Titanium-Silver Alloy Miniplates for Mandibular Fixation: In Vitro and In Vivo Study.

PURPOSE: Titanium (Ti) alloys have received considerable attention as materials for oral and maxillofacial surgery, which require high mechanical strength, osteosynthesis, and biocompatibility. The objective was to implant miniplates fabricated from commercially pure Ti (CP Ti) and newly developed Ti-silver (Ag) alloy in fractured mandibles of adult dogs after preliminary mechanical and biological characterization. MATERIALS AND METHODS: The surface characteristics, biocompatibility, and pre-osteoblast adhesion and proliferation of CP Ti (grade 3) and Ti-Ag (2 at% Ag) alloys were evaluated. Next, the bending strength of 6- and 8-hole miniplates fabricated from CP Ti and Ti-Ag was compared according to ISO (International Organization for Standardization) 9585. Six-hole miniplates were implanted for 12 weeks in fractured mandibles of adult dogs. The Ag ion concentration in each alloy and implanted bone block with soft tissue was measured by inductively coupled plasma mass spectroscopy after euthanasia according to ISO 10993-12. RESULTS: Precipitated Ag was detected in Ti-Ag by alpha- and beta-phase Ti in x-ray powder diffraction. The biocompatibility with pre-osteoblasts of Ti-Ag and CP Ti was comparable in terms of cytotoxicity, cell adhesion, and proliferation (P > .05). Ti-Ag miniplates had up to 3-fold greater bending strength than CP Ti miniplates (P < .05). An in vivo study showed that CP Ti and Ti-Ag miniplates had comparable soft and hard tissue regeneration ability (P > .05). Ag ions were detected in Ti-Ag alloys and applied mandible blocks. CONCLUSIONS: The results of this study suggest that Ti-Ag alloys can be used to produce miniplates with high mechanical properties, as well as considerable biocompatibility, osteosynthesis ability, and Ag ion-release properties. Further studies, including preclinical investigations, are required to enable clinical use of Ti-Ag bone plates.

Non-thermal atmospheric pressure plasma increased mRNA expression of growth factors in human gingival fibroblasts.

OBJECTIVES: The aim of this in vitro study was to investigate the effects of a non-thermal atmospheric pressure plasma jet (NTAPPJ) on the cellular activity of human gingival fibroblasts (HGF) for possible non-surgical application of it during gingival wound healing. MATERIALS AND METHODS: HGF cells were exposed with NTAPPJ for 1, 2, and 4 min and were investigated for cellular attachment, cell viability, morphology of attached cells, proliferation rate, and messenger ribonucleic acid (mRNA) expression of various growth factors. Also, scavengers for chemicals produced by NTAPPJ were used to identify the chemical species responsible for the effects. RESULTS: There was no significant change in the number of HGF cells attached or their proliferation following NTAPPJ exposure. Also, high cell viability resulted from exposure of all of HGF cells to NTAPPJ for 1, 2, and 4 min. However, cells were more stretched while the mRNA expressions of transforming growth factor and vascular endothelial growth factor were significantly increased following NTAPPJ exposure. Additionally, the scavenger test showed that nitric oxide is likely to be the chemical responsible for an increase of cellular activity. CONCLUSION: The results demonstrated that the NTAPPJ increased mRNA expressions of growth factors in human gingival fibroblasts. CLINICAL RELEVANCE: Application of NTAPPJ would be useful in gingival wound healing in clinics though additional studies confirming the effects would be needed.

Catechol-Functionalized Synthetic Polymer as a Dental Adhesive to Contaminated Dentin Surface for a Composite Restoration.

This study reports a synthetic polymer functionalized with catechol groups as dental adhesives. We hypothesize that a catechol-functionalized polymer functions as a dental adhesive for wet dentin surfaces, potentially eliminating the complications associated with saliva contamination. We prepared a random copolymer containing catechol and methoxyethyl groups in the side chains. The mechanical and adhesive properties of the polymer to dentin surface in the presence of water and salivary components were determined. It was found that the new polymer combined with an Fe(3+) additive improved bond strength of a commercial dental adhesive to artificial saliva contaminated dentin surface as compared to a control sample without the polymer. Histological analysis of the bonding structures showed no leakage pattern, probably due to the formation of Fe-catechol complexes, which reinforce the bonding structures. Cytotoxicity test showed that the polymers did not inhibit human gingival fibroblast cells proliferation. Results from this study suggest a potential to reduce failure of dental restorations due to saliva contamination using catechol-functionalized polymers as dental adhesives.

