The purpose of this study was to compare the accuracy of the working models fabricated by the subtractive and additive processing methods based on the 3-dimensional reconstruction model. A total of 20 models were fabricated with subtractive processing method from polymethyl methacrylate (PMMA) blocks using the stereolithography (STL) file of master gypsum model and another 20 models were fabricated with additive processing method using 3D printer with 0.025 mm of a layer thickness. The CAD-reference-model (CRM) and CAD-test-model (CTM) were superimposed by a software for accuracy analysis (Geomagic Qualify 13), where the STL files were transformed to point cloud data and the surface data (CRM and CTM) were subjected to initial alignment and followed by re-alignmented according to best-fit superimposition. The distances between surface data and all points, in this process, were converted to the root mean square (RMS) and averaged. In the experimental results, It was shown that the accuracy is higher in work model fabricated by additive processing method compared to one fabricated by subtractive one (p < 0.05). In addition, it is considered that the working model fabricated by subtractive processing method is to be clinically applicable by improving the improper reproducibility of the tooth surface and depressed area.
Calcium Sulfate ; Methods ; Polymethyl Methacrylate ; Printing, Three-Dimensional ; Tooth

The purpose of this study is to correlate the material properties of TiZr alloy material (Roxolid) and the mechanical strength of the implant fixture (BLT) through the maximum compressive load test and the fatigue test. Implant samples were purchased with BLT (Roxolid, Straumann, Switzerland) and Octa1 (cold-worked, Megagen Implant, Korea) fixtures made of two materials (TiZr and cold-worked Ti Grade 4). After the maximum compressive load test, the test specimens were analyzed with a optical microscope to confirm the fracture pattern. After the fatigue test, the samples that passed 5 million cycles were analyzed for the precision fit using a scanning electron microscope. Data were analyzed using Student's t-test (α=0.05). In the compressive load test, the small diameter (3.3 mm) implants with the same length and the common diameter (4.1 mm) implants had fracture or bending regardless of the material in both the test and control groups. The fatigue load showed the same results without significance and the gap between the fixture and abutment interface was within 10 µm in both the test and control groups in the precision fit test. There was no statistically significant difference in the maximum compressive load and fatigue test for the comparison of mechanical strength between two systems (BLT vs. Octa1) with same diameter and length, similar shapes and connections.
Alloys ; Fatigue

The purpose of this study was to investigate the effect of retaining holes on the denture base, as well as primer application, on the shear bond strength of denture base resin to the denture base. Using Trubyte Biotone artificial teeth, we selected a maxillary first molar and prepared a total of 80 teeth. Each prepared tooth was polished flat using a dental bar. The polished specimens were placed in the center of a silicon mold (diameter 30 mm, height 23 mm) and were embedded with clear acrylic resin (Ortho Jet, Lang Dental, USA). Forty specimens were shaped, using Fisher bar # 701 at the central part of the alveolar surface, to form retention holes. Each denture base resin was transferred to the resin after surface treatment, as instructed by the manufacturer. The highest shear bond strength (36.2 MPa) was achieved by heat-polymerized resin, when the retention hole and the primer were applied to the artificial tooth. The lowest shear bond strength (11.8 MPa) was achieved by auto-polymerized resin, when the primer was applied to the artificial tooth. The combination of heat-polymerized resin and artificial tooth resulted in a complex fracture pattern, whereas auto-polymerized resin and artificial tooth showed an adhesive fracture pattern.
Adhesives ; Denture Bases ; Dentures ; Fungi ; Molar ; Silicon ; Tooth ; Tooth, Artificial

