ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
Titanium mesh is commonly employed to reinforce missing alveolar ridges and promote bone regeneration around implants. However, the bioinertness of titanium mesh must be improved. This study evaluated the effect of improving bioactivity and bone regeneration by loading a calcium phosphate coating layer and ibandronate onto a titanium mesh with a nanotube-structured TiO2 layer. The surface treatment of titanium mesh was divided into four groups: (1) No treatment; (2) Formation of nanotube TiO2 layer; (3) Cyclic calcification pretreatment (calcium phosphate coating layer) after the formation of a nanotube TiO2 layer; (4) Calcium phosphate coating and ibandronate loading after the formation of a nanotube TiO2 layer. The release amount of ibandronate was analyzed using a UV spectrophotometer, and bioactivity was assessed through XRD, EDS, and HR FE-SEM to observe changes in the surface layer after immersion in simulated body fluid (SBF). Hydroxyapatite was uniformly distributed on the surface of the (4) group immersed in SBF, and calcium and phosphorus content also increased over time. This result supported that bioactivity was improved. The continuous release of ibandronate over 10 days may contribute to realizing a mechanism that improves osseointegration between bone and titanium mesh. These results showed that bioactivity was improved as calcium phosphate precipitated on the surface of the nanostructured titanium mesh. Additionally, it is believed that combined ibandronate can effectively increase the stability of titanium mesh and promote bone regeneration.
ABSTRACT
Improvements in the mechanical and optical properties of ceramic materials and the development of dentin adhesives have resulted in more successful results in anterior teeth restorations. Among them, porcelain laminate veneer (PLV) can achieve aesthetic improvement in a conservative way while minimizing tooth reduction. A female patient in her 20s visited for aesthetic improvement of the maxillary anterior teeth. The patient's chief complaint was aesthetic improvement of tooth discoloration after trauma and endodontic treatment, and a PLV restoration was decided to reflect the patient’s demand for minimal tooth reduction. IPS e.max Press, a lithium disilicate-based ceramic with high light transmittance and high strength, was chosen for porcelain laminate veneer. Inner surface of the veneer was treated with liner in order to block discoloration of the abutment teeth while maintaining translucency in the incisal edge. The patient was satisfied with the aesthetic result.
ABSTRACT
Lithium disilicate gradation block that have been recently introduced and used in dental clinics have superior light transmittance compared to zirconia-based restorations, so that when applied to anterior restorations, better esthetic results are expected. In addition, it has the advantage that the flexural strength is sufficient and chemical bonding with resin cement is possible. However, high transparency could be a disadvantage in the restoration of abutment teeth with severe discoloration, and various methods have been tried to compensate for this. In this study, in the restoration of central incisors with severe discoloration of the abutment, the inner surface of the crown made of lithium disilicate-based polychromatic blocks was treated with a liner to block the discoloration, and thus aesthetically satisfactory results were obtained.
ABSTRACT
Gelatin methacryloyl 3d mesh mimics the natural extracellular matrix which allow loading as promising drug delivery systems.However, insufficient mechanical and degradation properties remain the biggest obstacle for this material application. In this study, a modified hydrogel with natural phytochemical was developed to improve the antibacterial effect by the addition of ginger extract, a natural spicy used in traditional medicine. GelMA hydrogels with ginger extract were fabricated and their chemical and morphological characteristics were analyzed by Fourier transformer infrared spectroscopy and scanning electron microscopy, structural characteristic were evaluated by compressive test and surface wettability analysis. S. mutans, S. aureus and P. gingivalis were used to confirm the antibacterial effect of the modified hydrogels. The FT-IR spectra of the hydrogels modified with ginger presented an increase in intensity of some peaks in comparison with the 10% GelMA hydrogel. The pores of ginger-modified hydrogels decreased it size which affected the hydrogels physical properties, decreasing the compressive modulus and increasing the durability, swelling ratio and, hydrophobicity of the surface. The ginger-modified hydrogels exhibited excellent antibacterial properties against S. mutans and S. aureus at high concentrations of ginger extract, while P. gingivalis presented a higher sensitivity at all tested concentrations. Hence, this study concludes that ginger-modified GelMA hydrogels presented better antibacterial effect, durability over time and, swelling stability.
