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Osteogenic potential of nerve growth factor incorporated gelatin methacryloyl beads: An in vitro study using MC3T3-E1

Min-Jeong LEE ; Ji-Eun KIM ; Jung-eun CHOI ; Jae-Sung KWON

Korean Journal of Dental Materials.2024;51(2):109-118. doi:10.14815/kjdm.2024.51.2.109

Despite attempts to aid hard tissue regeneration using materials such as gelatin methacryloyl (GelMa), success has been limited. In this study, considering osteogenic differentiation and mineralization of MC3T3-E1 cells, nerve growth factor (NGF) was utilized for osteogenic differentiation by incorporating NGF into GelMA beads. GelMa beads with NGF (GBNGF) or without NGF (GB) were prepared. MC3T3-E1 cells were then encapsulated in GelMA beads fabricated by UV cross-linking. Live/Dead staining results showed that MC3T3-E1 cells in the GBNGF group exhibited more active cell-cell network formation and clearer spindle-shaped cell morphology than those in the GB group. Alizarin Red staining results revealed that MC3T3-E1 cells cultured in the GBNGF group had a higher amount of calcification indicated by a stronger red staining than those cultured in the GB group. Both results demonstrates that NGF could promote cell-cell and cell-matrix interactions, enhancing cell growth and osteogenic differentiation. In conclusion, the incorporation of NGF into GelMA beads can effectively promote growth and osteogenic differentiation of MC3T3-E1 cells. Therefore, GelMA beads containing NGF are expected to be utilized as a new therapeutic strategy for the regeneration of bone defects.

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Effects of different remineralizing agents on the shear bond strength of universal adhesive on enamel

Eunseon JEONG ; Sohyun PARK ; Kunhwa SUNG ; Sujung PARK ; Yoorina CHOI

Korean Journal of Dental Materials.2024;51(2):85-98. doi:10.14815/kjdm.2024.51.2.85

This study aimed to evaluate the effect of different remineralization agents on the shear bond strength (SBS) on enamel and to confirm remineralization capacity through quantitative light-induced fluorescence (QLF). Sixty non-carious human third molars were divided into eight groups based on remineralization agents agents (control, Tooth Mousse plusTM, Apapro, BGS-7 bioglass) and application time (24 h, 2 weeks). Enamel surfaces were prepared and treated with agents, followed by demineralization and remineralization. Quantitative Light-induced Fluorescence (QLF) assessed fluorescence loss and recovery. After adhesive application and composite restoration, shear bond strength (SBS) was measured. Statistical analysis included Shapiro-Wilk, ANOVA, Kruskal-Wallis, paired t-tests, Wilcoxon rank tests, and multiple comparison tests. SBS values did not show a significant difference between the groups according to the type and application time of the remineralization agents. QLF measurement, in the 24 h groups, showed no significant difference in the recovery amount between the groups. In the 2 week groups, a statistically significant difference was observed and the value was significantly higher in the BG group than that in the control group. There were no significant differences in the values based on the application time. Within the limitations of this study, bioactive glass showed higher remineralization ability than all the other experimental agents. The SBS was not affected by the remineralizing agent.

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Antimicrobial activity of water-soluble mangostin derivatives of ethanol extracts of Garcinia mangostana L. peel, and ethanol extracts of Psoralea corylifolia L. fruit and Glycyrrhiza uralensis root on oral bacteria associated with endodontic infections

So Young YOO ; Kyung-Hyun LEE ; Yun Kyong LIM ; Dae Sung LEE ; Joong-Ki KOOK

Korean Journal of Dental Materials.2024;51(2):99-108. doi:10.14815/kjdm.2024.51.2.99

