture base acrylic resins were fabricated with a thickness of 2mm and 16mm in diameter. Each seven specimen were measured for discoloration with spectrophotometer, while the others, five specimen, for surface hardness change with Barcol hardness tester, over time. Each 12 specimen were immersed into the 4 beakers of fermented foods(soy sauces, gochujangs, toenjangs, deionized water), and L*, a*, and b* values were measured for the color difference(_E*), on the 1st, 7th, and 28th day with spectrophotometer, with the measurement of surface hardness change. Each data observed was processed statistically. RESULTS: The findings are as follows; Discoloration 1. All of denture base resins was not influenced by the kind of fermented foods, except for QC20. 2. Soy sauce and red pepper paste caused more change for denture base resins than deionized water and soy bean paste, except for Perform. 3. Most significant change was shown in Lucitone199., whereas Perform. results in the least change for all immersed solution, with no statistical significance. Hardness change 1. Barcol hardness values in deposited specimens have been changed low degree, but with significant statistical change according to the kind of food and duration. 2. Lucitone199. has significantly lower Barcol hardness value than others do. CONCLUSION: Based on the above results, it suggests that the habitual intake of fermented foods is not helpful for the color stability of denture base acrylic resins because Soy sauce and red pepper paste mainly caused discoloration and surface hardness change. Particularly Lucitone199. shows specific discoloration and low surface hardness values. Therefore, it is recommended giving caution patients with denture of Lucitone199. especially against the habitual intake of fermented foods like soy sauce and red pepper paste.

The effect of fermented foods on the color change of soft denture liners / 대한치과보철학회지

STATEMENT OF PROBLEM: The clinical criteria of soft lining materials are resilience over an extended period, capability of forming a strong bond with denture base materials, dimensional stability, adequate tear strength, and color stability. Many researches and reports dealt with food colorants or denture cleanser, but not with fermented foods. PURPOSE: This study was designed to assess what fermented foods, such as soy sauce and red pepper paste that many Koreans have eaten, influence on the color stability of soft denture liners. MATERIAL AND METHODS: The color differences(delta E*) were measured by spectrophotometer with different immersion time. For the procedure, thirty disk-shape specimens per 4 soft denture liners(Molloplast-B(R), Ufi Gel SC(R), Dura Base(R), Sofreliner MS(R)) were fabricated with a thickness of 2mm and 16mm in diameter. Each 10 specimen were immersed into the beakers of fermented foods and distilled water, and L*, a*, and b* values were measured for the color difference(delta E*), on the 1st, 7th, and 28th day with spectrophotometer. RESULT AND CONCLUSION: 1. There were significant differences between samples(soy sauces, red pepper pastes, and distilled water) in Sofreliner MS(R) of 1st day after immersion(p<0.05). There were significant differences between samples in Sofreliner MS(R) and Ufi Gel SC(R) of 7th days after immersion(p<0.05). There were significant differences between samples in Molloplast-B(R) of 28th day after immersion(p<0.05). 2. In red pepper pastes, delta E* values of Molloplast-B(R), Ufi Gel SC(R), Sofreliner MS(R) were higher than 3.3. Those values were not clinically acceptable. In soy sauces, delta E* values of all denture liners were lower than 3.3. delta E* values of Ufi Gel SC(R) were higher than those of other denture liners. 3. Based on the above results, red pepper paste causes more discoloration than soy sauce.