ABSTRACT
Objective@#This study evaluated the effect of cyclic pre-calcification treatment on the improvement of bioactivity and osseointegration of Ti-6Al-4V miniscrews. @*Methods@#The experimental groups were: an untreated group (UT), an anodized and heat-treated group (AH), and an anodized treatment followed by cyclic pre-calcification treatment group (ASPH). A bioactive material with calcium phosphate was coated on the mini-screws, and its effects on bioactivity and osseointegration were evaluated in in vitro and in vivo tests of following implantation in the rat tibia. @*Results@#As a result of immersing the ASPH group in simulated body fluid for 2 days, protrusions appearing in the initial stage of hydroxyapatite precipitation were observed. On the 3rd day, the protrusions became denser, other protrusions overlapped and grew on it, and the calcium and phosphorus concentrations increased. The removal torque values increased significantly in the following order: UT group (2.08 ± 0.67 N·cm), AH group (4.10 ± 0.72 N·cm), and ASPH group (6.58 ± 0.66 N·cm) with the ASPH group showing the highest value (p < 0.05). In the ASPH group, new bone was observed that was connected to the threads, and it was confirmed that a bony bridge connected to the adjacent bone was formed. @*Conclusions@#In conclusion, it was found that the surface treatment method used in the ASPH group improved the bioactivity and osseointegration of Ti-6Al-4V orthodontic miniscrews.
ABSTRACT
The objective of the present study was to investigate the effects of heat treatment (HT) time on the optical properties, mechanical properties, and microstructure of lithium disilicate (Li 2 Si 2 O 5) glass-ceramic blocks. Samples were prepared by cutting lithium disilicate glass-ceramic blocks – Amber® Mill Prototype (AMP) and IPS e.max CAD (IEC) – into a disc shape (diameter of 12 mm and thickness of 1.2 mm) and evenly polishing the surface. Each sample was heat treated according to the manufacturer’s manual and HT holding time was set to 15, 30, 45, and 60 minutes according to different groups. The samples were tested by color difference analysis using a spectrophotometer. X-ray diffraction analysis, HR FE-SEM observation, Vickers hardness test, fracture toughness test, and biaxial flexural strength test were carried out. The acicular crystals of lithium disilicate became coarser and less transparent with increasing HT time. The results for color difference (ΔE * ) compared to VITA A2 standard shade showed that the difference was significantly higher in the AMP groups than the IEC groups (P<0.05). Translucency parameter (TP) values were significantly higher in the AMP groups than the IEC groups (P<0.05). The AMP30 group showed the highest TP value, while all other experimental groups showed the tendency of decrease in TP value with increase in HT time. Moreover, increase in TP value was associated with decrease in contrast ratio. When fracture toughness was measured by indentation fracture method, both AMP and IEC groups showed similar results with 1.77 MPa·m 1/2 after HT for 15 minutes. However, as HT time increased, the IEC groups showed significantly higher values than the AMP groups (P<0.05). X-ray diffraction analysis results showed that quartz (SiO 2) and cristobalite (SiO 2) peaks were observed together with the lithium disilicate (Li 2Si 2O 5) peak in the AMP groups, whereas a lithium phosphate (Li 3PO 4) peak was observed together with the lithium disilicate (Li 2Si 2O 5) peak in the IEC groups. With respect to biaxial flexural strength in the AMP groups, the AMP15 group (HT for 15 minutes) showed the highest value of (524.09±89.95) MPa, whereas the AMP60 group (HT for 60 minutes) showed the lowest value of (446.56±76.75) MPa, with a significant difference between the two groups (P<0.05). In the IEC groups, IEC30 group showed the highest value of (668.51±158.57) MPa and the IEC45 group showed the lowest value of (517.37±129.52) MPa, with a significant difference between the two groups (P<0.05). Within the limitations of the present study, it is concluded that if increased strength is required when fabricating restorations using lithium disilicate glass-ceramic, then changing the HT time could be considered as long as such change does not significantly alter the color tone.
