• The Journal of Korean Academy of Prosthodontics
• /
• v.45 no.3
• /
• pp.389-400
• /
• 2007

Statement of problem. Use of the conventional dental impression procedure is problematic in patients who have difficulty opening their mouth, difficulty breathing through their nose or tendency to gag. Purpose. It is necessary to make individual trays more comfortable for patients during impression taking procedure. It was reported at the KAP Annual Meeting 2001 Seoul that an improved impression technique was suitable for this purpose. In this study, the accuracy of the improved dental impression method for implant was compared with the conventional dental impression method. Material and methods. An oral simulator was made from clear acrylic resin block which had similar form of edentulous ridge. For setting up the standard, five fixtures were installed on it. Study casts were made using two kinds of impression techniques. One was the conventional method that was taken using silicone impression material and an individual resin tray under connection of inter-fixture relation. The other was the improved method in which was the connection of the impression coping and the thermoformed polymethyl methacrylate tray. In addition, two different study casts were made from the improved impression body. The coordinates of the fixture on the study model were measured by three-dimensional coordinate measuring equipment. Then the distances between each fixture were calculated and compared with that of oral simulator. Accuracy of the each impression method was also assessed. Results. The differences of inter-fixture dimension between study casts and simulator in the improved impression technique showed $0.014{\pm}0.016mm$ and $0.017{\pm}0.022mm$, respectively and that of the conventional method was $0.017{\pm}0.014mm$. There was no significant difference between the improved impression technique and conventional method. Conclusion. The improved impression technique is useful for multiple support implants.

• The Journal of Advanced Prosthodontics
• /
• v.8 no.3
• /
• pp.219-223
• /
• 2016

PURPOSE. This study aimed to create a digitized database of fabricated obturators to be kept for patients' potential emergency needs. MATERIALS AND METHODS. A chairside intraoral scanner was used to scan the surfaces of an acrylic resin obturator. The scanned data was recorded and saved as a single standard tessellation language file using a three-dimensional modeling software. A simulated obturator model was manufactured using fused deposition modeling technique in a three-dimensional printer. RESULTS. The entire obturator was successfully scanned regardless of its structural complexity, modeled as three-dimensional data, and stored in the digital system of our clinic at a relatively small size (19.6 MB). A simulated obturator model was then accurately manufactured from these data. CONCLUSION. This study provides a proof-of-concept for the use of digital technology to create a digitized database of obturators for edentulous maxillectomy patients.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.21 no.4
• /
• pp.215-221
• /
• 2011

Objectives: This study was conducted to evaluate the exposure level of hazardous chemical agents for dental technicians in Ulsan. Methods: We measured airborne total dusts and metals such as Nickel, Manganese, Cobalt, and Chromium in 10 dental laboratories by the NIOSH Methods 0500 and 7300, respectively. Methyl methacrylate (MMA), a key ingredient in acrylic resin, was also monitored using passive samplers for long-term sampling and Tenax tubes for short-term sampling. Results: Measured levels of all items were below 10% of the Korean exposure limit except for Nickel. The geometric mean concentration and geometric standard deviation of total dust, Nickel, and MMA were $0.14mg/m^3$ (2.16), $165.3{\mu}g/m^3$ (3.31), and 0.2 ppm (2.5) respectively. Airborne Nickel concentration of two dental laboratories exceeded the exposure limit ($1000{\mu}g/m^3$). The major emission sources of Nickel were metal trimming and casting processes. Conclusions: We found that Nickel, a carcinogen, should be controled most urgently to protect dental technicians.

• Journal of Technologic Dentistry
• /
• v.3 no.1
• /
• pp.9-16
• /
• 1981

A comparative study was conducted to evaluate the relationship of investing medium to the amount of vertical occlusal changes and to the differences of surface smoothness during denture construction. Three groups of 20 dentures, 30 sets of upper and lower were fabricated of conventional heatcuring acrylic denture base resin, using silicone-gypsum molding techniques, with or without covering the occlusal surfaces of the teeth by artificial stone and all-gypsum molding techniques. The distance between the two reference points indented by 1/2 round bur on the upper and lower frontal surfaces of each articulator were measured and recorded before processing and again after processing and remounting of each denture on the articulator. The differences between the two recordings indicated the amount of vertical opening during denture processing. The difference of surface smoothness were investigated and determined by 3 observers continual comparing of the two randomly selected dentures with each other, which were seperately selected as pairs from the different two groups of 20. The results obtained were as follows: 1. During resin processing no statistically significant differences of the amount of vertical occlusal changes were detected between any of the two groups of two silicone-gypsum and one allgypsum molding techniques, although the amount of vertical opening was somewhat increased when silicone-gypsum molding technique was used. 2. Surface smoothness of the processed denture was makedly by increased when silicone-gypsum molding technique was used.

