• The Korean Journal of Physiology and Pharmacology
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• v.26 no.1
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• pp.37-45
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• 2022

The aim of the present study was to investigate the physiological role of nicotinamide phosphoribosyltransferase (NAMPT) associated with odontogenic differentiation during tooth development in mice. Mouse dental papilla cell-23 (MDPC-23) cells cultured in differentiation media were stimulated with the specific NAMPT inhibitor, FK866, and Visfatin (NAMPT) for up to 10 days. The cells were evaluated after 0, 4, 7, and 10 days. Cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The mineralization assay was performed by staining MDPC-23 cells with Alizarin Red S solution. After cultivation, MDPC-23 cells were harvested for quantitative PCR or Western blotting. Analysis of variance was performed using StatView 5.0 software (SAS Institute Inc., Cary, NC, USA). Statistical significance was set at p < 0.05. The expression of NAMPT increased during the differentiation of murine odontoblast-like MDPC-23 cells. Furthermore, the up-regulation of NAMPT promoted odontogenic differentiation and accelerated mineralization through an increase in representative odontoblastic biomarkers, such as dentin sialophosphoprotein, dentin matrix protein-1, and alkaline phosphatase in MDPC-23 cells. However, treatment of the cells with the NAMPT inhibitor, FK866, attenuated odontogenic differentiation, as evidenced by the suppression of odontoblastic biomarkers. These data indicate that NAMPT regulated odontoblastic differentiation through the regulation of odontoblastic biomarkers. The increase in NAMPT expression in odontoblasts was closely related to the formation of the extracellular matrix and dentin via the Runx signaling pathway. Therefore, these data suggest that NAMPT is a critical regulator of odontoblast differentiation during tooth development.

• The Journal of Advanced Prosthodontics
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• v.7 no.3
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• pp.214-223
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• 2015

PURPOSE. To measure the surface loss of dental restorative zirconia and the short-term bond strength between an indirect composite resin (ICR) and zirconia ceramic after various sandblasting processes. MATERIALS AND METHODS. Three hundred zirconia bars were randomly divided into 25 groups according to the type of sandblasting performed with pressures of 0.1, 0.2, 0.4 and 0.6 MPa, sandblasting times of 7, 14 and 21 seconds, and alumina powder sizes of 50 and $110{\mu}m$. The control group did not receive sandblasting. The volume loss and height loss on zirconia surface after sandblasting and the shear bond strength (SBS) between the sandblasted zirconia and ICR after 24-h immersion were measured for each group using multivariate analysis of variance (ANOVA) and Least Significance Difference (LSD) test (${\alpha}$=.05). After sandblasting, the failure modes of the ICR/zirconia surfaces were observed using scanning electron microscopy. RESULTS. The volume loss and height loss were increased with higher sandblasting pressure and longer sandblasting treatment, but they decreased with larger powder size. SBS was significantly increased by increasing the sandblasting time from 7 seconds to 14 seconds and from 14 seconds to 21 seconds, as well as increasing the size of alumina powder from $50{\mu}m$ to $110{\mu}m$. SBS was significantly increased from 0.1 MPa to 0.2 MPa according to the size of alumina powder. However, the SBSs were not significantly different with the sandblasting pressure of 0.2, 0.4 and 0.6 MPa. The possibilities of the combination of both adhesive failure and cohesive failure within the ICR were higher with the increases in bonding strength. CONCLUSION. Based on the findings of this study, sandblasting with alumina particles at 0.2 MPa, 21 seconds and the powder size of $110{\mu}m$ is recommended for dental applications to improve the bonding between zirconia core and ICR.

• Journal of Technologic Dentistry
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• v.22 no.1
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• pp.57-67
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• 2000

The 2 key bridge system has been developed to make crownless bridges without damaging sound teeth. Strong bridge work of single or multiple pontics is possible for replacing both anterior and posterior teeth. It is incresingly considerde to be unacceptable, by dentists as well as patients, to fully grind down healthy elements in order fit a conventional bridges. Because this technique uses a combination of hole and adhesive fitting, it has a number of adventages over etched bridges and conventional bridges: - In comparison with conventional bridges, hardly and healthy dental tissue is sacrificed - Due to the lack of crown edges there is no periodontal pressure, as is the case with conventional bridges - The treatment procedure is straight forward and involves less time than conventional bridges. - The treatment is largely resiverable and repairable

• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.65-69
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• 2008

Recently, zirconia is widely used in the field of dental ceramics thanks to the proliferation of CAD/CAM systems. Accordingly, different types of zirconia block are being solid in the market. However, there are no precise, objective standards for properties of zirconia. This study concerns the flexural strength of zirconia ceramic for CAD/CAM block. The test specimens used for this study were ZirBlank(Acucera), ZirBlank shade(Acucera), VITA, Cercon(Densply) and Cerasys. The test results suggest that ZirBlank shade block shows the highest flexural strength and density among the zirconia blocks tested. Its flexural strength was $971{\pm}58MPa$ and its density was 99.89%. On the other hand, Cerasys block shows the lowest flexural strength of $576{\pm}36MPa$ and the lowest density of 94.85%. Given all, the density of the specimens is found to be directly proportional to strength and inversely to grain size.

• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.71-77
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• 2008

Acrylic resin has been widely used for dental care since it requires relatively simple equipment for treatment and less time and cost are needed to make it and, furthermore, proper strength, dimensional stability as well as durability are ensured after treatment. A survey of denture users showed, however, that more than 60% of dentures installed need repair each year, $22{\sim}30%$ of which are due to falling out of teeth. This study is aimed at exploring the means to increase bonding strength of denture by reducing the causes for falling out of teeth during the processing of dentures. For this aim, the bonding strength of dentures was compares and analyzed before and after the glazed surface of teeth contacting denture was eliminated. From the analysis, it was revealed that there was a difference of 4.3MPa in average in bonding strength between 20MPa for the glazed surface not eliminated and 24.3MPa for the glazed surface eliminated.

• Journal of Technologic Dentistry
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• v.44 no.4
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• pp.154-160
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• 2022

The need for repairing removable dentures has grown as the population had aged. The direct methods allow existing dentures to be repaired without interrupting their use. However, if patient compliance is low, direct methods may be challenging. Moreover, attaching an artificial tooth to a metal base is a complicated procedure because it necessitates casting a retentive element and soldering it to a metal base. This clinical report describes how to add an artificial tooth to a metal base, reline denture bases, and reestablish occlusion on relined removable dentures using indirect methods. Existing removable dentures were successfully repaired and their service life was efficiently extended using the methods described.

• Journal of the Korea Convergence Society
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• v.12 no.11
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• pp.257-263
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• 2021

This study analyzed the factors affecting online class satisfaction and tried to use it as basic data for more effective class management. The survey was collected on 208 students majoring in dental laboratory technology in Jeonbuk and Chungbuk. The data were analyzed by reliability analysis, descriptive stastistics, compare means(t-test, one-way ANOVA), Pearson's correlation coefficient and stepwies multiple regression analysis(SPSS program). The analysis results showed that expected benefit of time was 3.87, expected benefit of learning was 3.30, technology familiarity was 3.40, and class satisfaction was 3.21. The most influential factor in class satisfaction was technology familiarity. In order to increase the online class satisfaction, it is necessary to build a learning environment to improve the ability to learning tools used in classes and technology familiarity with the online class system.

• Journal of Korean society of Dental Hygiene
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• v.13 no.2
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• pp.361-368
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• 2013

Objectives : The purpose of this in vitro study was to evaluate the effect of firing cycles on the marginal and internal fit of metal ceramic crown. Methods : Ten same cases of stone models (abutment teeth 11) were manufactured. Ten cobalt-chrome cores were made per each models and the marginal and internal fit was evaluated through a silicone replica technique. The marginal and internal fit of specimens was measured twice. The first measurement was done after manufacturing cobalt-chrome alloy core and the second measurement was done after porcelain firing. T-test of paired sample for statistical analysis was executed with SPSS 12.0K for Windows (${\alpha}$=0.05). Results : Mean(SD) marginal and internal fit were 77.1(23.3) ${\mu}m$ for the cobalt-chrome alloy core group and 84.4(21.9) ${\mu}m$ for the metal-ceramic crown group. They were statistically significant differences between groups for marginal and internal fit (p<.05). Conclusions : All metal ceramic crowns showed marginal and internal fit ranged within the current clinical recommendations.

• Journal of Technologic Dentistry
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• v.38 no.3
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• pp.151-156
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• 2016

Purpose: The dental implant should be enough to endure chewing load and it's required to have efficient design and use of implant to disperse the stress into bones properly. This study was to evaluate the stress distribution on a supporting bone by lengths and diameters of the implant fixture. Methods: The modeling and analysis of stress distribution was used for the simple molar porcelain crown model by Solidworks as FEM program. It was designed on applying with tightening torque of 20 Ncm of a abutment screw between a cement retained crown abutment and a fixture. The fixtures of experimental model used 10, 13mm by length and 4, 5mm by diameter. A external vertical loading on the two buccal cusps of crown and performed finite element analysis by 100 N. Results: The maximum von Mises stress(VMS) of all supporting bone models by fixture length and diameter were concentrated on the upper side of supporting compact bone. The maximum stress of each model under vertical load were 164.9 MPa of M410 model, and 141.2 MPa of M413 model, 54.3 MPa of M510 model, 53.6 MPa of M513 model. Conclusion: The stress reduction was increase of fixture's diameter than it's length. So it's effective to use the wider fixture as possible to the conditions of supporting bone.

• Journal of Technologic Dentistry
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• v.19 no.1
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• pp.43-54
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• 1997

This investigation is carried out of inqurie into the effects of the accelerator on the setting time and haedness when it is used with plaster products. Plaster($\beta$), dental hard stone($\alpha$), and limproved dental hard stone($M{\alpha}$) are selected as the objects of the investigation, since they are most common materials for dental plaster products. Setting time is gauged by means of Vicket Needle and Gilmore Needle, and hardness is gauged by means of Brinell and Vicket Hardness machines. Samples of each material are made in the standerd water powder ratio and with the accelerator repectively, Every material is tested five times each. The results of the tests are as fallow : 1) In each case the setting time is shortened when the accelerator is used. 2) Of the three materials the hardness of the plaster was lowest A($\beta$) < B($\alpha$) < C($M{\alpha}$)} 3) In each case the hardness of the samples made in the standard water powder ratio were higher than that of the sample made with the accelerator. A1 > A2 ; B1>B2 ; C1>C2 4) Final Conclusion : Higher quality cast is expected when it is made in the standard water powder ratio.