• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.4
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• pp.215-221
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• 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 dental hygiene science
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• v.13 no.2
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• pp.135-141
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• 2013

One factor for successful prognosis of finished dental prosthesis is good marginal fit. The purpose of this study in vitro investigation was to compare the marginal fit of all-ceramic crown before and after porcelain veneering, to evaluate the influence of high temperature of the porcelain firing on the fit. For this experiment, model of abutment tooth of maxillary right central incisor was prepared. Ten working models were produced. Ten zirconia cores were made by dental computer aided design/computer aided manufacturing system. The marginal fit of specimens were examined using silicone replica technique. Silicone replicas were sectioned four times and were measured through a digital microscope (${\times}160$). Marginal fit is a distance connected between edge end part of specimen and abutment margin. Each specimens was measured twice, the first measurement was done prior to veneering porcelain firing, while the second measurement was done after the porcelain firing to evaluate this process. Statistical analyses were performed with paired t-test. $Mean{\pm}SD$ marginal fit was $60.8{\pm}14.2{\mu}m$ for zirconia core and $86.1{\pm}13.3{\mu}m$ for all-ceramic crown. They were statistically significant differences (p<0.001). But all specimens showed a marginal fit where the gap widths ranged within the clinical recommendation ($120{\mu}m$), all-ceramic crown production using the zirconia core was adequate.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.1
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• pp.42-51
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• 2022

Esthetic restoration of maxillary anterior implant heavily depends on the direction of installation of implant fixture. In patients with malpositioned implant, it is crucial to communicate the limitations of prosthetic outcome with the patient before starting on a restoration. To facilitate the communication, three-dimensional virtual representation by superimposing facial and intraoral digital scans with Computed Tomography (CT, dicom file) was used for visualization of the limitations of prosthesis. Through digital diagnostic wax-up, the profile of right maxillary anterior incisor implant was expected to be protrusive, which the patient was not satisfied with. Since the patient already had done root canal treatment on left maxillary anterior incisor due to previous trauma, a new prosthetic design including both right and left maxillary anterior incisors was presented to the patient. The second design was chosen and his comments were delivered to dental lab. The patient was satisfied with the new prosthesis, aesthetically and functionally.

• Journal of Technologic Dentistry
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• v.7 no.1
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• pp.41-51
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• 1985

This study has been to survey the present situation of satisfaction to the occupation and dental laboratory by means of selscting 200 dental technicians who are woked in Pusan, Deagu, Kwangju, Deajun. Questionaires were distributed to them and the summerized results were as follows; 1. In general, the dental technician's satisfaction of the occpation was revealed as moderate(Mn, 2.83), the dental technician's satisfaction of the laboratory was revealas moderate(Mn, 2.80). The highest degree item out of the satisfaction of occpation was the outlook(Mn, 3.23), and the lowest degree item was the advancement and the rise to a high position(Mn, 2.22). The highest degree item out of the satisfaction of laboratory was dental material(Mn, 3.07), and the lowest degree item was the equipment of dust collection(Mn, 2.49) 2. By age, the highest degree item out of the satisfaction of occpation was 30 to 43 group(Mn, 3.28), 50 and over group was the lowest degree item(Mn, 2.89). The highest degree item out of the satisfaction of laboratory was 40 to 50 group(Mn, 3.10), the lowest degree item was 35 to 39 group(Mn, 2.88). 3. By school career, the satisfaction of occpation and dental laboratory were higher in the graduated college group than the graduated highschool group. 4. By personal health state, the highest degree item of the satisfaction of occpation was the health group(Mn, 3.25). The highest degree item of the satisfaction of laboratory was the unhealthy group(Mn, 3.07). 5. By religion, the satisfaction if iccupation of laboratory ws higher in the religious group than the non-religious group. 6. By job career, the highest degree item of occupation satisfaction was 15 to 20 years group(Mn, 3.27), the lowest degree item was 20 and over group(Mn, 3.02). The highest degree item out of the satisfaction of laboratory was 15 to 20 years group(Mn, 3.05), The lowest degree item was 7 to 10 years group (Mn, 2.90). 7. By job position, the highest degree item out of satisfaction of occupation was the chief of laboratory group(Mn, 3.33), the head of laboratory group was the lowest degree item(Mn, 3.07). The hightest degree item out of the satisfaction of laboratory was the head of laboratory group(Mn, 3.10), the lowest degree item was the chief of laboratory group(Mn, 2.88). 8. By the place of employment, the degree of occpational satisfaction by items was found that the highest degree in the group engagel in general hospital(Mm, 3.43), the group engaged in dental clinic and hospital(Mn. 3.24), and the dental laboratory group(Mn. 3.14) in order. The difference among the group was significant emough(P<0.05). The highest degree item out of the satisfaction of laboratory was dental laboratory group(Mn. 2.70). The difference among the group was significant emough(P<0.01). 9. By monthly salary, the highest degree item out of the satisfaction of occupation was ￦500,000 to 600,000 group(Mn. 3.32), the lowest degree item was ￦600,000 and over group(Mn, 3.07). The highest degree item out of the laboratory satisfaction was ￦100,000 to 200,000 group(Mn, 3.03), the lowest degree group was ￦300,000 to 400,000 group(Mn, 2.95). 10. As compared with the degree of satisfaction according to job satisfaction, the highest degree item out of the occupational satisfaction was much satisfied group(Mn, 3.65), the lowest degree item was non-satisfied group(Mn, 2.68). The difference among the group was significant enough(P<0.05). The highest degree item out of the satisfaction of laboratory was non-satisfied group(Mn, 30.9), the lowest degree item was satisfied group(Mn, 2.84). The difference among the group was significant enough(P<0.01).