This study was performed to evaluate the antibacterial activity of water-soluble mangostin derivatives (WsMD) of the ethanol extract of the peel of Garcinia mangostana L. (mangosteen) and the ethanol extracts of the fruit of Psoralea corylifolia L. and the root of Glycyrrhiza uralensis (licorice) against oral bacteria associated with endodontic infections. Cytotoxicity of the three natural products was tested on human embryonic kidney 293 cells (HEK 293) using the methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay or the cell counting method. Antimicrobial activity was evaluated based on the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The highest concentrations of the WsMD of the ethanol extract of the peel of mangosteen and ethanol extracts of P. corylifolia L. fruit and licorice root without cytotoxic effects on HEK 293 cells were 20, 400, and 320 µg/ml, respectively. The MIC and MBC values of the WsMD of the ethanol extract of the peel of mangosteen and ethanol extracts of P. corylifolia L. fruit against 35 isolates (23 species) of pulpitis- and periapical disease-causative bacteria were 1.25–20 µg/ml and 25–200 µg/ml, respectively, except for Dialister invisus KCOM 1973. The ethanol extract of licorice root had MBC values of 40–320 µg/ml against 27 of 35 bacterial strains. These results showed that the WsMD of the ethanol extract of mangosteen peel had the highest antibacterial activity among the three natural extracts and suggested it as a potential root canal irrigation agent.

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Review and latest trends of dental ceramic restorative materials

Seon-Mi BYEON ; Kyeong-Seon KIM ; Jae-Woo SHIN ; Jung-Hwan LEE ; Jeong-Hui JI ; Min-Soo BAE ; Yong-Seok JANG ; Min-Ho LEE ; Tae-Sung BAE

Korean Journal of Dental Materials.2024;51(1):1-14. doi:10.14815/kjdm.2024.51.1.1

Prosthodontic treatment is being performed for morphology and functional restoration due to damage and loss of teeth. As the aesthetic demands of patients increase, interest in ceramic materials with shades and translucency similar to natural teeth has increased.Recently, the manufacturing and processing technology of ceramic materials has greatly improved, and the market for dental ceramic materials is growing rapidly. The purpose of this literature review and evaluation is to provide information on the classification and properties of dental ceramic materials with excellent aesthetics and fracture resistance. In this article, it is classified as follows: I) Dental porcelain; II) Sinterable all-ceramic; III) Glass-ceramic for casting; IV) Glass-infiltrated alumina ceramic; V) Glass-ceramic ingots for heat-pressing technique; Vl) Blocks for CAD/CAM; Vll) Ceramic for CAD/3D printing. Dental ceramic materials and their restoration manufacturing methods have evolved significantly over the past decade. As a result, the manufacturing method of restorations has progressed from the layered firing technique of powdered materials or heat-pressing technique to the cutting and processing of single and multi-layer blocks using CAD/CAM technology, leading to the introduction of CAD/3D printing technology. In this manuscript, we will review the types of ceramic materials used in the fabrication of dental restorations and their advantages and disadvantages.

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Development of a new bite force measurement device and its application in the diagnosis of periapical disease

Keon-Hee LEE ; In-Bog LEE

Korean Journal of Dental Materials.2024;51(1):43-52. doi:10.14815/kjdm.2024.51.1.43

The purpose of this study was to develop a new bite force measurement device with a force sensing resistor (FSR), and to evaluate its usefulness in the diagnosis of periapical disease. The principle of this device is based on a decrease in resistance when force is applied to the sensor. The resistance is changed into voltage, processed and displayed on an LCD monitor. The relationship between the force applied to the device and the output value was analyzed using the U-Mechanics Analyser (IB Systems, Seoul, Korea). The bite forces of teeth with apical periodontitis and those without periodontitis on the opposite side were measured and compared. The output value was expressed as a logarithmic function of force, or the force was represented as an exponential function of output value. Teeth with apical periodontitis showed relatively lower bite force, and the reduction rate ranged from 18.5% to 40.7%. Based on these results, it is suggested that the newly developed bite force measurement device can quantitatively measure the bite force of individual teeth, and can be useful in the diagnosis of periapical disease.

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Bonding silica-containing CAD/CAM dental blocks to composite resin with universal adhesives

Chi-Yong PARK ; Minjeong SHIN ; Shin Hye CHUNG ; Young-Seok PARK ; Bum-Soon LIM

Korean Journal of Dental Materials.2024;51(1):63-84. doi:10.14815/kjdm.2024.51.1.63