Air atmospheric-pressure plasma-jet treatment enhances the attachment of human gingival fibroblasts for early peri-implant soft tissue seals on titanium dental implant abutments.

OBJECTIVE: Although dental implants are commonly used for tooth restoration, there is a lack of studies of treatment regimens for preventing extra-oral infection and decreasing osseointegration failures by establishing early peri-implant soft tissue seals on titanium dental implant abutments. In this study, air atmospheric-pressure plasma-jet (AAPPJ) treatment was applied to titanium disks to assay the potential for early peri-implant soft tissue seals on titanium dental implant abutment. MATERIALS AND METHODS: After titanium disks were treated with AAPPJ for 10 s at 250, 500, 1000 and 1500 sccm, surface analysis was performed; the control group received air only or no treatment. Human gingival fibroblasts (HGF) were seeded onto the specimens for evaluating cell attachment and proliferation and adherent-cell morphology was visualized via confocal microscopy. RESULTS: In AAPPJ-treated specimens, the water contact angle decreased according to increased flow rate. Oxygen composition increased in XPS, but no topographical changes were detected. The effect of AAPPJ treatment at 1000 sccm was apparent 2 mm from the treated spot, with a 20% increase in early cell attachment and proliferation. Adherent HGF on AAPPJ-treated specimens displayed a stretched phenotype with more vinculin formation than the control group. CONCLUSIONS: Within the limitations of this study, the results indicate that AAPPJ treatment may enhance the early attachment and proliferation of HGF for establishing early peri-implant soft tissue seals on titanium dental implant abutments with possible favorable effects of osseointegration of dental implant.

Fabrication of bioactive, antibacterial TiO2 nanotube surfaces, coated with magnetron sputtered Ag nanostructures for dental applications.

We investigated whether a silver coating on an anodic oxidized titania (TiO2) nanotube surface would be useful for preventing infections in dental implants. We used a magnetron sputtering process to deposit Ag nanoparticles onto a TiO2 surface. We studied different sputtering input power densities and maintained other parameters constant. We used scanning electron microscopy, X-ray diffraction, and contact angle measurements to characterize the coated surfaces. Staphylococcus aureus was used to evaluate antibacterial activity. The X-ray diffraction analysis showed peaks that corresponded to metallic Ag, Ti, O, and biocompatible anatase phase TiO2 on the examined surfaces. The contact angles of the Ag nanoparticle-loaded surfaces were significantly lower at 2.5 W/cm2 input power under pulsed direct current mode compared to commercial, untreated Ti surfaces. In vitro antibacterial analysis indicated that a significantly reduced number of S. aureus were detected on an Ag nanoparticle-loaded TiO2 nanotube surface compared to control untreated surfaces. No cytotoxicity was noted, except in the group treated with 5 W/cm2 input power density, which was the highest input of power density we tested for the magnetron sputtering process. Overall, we concluded that it was feasible to create antibacterial Ag nanoparticle-loaded titanium nanotube surfaces with magnetron sputtering.

Air atmospheric pressure plasma jet pretreatment for drop-wise loading of dexamethasone on hydroxyapatite scaffold for increase of osteoblast attachment.

Periodontal disease affects alveolar bone resorption around the involved teeth. To gain bone height, bone graft materials have been widely used with drug carriers. Application of an atmospheric pressure plasma jet (APPJ) treatment is widely studied due to its ability to change surface characteristics without topographical change. The aim of this study is to identify whether the air APPJ (AAPPJ) treatment before drop-wise loading performance could change loaded amount of dexamethasone, and induce increase of cell attachment and proliferation. The results suggested that AAPPJ treatment decreased the contact angle down to about 13 degrees, which increased gradually but significantly lowered at least 4 days compared to no-treated group. After AAPPJ treatment, hydrocarbon was removed with change of zeta potential into positive charge. However, the AAPPJ treatment did not change the quantity or releasing profile of dexamethasone (p > 0.05). Confocal analysis combined with DNA proliferation analysis showed increase of osteoblast attachment and proliferation. Hence, AAPPJ could be a useful pretreatment method before drop-wise loading on HA scaffold with dexamethasone for increase of osteoblast attachment.

Positive control for cytotoxicity evaluation of dental vinyl polysiloxane impression materials using sodium lauryl sulfate.