ABSTRACT
The purpose of this study was to evaluate the structural characteristics of the thread length of orthodontic mini-screws and the effects of insertion and removal torques according to the formation of the cutting flute. Two types of mini-screws were made, with a thread length of 6.0 mm and a thread length of 3.3 mm. In order to examine the effect of flute formation, the experiment group was divided into a miniscrew test group with flute formation and an experiment group without flute formation. To evaluate the effect of flute formation, two flutes were formed at 180°on the circumference, and at the tip of the mini screw, up to 4 mm for thread length of 6.0 mm and 2.4 mm for thread length of 3.3 mm. A biomechanical test block formed of 2 mm cortical bone and 10 mm cancellous bone was used to eliminate the influence of the difference in cortical bone thickness and bone density according to the insertion site. 1 mm diameter guide hole was drilled on the test block and the mini-screw was placed vertically. Using a 0.1 N·cm precision digital torque gauge, the maximum torque value was recorded at this time by embedding it to the top of the screw under a static load of 1.2 kg and the value when it was removed in the opposite direction. The insertion torque values for the 6.0 mm and 3.3 mm length mini screws were (29.53±1.84) N·cm and (26.84±2.15) N·cm, and the removal torque values are (14.50±1.37) N·cm and (13.15±2.89) N·cm, respectively.There were no statistically significant differences (P>0.05). The flute of 6.0 mm mini-screws had no statistically significant difference in both insertion and removal torque values and increased to (30.13±1.97) N·cm and (18.65±1.10) N·cm (P>0.05). In experiments with 3.3 mm mini-screws, the insertion and removal torque values decreased to (20.99±3.94) N·cm and (11.32±2.03) N·cm, respectively, showing a statistically significant decrease only in the insertion torque values (P<0.05). The insertion and removal torque values of the mini-screw were not significantly increased even when the screw length was doubled, and the flute formation effect was different with the screw length.
ABSTRACT
The purpose of this study was to investigate the effect of glazing treatment of multi-colored zirconia disc and lithium disilicate block on the optical properties. From an Ultra Translucent Multi-Layered (UTML) disc containing 50% cubic crystal and a lithium disilicate-based Amber Mill Direct (AMD) block, the 1.2 mm thick specimens of the upper layer (T), the center (M), and the lower layer (B) were prepared. Three types of paste glaze of InSync Glaze Paste, IPS E.max Ceram Glaze Paste, and Amber Ceram G7 Glaze Paste were applied and fired to a uniform thickness on the surface of the specimen. CIE L * , a * , b * values were measured using a spectrophotometer and contrast and translucency were calculated. The bonding interface with the glaze layer was observed using HR FE-SEM. In the glazed groups, L * value increased, but a * value and b * value decreased. The translucency value measured in the untreated group was statically higher in the AMD groups than in UTML groups (P0.05), but significantly decreased compared to the untreated group after glazing treatment in the AMD group (P<0.05). The contrast ratios generally increased after glaze treatment compared to the untreated group. Since the glaze treatment can affect the optical properties of ceramic restorations, the choice of glaze should be considered important for the desired color by the dental technician.
