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The aim of this study was to evaluate the antimicrobial, stain and protein removal efficacy of denture or orthodontic appliance cleansers using in vitro test methods. Experimental cleansers were applied for experimental time in each evaluation method. To evaluate the microorganism removal efficacy, C. albicans and S. mutans removal rate was calculated from the specimen surface. Stain and protein removal rate was calculated using the spectrophotometer. Experimental cleansers significantly affected the microorganism removal rate for both C. albicans and S. mutans, as well as the stain and protein removal rates, at each experimental time (p

Demineralized white lesions are a common problem when using orthodontic resin cement, which can be prevented with the addition of antibacterial substances. However, the addition of antibacterial substances such as zinc oxide alone may result in the deterioration of the resin cement’s functions. Halloysite nanotubes (HNTs) are known to be biocompatible without adversely affecting the mechanical properties of the material while having the ability to load different substances. The purpose of this study was to prepare orthodontic resin cement containing HNT fillers loaded with ZnO (ZnO/HNTs) and to investigate its mechanical, physical, chemical, and antibacterial properties. A group without filler was used as a control. Three groups containing 5 wt.% of HNTs, ZnO, and ZnO/HNTs were prepared. TEM and EDS measurements were carried out to confirm the morphological structure of the HNTs and the successful loading of ZnO onto the HNTs. The mechanical, physical, chemical, and antibacterial properties of the prepared orthodontic resin cement were considered. The ZnO group had high flexural strength and water absorption but a low depth of cure (p < 0.05). The ZnO/HNTs group showed the highest shear bond strength and film thickness (p < 0.05). In the antibacterial test, the ZnO/HNTs group resulted in a significant decrease in the biofilm’s metabolic activity compared to the other groups (p < 0.05). ZnO/HNTs did not affect cell viability. In addition, ZnO was cytotoxic at a concentration of 100% in the extract. The nanocomposite developed in this study exhibited antimicrobial activity against S. mutans while maintaining the mechanical, physical, and chemical properties of orthodontic resin cement. Therefore, it has the potential to be used as an orthodontic resin cement that can prevent DWLs.

Background. The gaps at the margins of restorative composite resin can increase as the carious process occurs underneath the materials, causing further demineralization along the tooth cavity wall. The aim of this study was to evaluate the effects of restorative resin composite containing hydrated calcium silicate (hCS) filler on enamel protection against demineralization by simulating microleakage between the test material and teeth in a cariogenic environment. Methods. The experimental resin composites were composed of 70 wt% filler, which was mixed with a glass filler and hCS in a weight ratio of 70.0% glass (hCS 0), 17.5% hCS + 52.5% glass (hCS 17.5), 35.0% hCS + 35.0% glass (hCS 35.0), and 52.5% hCS + 17.5% glass (hCS 52.5). A light-cured experimental resin composite disk was positioned over a polished bovine enamel disk, separated by a 30-µm gap, and immersed in artificial saliva with pH 4.0 for 15, 30, and 60 days. After the immersion period, the enamel disk was separated from the resin composite disk and evaluated using a microhardness tester, atomic force microscopy, and polarized light microscopy. The opposing sides of the enamel and resin composite disks were observed using scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS). Results. The enamel surface showed a significant increase in microhardness, decrease in roughness, and remineralization layer as the proportion of hCS increased (P < 0.05). In the SEM image, enamel surface with hCS 35.0 and 52.5 after all experimental immersion periods showed a pattern similar to that of a sound tooth. Conclusions. The results demonstrated that increasing the hCS filler level significantly increased the prevention effect of enamel demineralization compared to restorative resin composites containing conventional dental glass filler. Despite some microleakage exposed to a cariogenic environment, these novel composites may be promising dental biomaterials for protecting teeth against demineralization and preventing secondary caries around the restorations.

