• Journal of Technologic Dentistry
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• v.22 no.1
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• pp.5-12
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• 2000

The gaps between the die margin worked and the casting body were measured with an optical microscope and compared after making crown prosthetic materials using three kinds of die material - dental stone, extra hard stone, epoxy resin - used in crown prosthesis. The results are as follows : 1. All the gaps between the cast cervical margin and the casting bodies were relatively good regardless of die materials used with the gaps under $50{\mu}m$, the allowable limit. 2. The cervical margin suitability of epoxy resin die was the highest among the three kinds of die material with the suitability value of $30.28{\pm}12.67$. 3. Among the four surfaces(buccal, lingual, mesial, distal) of all the casting bodies, buccal surface was the highest in the cervical margin suitability with the value of $25.93{\pm}15.51$.

• The Journal of Advanced Prosthodontics
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• v.14 no.3
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• pp.143-149
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• 2022

PURPOSE. Masticatory loading triggers active bone remodeling, altering alveolar bone mineral density (BMD). While dental implants are placed to bear masticatory loading, their influence on changing bone properties has not been fully investigated. Objective of this pilot study was to examine whether the dental implantation has an effect on BMD distribution of bone by comparing dentate, edentulous, and edentulous patients with implants. MATERIALS AND METHODS. Cone beam computed tomography (CBCT) images of 19 partially edentulous patients (Dent), 19 edentulous patients (Edent), and 16 edentulous patients who received implants in the mandible (Edent+Im), were obtained. CBCT images were also obtained from 5 patients within Edent+Im group, before implant placement and after implant loading. Basal cortical bone region of the mandible was digitally isolated. A histogram of gray levels proportional to BMD was obtained to assess mean, histogram standard deviation (HSD), fifth percentile of low and high values (Low₅ and High₅) of the BMD distribution. Multivariate analysis of variance and paired t-test were used to compare the BMD parameters among the 3 dental status groups and between pre- and post-implantation, respectively. RESULTS. Edentulous patients with implants had significantly greater HSD and High₅ values compared to edentulous patients (P < .013). All other comparisons were not significant (P > .097). Mean, HSD, and High₅ values significantly increased after receiving implants (P < .022). CONCLUSION. The current findings suggested that receiving dental implants promoted oral bone mineralization for edentulous patients. The longitudinal investigation could provide valuable information on understanding the effects of implantation on the behavior of oral bone quality.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.1
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• pp.49-57
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• 2004

Statement of problem : The increased awareness of esthetics in dentistry has brought the esthetic consideration in prosthetic restorations . Dental ceramics offer better esthetics for use of prosthetic restorations. Unfortunately, dental ceramic materials are not always the most suitable candidate materials since their inherently brittle nature. In recent years, basic research in ceramic science has led to the recognition or several approaches to strengthen and to enhance esthetics of ceramics. Several all ceramic systems use ceramic core and porcelain build up structures . Ceramic cores influence to strength of all ceramic crowns . So the strength of ceramic cores is important to all ceramic crowns. Purpose : The purpose of this study is to estimate the flexural strength of ceramic cores in some all ceramic systems. Material and method : A biaxial flexure test was conducted on three groups(Cergo, Empress 2, In-Ceram). Each group consisted of 30 discs of nearly identical dimension with a 0.5mm, 1.0mm, 1.5mm thickness and 12mm in diameter. The fracture load was recorded by Instron. Analysis of valiance(ANOVA) and Tukey's tests were performed using SAS statistical software. Results : 1.5mm thickness of specimens were significantly stronger than 0.5mm and 1.0mm thickness of specimens in Cergo and In-Ceram. But each sepecimen group of Empress 2 was no significantly strength by thickness. In order of In-Ceram, Empress 2 and Cergo has significantly stronger strength in the same thickness. Conclusion : In-Ceram is the strongest ceramic material in 3 materials. All the materials can be used according to the required characters.

