The immunogenic reaction and bone defect repair function of ε-poly-L-lysine (EPL)-coated nanoscale PCL/HA scaffold in rabbit calvarial bone defect.

Tissue engineering is a promising strategy for bone tissue defect reconstruction. Immunogenic reaction, which was induced by scaffolds degradation or contaminating microorganism, influence cellular activity, compromise the efficiency of tissue engineering, or eventually lead to the failure of regeneration. Inhibiting excessive immune response through modulating scaffold is critical important to promote tissue regeneration. Our previous study showed that ε-poly-L-lysine (EPL)-coated nanoscale polycaprolactone/hydroxyapatite (EPL/PCL/HA) composite scaffold has enhanced antibacterial and osteogenic properties in vitro. However, the bone defect repair function and immunogenic reaction of EPL/PCL/HA scaffolds in vivo remains unclear. In the present study, three nanoscale scaffolds (EPL/PCL/HA, PCL and PCL/HA) were transplanted into rabbit paraspinal muscle pouches, and T helper type 1 (Th1), T helper type 2 (Th2), T helper type 17 (Th17), and macrophage infiltration were analyzed after 1 week and 2 weeks to detect their immunogenic reaction. Then, the different scaffolds were transplanted into rabbit calvarial bone defect to compare the bone defect repair capacities. The results showed that EPL/PCL/HA composite scaffolds decreased pro-inflammatory Th1, Th17, and type I macrophage infiltration from 1 to 2 weeks, and increased anti-inflammatory Th2 infiltration into the regenerated area at 2 weeks in vivo, when compared to PCL and PCL/HA. In addition, EPL/PCL/HA showed an enhanced bone repair capacity compared to PCL and PCL/HA when transplanted into rabbit calvarial bone defects at both 4 and 8 weeks. Hence, our results suggest that EPL could regulate the immunogenic reaction and promote bone defect repair function of PCL/HA, which is a promising agent for tissue engineering scaffold modulation.

Alteration of occlusal vertical dimension induces signs of neuroplastic changes in corticomotor control of masseter muscles: Preliminary findings.

PURPOSE: To investigate the effect of altering occlusal vertical dimension (OVD) in patients with severe attrition on corticomotor control of the masseter muscles as assessed by navigated transcranial magnetic stimulation (nTMS). METHODS: Seven patients (58.6 ± 8.4 years) with decreased OVD due to severe attrition were given mandibular occlusal splints to alter the OVD with the instruction to wear during the whole awake time for a period of four weeks. Motor-evoked potentials (MEPs) and the motor cortex maps of the masseter muscles and first dorsal interosseous (FDI) muscles as control were recorded by nTMS at baseline and at least 4 weeks after the alteration of OVD. The stimulus-response curves of MEPs were analysed with two-way repeated-measures ANOVA, and the numerical rating scale scores, motor thresholds, onset latencies, motor cortex maps and centre of gravity (COG) were analysed with paired t tests. RESULTS: There was a significant increase in the amplitude of the masseter muscle MEPs (P = 0.036), but no change in the motor cortex map areas (P = 0.111) four weeks after the alteration of OVD. Furthermore, there was no significant difference in either the amplitude of the FDI muscle MEPs (P = 0.466) or the motor cortex map areas (P = 0.230) before and after OVD alteration. CONCLUSION: The results suggest that alteration of OVD in patients with severe attrition was associated with signs of neuroplastic changes in the corticomotor control of the masseter muscles. The results of the study may add to our understanding of the putative mechanisms related to cortical changes in response to OVD alterations.

Prevalence of dental erosion among people with gastroesophageal reflux disease in China.