ABSTRACT
This study was performed to evaluate the effects of microstructural change of zirconia surface on tensile bond strength with resin cement. The zirconia partially sintered block was cut into a size of 18 × 18 × 7 mm, and then the Zirface slurry (DMAX, Daegu, Korea) containing 15% and 30% zirconia was applied and followed by sintering at 1530 ℃ for 2 hours. Resin cement (PermaCem 2.0, DMG, Hamburg, Germany) was applied on zirconia specimen and polymerized to prepare an 18 × 18 × 14 mm block. In addition, for comparison of bond strength, specimens were prepared for the group that was polished and the group that was blasted at 3 atm using 110 µm alumina. Thereafter, all blocks were cut into a cross-sectional area of 1.0 × 1.0 mm to prepare 12 specimens. The specimens were immersed in distilled water at 37 ℃. for 10 days for aging treatment. A holder for tensile testing was attached to each of the specimens, and then a tensile force was applied at a crosshead speed of 0.5 mm/min to measure the fracture load. The fracture surfaces of each test piece was observed with a high-resolution field emission scanning electron microscope. Through the above tests, the following results were obtained. 1. On the blasted surface, zirconia grains were locally removed but on the Zirface treated surface, a porous microstructure was created on the zirconia surface. 2. Arithmetical mean deviation from the mean line ra was the highest in the blasted group and the lowest in the polished group, and as a result of Tukey analysis, there were statistically significant differences between all test groups (P<0.05). 3. The maximum tensile bond strength was 18.8±5.4 MPa in the Zirface 30% group, and as a result of Tukey analysis, there was a statistically significant difference from the other test groups (P<0.05). 4. As a result of observing the fracture surface after the tensile test with a high-resolution field emission scanning electron microscope, in the Zirface 30% group, cohesive fracture and interfacial fracture in the resin was observed, but the other test groups showed the interfacial fracture pattern. In conclusion, within the limits of this study, treating the zirconia surface with Zirface 30% to form a porous microstructure can contribute to the improvement of the bond strength between zirconia and resin cement.
ABSTRACT
Ginger has been used worldwide in traditional medicine. It has been reported that phenolic compounds such as gingerol and shogaol in ginger have beneficial cellular effect and antibacterial effect. The purpose of this study was to investigate the effect of gingerol and shogaol on the cytocompatibility for the osteoblastic cells and antibacterial activity against oral microorganisms. Chemical structures of gingerol and shogaol were determined by Fourier transform infrared (FT-IR). Thermal and pH stability was analyzed by UPLC assay. Streptococcus mutans, and Porphyromonas gingivalis were used to confirm the antibacterial effect of the ginger compounds and MC3T3-E1 cells were used to identify biocompatibility test. Cell viability and bacterial growth was determined by water-soluble tetrazolium salt (WST-8) colorimetric assay. Cellular morphology was identified with optical microscope after crystal violet staining. Cell differentiation and oxidative stress were evaluated by Alkaline phosphatase (ALP) assay and hydrogen peroxide colorimetric assay. The chemical bonding related with hydroxyl groups, carbonyl groups and aromatic ring was identified in all ginger compounds. Gingerol and shogaol presented good stability at acid and neutral pH at room temperature. All compounds showed better antibacterial effect against Porphyromonas gingivalis than Streptococcus mutans. 10-gingerol and all shogaol groups below 10-6 M presented suitable cytocompatibility for osteoblastic cells compared to control group. All groups showed similar Oxidative stress to control group, and ALP activity in all groups below 10-6 M was not statistically significant compared to control. Hence, this study concludes that shogaol groups presented better antibacterial effect and suitable cytocompatibility than gingerol groups.
ABSTRACT
This study was performed to evaluate the effect of cyclic precalcification treatment on the improvement of bioactivity of Ti-6Al-4V mini-screws. The cutted plate-shaped specimens of 10 mm × 10 mm dimensions, and a mini-screw with a diameter of 1.6 mm × 6.0 mm in length were used. Anodic oxidation treatment was carried out in a glycerol electrolyte solution containing 20 wt% H2O and 1.5 wt% NH 4F. Voltage of 20 V with current density of 20 mA/cm2 was applied for 1 hour to form a nanotube TiO2 layer. Afterwards, to improve the bioactivity, specimens were immersed in 0.5 vol% silica aqueous solution at 37 ℃ for 5 minutes, and then cyclic precalcification treatment with 0.05 M NH 4H2PO4and 0.01 M Ca(OH)2 solution at 90 ℃ was repeated with 20 times. Based on surface treatment the experimental groups were divided into three groups, namely untreated group (UT), anodized and heat-treated group (AH), and anodized, silica-treated, cyclic precalcified and heat-treated group (ASPH). There were TiO2 nanotubes completely self-aligned and formed in a dense structure on the surface after anodic oxidation treatment. A fine granular cluster layer of hydroxyapatite and octacalcium phosphate were formed on the surface after the cyclic precalcification treatment. As a result of immersion test in the simulated body fluid (SBF), bioactivity was confirmed to be improved by the precipitation of protrusions appearing at the initial stage of formation of hydroxyapatite.