Calcium silicate cement (CSC) is widely used as an endodontic material in clinical applications such as direct pulp capping, pulpotomy, or root canal. CSC has good biocompatibility, sealing properties, and the ability to enhance hard tissue regeneration. However, the disadvantage of CSC is the difficulty in handling when placing it into endodontic tissue due to the long setting time. Several attempts have been made to improve handling of CSC; however, these methods were limited by osteogenic properties. To overcome such a disadvantage, this study investigated the use of Pluronic F127 (F127) for the development easy-to-handle novel endodontic CSCs with osteogenic properties. In this case, different concentrations of F127 (5%, 10%, 20%, 30%, and 40%) were implemented to generate CSC specimens H5, H10, H20, H30, and H40, respectively. Calcium ion was continuously released for 28 days. In addition, each group resulted in apatite formation for 28 days corresponding to calcium ion release. The concentration of F127 showed opposite relationships with water solubility and compressive strength. The H20 group showed a high level of osteogenic activity compared to other groups at 14 days. Mineralization of the H20 group was higher than that of the other groups. This study indicates that the novel F127-based hydrogel with CSC can potentially be used as endodontic filler.

ObjectivesThe use of 16S ribosomal RNA gene sequencing analyses has rapidly increased in clinical oral studies. However, cohort-based clinical research has not sufficiently accounted for the periodic stability in oral microbiota. Herein, we aimed to assess the stability of the oral microbiome across time from an intervention-free “healthy” cohort. Materials and MethodsWe obtained 33 supragingival samples of 11 healthy participants from the biobank. For each participant, we processed one sample as baseline (T0) and two samples spaced at monthly (T1) and quarterly (T2) intervals for 16S ribosomal RNA gene sequencing analysis. ResultsWe observed that taxonomic profiling had a similar pattern of dominant genera, namely Rothia, Prevotella, and Hemophilus, at all-time points. Shannon diversity revealed a significant increase from T0 (pp

Biocompatibility is important for the 3D printing of resins used in medical devices and can be affected by photoinitiators, one of the key additives used in the 3D printing process. The choice of ingredients must be considered, as the toxicity varies depending on the photoinitiator, and unreacted photoinitiator may leach out of the polymerized resin. In this study, the use of ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (TPO-L) as a photoinitiator for the 3D printing of resin was considered for application in medical device production, where the cytotoxicity, colour stability, dimensional accuracy, degree of conversion, and mechanical/physical properties were evaluated. Along with TPO-L, two conventional photoinitiators, phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (BAPO) and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO), were considered. A total of 0.1 mol% of each photoinitiator was mixed with the resin matrix to prepare a resin mixture for 3D printing. The specimens were printed using a direct light processing (DLP) type 3D printer. The 3D-printed specimens were postprocessed and evaluated for cytotoxicity, colour stability, dimensional accuracy, degree of conversion, and mechanical properties in accordance with international standards and the methods described in previous studies. The TPO-L photoinitiator showed excellent biocompatibility and colour stability and possessed with an acceptable dimensional accuracy for use in the 3D printing of resins. Therefore, the TPO-L photoinitiator can be sufficiently used as a photoinitiator for dental 3D-printed resin.

Changes in intraoral pH can cause changes in the chemical decomposition and surface properties of treated resin-based pits and fissure sealants (sealant). The purpose of this study is to evaluate the release of bisphenol A (BPA) from sealants under three different pH conditions over time. The test specimen was applied with 6 sealants 5 mg each on a glass plate (10 × 10 mm) and photopolymerized. The samples were immersed for 10 min, 1 h, and 24 h in solutions of pH 3.0, 6.5, and 10.0 at 37 °C. BPA release was measured using a gas chromatography-mass spectrometer. A statistical analysis was performed by two-way ANOVA and one-way ANOVA to verify the effect of pH conditions and time on BPA release. The BPA concentration in the pH 3.0 group was higher at all points than with pH 6.5 and pH 10.0 (p < 0.05), and gradually increased over time (p < 0.05). As a result, it was confirmed that low pH negatively influences BPA release. Therefore, frequent exposure to low pH due to the consumption of various beverages after sealant treatment can negatively affect the sealant’s chemical stability in the oral cavity.