STATEMENT OF PROBLEM: Gastroesophageal reflux disease (GERD) is typically diagnosed based on symptoms of regurgitation and heartburn, although it may also manifest as asthma-like symptoms, laryngitis, or dental erosion. PURPOSE: The purpose of this prospective, cross-sectional study was to assess the prevalence of dental erosion in people with GERD and to evaluate the association between GERD and dental erosion. MATERIAL AND METHODS: The presence, severity, and pattern of dental erosion was assessed in 51 participants with GERD and 50 participants without GERD using the Smith and Knight tooth wear index. Medical, dietary, and dental histories were collected by questionnaire. Factors potentially related to dental erosion, including GERD, were evaluated by logistic regression. RESULTS: Dental erosion was observed in 31 (60.8%) participants with GERD and 14 (28%) participants without GERD. Bivariate analysis revealed that participants with GERD were more likely to experience dental erosion (crude odds ratio [cOR]: 2.74; 95% CI: 1.19, 6.32) than participants without GERD. Multivariate analysis also revealed that participants with GERD had a higher risk of dental erosion (adjusted odds ratio [aOR]: 3.97; 95% CI: 1.45, 10.89). Consumption of grains and legumes, the most frequently consumed foods in China, did not correlate with dental erosion. However, carbonated beverage consumption was significantly associated with GERD and dental erosion (aOR: 3.34; 95% CI: 1.01, 11.04; P=.04). CONCLUSIONS: GERD was positively correlated with dental erosion. Carbonated beverage consumption can increase the risk of both GERD and dental erosion.

Differential changes in gingival somatosensory sensitivity after painful electrical tooth stimulation.

We aimed to evaluate the effect of painful tooth stimulation on gingival somatosensory sensitivity of healthy volunteers in a randomized, controlled design. Thirteen healthy volunteers (six women, seven men; 28.4 ± 5.0 years) were included for two experimental sessions of electrical tooth stimulation: painful tooth stimulation and tooth stimulation below the sensory threshold (control). Eight of the human subjects participated in a third session without tooth stimulation. In all sessions, the somatosensory sensitivity of the gingiva adjacent to the stimulated tooth was evaluated with a standardized battery of quantitative sensory tests (QST) before, immediately after and 30 min after tooth stimulation. Painful tooth stimulation evoked significant decreases in warmth and heat pain thresholds (P < 0.001) as well as pressure pain thresholds (increased sensitivity) (P = 0.024) and increases in mechanical detection thresholds (decreased sensitivity) (P < 0.050). Similar thermal threshold changes (P < 0.019) but no mechanical changes were found after tooth stimulation below the sensory threshold (P > 0.086). No QST changes were detected in the session without tooth stimulation (P > 0.060). In conclusion, modest increased gingival sensitivity to warmth, painful heat and pressure stimuli as well as desensitization to non-painful mechanical stimulation were demonstrated after tooth stimulation. This suggests involvement of competing heterotopic facilitatory and inhibitory mechanisms. Furthermore, stimulation below the sensory threshold induced similar thermal sensitization suggesting the possibility of activation of axon-reflex-like mechanisms even at intensities below the perception threshold. These findings may have implications for interpretation of somatosensory results in patients with chronic intraoral pain.

Reliability of a new technique for intraoral mapping of somatosensory sensitivity.

Diagnosis of intraoral pain conditions may be facilitated by assessment of somatosensory sensitivity not only at a single test site but also at multiple test sites, that is, intraoral somatosensory mapping. No standardized mapping techniques are currently available. The aim of this study was to evaluate: (1) spatial variations in somatosensory sensitivity; (2) the reliability of a new technique for mapping of intraoral somatosensory sensitivity. Fifteen healthy volunteers participated in two experimental sessions. In each session, three mechanical stimuli (32 mN and 512 mN von Frey and electronic von Frey (EVF)) were each applied to 15 test sites in a 5 × 3 matrix located at the gingivomucosal area adjacent to the upper premolar region on both sides. A custom-made silicone-based template secured standardization of the test sites. The subjects rated the perceived intensity on a 0-50-100 numerical rating scale (NRS) for tactile (32 mN) and pinprick (512 mN) stimuli and determined the pinprick threshold (PiPT) by EVF by pushing a stop button. Analyses of variance for NRS scores and PiPT for all three stimulus modalities showed no significant differences between sessions or sides (p = 0.077), whereas there were significant site-to-site differences (p < 0.001). Generally, the anterior and apical regions were more sensitive than posterior and cervical regions. Intraclass correlation coefficients for between session reliability ranged between 0.76 and 0.87 for NRS scores and PiPT measures. In conclusion, good test-retest reliability of intraoral somatosensory mapping was found with the help of a new template, which can be used for further studies of intraoral pain mechanisms.