ABSTRACT
Surface treatment was conducted to reduce dissolution of Mg mesh and to improve bioactivity in physiological environment. Mg mesh was immersed in 40 wt% hydrofluoric (HF) solution for 2 hours to form a protective coating layer. Then, hydrothermal treatment was performed in a mixed solution of Ca(NO3)2·4H2O and Na2HPO 4 at 90 ℃ for 30 minutes, and cyclic precalcification treatment was conducted by soaking in each 0.06 M NH 4H 2PO4 solution and 0.011 M Ca(OH)2 solution in turn at 90 ℃. Immersion test was performed in simulated body fluid (SBF) to investigate solubility and bioactivity. Release characteristics were investigated after loading ibandronate to suppress initial bone resorption. Bone regeneration ability was evaluated through micro-CT analysis and conforming inflammatory cytokines levels in blood. Fine granular calcium phosphate-based materials were precipitated as clusters on the surface treated in cyclic precalcification. Agglomerated calcium phosphate precipitates on the surface were observed after SBF immersion. pH in SBF during immersion increased slowly in hydrothermal treatment and cyclic precalcification groups compared to pure Mg group. Release of ibandronate occurred over 6 days in cyclic precalcification treatment group (CP-H1). IL-1β and IL-6 were significantly lower than those of untreated group in all test groups except for the group (CP-H4) that was heat-treated at 400 ℃ after pretreatment with circulating calcification. As a result of micro-CT analysis, the new bone volume and density were significantly higher in the CP-H1 group. It was concluded that cyclic precalcification treatment after formation of fluorine protective layer on Mg mesh could retard the dissolution and enhanced bone regeneration ability.
ABSTRACT
The purpose of this study was to evaluate the structural characteristics of the thread length of orthodontic mini-screws and the effects of insertion and removal torques according to the formation of the cutting flute. Two types of mini-screws were made, with a thread length of 6.0 mm and a thread length of 3.3 mm. In order to examine the effect of flute formation, the experiment group was divided into a miniscrew test group with flute formation and an experiment group without flute formation. To evaluate the effect of flute formation, two flutes were formed at 180°on the circumference, and at the tip of the mini screw, up to 4 mm for thread length of 6.0 mm and 2.4 mm for thread length of 3.3 mm. A biomechanical test block formed of 2 mm cortical bone and 10 mm cancellous bone was used to eliminate the influence of the difference in cortical bone thickness and bone density according to the insertion site. 1 mm diameter guide hole was drilled on the test block and the mini-screw was placed vertically. Using a 0.1 N·cm precision digital torque gauge, the maximum torque value was recorded at this time by embedding it to the top of the screw under a static load of 1.2 kg and the value when it was removed in the opposite direction. The insertion torque values for the 6.0 mm and 3.3 mm length mini screws were (29.53±1.84) N·cm and (26.84±2.15) N·cm, and the removal torque values are (14.50±1.37) N·cm and (13.15±2.89) N·cm, respectively.There were no statistically significant differences (P>0.05). The flute of 6.0 mm mini-screws had no statistically significant difference in both insertion and removal torque values and increased to (30.13±1.97) N·cm and (18.65±1.10) N·cm (P>0.05). In experiments with 3.3 mm mini-screws, the insertion and removal torque values decreased to (20.99±3.94) N·cm and (11.32±2.03) N·cm, respectively, showing a statistically significant decrease only in the insertion torque values (P<0.05). The insertion and removal torque values of the mini-screw were not significantly increased even when the screw length was doubled, and the flute formation effect was different with the screw length.