Color stability of ceromers in three food colorants / 대한치과보철학회지

STATEMENT OF PROBLEM: Ceramic and composite resin have been used to fulfill the demand for esthetic prosthesis. However, ceramic is easy to break and wears off the opposite natural teeth. Conventional composite resin also has low abrasive resistance and color stability. Ceramic Optimized Polymer (ceromer) was developed in mid-1990s to overcome the shortfalls of ceramic and composite resin. Ceromer has similar abrasiveness with the natural tooth and has relatively high strength. Color stability affects esthetics and long-term prognosis of the prosthesis. PURPOSE: The purpose of this study was to compare color stability of ceromers(2 types : Artglass., Targis.) with ceramics(Vintage.-polishing, Vintage.-glazing). MATERIAL AND METHOD: The color difference(E*) was measured by spectrophotometer with different immersion time. Twenty disks, 3mm in thickness and 10mm in diameter, were fabricated for each specimen in shade A2(Vita Lumin shade guide). Specimens(5 samples in each group) were immersed in the food colorants(Red no.3, Yellow no.4, Blue no.1, Distilled water) for 24 hours, 48 hours and 72 hours respectively. L*, a* and b* value were measured with spectrophotometer (CM 503i : Minolta Co., Japan) and mean E* value was calculated for statistical analysis. RESULTS: The results of this study were obtained as follows. 1. The E* values of all test samples increased with the time of immersion. 2. The E* values of all materials increased in order of Distilled Water, Yellow no.4, Blue no.1 and Red no.3. There was significant difference between Red no.3 and the other food colorants(p<0.05). 3. The E* values increased in order of Vintage-glazing, Vintage-polishing, Artglass and Targis. There was significant difference between Vintage.-glazing and the other materials (p<0.05). CONCLUSION: By means of the above results, immersion time was found to be a critical factor for color stability of ceromer. For the long-term color stability of prosthesis it is recommended patients having ceromer prosthesis(Artglass., Targis.) to reduce the habitual intake of Red no.3 colorants con taining foods.

A study on the measurement of the implant stability using resonance frequency analysis / 대한치과보철학회지

STATEMENT OF PROBLEM: Successful osseointegration of endosseous threaded implants is dependent on many factors. These may include the surface characteristics and gross geometry of implants, the quality and quantity of bone where implants are placed, and the magnitude and direction of stress in functional occlusion. Therefore clinical quantitative measurement of primary stability at placement and functional state of implant may play a role in prediction of possible clinical symptoms and the renovation of implant geometry, types and surface characteristic according to each patients conditions. Ultimately, it may increase success rate of implants. PURPOSE: Many available non-invasive techniques used for the clinical measurement of implant stability and osseointegration include percussion, radiography, the Periotest., Dental Fine Tester. and so on. There is, however, relatively little research undertaken to standardize quantitative measurement of stability of implant and osseointegration due to the various clinical applications performed by each individual operator. Therefore, in order to develop non-invasive experimental method to measure stability of implant quantitatively, the resonance frequency analyzer to measure the natural frequency of specific substance was developed in the procedure of this study. MATERIAL AND METHOD: To test the stability of the resonance frequency analyzer developed in this study, following methods and materials were used: 1) In-vitro study: the implant was placed in both epoxy resin of which physical properties are similar to the bone stiffness of human and fresh cow rib bone specimen. Then the resonance frequency values of them were measured and analyzed. In an attempt to test the reliability of the data gathered with the resonance frequency analyzer, comparative analysis with the data from the Periotest was conducted. 2) In-vivo study: the implants were inserted into the tibiae of 10 New Zealand rabbits and the resonance frequency value of them with connected abutments at healing time are measured immediately after insertion and gauged every 4 weeks for 16 weeks. RESULTS: Results from these studies were such as follows: The same length implants placed in Hot Melt showed the repetitive resonance frequency values. As the length of abutment increased, the resonance frequency value changed significantly (p<0.01). As the thickness of transducer increased in order of 0.5, 1.0 and 2.0 mm, the resonance frequency value significantly increased (p<0.05). The implants placed in PL-2 and epoxy resin with different exposure degree resulted in the increase of resonance frequency value as the exposure degree of implants and the length of abutment decreased. In comparative experiment based on physical properties, as the thickness of transducer increased, the resonance frequency value increased significantly(p<0.01). As the stiffness of substances where implants were placed increased, and the effective length of implants decreased, the resonance frequencies value increased significantly (p<0.05). In the experiment with cow rib bone specimen, the increase of the length of abutment resulted in significant difference between the results from resonance frequency analyzer and the Periotest.. There was no difference with significant meaning in the comparison based on the direction of measurement between the resonance frequency value and the Periotest. value (p<0.05). In-vivo experiment resulted in repetitive patternes of resonance frequency. As the time elapsed, the resonance frequency value increased significantly with the exception of 4th and 8th week (p<0.05). CONCLUSION: The development of resonance frequency analyzer is an attempt to standardize the quantitative measurement of stability of implant and osseointegration and compensate for the reliability of data from other non-invasive measuring devices. It is considered that further research is needed to improve the efficiency of clinical application of resonance frequency analyzer. In addition, further investigation is warranted on the standardized quantitative analysis of the stability of implant.