Somatosensory profiling of intra-oral capsaicin and menthol in healthy subjects.

This study was designed to investigate the effect of surrogate orofacial pain models on the quantitative sensory testing (QST) profile in healthy participants. Capsaicin, menthol, or saline (control) were applied topically onto the gingiva of 15 healthy subjects for 15 min. During application, the subjects rated pain intensity on a score of 0-10, on an electronic visual analog scale (VAS). A standardized intra-oral QST protocol was performed before and immediately after application. Data obtained before and after application were compared using rank-sum tests, and QST profiles were made after Z-transformation. Application of capsaicin caused moderate levels of pain (VAS(peak)  = 6.0 ± 0.7), and application of menthol produced mild levels of pain (VAS(peak)  = 1.8 ± 0.6). Capsaicin induced hypersensitivity to warmth, heat pain and cold pain and hyposensitivity to mechanical stimuli. Menthol induced hypersensitivity to cold and warmth. Saline caused hypersensitivity to heat pain and hyposensitivity to mechanical stimuli. However, somatosensory profiles from Z-scores demonstrated sensory gains regarding warmth detection and heat pain only after application of capsaicin. In conclusion, a standardized battery of QST showed somatosensory changes after application of capsaicin, menthol and saline to the gingiva. However, the Z-score-based profiles may only reflect the most prominent somatosensory changes and thus represent a conservative approach for evaluation of data.

Optimized titanium dioxide nanotubes for dental implants: Estimation of mechanical properties and effects on the biological behaviors of human gingival fibroblasts and oral bacteria.

The long-term successes of implant restorations rely on both appropriate osseointegration and robust soft tissue integration (STI). Numerous studies have reported that titanium dioxide nanotube (TNT) arrays formed by electrochemical anodization (EA) can promote early osteogenesis, but the mechanical stability of such modifications is often ignored and remains underexplored. In addition, relatively little research has been done on their effects on soft tissues integration. In this study, we developed mechanically robust TNT arrays using an optimized EA system. Subsequently, we immobilized a peptide, specifically D-amino K122-4, onto the anodized TNTs via polydopamine (PDA) films to enhance their mechanical properties. Surface morphology and composition were characterized by scanning electron microscopy (SEM), atomic force microscopy, and X-ray photoelectron spectroscopy. Mechanical properties, including the elastic modulus and hardness of TNTs modified Ti surfaces, were assessed using the nano-indention test. The adhesive strength of TNTs films to the substrate was measured using the nano scratch test. Furthermore, we evaluated the adhesion, spreading, and proliferation of human gingival fibroblasts (HGFs) and periodontal pathogenic bacteria such as Streptococcus mutans (S.m) and F. nucleatum (F.n) on the surface. Results showed that the elastic modulus, hardness, and adhesive strength of anodized TNTs were significantly enhanced by the incorporation of the D-amino K122-4 peptide. Live-dead staining and SEM observation suggested a decreased surface colonization by both bacterial species. The antibacterial rate of S.m and F. n was 81.5% and 71.7%, respectively, evaluated by colony counting method. Additionally, results of CCK8 assay showed that modified TNTs slightly stimulated HGFs attachment and proliferation while producing enhanced fluorescence of integrin ß1 and F-actin, confirmed by laser confocal microscopy observation. Thus, D-amino K122-4 biofunctionalized TNTs present significantly improved mechanical properties, and the mechanically robust structures modulate HGFs proliferation and alignment, resulting in decreased bacteria growth. This novel strategy has the potential to create a surface coating for implants that exhibits superior mechanical robustness and enhanced surface-to-implant interactions.