Due to high demand but limited supply, there has been an increase in the need to replace autologous bone grafts with alternatives that fulfill osteogenic requirements. In this study, two different types of bone grafts were tested for their drug carrying abilities along with their osteogenic properties. Two different types of alendronate-loaded bone grafts, Bio-Oss (bovine bone graft) and InRoad (biphasic synthetic bone graft) were observed to see how different concentrations of alendronate would affect the sustained release to enhance osteogenesis. In this study, defected ovariectomize-induced osteoporotic rat calvarias were observed for 28 days with three different concentrations of alendronate (0 mg, 1 mg, 5 mg) for both Bio-Oss and InRoad. A higher concentration (5 mg) allowed for a more controlled and sustained release throughout the 28-day comparison to those of lower concentrations (0 mg, 1 mg). When comparing Bio-Oss and InRoad through histology and Micro-CT, InRoad showed higher enhancement in osteogenesis. Through this study, it was observed that alendronate not only brings out robust osteogenesis with InRoad bone grafts, but also enhances bone regeneration in an alendronate-concentration-dependent manner. The combination of higher concentration of alendronate and multiple porous bone graft containing internal micro-channel structure of InRoad resulted in higher osteogenesis with a sustained release of alendronate.

The aim of this study is to investigate the resistance of various fluoride-releasing restorative materials against the demineralization and remineralization of enamel surfaces, including those that have been recently introduced to the market. Three different fluoride-releasing restorative materials were considered: glass ionomer (FI), resin-modified glass ionomer (RL), and an alkasite restorative material (CN). The acid neutralization ability was investigated using pH measurement, and the concentrations of released fluoride and calcium ions were measured. Finally, the demineralization resistance and remineralization effects of enamel were observed using a microhardness tester and SEM. CN showed an initial substantial increase in pH followed by a steady increase, with values higher than those of the other groups (p &lt, 0.05). All three groups released fluoride ions, and the CN group released more calcium ions than the other groups (p &lt, 0.05). In the acid resistance test, from the microhardness and SEM images, the CN group showed effective resistance to demineralization. In the remineralization test, the microhardness results showed that the FI and CN groups recovered the microhardness from the values of the demineralized enamel surface (p &lt, 0.05). This was confirmed by the SEM images from remineralization tests, the CN group showed a recovered demineralized surface when immersed in artificial saliva for 7 days. In conclusion, alkasite restorative material can be an effective material when used in cariogenic environments.

Commercial mineral trioxide aggregate (MTA) materials such as Endocem MTA (EC), Dia-Root Bio MTA (DR), RetroMTA (RM), and ProRoot MTA (PR) are increasingly used as root-end filling materials. The aim of this study was to assess and compare the physicochemical and mechanical properties and cytotoxicity of these MTAs. The film thicknesses of EC and DR were considerably less than that of PR, however, RM’s film thickness was greater than that of PR. In addition, the setting times of EC, DR, and RM were shorter than that of PR (p &lt, 0.05). The solubility was not significantly different among all groups. The three relatively new MTA groups (EC, DR, and RM) exhibited a significant difference in pH variation and calcium ion release relative to the PR group (p &lt, 0.05). The radiopacity of the three new MTAs was considerably less than that of PR. The mechanical strength of RM was not significantly different from that of PR (p &gt, 0.05), however, the EC and DR groups were not as strong as PR (p &lt, 0.05). All MTA groups revealed cytocompatibility. In conclusion, the results of this study confirmed that EC, RM, DR, and PR exhibit clinically acceptable physicochemical and mechanical properties and cell cytotoxicity.

Flowable resins used for dental restoration are subject to biofilm formation. Zinc has antibacterial properties. Thus, we prepared a zinc-doped phosphate-based glass (Zn-PBG) to dope a flowable resin and evaluated the antibacterial activity of the composite against Streptococcus mutans (S. mutans) to extrapolate the preventative effect toward secondary caries. The composites were prepared having 0 (control), 1.9, 3.8, and 5.4 wt.% Zn-PBG. The flexural strength, elastic modulus, microhardness, depth of cure, ion release, inhibition zone size, and number of colony-forming units were evaluated and analyzed using ANOVA. The flexural strength of the control was significantly higher than those of Zn-PBG samples (p &lt, 0.05). However, all samples meet the International Standard, ISO 4049. The microhardness was not significantly different for the control group and 1.9 and 3.8 wt.% groups, but the 5.4 wt.% Zn-PBG group had a significantly lower microhardness (p &lt, 0.05). Further, the composite resins increasingly released P, Ca, Na, and Zn ions with an increase in Zn-PBG content (p &lt, 0.05). The colony-forming unit count revealed a significant reduction in S. mutans viability (p &lt, 0.05) with increase in Zn-PBG content. Therefore, the addition of Zn-PBG to flowable composite resins enhances antibacterial activity and could aid the prevention of secondary caries.

