• Journal of Korean Dental Science
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• v.12 no.1
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• pp.13-19
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• 2019

Purpose: The aim of this study was to compare the flexural strength of provisional fixed dental prostheses which was three-dimensional (3D) printed by several build directions. Materials and Methods: A metal jig with two abutment teeth and pontic space in the middle was fabricated. This jig was scanned with a desktop scanner and provisional restoration was designed on dental computer-aided design program. On the preprocessing software, the build angles of the restorations were arranged at $0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, and $90^{\circ}$ and support was added and resultant structure was sliced to a thickness of $100{\mu}m$. Processed restorations were printed with digital light processing type 3D printer using poly methyl meta acrylate-based resin. After washing and post-curing, compressive loading was applied at a speed of 1 mm/min on a metal jig fixed to a universal testing machine. The maximum pressure at which fracture occurred was measured. For the statistical analysis, build direction was set as the independent variable and fracture strength as the dependent variable. One-way analysis of variance and Tukey's post hoc analysis was conducted to compare fracture strength among groups (${\alpha}=0.05$). Result: The mean flexural strength of provisional restoration 3D printed with the build direction of $0^{\circ}$ was $1,053{\pm}168N$; it was $1,183{\pm}188N$ at $30^{\circ}$, $1,178{\pm}81N$ at $45^{\circ}$, $1,166{\pm}133N$ at $60^{\circ}$, and $949{\pm}170N$ at $90^{\circ}$. The group with a build direction of $90^{\circ}$ showed significantly lower flexural strength than other groups (P<0.05). The flexural strength was significantly higher when the build direction was $30^{\circ}$ than when it was $90^{\circ}$ (P<0.01). Conclusion: Among the build directions $0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, and $90^{\circ}$ set for 3D printing of fixed dental prosthesis, an orientation of $30^{\circ}$ is recommended as an effective build direction for 3D printing.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.239-245
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• 2016

Purpose: The purpose of this study was to identify clinical complications in removable partial denture (RPD) with implant-supported surveyed prostheses, and to analyze the factors associated with the complications such as location of the implant, splinting adjacent prostheses, the type of retentive clasps, Kennedy classification, and opposing dentition. Materials and Methods: A retrospective clinical study was carried out for 11 patients (7 male, 4 female), mean age of 67.5, who received RPD with Implant-supported surveyed prostheses between 2000 and 2016. The mechanical complications of 11 RPDs and 37 supporting implant prostheses and the state of natural teeth and peripheral soft tissue were examined. Then the factors associated with the complications were analyzed. Results: The average of 3.4 implant-supported prostheses were used for each RPD. Complications found during the follow-up period of an average of 42.1 months were in order of dislodgement of temporary cement-retained prostheses, opposing tooth fracture/mobility, screw fracture/loosening, clasp loosening, veneer porcelain fracture, marginal bone resorption and mobility of implant, artificial tooth fracture. Complications occurred more frequently in anterior region compared to posterior region, non-splinted prostheses compared to splinted prostheses, surveyed prostheses applied by wrought wire clasp compared to other clasps, and natural dentition compared to other removable prostheses as opposing dentition. There were no significant differences in complications according to the Kennedy classification. Conclusion: All implant-assisted RPD functioned successfully throughout the follow-up. However, further clinical studies are necessary because the clinical evidences are still not enough to guarantee the satisfactory prognosis of implant-assisted RPD for long-term result.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.1
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• pp.41-45
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• 2009

Background: Reduced bone height is one of the major problems faced in restoring tooth loss with implants. By the use of short implants, it is possible to reduce complicated and invasive treatment such as bone graft, allowing more simple surgery. But short implants are generally considered to have lower success rates than that of standard implants. Purpose: To assess the results of short Straumann implants by a retrospective study of short Straumann implants with TPS(titanium plasma-sprayed) and SLA(sandblasted, large grit, acid etched) surfaces. Materials and methods: 173 implants in 106 patients who received short Straumann implant surgery(${\le}8\;mm$) in the department of oral and maxillofacial surgery, Kyunghee Dental Hospital, from February 1996 to October 2006 were selected and studied. All of the implants were followed up after prosthetic rehabilitation. The average follow-up period was 34 months with 119 months as the longest follow up period. The average follow-up period after prosthetic rehabilitation was 31 months. 64 females(60.4%) and 42 males(39.6%) participated in the research with the age range of 19 to 85(mean age 47). 20 patients(18.9%) were under 40, 85 patients(80.2%) were over 40 and under 70, and only one patient(0.9%) was over 70 years old. Results: 27 implants(15.6%) had TPS surface while 146 implants(84.4%) had SLA surface. 9 implants(5.2%) were 3.3, 108 implans(62.4%) were 4.1mm and 56 implants(32.4%) were 4.8mm in diameter. 167 implants(96.5%) were 8mm and 6 implants(3.5%) were 6mm in length. There were 24 implants(13.9%) on the maxillas and 149 implants(68.8%) on the mandibles. 119 implants(68.8%) were rehabilitated with FPD(fixed partial denture), 47 implants(27.2%) with single crowns and 4 implants(2.3%) with overdentures. Among the fixed partial dentures, 30 of them were splinted with short implants only. After over an year of follow-up period, 139 implants(96.5%) out of 144 implants showed marginal bone loss of less than 1mm. 3 out of 173 implants failed showing 98.27% survival rate. Conclusions: The use of short Straumann implants(${\le}8mm$) can be a simple and reliable treatment method in minimal residual bone height.