• Journal of dental hygiene science
• /
• v.22 no.3
• /
• pp.139-147
• /
• 2022

Background: Temporary crown resins are used prior to prosthesis placement, indicating the importance of aesthetics. The aim of this study was evaluate the color stability of various staining solutions according to the color of temporary crown resins using VITA Easyshade^Ⓡ V. Methods: The temporary crowns used were the powder-liquid type and included four shades. A total of 36 specimens were fabricated in the form of disks with a diameter of 1.8 mm and a depth of 2 mm. They were divided into four groups of nine each, and staining was performed for seven days by precipitation in 3 mL of three staining solutions composed of distilled water, black coffee, and red wine. Color and color stability evaluations were performed by a trained examiner using a digital spectrophotometer (VITA Easyshade^Ⓡ V). Color stability was analyzed using the ΔE value. Results: Because of the color stability evaluation using the ΔE value, the difference between three and seven days was significant in the specimen I and III groups (p<0.05). Further, post hoc analysis showed that the ΔE value of red wine was significant, indicating that the color stability in red wine was low. The ΔE values in group II between days three and seven were statistically significant (p<0.05). Post hoc analysis showed that distilled water, coffee, and wine had the highest ΔE values on day three. On day seven, the ΔE value for wine was significant, and the color stability was low. There was no significant difference in group IV according to the staining period and staining solution; therefore, color stability was high (p>0.05). Conclusion: This study showed that most temporary resin restorations exhibited color stability in the staining solution. The darker the color of the temporary resin restoration, the higher the color stability against extrinsic staining.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.28 no.3
• /
• pp.253-268
• /
• 2012

Full-mouth reconstruction of a patient using dental implants is a challenge if there is vertical and horizontal bone resorption, since this includes the gingival area and restricts the position of the implants. however, hard- and soft-tissue grafting may allow the implants to be placed into the desired position. Although it is possible to regenerate lost tissues, an alternative is to use fixed detachable prostheses that restore the function and the esthetics of the gingiva and teeth. Various material combinations including metal/acrylic, metal/ceramic, and zirconia/ceramic have been used for constructing this type of restoration. Other problems include wear, separation or fracture of the resin teeth from the metal/acrylic prosthesis, chipping or fracture of porcelain from the metal/ceramic or zirconia/ceramic prosthesis, and fracture of the framework in some free-end prostheses. With virtually unbreakable, chip-proof, life-like nature, monolithic zirconia frameworks can prospectively replace other framework materials. This clinical report describes the restoration of a patient with complete fixed detachable maxillary and mandibular prostheses made of monolithic zirconia with dental implants. The occluding surfaces were made of monolithic zirconia, to decrease the risk of chipping or fracture. The prostheses were esthetically pleasing, and no clinical complications have been reported after two years.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.39 no.4
• /
• pp.222-228
• /
• 2023

Attrition is the loss of tooth hard tissue due to contact between teeth, and in severe cases, dentin is exposed, accompanied by selective corrosion and excessive wear of teeth, which is called cupping. If these lesions are left untreated, the size of the lesion gradually increases, breaking the unsupported enamel, resulting in a decrease in aesthetics and chewing function. In this case report, patients with cupping and enamel fracture due to severe attrition were directly restored using a resin with soft properties containing organic fillers. In the follow-up observation six years later, most of the filling of the occlusal surface was eliminated, but the filling on the buccal surfaces remained relatively intact, and it was confirmed that this type of resin was suitable for the area where the occlusal force was relatively weak rather than the area where the occlusal force was greatly applied.

• The Journal of the Korean dental association
• /
• v.34 no.12 s.331
• /
• pp.855-860
• /
• 1996

치과용 복합레진은 bis GMA형의 monomer가 개발되고, 무기 filler가 첨가되어 물리적인 성질이 더욱 향상되었으며, 또한 법랑질에 대한 산부식법을 통하여 치아에 대한 결합력을 높을 수 있는 방법이 도입되면서 치과용 수복물로서 각광을 받아 왔다. 특히 복합레진은 이전까지 이용되었던 silicate cement 이나 acrylic resin에 비하여 변색이 적고, 원래의 형태를 비교적 잘 유지하는 장점을 가져서 전치부의 수복에 유용한 재료로 인식되었다. 복합레진을 이용한 전치부의 수복은 비교적 적은 치질의 삭제만으로도 가능하고, 심미적으로도 우수한 결과를 보이고 있어서 올바른 술식을 통하여 적절히 이용한다면 좋은 임상적인 결과를 얻을 수 있는 것이 사실이지만 재료학적인 한계가 아직 까지는 엄연히 존재한다. 복합레진을 이용한 전치부의 수복에 있어서, 복합레진의 문제점과 이를 줄이기 위한 방법, 임상시의 주의점 등에 관해 살펴보도록 한다.

• The Journal of Advanced Prosthodontics
• /
• v.4 no.4
• /
• pp.248-253
• /
• 2012

Maxillary obturator prosthesis is the most frequent treatment option for management of partial or total maxillectomy. Heavy weight of the obturators is often a dislocating factor. Hollowing the prosthesis to reduce its weight is the well established fact. The alternate technique to hollow-out the prosthesis has been described in this article which is a variation of previously described processing techniques. A pre-shaped wax-bolus was incorporated inside the flasks during packing of the heat-polymerized acrylic resin to automatically create the hollow space. The processing technique described is a single step flasking procedure to construct a closed-hollow-obturator prosthesis as a single unit. To best understand the technique, this article describes management of a patient who had undergone partial maxillectomy secondary to squamous cell carcinoma rehabilitated with a hollow-obturator prosthesis.

• The Journal of the Korean dental association
• /
• v.14 no.3
• /
• pp.239-243
• /
• 1976

Bilateral true bony ankylosis of temporomandibular joint is extremely rare. Treatment in all cases should be surgical. Considerable difficulty has been encountered by surgeons in the judgment of the planning of the treatment for ankylosis : either by gap arthroplasty treatment because of no recurrence and the excelent results obtained. I performed an osteoarthrotomy and interposition arthroplasty bilaterally, using combined materials consisting of acrylic resin and gold plate. My experience with alloplasty in ankylosed temporomandibular joints is pressented.