• The Journal of Advanced Prosthodontics
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• v.10 no.1
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• pp.18-24
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• 2018

PURPOSE. In literature, many studies compare survival rates of different types of FPDs. Most of them compared restorations, which originated from one university, but from different clinicians. Data about restoration survival rates by only one experienced dentist are very rare. The aim of this study was to evaluate the survival rate of all-ceramic FPDs without the blurring effects of different clinicians. MATERIALS AND METHODS. 153 veneered-zirconia FPDs were observed for follow-up. 22 patients received 131 single crowns and 22 bridges. Because of the different bridge lengths, one unit was defined as a restored or replaced tooth. In total, 201 units were included. Only the restorations performed by the same clinician and produced in the same dental laboratory from 2011 to 2016 were included. Considered factors were defined as "type of unit", "type of abutment", "intraoral region", and "vitality". Modified UHPHS criteria were used for evaluation. Statistical analysis was performed using cox-regression. RESULTS. 189 units (94.0%) showed no kind of failure. 5 chippings (2.4%) could be corrected by intraoral polishing. 4 units (1.9%) exhibited spontaneous decementation. These polishable and recementable restorations are still in clinical use. Chippings or decementations, which lead to total failure, did not occur. One unit was completely fractured (0.5 %). Biological failures (caries, periodontitis or periimplantitis) did not occur. The statistical analysis of the factors did not reveal any significant differences. CONCLUSION. Modern all-ceramic FPDs seem to be an appropriate therapy not only for single restorations but for complex occlusal rehabilitations.

• The Journal of the Korean dental association
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• v.52 no.6
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• pp.354-362
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• 2014

With the development of digital dentistry, various intra-oral scanners which acquire intraoral image without conventional impression taking and stone pouring steps have been introduced. Fixed dental prostheses such as inlay, onlay, crown, and bridge fabricated by CAD/CAM technique combined with digital impressions is getting popular due to the recent rapid progress of digital impression taking system. In comparison with traditional prosthetic procedure, the advantages of intraoral image acquiring and CAD/CAM technique are as follows; the omission of conventional impression materials, reduced workflow step, and increased efficiency by online communication with clinic and laboratory. This review article covers some opinions about the suitable scanning procedures for the various prosthodontic treatments and the utilization of digital intraoral scanner and CAD/CAM system.

• Journal of Technologic Dentistry
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• v.41 no.3
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• pp.203-209
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• 2019

Purpose: The purpose of this study was to investigate the mechanical properties of polymer prosthetic and restorative materials for dental CAD/CAM using two test method; surface characteristics and shear bond strength. Methods: Commercialized CAD/CAM polymer blanks were investigated; One kinds of PMMA, and one PEKK blanks. A total of 20 PMMA and PEKK specimens were prepared, and each group was divided into 10 specimens. Average surface roughness was observed under surface profilometer. The contact angle was measured with a surface electrooptics. The bond strength was evaluated by a universal testing machine at a crosshead speed of 5mm/min. The data were statistically analyzed using independent t-test and Fisher's exact test(P<0.05). Results: The PMMA and PEKK group showed a significant difference in the shear bond strength with the composite resin(P<0.05). The surface roughness of the PEKK group was higher than that of the PMMA group. The fracture mode were observed in PEKK groups with 50% showing adhesive remnant index score. Conclusion: PEEK is used as substructure material and composite veneering material is applied. PEKK resins will contribute to the development of successful products that will provide structural and aesthetic satisfaction.

• The Journal of Advanced Prosthodontics
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• v.4 no.4
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• pp.204-209
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• 2012

PURPOSE. The aim of this systematic review is to address treatment outcomes of Mandibular implant overdentures relative to implant survival rate, maintenance and complications, and patient satisfaction. MATERIALS AND METHODS. A systematic literature search was conducted by a PubMed search strategy and hand-searching of relevant journals from included studies. Randomized Clinical Trials (RCT) and comparative clinical trial studies on mandibular implant overdentures until August, 2010 were selected. Eleven studies from 1098 studies were finally selected and data were analyzed relative to number of implants. RESULTS. Six studies presented the data of the implant survival rate which ranged from 95% to 100% for 2 and 4 implant group and from 81.8% to 96.1% for 1 and 2 implant group. One study, which statistically compared implant survival rate showed no significant differences relative to the number of implants. The most common type of prosthetic maintenance and complications were replacement or reattaching of loose clips for 2 and 4 implant group, and denture repair due to the fracture around an implant for 1 and 2 implant groups. Most studies showed no significant differences in the rate of prosthetic maintenance and complication, and patient satisfaction regardless the number of implants. CONCLUSION. The implant survival rate of mandibular overdentures is high regardless of the number of implants. Denture maintenance is likely not inflenced substantially by the number of implants and patient satisfaction is typically high again regardless os the number of implants.

