• The Journal of Korean Academy of Prosthodontics
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• v.52 no.3
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• pp.177-185
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• 2014

Purpose: This study is designed to investigate the various impacts of different types of scaler tips such as cooper alloy base tip and the others on the surface roughness of teeth and implant by the method which is currently in clinical use. Materials and methods: Four different types of disc shaped porcelain, titanium, zirconia, and Type III gold alloy dental materials sized 15 mm diameter, 1.5 mm thickness were used for the experiment. Plastic hand curette (Group PS), cooper alloy new tip (Group IS), and stainless steel tip (Group SS) were used as testing appliances. A total of 64 specimens were used for this study; Four specimens for each material and appliance group. Surface roughness was formed with 15 degree angle in ultrasonic scaler tip and with 45 degree angle in hand curette of instrument tip and the specimen surface with 5 mm long, one horizontal-reciprocating motion per second for 30 seconds by 40 g force. To survey the surface roughness of each specimen, a field emission scanning electron microscope, an atomic force microscope, and a surface profiler were used. (Ra, ${\mu}m$). Results: According to SEM, most increased surface roughness was observed in SS group while IS groups had minimal roughness change. Measurement by atomic force microscope presented that the surface roughness of SS group was significantly greater than those of PS, IS and control groups in the type III gold alloy group (P<.05). IS group showed lesser surface roughness changes compared to SS group in porcelain and gold alloy group (P<.05). According to surface profiler, surface roughness of SS group showed greater than those of PS, IS and control groups and IS group showed lesser than those of SS group in all specimen groups. Type III gold alloy group had large changes on surface roughness than those of porcelain, titanium, zirconia (P<.05). Conclusion: The result of this study showed that newly developed copper alloy scaler tip can cause minimal roughness impacts on the surface of implant and dental materials; therefore this may be a useful alternative for prophylaxis of implant and restored teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.443-454
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• 2008

Statement of problem: A clinically successful color match is one of the important factor to get an esthetic dental restoration. Dental shade guides are commonly used to evaluate tooth color in restorative procedure. But numerous reports have indicated that common shade guides do not provide sufficient spectral coverage of the natural tooth colors. To address issues associated with the shade guide, distinct avenues have been pursued objective spectrophotometric / colorimetric assessment. Purpose: This study compared the accuracy of tooth color selection of spectrophotometer with that of human visual determination. Three main factors were investigated, namely, the effect of light, the individual variation and the experience of the observer. Material and methods: At the first experiment, on ten patients, one operator independently selected the best matching shade to the unrestored maxillary central incisor, using a Vita Classical Shade Guide in the morning, at noon and in the afternoon. The same teeth were measured by means of a reflectance spectrophotometer. At the second experiment, on ten patients, ten operators (5 experts, 5 novices) selected and measured by the same method above at noon. At the third experiment, the results of the second experiment were divided into two groups, expert and novice, and analyzed. Results: 1. There was significant difference between visual and spectrophotometric assessment (mean ${\Delta}E$ values) in experiment 1, 2, 3 (P < .05). 2. There was no significant difference between experts and novices group, when comparing with each visual and spectrophotometric assessment (mean ${\Delta}E$ values). Conclusion: Spectrophotometer could be used to analyze the shade of natural tooth objectively. Thereby, this method offers the potential tominimize considerably the need for corrections or even remakesafter intraoral try-in of restoration. Furthermore, to achieve its advantage, both the shade-matching environment and communication between dentist and technician should be optimized with use of visual and instrumental shade-matching systems.

• Restorative Dentistry and Endodontics
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• v.35 no.5
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• pp.387-394
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• 2010

Objectives: The purpose of this study was to evaluate the whitening efficacy and longevity of home bleaching. Materials and Methods: A total of 28 patients were divided into either experimental group (Opalescence F; 15% carbamide peroxide) or control group randomly. The patients in experimental group were instructed to wear individual trays applied with bleaching gel for 2 hours a day for 4 weeks. Any treatments weren't applied to the patients in control group. The color measurements of central incisors, lateral incisors & canines of upper and lower arch were recorded at base line, immediately after the finishment of treatmemt (4 weeks), 8 weeks and 12 weeks using Colorimeter (Chroma Meter, 2600d Konica Minolta co.) and Vitapan classical shade guide (Vita Zahnfabrik). Results: A significantly stronger color change was observed for overall teeth samples in experimental group immediately after treatment (at 4 weeks) compared to ones in control group (p < 0.05). There was also a significant difference between baseline and 8 weeks or 12 weeks separately though color rebouncing phenomenon occurred as time went by (p < 0.05). Conclusions: The clinical effecacy and longevity of home bleaching without combined application of in-office bleaching was observed through this experiment.