Shade analysis of anterior teeth using digital shade analysis system / 대한치과보철학회지

STATEMENT OF PROBLEM: A scientific examination and understanding of overall aspects of the natural dentition is the first step involved in making a satisfactory selection in the shade of an aesthetic prosthesis. Proper natural shade selection of the prosthetic restoration that is in harmony with the remaining dentition is as important aesthetically, as harmony of form and function in the anterior dentition. Clinically, the most commonly applied method of shade selection has been visual, but because of the subjective nature inherent to this method, shade selection results are variable and can be influenced by such factors as the technician, the type of shade guide used, and the type and intensity of the lighting. PURPOSE: The purpose of this study was to develop a more objective and scientific approach to examining and understanding the shade of teeth, which has in turn lead to the development of a number of shade analysis devices that present a more objective method of shade analysis. MATERIAL AND METHOD: In this study, the shades of healthy anterior teeth were examined and analyzed using the recently developed digital shade analysis of the ShadeScan(TM) System. The study examined 80 individuals in their twenties, 40 males and 40 females, presenting 6 healthy, unrestored maxillary anterior teeth. Tooth brushing and oral prophylaxis were performed prior to evaluation. The ShadeScan handpiece was used to acquire images of the 6 maxillary anterior teeth. These images were analyzed using the Vita/Classical mode of the ShadeScan(TM) Software, and shade maps of each tooth were acquired and divided into cervical, middle, and incisal thirds. The shade distribution of each third, left and right symmetry, and gender differences were investigated and analyzed. RESULTS: The results of the study are as follows: 1. An overwhelming majority of the examined teeth were found to possess shades belong to Group A, with the greatest variations occurring at the middle and cervical thirds of the maxillary central and lateral incisors, in both male and female subjects. 2. Canines of both male and female subjects showed left and right symmetry with uniform shade distribution of A4 and C4, while the lateral and central incisors showed left-right symmetry of the incisal 1/3 with a uniform shade distribution of A2 and A3 shades. 3. No significant differences in shade distribution were seen between genders in maxillary canines, whereas maxillary central and lateral incisors showed differences at the middle and cervical thirds between male and female subjects. The results of this study show that with the exception of maxillary canines, maxillary anterior teeth display a diverse shade distribution as well as gender differences. CONCLUSION: Clinically, when making a shade selection using the existing shade guide, one must consider the fact that even a single tooth consists of a variety of shades. The results of this study show that when selecting a shade from a number of groups is difficult, shades from A group are the most consistent with the natural shade of maxillary anterior teeth.

On the marginal fidelity of all-ceramic core using CAD/CAM system / 대한치과보철학회지

Novel methods producing supplementary and prosthetic material by cutting or discharge processing via computer design have been proposed as alternatives for traditional casting methods and are being utilized for commercial purposes. The CAD/CAM system used in dentistry can be classified into three-dimensional input of target values, restoration design, and material processing. The marginal fidelity in production of In-Ceram core has important clinical implications and is a key consideration issue in CAD/CAM production as well. Through this research, the author arrived at the following conclusion after conducting comparison analysis of marginal fidelities between the In-Ceram core produced via CAD/CAM and that produced through the traditional method: 1. In the cases of mesial, distal, and lingual margins, the core margins via CAD/CAM produced lower values than those via the traditional method, but the differences were found to be statistically insignificant. 2. In the case of labial flange, the core margins via CAD/CAM produced lower values than those via the traditional method and the differences were found to be statistically significant. (p<0.05) 3. In comparision with overall marginal fidelity, the core margins via CAD/CAM produced lower values than those via the traditional method, but the differences were found to be statistically insignificant. 4. Among the core margins produced via the traditional method did not have statistically significant differences but for those produced via CAD/CAM had statistically significant differences between labial and lingual sides and between labial and mesial sides. (p<0.05)