The bond strength to the silicate-based CAD/CAM blocks may be affected by the composition and microstructure of the silicatebased blocks, surface treatment, and the properties of the applied adhesive. In this study, the shear bond strength to the silicate blocks with various universal adhesives after sandblasting or HF-treatment was measured, and the effects of the additional silane application after surface treatments are evaluated. Six silica-containing blocks and five universal adhesives currently used in dental clinics were selected. After polishing the silicate block surface, the specimens were divided into two groups. The first groups were HF-treated and the second groups were sandblasted with alumina, and the surface roughness, contact angle, and microstructure were analyzed by CLSM (Confocal Laser Scanning Microscope), contact angle analyzer, and FE-SEM (Field Emission Scanning Electron Microscope).Composite resin (2 mm diameter) was bonded with universal adhesive to silicate blocks and stored in a 37 ℃ water bath for 24 hours, and the shear bond strength was measured using a universal testing machine. The measured values were statistically analyzed using the Tukey-multiple comparison test (α=0.05). For hybrid composite ceramics, there was no significant difference in bond strength between sandblasting or HF-treatment, and additional silane application may not be necessary when bonding with a universal adhesive, whereas for leucite-reinforced and lithium disilicate glass-ceramics, HF-treatment may be more favorable for adhesion than sandblasting, and additional silane application appears to be necessary even when applying a universal adhesive.

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Physicochemical properties and biocompatibility of polypyrrole-coated polycaprolactone nanofibers for guided tissue regeneration

Taekhyun KWON ; Hyungjoon SHIM ; Min-Ho HONG

Korean Journal of Dental Materials.2024;51(1):29-42. doi:10.14815/kjdm.2024.51.1.29

Polycaprolactone (PCL) nanofibers are widely used in the field of tissue regeneration as a biodegradable material. However, there is a limitation in that low hydrophilicity and tissue cannot be directly regenerated. Recent studies have shown that polypyrrole (PPy) has potential in the field of tissue engineering due to its electrical conductivity and biocompatibility. Meanwhile, the electrospinning has the advantage of using most polymers and of facilitating a porous structure suitable for tissue regeneration, so the nanofibers were fabricated through electrospinning. The purpose of this study is to evaluate the physicochemical properties and biocompatibility of PCL nanofibers coated with PPy for guided tissue regeneration. To this end, PCL nanofibers coated with four types of concentration groups were prepared. The group was named according to the concentration ratio of PPy, and the control pure PCL containing no PPy and 20PPy, 30PPy, and 40PPy containing 20 wt%, 30 wt%, and 40 wt%, respectively, consisted of the experimental group. The mixed solution of PCL and pyrrole monomer was electrospun. Then precipitate in an iron (III) chloride(FeCl3 ) solution as an oxidizing agent which contains pyrrole monomer and polymerized. A tensile test was performed to confirm mechanical properties, and surface hydrophilicity was confirmed through measurement of contact angle.Electrical conductivity was also confirmed through measurement of resistance values. Lastly, cytotoxicity evaluation was performed using fibroblast (L929) and preosteoblast (MC3T3-E1) cell lines to confirm biocompatibility. The results were evaluated as one-way ANOVA (p-value = 0.05), and post-analysis was performed using Tukey’s post-hoc test. PPycoated PCL nanofibers showed no statistically significant decrease in mechanical strength compared to PPy-uncoated PCL nanofibers, while electrical conductivity increased significantly at all concentrations. When 30wt% or more of PPy was coated, hydrophilicity was significantly increased compared to the PPy-uncoated PCL nanofibers. Regardless of the concentration of PPy, cytotoxicity was not shown in all groups. Accordingly, it is expected that the PPy-coated PCL fibers may be applied as a material for guided tissue regeneration. This is because of improved hydrophilicity and electrical conductivity without deteriorated physical properties and cytotoxicity.

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Effects of low-frequency positive square wave voltage on putative periodontal pathogen Aggregatibactor actinomycetemcomitans

Hwa-Mok KIM ; Jeong-Hwan PARK ; Young Mi JEON ; Jong Ghee KIM ; Young Seok JANG ; Min Ho LEE ; Tae-Sung BAE

Korean Journal of Dental Materials.2024;51(1):15-28. doi:10.14815/kjdm.2024.51.1.15