• The Journal of Advanced Prosthodontics
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• v.9 no.5
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• pp.402-408
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• 2017

PURPOSE. The goal of this study was to compare the adhesion of Candida albicans to the surfaces of CAD/CAM and conventionally fabricated complete denture bases. MATERIALS AND METHODS. Twenty discs of acrylic resin poly (methyl methacrylate) were fabricated with CAD/CAM and conventional procedures (heat-polymerized acrylic resin). The specimens were divided into two groups: 10 discs were fabricated using the CAD/CAM procedure (Wieland Digital Denture Ivoclar Vivadent), and 10 discs were fabricated using a conventional flasking and pressure-pack technique. Candida colonization was performed on all the specimens using four Candida albicans isolates. The difference in Candida albicans adhesion on the discs was evaluated. The number of adherent yeast cells was calculated by the colony-forming units (CFU) and by Fluorescence microscopy. RESULTS. There was a significant difference in the adhesion of Candida albicans to the complete denture bases created with CAD/CAM and the adhesion to those created with the conventional procedure. The CAD/CAM denture bases exhibited less adhesion of Candida albicans than did the denture bases created with the conventional procedure (P<.05). CONCLUSION. The CAD/CAM procedure for fabricating complete dentures showed promising potential for reducing the adherence of Candida to the denture base surface. Clinical Implications. Complete dentures made with the CAD/CAM procedure might decrease the incidence of denture stomatitis compared with conventional dentures.

• The Journal of Advanced Prosthodontics
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• v.8 no.6
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• pp.457-464
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• 2016

PURPOSE. The aim of this study was to determine whether two methods of documentation, print and electronic forms, for the assessment of patient-reported outcomes (PRO) in complete denture wearers provide comparable results. The study also quantified the time needed for filling the forms by each method. MATERIALS AND METHODS. Thirty participants enrolled in a university clinic answered two forms (a questionnaire for denture satisfaction and OHIP-EDENT). They provided answers with two application methods in a random order, with a one-month interval between them: (1) electronic forms on a tablet computer; and (2) print forms. The methods were compared in terms of mean results, correlation/agreement, internal consistency, and spent time. RESULTS. Mean results for both methods were similar for each denture satisfaction item (100-mm VAS) and OHIP-EDENT summary score. Both questionnaires presented good internal consistency regardless of the application method (Cronbach's ${\alpha}=0.86$ or higher). Correlation and agreement between the methods regarding specific items was at least moderate for the majority of cases. Mean time for the electronic and print forms were 9.2 and 8.5 minutes, respectively (paired t test, P=.06, non-significant). CONCLUSION. The electronic method is comparable to print forms for the assessment of important PRO of prosthetic treatment for edentulism, considering the results and time needed. Findings suggest the viability of replacing print forms with a tablet for applying the tested inventories in clinical trials.

• Journal of Digital Convergence
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• v.16 no.4
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• pp.195-203
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• 2018

This study was conducted to investigate the types and methods of dental impression materials used in dental clinics in south Korea, the questionnaire was surveyed by a self-administered method for one dentist in a one dental clinic, the collected data were statistically analyzed using SPSS 20. The most frequently used addition silicone impression materials were used in most dental treatment. It was confirmed that the method of taking impression materials having different flow properties(light body and heavy body) was most preferred at one time, also, the implant impression taking method was the most preferred for two rubber impression materials with different flow properties, both direct and indirect. There were statistically significant differences in age and clinical experience between the methods of impression taking of casting restorations and prosthetic according to general characteristics. These results are expected to be helpful for the development of theoretical and practical work based on the basic data for impression material development and research and the preference of impression materials required for dental professional in clinical practice.