A Comparative Study on the Accuracy of Master Casts by Implant Impression Techniques / 대한치과보철학회지

As the inaccuracy which was made in implant impression prevented passive fit,it needed to solder the sectioned framework at several locations to correct the inaccuracy. Many clinicians have suggested impression techniques which could make passive fit between implant and superstructure. The purpose of this research was to measure and compare the accuracy of three methods of taking impression with the strain amplifier. The experimental groups were classified as follows : Group I; splinted the two parts with Futar D Occlusion. Group II; splinted the two parts with DuraLay. Group III; didn't splint the two parts. The results were as follows ; 1.The values of strain in the vertical and horizontal surfaces were increased in the order of groupI,group II and group III. 2.Group I showed higher accuracy of the duplicated casts in the vertical and horizontal surfaces than group IIand group III(p<0.05). 3.There were no significant differences in the accuracy of the duplicated casts between group IIand groupIII. From the above results,it is considered that the splinting method of impression copings could make an influence on the accuracy of the master casts.To improve the accuracy of the master casts, splinting the squared impression copings with the additional silicone occlusion materials is recommendable.

A Study on the Void Formation And Detail Reproduction According to The Various Impression Materials And Mixing Methods / 대한치과보철학회지

Void-free impression taking is important for the fabrication of accurate dental restorations.One of the essential properties of an impression material used for indirect fabrication of precision castings is the reproduction of the fine detail. The objective in this study was to determine the influence of mixing methods on the number of voids and surface detail reproduction.The number of voids and surface detail reproduction were evaluated with the stereomicroscope SZ-PT and photographed. The results were as follows; 1.In comparison of the void formation according to mixing methods of all impression materials,mechanical mixing was better than hand mixing and there was significant difference(P<0.05). 2.In comparison of the void formation according to hand mixing of alginate impression materials(TOKUSO A-1 alpha ,CAVEX IMPRESSIONAL ,AROMA FINE DF III), there was no significant difference among alginate groups.But the number of void was increased in the order of Panasil contact,TOKUSO A-1alpha , Permlastic light bodied and there was significant difference(P<0.05). 3.In comparison of the void formation according to mechanical mixing of alginate impression materials(TOKUSO A-1 alpha, CAVEX IMPRESSIONAL, AROMA FINE DF III), there was no significant different among alginate groups.But the number of void was decreased in order of TOKUSO A-1 alpha, Permlastic light bodied,Panasil contact and there was significant difference(P<0.05). 4.In comparison of the surface detail reproduction according to mixing methods of 3 types of impression materials(TOKUSO A-1 alpha, Permlastic light bodied,Panasil contact), there was no significant difference between hand mixing and mechanical mixing method 5.The surface detail reproduction was only influenced by impression materials,and produced better in order of TOKUSO A-1alpha, Panasil contact,Permlastic light bodied.There was significat difference among 3 type of impression materials(P<0.05). From the above results,void formation is influenced by mixing methods and surface detail reproduction is influenced by impression materials than mixing methods.Therefore,to fabricate accurate restorations,proper impression material and mechanical mixing method are more effective and available clinically.

Optical Effects Of Nonmetallic Post And Core Systems On All-Ceramic Crowns / 대한치과보철학회지

Recently as the esthetic concerns about dental prosthesis have been increased, the nonmetallic post and core systems have been introduced clinically to improve the color and the low optical transmittance of conventional casting metal post and core systems. The purpose of this study was to compare and analyze the optical transmittance and the shade changes of all-ceramic crowns with two nonmetallic post and core systems. The experimental groups were classified as follows: Total 27 specimens(9 samples in each group) were evaluated. Group I: Natural teeth as a control group. Group II: CosmoPost and Empress(R) core (Ivoclar-Vivadent, Liechtenstein). Group III: LIGHT-POST(TM) and LIGHT-CORE(TM)(Bisco, U.S.A.). In all groups, all-ceramic crowns were fabricated with the same shade of IPS Empress(R)II(Ivoclar-Vivadent, Liechtenstein) after abutment preparation, and then two kinds of spectrophotometers, UV 3101 PC(Shimadzu,Japan) and CM 503i(Minolta Co., Ltd., Japan), were used to measure the optical transmittance and the color value. The following results were obtained: 1. The optical transmittance of each group without all-ceramic crowns, was siginificantly decreased in order of Group III, I and II(p<0.05). 2. The optical transmittance of each group with all-ceramic crowns cemented, were siginificantly decreased in order of Group I, II and III(p<0.05). 3. In comparison with the shade of all-ceramic crowns, there were no significant differences between groups regardless of the cementation. 4. In comparison with the shade changes in each group after the cementation of all-ceramic crowns, there were no significant differences between groups. From the above results, it is thought that the selection among materials used in this study doesn't influence greatly the esthetic restoration, because the differences of optical transmittance were so small that those were clinically insignificant.