• Journal of dental hygiene science
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• v.14 no.3
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• pp.417-423
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• 2014

The aim of this study was to evaluate the relationship between prosthetic status and health related quality of elderly by using EuroQol-5 dimension (EQ-5D) which is a standardized instrument used as a measure of health outcome. Data from 1,179 elderly subjects (over 65 years old) from the fifth Korea National Health and Nutrition Examination Survey were used in our analysis. Oral examination were conducted to obtain wearing prosthetic and needed prosthetic. EQ-5D is a widely used health condition measuring instrument. It consists of the five dimensions: Mobility, Self-care, Usual activities, Pain/discomfort and Anxiety/depression. EQ-5D index is a score calculated out of a weighting system. In this study, the mean score of the EQ-5D index among the elderly was 0.86. For EQ-5D index gender, female showed statistically significantly lower quality of life than male. The related factors EQ-5D index, when the lower demand for fixed prosthodontics and full denture. Wearers in partial and complete denture than non-wearers showed higher EQ-5D index. In order to improve EQ-5D index among the elderly who demand prosthetic status, which has lost its function through providing proper dental prostheses.

• The Journal of Advanced Prosthodontics
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• v.4 no.2
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• pp.89-92
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• 2012

PURPOSE. Adequate passive-fitting of one-piece cast 3-element implant-supported frameworks is hard to achieve. This short communication aims to present an alternative method for section of one-piece cast frameworks and for casting implant-supported frameworks. MATERIALS AND METHODS. Three-unit implant-supported nickel-chromium (Ni-Cr) frameworks were tested for vertical misfit (n = 6). The frameworks were cast as one-piece (Group A) and later transversally sectioned through a diagonal axis (Group B) and compared to frameworks that were cast diagonally separated (Group C). All separated frameworks were laser welded. Only one side of the frameworks was screwed. RESULTS. The results on the tightened side were significantly lower in Group C ($6.43{\pm}3.24{\mu}m$) when compared to Groups A ($16.50{\pm}7.55{\mu}m$) and B ($16.27{\pm}1.71{\mu}m$) ($P$ <.05). On the opposite side, the diagonal section of the one-piece castings for laser welding showed significant improvement in the levels of misfit of the frameworks (Group A, $58.66{\pm}14.30{\mu}m$; Group B, $39.48{\pm}12.03{\mu}m$; Group C, $23.13{\pm}8.24{\mu}m$) ($P$ <.05). CONCLUSION. Casting diagonally sectioned frameworks lowers the misfit levels. Lower misfit levels for the frameworks can be achieved by diagonally sectioning one-piece frameworks.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.2
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• pp.119-130
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• 2007

Purpose: This investigation was designed to estimate the flexure strength, density, and microstructure of the colored and uncolored zirconia oxide ceramics for fixed partial denture. Material and Methods: LAVATM All Ceramic(3M-ESPE, USA), Cercon Smart Ceramic(Dentsply, USA), and Z-match Ceramic(DentAim, Korea) were used for this study. All specimen was fabricated by ASTM C1161. After preparing $25{\times}2{\times}1.5mm$ of rectangular column and sitting rectangular column on universal test machine (UTM), external supporting point distance is 20.0 mm, internal supporting point distance is 10.0 mm. Specimen was loaded with 0.2 mm/min of cross head speed until fracture and at the time of broken of specimen, measuring loading value with PC software. Results: The results were obtained as follows: 1. Flexure strength of uncolored zirconia was higher than that of colored zirconia. 2. In uncolored zirconia, flexure strength of LAVATM Ceramic was more higher than the other ceramics, and it showed statistical difference between LAVATM Ceramic and Cercon Smart Ceramic (P<0.05). 3. In colored zirconia, flexure strength of LAVATM Ceramic was more higher than the other ceramics too, but they did not show statistical difference (p>0.05). 4. In Weibull analysis, Characterastic strength was showed highest value to uncolored LAVATM Ceramic and lowest value to Z-match ceramic, and Weibull modulus(m) of uncolored zirconia was higher than that of colored zirconia. 5. In XRD analysis, all group except Z-match showed high peak of t-ZrO2 but they did not show m-ZrO2. Colored zirconia group showed lower peak of t-ZrO2 than that of uncolored zirconia group.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.4
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• pp.363-373
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• 2006