• Restorative Dentistry and Endodontics
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• v.36 no.1
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• pp.26-36
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• 2011

Objectives: In the present study, three kinds of tissues cells (pulp, gingiva, and periodontal ligament) were investigated if those cells express MMP and TIMP when they were stimulated with neuropeptides (substance P, CGRP) or proinflammatory cytokine, TNF-$\alpha$. Materials and Methods: The cells cultured from human dental pulp (PF), gingiva (GF) and periodontal ligament were (PDLF) stimulated with Mock, SP, TNF-$\alpha$, and CGRP for 24 hrs and 48 hrs. for an RNase protection assay and Enzyme Linked Immunosorbent Assay. Cells (PF, GF and PDLF) seeded in 100 mm culture dish were stimulated with SP ($10^{-5}$, $10^{-8}\;M$) or only with medium (Mock stimulation) for 4hrs and for 24 hrs for RNase Protection Assay, and they were stimulated with CGRP ($10^{-5}\;M$) and TNF-$\alpha$(2 ng/mL) for 24 hrs and with various concentraion of TNF-$\alpha$(2, 10, and 100 ng/mL) for Rnase Protection Assay with a human MMP-1 probe set including MMP 1, 2, 8, 7, 8, 9, 12, and TIMP 2, 3. In addition, cells (PF, GF and PDLF) were stimulated with Mock and various concentraion of TNF-$\alpha$(2, 10, and 100 ng/mL) for 24 hrs and with TNF-$\alpha$(10 ng/mL) for 48 hrs, and the supernatents from the cells were collected for Enzyme Linked Immunosorbent Assay (ELISA) for MMP-1 and MMP-13. Results: The expression of MMPs in PF, GF, PDLF after stimulation with SP and CGRP were not changed compared with Mock stimulation for 4 hrs and 24 hrs. The expression of MMP-1, -12, -13 24 hrs after stimulation with TNF-$\alpha$ were upregulated, however the expression of TIMP-3 in PF, GF, PDLF after stimulation with TNF-$\alpha$ were downregulated. TNF-$\alpha$(2 ng/mL, 10 ng/mL, 100 ng/mL) increased MMP-1 and MMP-12 expression in PF dose dependently for 24 hrs. Conclusions: TNF-$\alpha$ in the area of inflammation may play an important role in regulating the remodeling of dentin, cementum, and alveolar bone.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.193-202
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• 2016

Purpose: This study was performed in order to assess the effect of the surface treatment methods and the use of bonding agent on the shear bond strength (SBS) between the aged CAD-CAM (computer aided design-computer aided manufacturing) hybrid materials and added composite resin. Materials and methods: LAVA Ultimate (LU) and VITA ENAMIC (VE) specimens were age treated by submerging in a $37^{\circ}C$ water bath filled with artificial saliva (Xerova solution) for 30 days. The surface was ground with #220 SiC paper then the specimens were divided into 9 groups according to the combination of the surface treatment (no treatment, grinding, air abrasion with aluminum oxide, HF acid) and bonding agents (no bonding, Adper Single Bond 2, Single Bond Universal). Each group had 10 specimens. Specimens were repaired (added) using composite resin (Filtek Z250), then all the specimens were stored for 7 days in room temperature distilled water. SBS was measured and the fractured surfaces were observed with a scanning electron microscope (SEM). One-way ANOVA and Scheffe test were used for statistical analysis (${\alpha}=.05$). Results: Mostly groups with bonding agent treatment showed higher SBS than groups without bonding agent. Among the groups without bonding agent the groups with aluminum oxide treatment showed higher SBS. However there was no significant difference between groups except two subgroups within LU group, which revealed a significant increase of SBS when Single Bond Universal was used on the ground LU specimen. Conclusion: The use of bonding agent when repairing an aged LAVA Ultimate restoration is recommended.