OBJECTIVES: Vinyl polysiloxane (VPS) is elastomeric dental impression material which, despite having very few reports of adverse reactions, has shown high levels of cytotoxicity that is difficult to be interpreted without referencing to the positive control material. Therefore, in this study, positive control VPS was developed using sodium lauryl sulfate (SLS) for the reference of cytotoxicity test. MATERIALS AND METHODS: The positive control VPS with SLS was formed with a different proportion of SLS (0, 1, 2, 4, 8 and 16 wt%) added to the base. The cytotoxicity test was then carried out using the extractions or dilutions of the extractions from each of the test samples using murine fibroblast cells (L929). RESULTS: The final product of positive control VPS behaved similar to commercially available VPS; being initially liquid-like and then becoming rubber-like. Ion chromatography showed that the level of SLS released from the product increased as the proportion of added SLS increased, consequently resulting in an increased level of cytotoxicity. Also, the commercially available VPS was less cytotoxic than the positive control VPS with more or equal to 2 wt% of SLS. However, even the VPS with the highest SLS (16 wt%) did not cause oral mucosa irritation during the animal study. CONCLUSIONS: The positive control VPS was successfully produced using SLS, which will be useful in terms of providing references during in vitro cytotoxicity testing.

Cytotoxicity evaluation of zinc oxide-eugenol and non-eugenol cements using different fibroblast cell lines.

OBJECTIVES: Despite being commonly used as temporary cements in dentistry, there is a lack of studies regarding the cytotoxicity of zinc oxide-eugenol (ZOE) and zinc oxide non-eugenol (ZONE) cements. In addition, cytotoxicity evaluation of the materials often involves animal-based cells. Therefore, in this study, a cytotoxicity evaluation of commercially available ZOE and ZONE cements was carried out using both animal and human-based cells. MATERIALS AND METHODS: The extraction or dilution of the extraction from four commercially available cements (two zinc oxide-eugenol and two zinc oxide non-eugenol) was tested for cytotoxicity, using three different cells and a water-soluble treatzolium salt assay. The results were confirmed using a confocal laser microscope following calcein AM and ethidium homodimer-1 staining. RESULTS: The results showed that there was a significant difference in cell viability depending on which cell was used, even when the same material was tested. Generally, L929 showed relatively low cell viability with a low EC50 (effective concentration of extracts that caused 50% of cell viability compared to the control) value compared to both HGF-1 and hTERT-hNOF. Such results were also confirmed by a confocal laser microscope. CONCLUSIONS: Careful consideration on interpreting the results for cytotoxicity evaluation of ZOE and ZONE cements is needed when different cells are used.

Characterization of hydroxyapatite containing a titania layer formed by anodization coupled with blasting.

OBJECTIVES: The modification of dental implant surface by increasing the surface roughness or/and altering chemical composition have been attempted. Among them, hydroxyapatite (HA) coatings are typically bioactive. On the other hand, titania coatings have good corrosion resistance and biocompatibility. Therefore, the objective of this study was to fabricate HA containing a titania layer using an HA blasting and anodization method to benefit from the advantages of both, followed by surface characterization and biocompatibility. MATERIALS AND METHODS: HA blasting was performed followed by microarc oxidation (MAO) using various applied voltages (100, 150, 200, 250 V). For surface characterization, the microstructure of the surface, surface phase and surface roughness were observed. Bonding strength was measured using a universal testing machine and potentiodynamic corrosion testing was performed. Biocompatibility was evaluated based on bioactivity and cell proliferation test. RESULTS: The porous titanium oxide-containing HA was formed at 150 and 200 V. These surfaces were a lower corrosion current compared to the titanium treated only with HA blasting. In addition, composite treated titanium showed a rougher surface and tighter bonding strength compared to the titanium treated only with MAO. Biocompatibility demonstrated that HA/Titania composite layer on titanium showed a rapid HA precipitation and also enhanced cell proliferation. CONCLUSIONS: These results suggested that HA containing titania layer on titanium had not only excellent physicochemical, mechanical and electrochemical properties, but also improved bioactivity and biological properties that could be applied as material for a dental implant system.

The disinfection of impression materials by using microwave irradiation and hydrogen peroxide.