The surface molecular chemistry, such as amine functionality, of biomaterials plays a crucial role in the osteogenic activity of relevant cells and tissues during hard tissue regeneration. Here, we examined the possibilities of creating amine functionalities on the surface of titanium by using the nonthermal atmospheric pressure plasma jet (NTAPPJ) method with humidified ammonia, and the effects on human mesenchymal stem cell (hMSC) were investigated. Titanium samples were subjected to NTAPPJ treatments using nitrogen (N-P), air (A-P), or humidified ammonia (NA-P) as the plasma gas, while control (C-P) samples were not subjected to plasma treatment. After plasma exposure, all treatment groups showed increased hydrophilicity and had more attached cells than the C-P. Among the plasma-treated samples, the A-P and NA-P showed surface oxygen functionalities and exhibited greater cell proliferation than the C-P and N-P. The NA-P additionally showed surface amine-related functionalities and exhibited a higher level of alkaline phosphatase activity and osteocalcin expression than the other samples. The results can be explained by increases in fibronectin absorption and focal adhesion kinase gene expression on the NA-P samples. These findings suggest that NTAPPJ technology with humidified ammonia as a gas source has clinical potential for hard tissue generation.

Titanium is commonly used as a biomaterial for dental implants. In this study, we investigated the antibacterial properties of titanium samples following treatment with a non-thermal atmospheric pressure plasma jet (NTAPPJ) on bacteria with two different cell wall structures, including gram-positive and gram-negative bacteria. The hydrophilicity and surface energy of titanium surfaces were significantly increased after NTAPPJ treatment without altering topographical features. Changes in the chemical composition and reductive potential were observed on the NTAPPJ-treated titanium surfaces. The adhesion and biofilm formation rate of bacteria were significantly reduced on the NTAPPJ-treated titanium surfaces compared with the untreated samples, which was confirmed by fluorescent imaging. Regarding the comparison between gram-positive and gram-negative bacteria, both adhesion and the biofilm formation rate were significantly lower for gram-negative bacteria than gram-positive bacteria on samples treated for longer durations with the NTAPPJ. Transmission electron microscopy imaging showed a comparably more disruptive membrane structure of gram-negative bacteria than gram-positive bacteria on the NTAPPJ-treated surfaces. Our results indicated that the NTAPPJ treatment could be useful for preventing bacterial adhesion and biofilm formation on titanium dental implant surfaces, while the reductive potential on surfaces treated by the NTAPPJ could cause oxidation of bacteria, which could be more sensitive to gram-negative bacteria due to differences in the cell wall structure.

The objective of this study was to investigate the effects of hydrated calcium silicate filler (hCS) on resin-based pit and fissure sealants&rsquo, acid neutralization, calcium ion release, and mechanical and physical properties. To produce the hCS filler, Portland cement (CS) was mixed with distilled water and ground into fine particles. The particles were then mixed with silanized glass filler and added to a photo-activated resin matrix. To evaluate the acid neutralization and calcium ion release properties, the specimens were immersed in a pH 4.0 lactic acid solution and distilled water for 28 days. Also, the flexural strength, depth of cure, water sorption, and solubility were tested. All of the groups containing hCS and CS required less than one minute to increase the pH from 4.0 to 5.5. With 50% hCS, the calcium ion release was higher than 50% CS in the distilled water at the initial time. The flexural strength and depth of cure decreased according to the increasing proportion of hCS added. The water sorption and solubility had an increasing trend as increasing proportions of hCS were added. These findings showed that pit and fissure sealant containing hCS exhibit superior acid neutralization and calcium release properties, and may be promising for caries-inhibiting dental material.

Porous hydroxyapatite (HAp) scaffolds are commonly used for hard tissue regeneration because of their biocompatibility and osteoconduction properties, but they are limited in terms of bioactivity a...