Evaluation of marginal gap of lithium disilicate glass ceramic crowns with optical coherence tomography.

Marginal gap (MG) was the most important factor to evaluate the success of crowns. The study was to assess the MG of lithium disilicate glass ceramic crowns with spectral domain optical coherence tomography (OCT) and stereomicroscopy in vitro, and to provide evidence to measure the MG with OCT. Consistency was observed between OCT and stereomicroscopy to measure the MG after cementation. There was no significant difference between the MG of lithium disilicate glass ceramic crowns using OCT and stereomicroscopy (OCT 59.55 ± 7.22 µm, stereomicroscope 59.48 ± 6.53 µm, P = 0.736) after cementation. OCT was a noninvasive diagnostic technique to measure the MG of lithium disilicate glass ceramic crowns.

Bridging the gap: Optimized fabrication of robust titania nanostructures on complex implant geometries towards clinical translation.

Electrochemically anodized titanium surfaces with titania nanostructures (TNS; nanopores, nanotubes, etc.) have been widely applied as therapeutic bone/dental implant modifications. Despite the numerous advancements in the field of electrochemical anodization (EA), in terms of translation into the current implant market, research gaps in this domain include the lack of fabrication optimization, performed on a substrate of conventional implant surface/geometry, and inadequate mechanical stability. In the current study, we investigate the role of substrate pre-treatment on achieving desired nanotopographies for the purpose of reproducing optimized nanostructures on the complex geometry of commercial implant surfaces, as well as in-depth mechanical stability testing of these nano-engineered coatings. The results confirmed that: (a) substrate polishing/smoothening may be insignificant with respect to fabrication of well-ordered and high quality TNS on micro-rough implants with preserved underlying micro-roughness; (b) optimized outcomes can be successfully translated onto complex geometries characteristic of the current implant market, including dental implant abutments and screws (also applicable to a wider implant market including orthopaedics); (c) mechanical stability testing revealed improved modulus and hardness values as compared to conventional nanotubes/pores. We believe that such optimization advances the existing knowledge of titanium anodization and anodized implants towards integration into the current implant market and successful clinical translation.

Understanding and augmenting the stability of therapeutic nanotubes on anodized titanium implants.

Titanium is an ideal material choice for orthopaedic and dental implants, and hence a significant amount of research has been focused towards augmenting the therapeutic efficacy of titanium surfaces. More recently the focus has shifted to nano-engineered implants fabricated via anodization to generate self-ordered nanotubular structures composed of titania (TiO2). These structures (titania nanotubes/TNTs) enable local drug delivery and tailorable cellular modulation towards achieving desirable effects like enhanced osseointegration and antibacterial action. However, the mechanical stability of such modifications is often ignored and remains underexplored, and any delamination or breakage in the TNTs modification can initiate toxicity and lead to severe immuno-inflammatory reactions. This review details and critically evaluates the progress made in relation to this aspect of TNT based implants, with a focus on understanding the interface between TNTs and the implant surface, treatments aimed at augmenting mechanical stability and strategies for advanced mechanical testing within the bone micro-environment ex vivo and in vivo. This review article extends the existing knowledge in this domain of TNTs implant technology and will enable improved understanding of the underlying parameters that contribute towards mechanically robust nano-engineered implants that can withstand the forces associated with implant surgical placement and the load bearing experienced at the bone/implant interface.

Antibacterial activity and cytocompatibility of an implant coating consisting of TiO2 nanotubes combined with a GL13K antimicrobial peptide.