ABSTRACT
The purpose of this study was to investigate the effect of glazing treatment of multi-colored zirconia disc and lithium disilicate block on the optical properties. From an Ultra Translucent Multi-Layered (UTML) disc containing 50% cubic crystal and a lithium disilicate-based Amber Mill Direct (AMD) block, the 1.2 mm thick specimens of the upper layer (T), the center (M), and the lower layer (B) were prepared. Three types of paste glaze of InSync Glaze Paste, IPS E.max Ceram Glaze Paste, and Amber Ceram G7 Glaze Paste were applied and fired to a uniform thickness on the surface of the specimen. CIE L * , a * , b * values were measured using a spectrophotometer and contrast and translucency were calculated. The bonding interface with the glaze layer was observed using HR FE-SEM. In the glazed groups, L * value increased, but a * value and b * value decreased. The translucency value measured in the untreated group was statically higher in the AMD groups than in UTML groups (P0.05), but significantly decreased compared to the untreated group after glazing treatment in the AMD group (P<0.05). The contrast ratios generally increased after glaze treatment compared to the untreated group. Since the glaze treatment can affect the optical properties of ceramic restorations, the choice of glaze should be considered important for the desired color by the dental technician.
ABSTRACT
This study was performed to evaluate the effects of microstructural change of zirconia surface on tensile bond strength with resin cement. The zirconia partially sintered block was cut into a size of 18 × 18 × 7 mm, and then the Zirface slurry (DMAX, Daegu, Korea) containing 15% and 30% zirconia was applied and followed by sintering at 1530 ℃ for 2 hours. Resin cement (PermaCem 2.0, DMG, Hamburg, Germany) was applied on zirconia specimen and polymerized to prepare an 18 × 18 × 14 mm block. In addition, for comparison of bond strength, specimens were prepared for the group that was polished and the group that was blasted at 3 atm using 110 µm alumina. Thereafter, all blocks were cut into a cross-sectional area of 1.0 × 1.0 mm to prepare 12 specimens. The specimens were immersed in distilled water at 37 ℃. for 10 days for aging treatment. A holder for tensile testing was attached to each of the specimens, and then a tensile force was applied at a crosshead speed of 0.5 mm/min to measure the fracture load. The fracture surfaces of each test piece was observed with a high-resolution field emission scanning electron microscope. Through the above tests, the following results were obtained. 1. On the blasted surface, zirconia grains were locally removed but on the Zirface treated surface, a porous microstructure was created on the zirconia surface. 2. Arithmetical mean deviation from the mean line ra was the highest in the blasted group and the lowest in the polished group, and as a result of Tukey analysis, there were statistically significant differences between all test groups (P<0.05). 3. The maximum tensile bond strength was 18.8±5.4 MPa in the Zirface 30% group, and as a result of Tukey analysis, there was a statistically significant difference from the other test groups (P<0.05). 4. As a result of observing the fracture surface after the tensile test with a high-resolution field emission scanning electron microscope, in the Zirface 30% group, cohesive fracture and interfacial fracture in the resin was observed, but the other test groups showed the interfacial fracture pattern. In conclusion, within the limits of this study, treating the zirconia surface with Zirface 30% to form a porous microstructure can contribute to the improvement of the bond strength between zirconia and resin cement.