The purpose of the study was to evaluate the adhesion between dental core resin and epoxy resin-based fiber post after treatment with non-thermal atmospheric pressure plasma (NTAPP) and compare with conventional methods of epoxy resin-based fiber post treatments. Contact angle was measured on the surface of epoxy resin before and after NTAPP treatment and X-ray photoelectron spectroscopy was used to analyze the surface chemistry. Finally, two shear bond strength tests were carried out, shear bond strength between core resin and epoxy resin for comparison between NTAPP treated and untreated sample, and push-out shear bond strength between core resin and NTAPP treated commercially available epoxy resin-based fiber post for comparison between NTAPP treated samples with conventionally treated samples. Contact angle on the surface of epoxy resin generally decreased with increasing NTAPP treatment time with presence of surface chemical changes. Also, there was significantly higher shear bond strength and push-out shear bond strength between epoxy resin and core resin for NTAPP treated epoxy resin, even to the conventionally treated epoxy resin-based fiber post with hydrofluoric acid or silane. In conclusion, new technology of NTAPP has potential for application on the epoxy resin-based fiber post to improve endodontic restoration success rate.

Objectives: To determine whether the success rate and primary stability of surface-treated miniscrews differ from those of nontreated miniscrews. Materials and Methods: Patients who required one or more miniscrews for the same reason in each quadrant were recruited into a single-blinded, split-mouth, randomized, controlled trial with a 1:1 allocation ratio. Self-drilling miniscrews with two surface types were used: those with no surface treatment, and those with an acid-etched surface treatment. The cumulative success rate and primary stability of each type of miniscrew were examined, and factors potentially affecting the success and failure of miniscrews were investigated. Results: Forty patients were included in the study, with a total of 98 orthodontic miniscrews. The overall success rate was 88.8%, and the respective success rates for acid-etched and machined surface miniscrews were 91.8% and 85.7%. The respective mean insertion torques were 13.62 ± 5.95 N·cm and 13.38 ± 4 N·cm, and periotest values measured immediately after insertion were −0.50 ± 2.77 for acid-etched miniscrews and −0.28 ± 3.36 for machined surface miniscrews. There was no significant difference in the mean insertion torques and periotest values according to surface treatment and jaw. Conclusions: Neither the success rate nor the primary stability of acid-etched surface miniscrews and machined surface miniscrews differed significantly. There is a high possibility that miniscrews will fall out in patients who have an open bite or those who require total distalization.

Objective This study was performed to investigate an appropriate degree of prestretch for orthodontic synthetic elastomeric chains focusing on time-dependent viscoelastic properties. Methods Orthodontic synthetic elastomeric chains of two brands were prestretched to 50, 100, 150, and 200% of the original length in one and three cycles, and the hysteresis areas of the obtained stress-strain curves were determined. Acrylic plates were employed to maintain constant strain during the experiment. A total of 180 samples were classified into nine groups according to brand, and their stresses and permanent deformations were measured immediately after prestretch (0 hour), after 1 hour and 24 hours, and after 1, 2, 3, 4, 5, 6, 7, and 8 weeks. The relationship between stress relaxation and permanent deformation was investigated for various degrees of prestretch, and the estimated stress resulting from tooth movement was calculated. Results The degree of prestretch and the stress relaxation ratio exhibited a strong negative correlation, whereas no correlation was found between the degree of prestretch and the average normalized permanent strain. The maximal estimated stress was observed when prestretch was performed in three cycles to 200% of the original length. Conclusions Although prestretch benefited residual stress, it did not exhibit negative effects such as permanent deformation. The maximal estimated stress was observed at the maximal prestretch, but the difference between prestretch and control groups decreased with time. In general, higher residual stresses were observed for product B than for product A, but this difference was not clinically significant.