STATEMENT OF PROBLEM: Microwave irradiation and immersion in solutions have been recommended for denture disinfection. However, the effect of dry conditions and impression materials has not been completely evaluated. PURPOSE: The purpose of this study was to evaluate the effectiveness of microwave irradiation and hydrogen peroxide for the disinfection of dental impression materials. MATERIAL AND METHODS: Specimens (diameter 10 mm, thickness 2 mm) were made with polyvinyl siloxane. Experimental groups were treated with hydrogen peroxide (group H), microwave irradiation (group M), and a combination of both hydrogen peroxide and microwave irradiation (group MH) for 1 minute, 2 minutes, and 3 minutes. The control group was untreated. The total sample size was 120. The specimens were divided into 2 groups, those exposed to Streptococcus mutans and those exposed to Escherichia coli. The disinfection effect and physical properties (contact angle, compatibility with gypsum, strain in compression, tear strength) were evaluated. RESULTS: All 3 groups (H, M, MH) were effective in reducing the number of colony forming units (CFU) per unit volume (mL) for both S mutans and E coli compared with the control. The most significant reduction in the CFU/mL of both bacteria was noted in the MH group and was used to compare either treatment alone (P<.05). No statistically significant difference was noted between the control and treatment groups in terms of all of the physical properties tested (P>.05). CONCLUSIONS: Microwave irradiation was identified as a useful disinfection method against S mutans and E coli, especially when combined with H2O2, without adversely affecting the physical properties of dental impression materials.

Cytotoxicity test of dentin bonding agents using millipore filters as dentin substitutes in a dentin barrier test.

OBJECTIVES: The purpose of this study was to find proper dentin substitute for standardized dentin barrier test and perform the cytotoxicity test of commercial bonding agents with the proper substitute. MATERIALS AND METHODS: The three-dimensional cells attached to dentin disc or millipore filters as the dentin substitute were tested in a dentin barrier test by perfusion. MTT assay was performed as an evaluation method for the cell survival rate. The cytotoxicity test of serial phenol dilution by bovine dentin disc was done to determine a standard toxic material, and the test of this proper phenol by using various millipore combinations was performed to find the suitable dentin substitute. Also, the cytotoxicity test of bonding agents was performed by this standardized substitute. The cell viability was expressed as percentages of untreated group. RESULTS: Phenol concentration of 0.05 % was selected as the standard toxic material. The different combinations of millipore filters--two sheets of 0.45 µm, two sheets of 0.22 µm, and the combination of 0.65, 0.45, and 0.22 µm--showed similar cytotoxicity to natural dentin discs by 0.05 % phenol (p > 0.05). The millipore combination of 0.65, 0.45, and 0.22 µm that had structural similarity to natural dentin discs was used as the substitute for cytotoxicity test of bonding agents. The toxic level of Adper Prompt L-Pop using the selected substitute was significantly the highest among four kinds of dentin bonding agents (p < 0.05). Also, the dentin barrier test by the substitute showed constant results compared with the one by the natural dentin disc. CONCLUSIONS: The millipore filter combination of 0.65, 0.45, and 0.22 µm could be used as the substitute for the cytotoxicity test of materials applied to dentin. CLINICAL RELEVANCE: Dentin barrier test by standardized substitutes would be helpful for considering the potential toxicity of dentin bonding agents prior to clinical adaptations and reducing the variations of natural bovine dentin that has individually different characteristics.

Modification of TiO(2) nanotube surfaces by electro-spray deposition of amoxicillin combined with PLGA for bactericidal effects at surgical implantation sites.

OBJECTIVE: To fabricate the antibiotic-releasing coatings on TiO(2) nanotube surfaces for wide applications of implant and bone plate in medical and dental surgery, the optimal deposition time of amoxicillin/PLGA solution simultaneously performing non-toxicity and a high bactericidal effect for preventing early implant failures was found. MATERIALS AND METHODS: FE-SEM, ESD and FT-IR were used for confirming deposition of amoxicillin/PLGA on the TiO(2) surface. Also, the elution of amoxicillin/PLGA in a TiO(2) nanotube surface was measured by a UV-VIS spectrophotometer. The bactericidal effect of amoxicillin on the TiO(2) nanotube surface was evaluated by using Staphylococcus aureus (S. aureus). The cytotoxicity and cell proliferation were observed by WST assay using MC3T3-E1 osteoblast cells. RESULTS: The results indicated that the TiO(2) nanotube surface controlled by electro-spray deposition time with amoxicillin/PLGA solution could provide a high bactericidal effect against S. aureus by the bactericidal effect of amoxicillin, as well as good osteoblast cell proliferation at the TiO(2) nanotube surface without toxicity. CONCLUSIONS: This study used electro-spray deposition (ESD) methodology to obtain amoxicillin deposition in nanotube structures of TiO(2) and found the optimal deposition time of amoxicillin/PLGA solution simultaneously performing non-toxicity and a high bactericidal effect for preventing early implant failures.