Prevention of implant-associated infections at an early stage of surgery is highly desirable for the long-term efficacy of implants in dentistry and orthopedics. Infection prophylaxis using conventional antibiotics is becoming less effective due to the development of bacteria resistant to multiple antibiotics. An ideal strategy to conquer bacterial infections is the local delivery of antibacterial agents. Therefore, antimicrobial peptide (AMP) eluting coatings on implant surfaces is a promising alternative. In this study, the feasibility of utilizing TiO2 nanotubes (TNTs), processed using anodization, as carriers to deliver a candidate AMP on titanium surfaces for the prevention of implant-associated infections is assessed. The broad-spectrum GL13K (GKIIKLKASLKLL-CONH2) AMP derived from human parotid secretory protein was selected and immobilized to TNTs using a simple soaking technique. Field emission scanning electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy, and liquid chromatography-mass spectrometry analyses confirmed the successful immobilization of GL13K to anatase TNTs. The drug-loaded coatings demonstrated a sustained and slow drug release profile in vitro and eradicated the growth of Fusobacterium nucleatum and Porphyromonas gingivalis within 5 days of culture, as assessed by disk-diffusion assay. The GL13K-immobilized TNT (GL13K-TNT) coating demonstrated greater biocompatibility, compared with a coating produced by incubating TNTs with equimolar concentrations of metronidazole. GL13K-TNTs produced no observable cytotoxicity to preosteoblastic cells (MC3T3-E1). The coating may also have an immune regulatory effect, in support of rapid osseointegration around implants. Therefore, the combination of TNTs and AMP GL13K may achieve simultaneous antimicrobial and osteoconductive activities.

Effect of Experimental Periodontal Ligament Pain on Gingival Somatosensory Sensitivity.

AIMS: To use a randomized, blinded, crossover design to evaluate the possible heterotopic effects of experimental periodontal ligament pain on adjacent gingival somatosensory sensitivity. METHODS: A total of 12 healthy volunteers (8 female, 4 male; mean age ± standard error in means (SEM): 28 ± 1 years) participated in two randomized experimental quantitative sensory testing (QST) sessions, one in which capsaicin (experimental) was injected into the periodontal ligament and one in which isotonic saline (control) was injected. A total of 13 standardized QST measures were obtained on the buccal attached gingiva of a maxillary central incisor before, immediately after, and 30 minutes after injection of 30 µL of 5% capsaicin or isotonic saline into the periodontal ligament of the same incisor. The injection-evoked pain was evaluated on a 0-10 numeric rating scale (NRS). QST data were analyzed with two-way repeated measurement analysis of variance. RESULTS: Capsaicin injected into the periodontal ligament evoked moderate levels of pain (mean peak NRS ± SEM: capsaicin: 5.5 ± .7; control: 0.6 ± 0.5 [P < .001]). Capsaicin injected into the periodontal ligament significantly modulated gingival somatosensory sensitivity: increased sensitivity to warmth and painful heat stimuli occurred immediately and 30 minutes after the injection (P < .025), whereas decreased sensitivity to both tactile and painful mechanical stimuli (P < .011) occurred immediately after the injection and to painful mechanical stimuli only after 30 minutes (P = .016). No somatosensory changes were detected following the injection of isotonic saline (P > .050). CONCLUSION: Capsaicin injected into the periodontal ligament caused gain of heterotopic somatosensory sensitivity toward warmth and painful heat stimuli as well as reduction in mechanical sensitivity of the gingiva adjacent to the injected tooth. These findings may have implications for interpretation of somatosensory functions in patients with chronic intraoral pain, where gingival somatosensory profiles similar to those detected after capsaicin injection in the present study may be interpreted as signs of nerve damage.

Comparison of high-titer lactic acid fermentation from NaOH- and NH3-H2O2-pretreated corncob by Bacillus coagulans using simultaneous saccharification and fermentation.