Although various oral pathogens are inactivated by non-thermal atmospheric pressure plasma (NTAPP), the in vivo effects of NTAPP are poorly understood. The first aim of this study was to examine the antibacterial activity of microwave-pulsed NTAPP against Staphylococcus aureus in artificial saliva to mimic oral environmental conditions. The second aim was to determine the influence of microwave-pulsed NTAPP on human gingival fibroblasts (HGFs). The microwave-pulsed NTAPP reduced bacterial viability (as measured by colony forming units [CFU]) to a greater extent in artificial saliva than in saline. Extending the post-treatment incubation time increased bacterial inactivation in artificial saliva compared to saline. HGFs viability was unaffected by microwave-pulsed NTAPP for bacterial inactivation. Rather, HGFs proliferation increased after a 5-min microwave-pulsed NTAPP. Less tumor necrosis factor alpha was released by microwave-pulsed NTAPP-treated HGFs stimulated with lipopolysaccharide (LPS) than by untreated, LPS-stimulated HGFs; thus, plasma appeared to suppress the inflammatory response. Our study suggests that microwave-pulsed NTAPP may have stronger in vivo antibacterial activity than in vitro activity, and that microwave-pulsed NTAPP may have the additional advantage of suppressing gingival inflammatory responses.

OBJECTIVE The purpose of this study was to examine the effect of commercially available fluoride-containing oral rinses on the corrosion behavior of titanium alloys, which are the main components of orthodontic miniscrews. METHODS Four commercially available oral rinses (solution A, pH 4.46/260 ppm fluoride; solution B, pH 4.41/178 ppm fluoride; solution C, pH 6.30/117 ppm fluoride; and solution D, pH 4.17/3.92 ppm fluoride) were tested on titanium alloy (Ti-6Al-4V) circular plates, and saline was used as the control. The open-circuit potential and potentiodynamic polarization of these materials were measured. Thereafter, all samples were evaluated under a field-emission scanning electron microscope. RESULTS Among the tested oral rinses, except solution D, the more the fluoride content was, the greater was the corrosion potential downtrend; the corrosion resistance of the titanium alloy sample was also lowered significantly (p < 0.05). Field-emission scanning electron microscopic analysis of the surface morphology of the titanium alloy samples revealed that all samples had some defects, crevices, or pitting after exposure to the oral rinses than before treatment. In particular, the samples in solution A showed the most changes. CONCLUSIONS Commercially available oral rinses having a high fluoride concentration and a low pH may reduce the corrosion resistance of titanium alloys used in dental appliances such as orthodontic titanium miniscrews and brackets.

OBJECTIVE The aim of this study was to compare recycled and unused orthodontic miniscrews to determine the feasibility of reuse. The comparisons included both miniscrews with machined surfaces (MS), and those with etched surfaces (ES). METHODS Retrieved MS and ES were further divided into three subgroups according to the assigned recycling procedure: group A, air-water spray; group B, mechanical cleaning; and group C, mechanical and chemical cleaning. Unused screws were used as controls. Scanning electron microscopy, energy-dispersive X-ray spectrometry, insertion time and maximum insertion torque measurements in artificial bone, and biological responses in the form of periotest values (PTV), bone-implant contact ratio (BIC), and bone volume ratio (BV) were assessed. RESULTS Morphological changes after recycling mainly occurred at the screw tip, and the cortical bone penetration success rate of recycled screws was lower than that of unused screws. Retrieved ES needed more thorough cleaning than retrieved MS to produce a surface composition similar to that of unused screws. There were no significant differences in PTV or BIC between recycled and unused screws, while the BV of the former was significantly lower than that of the latter (p < 0.05). CONCLUSIONS These results indicate that reuse of recycled orthodontic miniscrews may not be feasible from the biomechanical aspect.

The purpose of this study was to evaluate the change in the retentive forces of four different titanium-based implant attachment systems during the simulation of insert&ndash, removal cycles in an artificial oral environment. Five types of titanium-based dental implant attachment systems (Locator, Kerator, O-ring, EZ-Lock, and Magnetic) were studied (n = 10). The specimens underwent insert&ndash, removal cycles in artificial saliva, and the retentive force was measured following 0, 750, 1500, and 2250 cycles. Significant retention loss was observed in all attachment systems, except the magnetic attachments, upon completion of 2250 insertion and removal cycles, compared to the initial retentive force (p &lt, 0.05). A comparison of the initial retentive forces revealed the highest value for Locator, followed by the Kerator, O-ring, EZ-Lock, and Magnetic attachments. Furthermore, Kerator demonstrated the highest retentive loss, followed by Locator, O-ring, EZ-Lock, and Magnetic attachments after 2250 cycles (p &lt, 0.05). In addition, the Locator and Kerator systems revealed significant decrease in retentive forces at all measurement points (p &lt, 0.05). The retention force according to the insert&ndash, removal cycles were significantly different according to the types of dental implant attachment systems.