Statement of Problem : The accuracy and dimensional stability of elastomeric impression materials have been the subject of numerous investigation. Few studies have addressed the effect of changes in time on the dimensional stability of impression materials. Purpose: The purpose of this investigation was to evaluate the effects of elastomeric impression materials and storage time on dimensional stability. Materials and methods: A total of 75 impressions were made of epoxy resin dies mimicked prepared 3-unit fixed partial denture. The dies had 1 buccolingual, 1 mesiodistal and 1 occlusogingival lines and interpreped dot. Impression materials investigated included two polyether impression materials and three polyvinylsiloxane impression material. 15 specimens were made of each impression material and poured by type IV stone over times (30 minutes, 24 hours, 72 hours) after mixing; the same examiner measured each specimen 3 times at a magnification of 3.5$\times$. All statistical tests were performed with the level of significance set at .05. Results : The results indicated that significant difference at any measuring point of stone dies of the polyether impression materials and when measurements at 30 minutes, 24 hours, and 72 hours were compared ; the length of measuring point increased significantly as time passed by. However this result is not significant clinically. Analysis also showed significant differences at any measuring point when polyvinylsiloxane and polyether impression materials were compared and significant differences clinically. Conclusion: Under the conditions of this study, the shrinkage rate of the polyvinylsiloxane and polyether impression materials significantly increased as time passed by. The polyether impression materials showed higher shrinkage significantly, while the shrinkage rate of all five materials showed a significant time-dependent increase.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.1
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• pp.46-52
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• 2017

Provisional restoration plays an important role in the process of restoration with fixed partial denture by providing protection and restoring function and esthetics of abutment tooth. This is especially true in patients requiring use of provisional prosthesis for a long term. However, such situations may lead to higher possibility of provisional prosthesis fracture, and if expected so, reinforcement of provisional prosthesis should be considered. In this article, a patient requiring prosthetic treatment with increase of vertical dimension of occlusion was introduced. Due to increased vertical dimension of occlusion, the provisional restoration was expected to withstand relatively larger amount of load during a relatively long observation period. In order to minimize possible occurrence of fracture, reinforcement of the provisional restoration was sought by insertion of cast-metal framework and by using bis-acryl resin. The reinforced provisional restoration showed satisfactory results during the observation period of 4 months.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.3
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• pp.262-272
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• 2015

Loss of molar support and abnormal jaw relationship lead to occlusal disharmony and cause pathologic signs. Full mouth rehabilitations with reestablishment of occlusal schemes are needed. In this case, the 75 year-old female patient showed posterior bite collapse, irregular occlusal plane and Class II jaw relationship. By observing her profile and interocclusal distance, she was diagnosed as loss of occlusal vertical dimension. Treatment plan is to restore maxillay class I removable partial denture and mandibular fixed prosthesis and to establish vertical dimension and harmonious occlusal plane. Occlusal vertical dimension of 19 mm, which is obtained by 7.5 mm increase between maxillary right lateral incisor and mandibular canine, was established using temporary prosthesis via diagnostic wax-up. Patient adaptation with newly formed vertical dimension was verified during 8 week follow-up period. Within the information of interim prostheses, final restoration was constructed and delivered. The patient showed sound occlusal scheme and esthetic profile.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.6
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• pp.762-771
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• 2003

Statement of problem. In dentistry, the minimally prepared inlay resin-bonded fixed partial denture (FPD) made of new ceromer / fiber-reinforced composite (FRC) was recently introduced. However, the appropriate dimensions for the long-term success and subsequent failure strength are still unknown. Purpose. The aim of this study was to investigate the most fracture-resistible thickness combination of the ceromer / FRC using a universal testing machine and an AE analyzer. Material and Methods. A metal jig considering the dimensions of premolars and molars was milled and 56-epoxy resin dies, which had a similar elastic modulus to that of dentin, were duplicated. According to manufacturer's instructions, the FRC beams with various thicknesses (2 to 4 mm) were constructed and veneered with the 1 or 2 mm-thick ceromers. The fabricated FPDs were luted with resin cement on the resin dies and stored at room temperature for 72 hours. AE (acoustic emission) sensors were attached to both ends, the specimens were subjected to a compressive load until fracture at a crosshead speed of 0.5 mm/min. The AE and failure loads were recorded and analyzed statistically. Results. The results showed that the failure strength of the ceromer/FRC inlay FPDs was affected by the total thickness of the connectors rather than the ceromer to FRC ratio or the depth of the pulpal wall. Fracture was initiated from the interface and propagated into the ceromer layer regardless of the change in the ceromer / FRC ratio. Conclusion. Within the limitations of this study, the failure loads showed significant differences only in the case of different connector thicknesses, and no significant differences were found between the same connector thickness groups. The application of AE analysis method in a fiber-reinforced inlay FPD can be used to evaluate the fracture behavior and to analyze the precise fracture point.