• Restorative Dentistry and Endodontics
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• v.35 no.5
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• pp.353-358
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• 2010

Objectives: The purpose of this study was to measure the power density of light curing units transmitted through resin inlays fabricated with direct composite (Filtek Z350, Filtek Supreme XT) and indirect composite (Sinfony). Materials and Methods: A3 shade of Z350, A3B and A3E shades of Supreme XT, and A3, E3, and T1 shades of Sinfony were used to fabricate the resin inlays in 1.5 mm thickness. The power density of a halogen light curing unit (Optilux 360) and an LED light curing unit (Elipar S10) through the fabricated resin inlays was measured with a hand held dental radiometer (Cure Rite). To investigate the effect of each composite layer consisting the resin inlays on light transmission, resin specimens of each shade were fabricated in 0.5 mm thickness and power density was measured through the resin specimens. Results: The power density through the resin inlays was lowest with the Z350 A3, followed by Supreme XT A3B and A3E. The power density was highest with Sinfony A3, E3, and T1 (p < 0.05). The power density through 0.5 mm thick resin specimens was lowest with dentin shades, Sinfony A3, Z350 A3, Supreme XT A3B, followed by enamel shades, Supreme XT A3E and Sinfony E3. The power density was highest with translucent shade, Sinfony T1 (p < 0.05). Conclusions: Using indirect lab composites with dentin, enamel, and translucent shades rather than direct composites with one or two shades could be advantageous in transmitting curing lights through resin inlays.

• Restorative Dentistry and Endodontics
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• v.36 no.1
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• pp.37-49
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• 2011

Objectives: The aim of this study was to evaluate the surface color of indirect resin restoration according to the layering placement of different shade of incisal composite. Materials and Methods: In this study, CIE $L^*a^*b^*$ value of 16 Body composite of Tescera ATL (Bisco, Schaumburg IL,USA) was measured by spectrophotometer (NF999, Nippon Denshuku, Japan), and compared to CIE $L^*a^*b^*$ value of Vitapan shade guide. Nine shade Incisal composite of Tescera ATL were buildup to 1 mm thickness on Body composites inlay block, and CIE $L^*a^*b^*$ value was measured. Incisal composite was ground to 0.5 mm thickness and CIE $L^*a^*b^*$ value was re-measured. Color difference between Body composite and Incisal composites layered on Body composite was calculated as a function of thickness. Results: Color difference between corresponding shade of Tescera Body composite and Vitapan shade guide was from 6.88 to 12.80. $L^*$ and $b^*$ value was decreased as layering thickness of Incisal composite on Body composite was increased. But, $a^*$ value did not show specific change tendency. Conclusions: Surface color difference between Body composites and Incisal composites layered on Body composite was increased as the layering thickness of Incisal composite increased (p < 0.05).