The purpose of this study is to evaluate the effects of polymerization conditions on the flexural strength and transparency of orthodontic acrylic resin. Materials and methods: The specimens were prepared by applying pressure of 1 bar, 2 bar and 4 bar in air, room temperature water, 50℃ water and 70℃ water. The flexural strength of each specimen was measured using a universal testing machine and the translucency parameter (TP) was calculated by measuring the CIE L*a*b* value of each specimen using a spectrophotometer. The flexural strength of orthodontic acrylic resin was the highest in water at 50℃, and the flexural strength was significantly lower in the order of 70℃ water, room temperature water and air (P < 0.01). As the pressure increased, the flexural strength of orthodontic acrylic resin did not show any significant difference (P>0.05). The transparency of orthodontic acrylic resin showed the highest value in air and was significantly lower in the order of room temperature, 50℃ water and 70℃ water (P < 0.001). The transparency of orthodontic acrylic resin did not show any significant difference with increasing pressure (P>0.05). Within the limits of this study, the flexural strength and transparency of the orthodontic acrylic resin differ according to polymerization conditions, but there is no difference according to the pressure.
Polymerization ; Polymers ; Water

The purpose of this study was to evaluate the shear bond strengths between various hybrid computer-aided design (CAD)/computer-aided manufacturing (CAM) restorative materials and repairing resin. Two resin network-based hybrid (Lava Ultimate and Polyglass), one ceramic framework-based hybrid (Enamic), and one zirconia (Zenotec Zr bridge) CAD/CAM restorative materials were used in this study. The shear bond strength test and failure modes of four experimental groups designated LUS (Lava Ultimate), ENA (Enamic), PGB (Polyglass), and ZBR (zirconia control group) were characterized in this study. The hybrid CAD/CAM restorative materials showed stronger shear bond strengths in the sequence of PGB, LUS, and ENA (P < 0.05). The shear bond strengths of PGB and LUS groups showed significantly higher than those of ZBR (P < 0.05), while ENA did not show any significant difference from ZBR (P < 0.05). The PEG and LUS groups mostly exhibited cohesive failure, but the ENA and ZBR groups predominantly showed adhesive failure. Therefore, resin network-based hybrid CAD/CAM restorative materials such as Lava Ultimate and Polyglass should be more useful for intra-oral repairs.
Adhesives ; Ceramics ; Composite Resins ; Computer-Aided Design ; Prostaglandins B

In this study, gold nanotubes were fabricated by electrophoretic deposition using a titania nanotube layer as a template, and then the surface characteristics, biocompatibility and antibacterial effect of gold nanotubes were evaluated. Gold nanotubes of 100 nm diameter were fabricated by depositing 4 nm and 15 nm gold nanoparticles on anodized 100 nm titania nanotubes by citrate reduction and electrophoretic deposition. As a result of the UV-Vis diffuse spectrophotometer, 4 nm and 15 nm gold nanotubes showed strong absorption at 702~774 nm and 753~760 nm, respectively. Also, the maximum absorption wavelength was shifted to the longer wavelength as the coating time of the gold nanoparticles increased. FE-SEM observation and EDX analysis resulted that 0.1~0.5 wt% gold nanoparticles uniformly were stacked on the top layer of titania nanotubes. As a result of MTT cell test, the relative absorbance value of all experimental groups after 24 hours and 48 hours of incubation exceeded 70% indicating excellent biocompatibility. The effect of the near infrared laser light on the adhesion and growth of gold nanotubes showed excellent antibacterial activity regardless of the coating time of gold nanoparticles. Therefore, it is confirmed that the gold nanotube coating technology based on the titania nanotube template is supposed to be highly applicable to a titanium implant surface treatment technology with the remote control thermal treatment of a near-infrared laser.
Absorption ; Citric Acid ; Nanoparticles ; Nanotubes ; Titanium