Modified cytotoxicity evaluation of elastomeric impression materials while polymerizing with reduced exposure time.

OBJECTIVE: Cytotoxicity evaluation is an important step in biocompatibility assessment of dental impression materials. Previously, cytotoxicity evaluations were carried out on already set ('set') impression materials for contact time or extraction time of 24 h or longer in duration. However, clinically, dental impression materials are in contact with oral tissue while they are being set ('polymerizing'), for no longer than 10 min. Hence, the aim of this study was to investigate the difference in results between 'polymerizing' and 'set' forms of impression materials as well as the difference in results between longer duration of contact or extraction time (12 or 24 h) and shorter duration of time (15 or 30 min). MATERIALS AND METHODS: Seven dental impression materials of different chemical compositions were tested. Two commonly used in vitro tests were used-test on extraction and test by direct contact. Both 'polymerizing' and 'set' forms of impression materials were used with different durations of extraction and contact (15 min, 30 min, 12 h and 24 h). RESULTS: There were significant (p < 0.05) differences of cell viability and cell proliferation between the 'polymerizing' and 'set' impression materials. Also, significant (p < 0.05) differences were noted with variance in duration of time. CONCLUSION: In light of the results, it is recommended to use a 'polymerizing' state of dental impression material for cytotoxicity evaluation, with 15 or 30 min of contact between cell and dental impression materials and an extraction time of 15 or 30 min that is more reflective of clinical situations.

Mechanical Properties and Wear Resistance of Commercial Stainless Steel Used in Dental Instruments.

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 < 0.05). The mass before and after wear were found to have no significant difference among groups (p > 0.05), but there was a significant difference in the wear volume loss (p < 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.

Cytocompatibility and electrochemical properties of Ti-Au alloys for biomedical applications.

The purpose of this study was to develop Ti-Au alloys with a higher resistant to corrosion, better biocompatibility, and better mechanical properties than the commercially pure titanium and its alloys. Ti-Au alloys were designed with a gold content that ranged from 0 to 5.0 at % in steps of 1.0 at %. Properties of the alloys including chemical composition, microstructure, phase, hardness, electrochemical properties, and the cytotoxicity were investigated. Only the alpha phase existed in the Ti-Au alloys. The addition of gold to the titanium decreased the alpha to beta transformation temperature. The acicular alpha phase became thinner and the hardness value increased with increasing gold content. In the electrochemical tests, Ti-Au alloys had a higher resistant to corrosion than had pure titanium and did not exhibit pitting corrosion in artificial saliva. The cytotoxicities of the Ti-Au alloys were similar to that of pure titanium. Therefore, Ti-Au alloys could be used as biomaterials in the medical and dental fields.

Photocatalytic antibacterial effect of TiO(2) film formed on Ti and TiAg exposed to Lactobacillus acidophilus.

When irradiated under near-ultraviolet (UV) light, TiO(2) exhibits strong bactericidal activity. The TiO(2) photocatalyst would be effective on orthodontic appliances after its antibacterial effect on the carcinogenic microorganism Lactobacillus acidophilus is evaluated. To compare the antibacterial effect of two crystalline forms of TiO(2), rutile and anatase, thermal oxidation and anodic oxidation were employed to form each structure, respectively. The antibacterial effect of TiO(2) film on TiAg was also compared with that on Ti. Bacterial solutions were pipetted onto the TiO(2)-coated specimen and illuminated with UVA (2 x 15 W, black light, 356 nm) up to 100 min and the reaction solutions were incubated to count the colony-forming units. The antibacterial activity of the coated specimens was similar to that of the uncoated group. The antibacterial activity of the coated specimens of TiAg was not different from that of Ti. TiO(2) coatings formed on both Ti and TiAg specimens did not exhibit cytotoxicity on the L-929 cells of mice.

Immunomodulatory/anti-inflammatory effect of ZOE-based dental materials.