Lignocellulose is one of the most abundant renewable feedstocks that has attracted considerable attention as a substrate for biofuel and biochemical production. One such biochemical product, lactic acid, is an important fermentation product because of its great potential for the production of biodegradable and biocompatible polylactic acid. High-titer lactic acid production from lignocellulosic materials has been achieved recently; however, it requires biodetoxification or results in large amounts of waste washing water. In this study, we employed two alkaline pretreatment methods and compared their effects on lactic acid fermentation of pretreated corncob by Bacillus coagulans LA204 using fed-batch simultaneous saccharification and fermentation under non-sterile conditions. The lactic acid titer, yield, and productivity from 16% (w/w) NaOH-pretreated and washed corncob were 122.99 g/L, 0.77 g/g corncob, and 1.37 g/L/h, respectively, and from 16% NH3-H2O2-pretreated and washed corncob were 118.60 g/L, 0.74 g/g corncob, and 1.32 g/L/h, respectively. Importantly, the lactic acid titer, yield, and productivity from 18.4% NH3-H2O2-pretreated and unwashed corncob by using fed-batch simultaneous saccharification and fermentation reached 79.47 g/L, 0.43 g/g corncob, and 1.10 g/L/h, respectively, demonstrating that this method is possible for industrial applications and saves washing water.

Spatial and Temporal Effects of Capsaicin and Menthol on Intraoral Somatosensory Sensitivity.

AIMS: To assess the spatial and temporal sensory effects of the topical application of capsaicin and menthol on the gingiva of healthy volunteers. METHODS: Capsaicin, menthol, and saline (control) were applied topically on the gingiva in the maxillary premolar area of healthy volunteers for 15 minutes. Pain intensity was rated on a 0 to 10 visual analog scale (VAS). Before, immediately after, and 30 minutes after application, three mechanical stimuli were applied at 15 gingival sites: fixed-intensity stimuli were applied by 32 mN and 512 mN von Frey filaments, and stimuli of increasing intensity were applied by an electronic von Frey (EVF, 10 g/s). The EVF was used to test the pinprick pain threshold (PiPT). The perceived pain from filament stimulation was rated on a 0-50-100 numeric rating scale (NRS). Analysis of variance for repeated measures was used to analyze the NRS scores, PiPT values, the number of hypersensitive or hyposensitive test sites, and the coordinates of the center of gravity (COG) of somatosensory sensitivity. RESULTS: The mean ± SEM VAS score of pain intensity produced by the application of capsaicin (4.6 ± 0.5) was significantly higher than that produced by menthol (0.3 ± 0.2) and saline (0.1 ± 0.1) (P < .001). Capsaicin induced local desensitization to all stimuli (P < .047) , and at the application site, capsaicin induced significant desensitization to 512 mN stimuli (P = .003). Menthol did not induce significant somatosensory changes (P > .147), and saline induced slight desensitization in two sites surrounding the application site (P < .023). The COG coordinates did not shift significantly over time during any condition (P > .125). CONCLUSION: Capsaicin but not menthol induced mechanical desensitization in the application area but not in the surrounding areas.

High-titer lactic acid production from NaOH-pretreated corn stover by Bacillus coagulans LA204 using fed-batch simultaneous saccharification and fermentation under non-sterile condition.

Lactic acid (LA) is an important chemical with various industrial applications. Non-food feedstock is commercially attractive for use in LA production; however, efficient LA fermentation from lignocellulosic biomass resulting in both high yield and titer faces technical obstacles. In this study, the thermophilic bacterium Bacillus coagulans LA204 demonstrated considerable ability to ferment glucose, xylose, and cellobiose to LA. Importantly, LA204 produces LA from several NaOH-pretreated agro stovers, with remarkably high yields through simultaneous saccharification and fermentation (SSF). A fed-batch SSF process conducted at 50°C and pH 6.0, using a cellulase concentration of 30 FPU (filter paper unit)/g stover and 10 g/L yeast extract in a 5-L bioreactor, was developed to produce LA from 14.4% (w/w) NaOH-pretreated non-sterile corn stover. LA titer, yield, and average productivity reached 97.59 g/L, 0.68 g/g stover, and 1.63 g/L/h, respectively. This study presents a feasible process for lignocellulosic LA production from abundant agro stovers.