Effect of cooling rate during oxidation treatment on the hardness change by post firing heat treatment of a Pd-Cu-Ga-Zn alloy after simulated porcelain firing was investigated and the following results were obtained. In the firing simulated specimens after quenching during the oxidation treatment, the hardness did not increase by post-firing heat treatment. However, in the firing simulated specimens after slow cooling during the oxidation treatment, post-firing heat treatment for 25 minutes was effective in increasing the hardness (p < 0.05). In the firing simulated specimens after quenching during the oxidation treatment, the significant decrease in hardness during the post-firing heat treatment was attributed to the coarsening of fine precipitates formed in the matrix and plate-like precipitates. In the firing simulated specimens after slow cooling during the oxidation treatment, the increase in hardness during the post-firing heat treatment for 25 minutes was due to precipitation hardening. From these results, it was found that the cooling rate during the oxidation treatment affected the change of hardness by the post-firing heat treatment after the simulated firing. From these results, post-firing heat treatment increased the hardness of the Pd-Cu-Ga-Zn alloy only when the cooling rate during the oxidation treatment was slow.
Alloys ; Dental Porcelain ; Fires ; Hardness ; Hot Temperature

The purpose of the study is to compare and analyze the accuracy of digital images obtained from impression and stone model with model scanner and to find out clinical effectiveness. A mandibular left first molar composite resin tooth was made for abutment. Digital models were obtained with a same model scanner(Ceramill Map 400, Amann Girrbach, Austria); (1) Fabricated resin model was scanned(Group C). (2) 10 impressions were taken with putty and polyvinyl siloxane, then were scanned (Group I). (3) Type IV stone was poured in each impressions made in step(2) and 10 stone models were scanned(Group S). 3 dimensional super-impositional program (Geomagic control X, 3D Systems, USA) was used to analyze the STL files. Stone model scan(Group S) showed lower deviation than impression scan(Group I) compared to the control group(P < 0.001). Both Group I and Group S showed signs of expansion in the occlusion surface and margin surface while showing contraction in the axial surface. The deviations were smaller in order of occlusal plane, horizontal plane of margin and axial plane. Within the limited boundary of this study, the digital model obtained from stone model scan showed smaller deviation than the digital model obtained from impression scan.
Dental Occlusion ; Molar ; Polyvinyls ; Siloxanes ; Tooth ; Treatment Outcome

The purpose of this study was to examine effects of bioactive glass on Vickers hardness of bleached enamel surface. Enamel specimens were bleached with 15% carbamide peroxide (CP) for 14days. After bleaching, Artificial saliva (AS), 45S5 bioactive glass (BAG) and fluoride varnish (FV) are applied each specimens (n=10). The Vickers hardness of the specimens was measured before and after the bleaching, after the remineralized treatment at 1 day and after 7 and 14 days. The Vickers hardness on enamel surface after bleaching decreased statistically (p < 0.05) compared to before bleached enamel surface. The Vickers hardness increased significantly in the BAG and FV groups compared to the AS group values at 1 day and 7 days after remineralization (P < 0.05). 45S5 bioactive glass rapidly increase Vickers hardness of the bleached enamel surface.
Dental Enamel ; Fluorides ; Glass ; Hardness ; Paint ; Saliva, Artificial ; Urea

The aim of this study was to investigate the antibacterial effect of fluoride varnish with antibacterial agents on Streptococcus mutans (S. mutans). Experimental fluoride varnish (EFV) with 5% NaF was fabricated. Five antibacterial agents were tested with 1 mM and 10 mM concentrations, respectively: Bakuchiol (BAK), Bavachalcone (BCC), Isobavachromene (IBC), and Bavachromene (BCM). MIC and MBC test was performed by antibacterial agents with and without EFV using 1.1 × 10¹⁰ CFU/ml of S. mutans. Cell viability test were performed using MTT test. Statistical analysis was done with ANOVA and Duncan's multiple range test at α=0.05. In the antibacterial agents without EFV, the MIC of BAK, BCC, and IBC was the lowest (0.015 mM), and the MBC of BAK was the lowest (0.031 mM). For the antibacterial agents with EFV, the MIC (0.031 mM) and MBC (0.062 mM) of BAK was the lowest, respectively. In MTT test, 1 mM BCM showed the highest cell viability (P < 0.05). This study suggest that BAK can be applied the fluoride varnish under the control of the concentration to develop antibacterial fluoride varnish.
Anti-Bacterial Agents ; Cell Survival ; Fluorides ; Microbial Sensitivity Tests ; Paint ; Streptococcus mutans