• Restorative Dentistry and Endodontics
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• v.32 no.3
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• pp.248-259
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• 2007

The aim of this research was to study the effect of intermittent polymerization on marginal adaptation by comparing the marginal adaptation of intermittently polymerized composite to that of continuously polymerized composite. The materials used for this study were Pyramid (Bisco Inc., Schaumburg, U.S.A.) and Heliomolar (Ivoclar Vivadent, Liechtenstein) . The experiment was carried out in class II MOD cavities prepared in 48 extracted human maxillary premolars. The samples were divided into 4 groups by light curing method: group 1- continuous curing (60s light on with no light off), group 2-intermittent curing (cycles of 3s with 2s light on & 1s light off for 90s); group 3- intermittent curing (cycles of 2s with 1s light on & 1s light off for 120s); group 4- intermittent curing (cycles of 3s with 1s light on & 2s light off for 180s). Consequently the total amount of light energy radiated was same in all the groups. Each specimen went through thermo-mechanical loading (TML) which consisted of mechanical loading (720,000 cycles, 5.0 kg) with a speed of 120 rpm for 100hours and thermocycling (6000 thermocycles of alternating water of $50^{\circ}C$ and $55^{\circ}C$). The continuous margin (CM) (%) of the total margin and regional margins, occlusal enamel (OE), vertical enamel (VE), and cervical enamel (CE) was measured before and after TML under a $\times200$ digital light microscope. Three-way ANOVA and Duncan's Multiple Range Test was performed at 95% level of confidence to test the effect of 3 variables on CM (%) of the total margin: light curing conditions, composite materials and effect of TML. In each group, One-way ANOVA and Duncan's Multiple Range Test was additionally performed to compare CM (%) of regions (OE, VE CE). The results indicated that all the three variables were statistically significant (p < 0.05). Before TML, in groups using Pyramid, groups 3 and 4 showed higher CM (%) than groups 1 and 2, and in groups using Heliomolar. groups 3 and 4 showed higher CM (%) than group 1 (p < 0.05). After TML, in both Pyramid and Heliomo)ar groups, group 3 showed higher CM (%) than group 1 (p < 0.05) CM (%) of the regions are significantly different in each group (p < 0.05). Before TML, no statistical difference was found between groups within the VE and CE region. In the OE region, group 4 of Pyramid showed higher CM (%) than group 2, and groups 2 and 4 of Heliomolar showed higher CM (%) than group 1 (p < 0.05). After TML, no statistical difference was found among groups within the VE and CE region. In the OE region, group 3 of Pyramid showed higher CM (%) than groups 1 and 2, and groups 2,3 and 4 of Heliomolar showed higher CM (%) than group 1 (p < 0.05). It was concluded that intermittent polymerization may be effective in reducing marginal gap formation.

• Journal of dental hygiene science
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• v.16 no.5
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• pp.349-354
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• 2016

The purpose of this study was to evaluate the efficacy of the newly-developed $Qraypen^{TM}$ (All In One Bio, Korea) system for the diagnosis of early proximal caries by comparing it with the conventional methods of visual inspection and periapical radiography. This study was carried out from July 2015 to April 2016 targeting 32 children aged 7~12 years who visited Y-Dental Clinic for school oral health examinations. Two investigators selected and examined a total of 153 primary molars that had not undergone restorative treatment. Comparisons were carried out between visual inspections, readings of posterior periapical radiography images, and readings of $Qraypen^{TM}$ images. This study revealed that the percentage of interproximal surfaces of primary molar teeth without caries incidence was 83.7% using $Qraypen^{TM}$ imaging and 84.9% using visual inspection and periapical radiography. The differences between the two methods were not statistically significant. Thus, $Qraypen^{TM}$ is expected to be a useful and convenient auxiliary diagnostic device that can facilitate the detection of hidden proximal caries in primary molars.