The aim of this study was to fabricate bioresorbable polylactide (PLA) membranes by 3D printing and compare their properties to those of the membranes fabricated by the conventional method and compare the effect of different pore sizes on the properties of the 3D-printed membranes. PLA membranes with three different pore sizes (large pore-479 &mu, m, small pore-273 &mu, m, and no pore) were 3D printed, and membranes fabricated using the conventional solvent casting method were used as the control group. Scanning electron microscopy (SEM) and micro-computed tomography (&micro, CT) were taken to observe the morphology and obtain the porosity of the four groups. A tensile test was performed to compare the tensile strength, elastic modulus, and elongation at break of the membranes. Preosteoblast cells were cultured on the membranes for 1, 3 and 7 days, followed by a WST assay and SEM, to examine the cell proliferation on different groups. As a result, the 3D-printed membranes showed superior mechanical properties to those of the solvent cast membranes, and the 3D-printed membranes exhibited different advantageous mechanical properties depending on the different pore sizes. The various fabrication methods and pore sizes did not have significantly different effects on cell growth. It is proven that 3D printing is a promising method for the fabrication of customized barrier membranes used in GBR/GTR.

The blending effect (BE) plays an important role in esthetics of the composite resin. The objective of this study was to determine the extents to which filler size and content affect the BE. Three types of fillers (0.7, 1.0, and 1.5 µm) were mixed at weight contents of 60, 70, 75, and 80%. This study simulated clinical class 3 or 4 cavities and quantitatively measured the color diffusion of the objects next to the cavities based on the CIELab color space. For each filler size, there was a trend of increasing BE as the filler content was increased. The translucency parameter (TP) exhibited the opposite trend of decreasing (p

The aim of this study was to investigate the element composition and grain size of commercial dental instruments used for ultrasonic scaler tips, which are composed of stainless-steel materials. The differences in mechanical properties and wear resistances were compared. The samples were classified into 4 groups in accordance with the manufacturer, Electro Medical Systems, 3A MEDES, DMETEC and OSUNG MND, and the element compositions of each stainless-steel ultrasonic scaler tip were analyzed with micro-X-ray fluorescence spectrometry (μXRF) and field-emission scanning electron microscopy (FE-SEM) with energy-dispersive X-ray spectroscopy (EDS). One-way ANOVA showed that there were significant differences in shear strength and Vickers hardness among the stainless-steel ultrasonic scaler tips depending on the manufacturer (p &lt, 0.05). The mass before and after wear were found to have no significant difference among groups (p &gt, 0.05), but there was a significant difference in the wear volume loss (p &lt, 0.05). The results were then correlated with μXRF results as well as observations of grain size with optical microscopy, which concluded that the Fe content and the grain size of the stainless steel have significant impacts on strength. Additionally, stainless-steel ultrasonic scaler tips with higher Vickers hardness values showed greater wear resistance, which would be an important wear characteristic for clinicians to check.

Despite numerous advantages of using porous hydroxyapatite (HAp) scaffolds in bone regeneration, the material is limited in terms of osteoinduction. In this study, the porous scaffold made from nanosized HAp was coated with different concentrations of osteoinductive aqueous methylsulfonylmethane (MSM) solution (2.5, 5, 10, and 20%) and the corresponding MH scaffolds were referred to as MH2.5, MH5, MH10, and MH20, respectively. The results showed that all MH scaffolds resulted in burst release of MSM for up to 7 d. Cellular experiments were conducted using MC3T3-E1 preosteoblast cells, which showed no significant difference between the MH2.5 scaffold and the control with respect to the rate of cell proliferation (p &gt, 0.05). There was no significant difference between each group at day 4 for alkaline phosphatase (ALP) activity, though the MH2.5 group showed higher level of activity than other groups at day 10. Calcium deposition, using alizarin red staining, showed that cell mineralization was significantly higher in the MH2.5 scaffold than that in the HAp scaffold (p &lt, 0.0001). This study indicated that the MH2.5 scaffold has potential for both osteoinduction and osteoconduction in bone regeneration.