A STUDY THE SHADE CHANGE OF SEVERAL KINDS OF ALL CERAMIC CROWNS USED FOR METAL DOWEL CORE / 대한치과보철학회지

The purpose of this study is to compared and analyze the shade changes(deltaE)about In-Ceram(R),IPS-Empress(R),OPC(R) by using of the spectrophotometer arising from initial status and before and after cementation of the resin cement mounted on the metal core. We used a couple of statistics such as 'One-Way ANOVA'and Multiple Range Test. We could be able to verify significantly what is being discussed here up to 95%. The results drawn from our research are as follows: 1. At the time of our experiments regarding the initial shapes of all-ceramic and mounting status of all-ceramic on the metal crown(deltaE1), and a comparison of mounting of all ceramic on the metal crown with all-ceramic cemented on the metal core(deltaE2), at the time of shade change of initial shapes and after we cemented on the metal core. (1) no significant difference among all-ceramics was found. (2) no particular difference was found regarding the In-Ceram(R) (3) a significant difference between the deltaE1 and deltaE2 regarding the IPSS-Empress(R) was found (P<0.05). (4) a significant difference between the deltaE1 and deltaE2 regarding the OPC? was found (P<0.05). 2. When we compared the shade changes (deltaE) resulted from before and after the cementation on each of the parts involved of some all-ceramic . we could be able to find shape change increase from incisal third, middle third, and cervical third in that order in In-Cream(R)(spinell), IPS Empress(R) and OPC(R) all. In addition , we could be able to find a siginificant difference between cervical third and incisal third, middle third. (P<0.05) From what we have just seen, we might conclude that there is a significant shade change difference before and after the cementation with respect to IPS-Empress(R)and OPC(R). In addition, we could also be able to find more shade change difference at the cervical third rather than incisal third and middle third depending on the parts involved.

A STUDY ON THE EFFECT OF THERMOCYCLING TO THE PHYSICAL PROPERTIES OF DENTURE LINERS / 대한치과보철학회지

For the improvement of denture fitness of changed residual ridge, denture liner can be used. Denture liner should be very stable physically in various environments of the mouth as well as be bonded strongly with denture resin. In this study, the specimens bonded with four kinds of soft denture liner and three kinds of hard denture liner were used to test the physical properties of the liners. All experimental groups were stored in 37+/-1degrees C distilled water for 24hours, followed by thermocycling between 15degrees C and 45degrees C with 15 second dwell time. 1000, 2000, 3000 cycles of thermocycling were excuted and physical properties were measured by Instron Universal Testing Machine. The obtained results were as follows: 1. In tensile bond test of soft liners, it was shown that both of Molloplast-B(R) specimens before and after thermocycling had the highest tensile strength, and in case of hard liners, Dura-liner II(R)speimen had the highest tensile strength before and after thermocycling. Depending on thermocycling, Soft-Relining(R), Denture-Relining(R),Molloplast-B(R), Coe-soft(R) and Kooliner(R) specimen showed significant difference(p<0.05). 2. In strain test of soft liners, it was shown that Molloplast-B(R) specimen before thermocycling and the Coe-soft(R) after thermocycling showed highest results, and in case of hard liners, the Dura-Liner II(R) speimen before and after thermocycling had the highest result. Depending on thermocycling. Denture-Relinig(R). Molloplast-B(R) and Dura-Lner II(R) specimen showed significant difference(p<0.05). 3. In Maximum distance test of soft liners, the Molloplast-B(R) specimen before thermocycling and the Coe-soft(R) after thermocycling showed highest results, and in case of hard liners, the Dura-Liner II(R) specimen before and after thermocycling showed highest results. Depending on thermocycling, Denture-Relining(R), Molloplast-B(R) specimens showed significant difference(p<0.05). 4.In elasticity test of soft liners , the Molloplast-B(R) specimen before and after thermocycling showed highest results, and in case of hard liners, the Dura-Liner II(R) specimen before thermocycling and the Tokuso-Rebase (R) after thermocycling showed highest results. Depending on thermocycling, Soft-Relining(R) , Molloplast-B(R) specimens showed significant difference(p<0.05).