ABSTRACT
Ginger has been used worldwide in traditional medicine. It has been reported that phenolic compounds such as gingerol and shogaol in ginger have beneficial cellular effect and antibacterial effect. The purpose of this study was to investigate the effect of gingerol and shogaol on the cytocompatibility for the osteoblastic cells and antibacterial activity against oral microorganisms. Chemical structures of gingerol and shogaol were determined by Fourier transform infrared (FT-IR). Thermal and pH stability was analyzed by UPLC assay. Streptococcus mutans, and Porphyromonas gingivalis were used to confirm the antibacterial effect of the ginger compounds and MC3T3-E1 cells were used to identify biocompatibility test. Cell viability and bacterial growth was determined by water-soluble tetrazolium salt (WST-8) colorimetric assay. Cellular morphology was identified with optical microscope after crystal violet staining. Cell differentiation and oxidative stress were evaluated by Alkaline phosphatase (ALP) assay and hydrogen peroxide colorimetric assay. The chemical bonding related with hydroxyl groups, carbonyl groups and aromatic ring was identified in all ginger compounds. Gingerol and shogaol presented good stability at acid and neutral pH at room temperature. All compounds showed better antibacterial effect against Porphyromonas gingivalis than Streptococcus mutans. 10-gingerol and all shogaol groups below 10-6 M presented suitable cytocompatibility for osteoblastic cells compared to control group. All groups showed similar Oxidative stress to control group, and ALP activity in all groups below 10-6 M was not statistically significant compared to control. Hence, this study concludes that shogaol groups presented better antibacterial effect and suitable cytocompatibility than gingerol groups.
ABSTRACT
The purpose of this study was to evaluate the effect of the reaction between investment material and zirconia on the strength of zirconia in the application of heat-pressing method. Sixty specimens were cut (24 mm×4 mm×0.5 mm) into plates from Zirtooth ™ Multi O-9814 block (∅98×14T, HASS, Gangwondo, Korea) and sintered at 1450℃. Specimens were divided into 6 subgroups according to the depending on the investement material; (a) UN group (Control), (b) PH group (Prime vest HS), (c) CP group (Calibra-press), (d) BV group (BC-Vest), (e) MH group (Microstar-HS), (f) F1 group (Formula 1). Five investment materials were buried according to the procedure recommended by the manufacturer and left at room temperature for 30 minutes. The investment mold was dried and maintained at an elevated temperature of 850℃ for 50 minutes. Then, Amber Lisi-POZ LT (HASS) was placed in a thermoformed electric furnace (Programat EP3000/G2, Ivoclar Vivadent, Schaan, Liechtenstein) together with the mold, heated to 915℃ at an elevation temperature of 45℃/min, and moored for 15 minutes. The specimens were loaded to fracture in a universal testing machine and the fracture surface was examined by a field-emission scanning electron microscopy (FE-SEM). The surface of the zirconia specimen with the investment material was analyzed by energy dispersive X-ray spectroscopy (EDS). The 3-point flexural strength test showed the highest value (1265.5 MPa) in the UN group and the lowest value (756.1 MPa) in the F1 group. As a result of EDS analysis, the largest amount of Si was detected in the F1 group, and the most interfacial changes occurred as a result of FE-SEM analysis. It was concluded that when the zirconia is buried with the investment material and the heat press molding is performed, the state of the interface is changed due to the investment material at the bonding interface while the strength is lowered.
ABSTRACT
The purpose of this study was to evaluate the influence of fabrication methods of lithium disilicate reinforced glass-ceramic crown on marginal and internal fit. Lithium disilicate reinforced glass-ceramic crowns were fabricated using ingots for heat press forming and blocks for CAD/CAM milling manufactured by Hass and Ivoclar/Vivadent. Dentiform of maxillary central incisor was prepared with a 6°taper and 1 mm deep chamfer margin and duplicated with silicone. Then the polyurethane resin was poured at silicone mold to produce working model. Marginal and internal fit were measured by the silicone replica technique. Each silicon replica was cut into labio-lingual and mesio-distal sections and the thickness of the light body silicon was measured. Fourteen reference points were determined and measured using a microscope. As a result of calculating and comparing the average value of 14 points in all groups, the measured value was within 120 µm, the clinically acceptable range suggested by previous literatures. In all groups, the marginal fit was smaller than the internal fit. At the margin area, significant differences were identified only between the ECM group and the EPM group, and there was no statistically significant difference between the remaining groups. At the deep chamfer area, the ECM and ABM group produced by the CAD system had excellent compatibility. In the axial wall and incisal area, ECM was superior to both EPC and EPM. Also, both ABM and APC groups were statistically significantly superior than APM.