• The Journal of the Korean dental association
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• v.53 no.4
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• pp.266-274
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• 2015

The price for health service are decided by very complicated process because many of factors are related with them. The RBRVS(resource-based relative value scale) were used to calculate the Korean health service fees including dental fees. This study aimed to compare dental fees of Korea with other countries, such as Japan, Germany, and the US for evaluating the adequacy. Dental fees were categorized as oral evaluation and imaging, dental treatment including restorative, periodontal, and surgical work, and preventive treatment and compared by each country. The official documents about dental fees were collected from Korea, Japan, Germany, and the US. Each fee was presented as their own currency at first. Then they were converted into Korean won (KRW) by applying the market exchange rates at a specific point of time. Finally the fees were adjusted by purchasing power parities (PPPs) which equalize the different currencies. In general, the level of Korean fees were markedly low compared to those of Japan, Germany, and the US. German fees were similar or higher than that of Japan, and the US. The Korean fees were lower than three other countries 1.2~4.1 times for oral evaluation and 2.2~7.3 times lower for panoramic radiography. The endodontic fees of Japan, Germany, and the US were higher 1.8~15.3 times and 4.0~35.9 times for the deciduous teeth extraction compared to the Korean. In Japan the prophylaxis was 3.2 times more priced than the Korean fee. Exceptionally, the fees for re-evaluation, amalgam filling, and scaling were lower priced in Japan than other countries. This study has limitations on the items in definition and contents of dental practices units which were not exactly comparable and differently determined by countries. However, this study is meaningful because it surveyed the price levels to compare four different countries and then applied PPPs adjustment. This finding can be used to develop the dental RBRVs of Korean national health insurance and will contribute to improving the payment systems of health care.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.3
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• pp.263-270
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• 2019

Current trends in restorative dentistry focus on improving the esthetics and keeping the sound dental tissues as long as possible. The aims of this case report were to describe the successful outcome of cubic-phase zirconia laminate veneers for a patient with isolated microdontia by using a digital workflow, and to describe their clinical implications. A 15-year-old female who had isolated microdontia in combination with spacing visited Ajou University Dental Hospital for esthetic treatment. In this case, 6 maxillary anterior teeth were restored with cubic-phase zirconia laminate veneers without tooth structure removal by using a digital impression, computer-aided design (CAD) software, and computer-aided manufacturing (CAM) procedures. At 6-month follow-up, no distinct mechanical and biological complications were detected and the prostheses exhibited satisfactory esthetics and functions. Due to its favorable tissue responses and enhanced translucency, cubic-phase zirconia can be a suitable strategy for a noninvasive esthetic approach.

• Restorative Dentistry and Endodontics
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• v.26 no.5
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• pp.409-417
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• 2001

The purpose of this study was to investigate the influence of light irradiation over self-priming adhesive on dentin bonding. After acid etching the exposed dentin, a self-priming adhesive (Prime&Bond$^{\circledR}$NT dental adhesive system Dentsply DeTrey, GmbH, Konstanz, Germany) was applied and light irradiation was done for 20 sec with regular intensity (600 mW/$\textrm{cm}^2$) in group I and for 3 sec with ultra-high intensity (1930 mW/$\textrm{cm}^2$) in group III. No light irradiation was done over self-priming adhesive in groups II and IV. Composite resin was added on the self-priming adhesive and irradiated for 40 sec with regular intensity (600 mW/$\textrm{cm}^2$) in groups I and II and for 3 sec with ultra-high intensity (1930 mW/$\textrm{cm}^2$) in groups III and IV. To see the effect of light curing time on dentin bonding, another 3 group specimens were prepared. Without light-irradiation over self-priming adhesive, added composite resin was irradiated for 3, 6, or 12 sec with ultra-high intensity light. After bonded specimens were stored in 37$^{\circ}C$ distilled water for 24 hours, shear bond strength were measured using a universal testing machine (4202, Instron, Instron Co., U.S.A.) and fractured surfaces were examined under a stereomicroscope (SZ-PT Olympus, Japan). Statistical analysis were done with one-way, two-way ANOVA and chi-square test. The results were as follows : 1. The shear bond strengths from the groups irradiated over self-priming adhesive were significantly higher than those from the groups without irradiation (p<0.05). 2. There was no significant shear bond strength difference between regular intensity light irradiation groups and ultra-high intensity ones (p>0.05). 3. There was no significant shear bond strength difference among various irradiation time groups with ultra-high intensity ones (p>0.05). 4. In stereomicroscopic examination of fractured surfaces, adhesive-cohesive mixed failure mode was mostly seen in all groups, and there was no significant difference in failure mode among groups (p>0.05).