A STUDY ON THE HEAT GENERATION OF BONE DRILLING BURS ACCORDING TO IRRIGATION DURING IMPLANTATION OF DENTAL IMPLANT / 대한치과보철학회지

There are a lot of elements affecting the success of implant prosthesis. The quality of surgical procedure is considered as one of the key factors. To avoid the excess heat generation is an important element of successful osseointegration and it can be achieved by using a gentle surgical technique with a sharp instrument in bone drilling. This study was performed to measure and analyze comparatively the heat transmitted to surrounding bone at a distance of 0.5mm from the periphery of the drill hole in each drilling stage. The results were as follows. In standard system, the temperature of surrounding bone tissue ranged from 29.2degrees Cto 48.3degrees C with irrigation and from 34.6degrees C to 84.3degrees C without irrigation. And in wide system, the temperature of surrounding bone tissue ranged from 29.5degrees C to 52.5degrees C with irrigation and from 34.8degrees C to 87.8degrees C without irrigation. And the temperature ranges exceeded the threshold without irrigation, while showing less than the threshold by the cooling effect of irrigation. In comparing standard system with wide system, although there was no significant difference, 4.3mm pilot and 4.3mm twist drill of wide system showed high value and wide system showed slightly high elevation of temperature in all depth in fixture installation In the finite element analysis, the calculated value by the Fourier's cooling law were applied to the bone drilling surface. And through analysis using different irrigation temperatures at 28degrees C, 15degrees C and 5degrees C, and according to the time. The result was that the cooling water at least below 15degrees C was required to maintain the temperature of surrounding bone less than threshold in bone drilling, the cooling water below 5degrees C was required to gain more sufficient cooling effect, and cooling over 5 seconds was needed after bone drilling for sufficient effect.

EXPERIMENTAL STUDY OF PERI-IMPLANT TISSUE REACTION IN OVARIECTOMIZED OSTEOPOROTIC RATS / 대한치과보철학회지

This study was designed to investigate the peri-implant tissue reaction in ovariectomized osteoporotic female rats, and to evaluate effects of estrogen, calcitonin, parathyroid hormone on the bone - implant interface in osteoporotic rats. 120 Sprague - Dawley rats were used in this experiments. Osteoporosis was induced by bilateral ovariectomy. They were divided 5 groups ; sham-operated control group(Sham), ovariectomized group (OVX), OVX and estrogen treated group (OVX+E), OVX and PTH treated group (OVX+PTH), and OVX and calcitonin treated group (OVX+CT). Eight weeks after ovariectomy, two titanium screw implants were inserted into the left tibia of each rat. Eight weeks after the insertion of the implants, the periotest values (PTV) of implant were examined, and the rats were sacrificed, and examined the reaction of bone tissue surrounding the implant both histologically and histomorphometrically. The bone density and ash weight of opposite right tibia were examined. Over 40 rats were fractured on left tibia that was implant inserted. On histologically finding, all groups were osseointegrated well, especially in OVX+PTH group. In OVX group, tibial cortical bone showed many large harversian canal and microfracture lines. The OVX+PTH group showed the lowest mean PTV (-2.33) (p0.05). But the OVX+CT group showed the highest mean bone density (5.45mg/cm3) and ash weight (56.12%) (p<0.05). The results indicate that PTH treatment enhances osseointegration of implant in OVX rats, and CT treatment depresses bone turnover and prevent the development of osteopenia in OVX rats.