The extremely low frequency-electromagnetic field (ELF-EMF) refers to the frequency range of 0-300 Hz. It has been reported that it causes biological effects on cell survival, growth, and function. Structural changes were observed in the cell membranes of bacteria exposed to a certain intensity of ELF-EMF, indicating that exposure of bacteria to ELF-EMF can directly affect the cell membrane and affect the survival and growth of bacteria. The purpose of this study was to investigate the effect of the application of low frequency square wave positive voltages on Aggregatibactor actinomycetemcomitans (A. actinomycetemcomitans), a putative pathogen of periodontal disease. A square wave positive voltage output of 20 V or less at low frequency (0-300 Hz) was applied to A. actinomycetemcomitans in a range of 60 minutes. Changes in the population of bacteria were observed by absorbance measurement, colony forming unit (CFU/ml) evaluation, and high-resolution field-emission scanning electron microscopy (HR FE-SEM). The results show that the most effective offset and frequency in inhibiting bacterial growth are 0.7V and 7.83 Hz (Schumann resonance). As the applied time increased and the voltage increased, it was effective in inhibiting bacterial growth. These results led to the conclusion that bacterial growth can be inhibited even at low frequencies below 10 Hz, and it was experimentally proven that the frequency, voltage setting, and exposure time of ELF-EMF have a significant effect on reducing the growth of A. actinomycetemcomitans.

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Evaluation of machining accuracy of zirconia Merlon fracture test models fabricated by subtractive and additive manufacturing

Heejung LEE ; Ji-Myung BAE ; Seunghan OH

Korean Journal of Dental Materials.2024;51(1):53-62. doi:10.14815/kjdm.2024.51.1.53

The machining accuracy of zirconia prostheses fabricated by the subtractive (SM) and additive manufacturing (AM) was evaluated using the Merlon fracture test model in ISO 18675 (2022). The SM specimens were fabricated by a DWX-51D (Roland, Sydney, NSW, Australia) using two zirconia blocks (Katana Zirconia HT; KH, Katana Zirconia STML; KS). The AM specimens were prepared by a DLP type 3D printer INNI-Ⅱ (AON, Gunpo, Korea) using zirconia liquid slurry (INNI-CERA; PZ). The specimen STL image was acquired using a model scanner (E3, 3 Shape A/S, Copenhagen, Denmark). The machining accuracy of the specimens was analyzed by the RMS method superimposing the reference STL image and the specimen STL image in image analysis software (Geomagic Control X, 3D Systems, Rock Hill, SC, USA). From the results of the machining accuracy analysis, the KH and KS groups showed statistically significantly better machining accuracy (lower RMS) than the PZ group (P<0.05). The KH and KS groups showed higher machining accuracy as the thickness decreased, and the 0.2 mm and 0.3 mm experimental groups showed statistically significantly better machining accuracy than the 0.4 mm experimental group (P<0.05). On the other hand, the PZ group showed better machining accuracy as the thickness increased, with the 0.4 mm group showing statistically significantly better machining accuracy than the 0.2 mm and 0.3 mm groups (P<0.05). Within the limitation of this study, the thickness of the final zirconia prosthesis fabricated by additive manufacturing should be at least 0.4 mm for clinical use in dentistry.

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Wear resistance of dental resin crowns in accordance with different additive manufacturing technologies and abrader types during chewing simulations

Myoung Ji CHOI ; Jae-Sung KWON

Korean Journal of Dental Materials.2023;50(4):217-231. doi:10.14815/kjdm.2023.50.4.217

Recently, dental resin crowns have been widely utilized in various applications through additive manufacturing (AM) technology in dentistry. Additionally, zirconia and metal crowns can be used as restorative and prosthetic materials, benefiting from a variety of advantages. However, the use of these materials may result in wear loss of temporary resin crowns fabricated using AM technology when they are used as antagonists. This study examined the wear resistance of dental resin crown specimens produced using different AM technologies against two common antagonist crown materials: zirconia and metal crown. Three types of dental resin crowns, produced using different methods, were examined: SLA, DLP, and FDM.The specimens were subjected to a two-body wear test with zirconia and cobalt-chrome alloy as the antagonists under specific conditions (5 mm, 2 mm, 5 kg, 1.2 Hz, 20,000 cycles). The SLA- and DLP-printed resins showed no significant difference in wear volume loss and wear maximal depth loss between the two differently produced specimens (p > 0.05). However, the FDM-printed resin showed a significantly increased wear volume loss and maximal depth loss compared to the other two specimens (p < 0.05). There was no significant difference in wear volume loss between zirconia and CoCr alloy abraders (p > 0.05). However, when examining the resin specimens, wear volume loss and wear depth loss deviation were generally higher when CoCr alloy was used compared to the use of the zirconia alloy as the abrader. In clinical terms, it can be concluded that the type of antagonists does not influence the wear resistance of temporary resin crowns.

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