OBJECTIVE: The study assessed the cytotoxicity and immunomodulatory/anti-inflammatory effect of extract from zinc oxide-eugenol (ZOE)-based dental materials during setting using immortalized human dental pulp stem cells (IHDPSCs) and mouse bone marrow monocytes (IMBMMs), and identified the responsible extract component. METHODS: In accord with the ISO 10993-12, we extracted a mixture of ZOE cement and sealer after a specified time. The extract was analyzed by two types of mass spectrometry (ICP-MS and GC-MS). Cell viability was evaluated with extract and serial concentrations of ZnCl2, ZnSO4, and eugenol liquid by WST assay. The immunomodulatory/anti-inflammatory effect of a ZOE component was determined by RT-PCR to detect the downregulatory effect of inflammatory mRNA expression after lipopolysaccharide (LPS)-induced inflammation. RESULTS: Zn2+ and eugenol (2-20ppm) were detected in the ZOE cement and sealer extracts. During the early stage of setting, significant cytotoxicity was observed in IHDPSCs and IMBMMs (p<0.05). The half maximal effective concentration of Zn2+ was 5-8ppm, whereas that of eugenol could not be detected within 80ppm. After extract treatment, the expression of inflammatory mRNA was significantly lower in inflamed IHDPSCs, but not inflamed IMBMMs, than in the LPS control (p<0.05). However, eugenol, not Zn2+, at 5-20ppm downregulated inflammatory mRNA expression in the inflamed IMBMMs with and without the exchange of LPS-pretreated medium. SIGNIFICANCE: ZOE was highly cytotoxic, especially during setting, to both cells due to Zn2+ while the immunomodulatory/anti-inflammatory effect of ZOE was induced by eugenol.

Antibacterial activity and effect on gingival cells of microwave-pulsed non-thermal atmospheric pressure plasma in artificial saliva.

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.

Evaluation of the accuracy and precision of four intraoral scanners with 70% reduced inlay and four-unit bridge models of international standard.

The aims of this study were to evaluate the feasibility of 70% reduced inlay and 4-unit bridge models of International Standard (ISO 12836) assessing the accuracy of laboratory scanners to measure the accuracy of intraoral scanner. Four intraoral scanners (CS3500, Trios, Omnicam, and Bluecam) and one laboratory scanner (Ceramill MAP400) were used in this study. The height, depth, length, and angle of the models were measured from thirty scanned stereolithography (STL) images. There were no statistically significant mean deviations in distance accuracy and precision values of scanned images, except the angulation values of the inlay and 4-unit bridge models. The relative errors of inlay model and 4-unit bridge models quantifying the accuracy and precision of obtained mean deviations were less than 0.023 and 0.021, respectively. Thus, inlay and 4-unit bridge models suggested by this study is expected to be feasible tools for testing intraoral scanners.

Non-thermal atmospheric pressure plasma functionalized dental implant for enhancement of bacterial resistance and osseointegration.

OBJECTIVE: Even though roughened titanium (Ti) and Ti alloys have been clinically used as dental implant, they encourage bacterial adhesion, leading to failure of the initial stability. Here, the non-thermal atmospheric pressure plasma jet (NTAPPJ) functionalized Ti and Ti alloy were investigated to promote cellular activities but inhibit the initial attachment of the adherent pioneer bacterium, Streptococcus sanguinis, without topographical changes. METHODS: After the produced radicals from NTAPPJ were characterized, bacterial adhesion to specimens was assessed by PrestoBlue assay and live-dead staining with or without the NTAPPJ functionalizing. After the surface was characterized using optical profilometry, X-ray photoelectron spectroscopy and contact angle analysis, the ions released from the specimens were investigated. In vitro initial cell attachment (4h or 24h) with adhesion images and alkaline phosphatase activity (ALP, 14 days) measurements were performed using rat bone marrow-derived mesenchymal stem cells. RESULTS: The initial bacterial adhesion to the Ti and Ti alloy was significantly inhibited after NTAPPJ functionalizing (p<0.05) compared to those without NTAPPJ functionalizing. The bacterial adhesion-resistance effect was induced by carbon cleaning, which was dependent on the working gas used on the Ti specimens (nitrogen>ammonia and air, p<0.05). The initial cell adhesion with well-developed vinculin localization and consequent ALP activity at 14days to the NTAPPJ-functionalized specimens were superior to the non-treated specimens. SIGNIFICANCE: For the promising success of dental implants, NTAPPJ functionalizing is suggested as a novel surface modification technique; this technique can help ensure the success of integration between the dental implants and bone tissues with less concern of inflammation.