Nanotubes Functionalized with BMP2 Knuckle Peptide Improve the Osseointegration of Titanium Implants in Rabbits.

To determine the effects of surface modification on implant osseointegration in vivo, we first immobilized polydopamine onto 70-nm diameter TiO2 nanotubes as an intermediate layer, and then conjugated a 21 amino acid peptide sequence (the so-called "knuckle peptide") of bone morphogenetic protein-2 (BMP-2) onto the nanotubes created by electrochemical anodization. We inserted these implants into the tibiae of rabbits and measured the gene expression and bone formation around them. The successful fabrication of BMP-2 knuckle peptide was confirmed by contact angle measurement, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The histological features and the amount of bone fluorescence around the implants on non-decalcified sections were investigated at 3, 5, 8, and 12 weeks after implantation using traditional light and fluorescence microscopy, and the gene expression of alkaline phosphatase, osterix, collagen-I, and tartrate-resistant acid phosphatase was examined by real-time PCR at 1, 2, 3, 4, and 5 weeks after implantation. The results demonstrated a significant increase in bone-implant contact, quantity of fluorescence, and gene expression levels of the bone attached to implants with immobilized BMP-2 knuckle peptide compared with the other two control groups. In conclusion, the surface functionalization of TiO2 nanotubes with BMP-2 knuckle peptide was beneficial for osseointegration and this approach could be further developed to improve Ti-based implants for various applications.

Antibacterial and osteogenic stem cell differentiation properties of photoinduced TiO2 nanoparticle-decorated TiO2 nanotubes.

AIM: To improve the antibacterial and mammalian cell compatibility properties of titania nanotubes (TNTs) anodized into titanium (Ti). MATERIALS & METHODS: 3-8-nm TiO2 nanoparticles were decorated on the surface and inside TNT (TNT-TiO2) through a hydrothermal method. After UV light treatment, two types of oral bacteria and stem cells were cultured on the samples to determine antibacterial and compatibility properties. RESULTS: TiO2 nanoparticles increased the surface area and photocatalysis of TNTs. Based on the photocatalysis effect and prolonged photo-induced wettability, the numbers of Streptococcus mutans and Porphyromonas gingivalis were lower on the surface of TNT-TiO2 than pure Ti and TNTs after the first 7 days. Specifically, for S. mutans, the glycosytransferase (gtf) genes were downregulated 0.1-0.2-fold on TNT-TiO2. Due to the different topography and high surface energy of TNT-TiO2, stem cells also showed improved osteogenic functions on TNT-TiO2. CONCLUSION: In this study, we demonstrated for the first time improved antibacterial properties and, at the same time, greater stem cell osteogenic capacity when decorating TNTs with nanosized TiO2 particles, which may significantly improve orthopedic and dental implant efficacy.

Optimizing stem cell functions and antibacterial properties of TiO2 nanotubes incorporated with ZnO nanoparticles: experiments and modeling.

To optimize mesenchymal stem cell differentiation and antibacterial properties of titanium (Ti), nano-sized zinc oxide (ZnO) particles with tunable concentrations were incorporated into TiO2 nanotubes (TNTs) using a facile hydrothermal strategy. It is revealed here for the first time that the TNTs incorporated with ZnO nanoparticles exhibited better biocompatibility compared with pure Ti samples (controls) and that the amount of ZnO (tailored by the concentration of Zn(NO3)2 in the precursor) introduced into TNTs played a crucial role on their osteogenic properties. Not only was the alkaline phosphatase activity improved to about 13.8 U/g protein, but the osterix, collagen-I, and osteocalcin gene expressions was improved from mesenchymal stem cells compared to controls. To further explore the mechanism of TNTs decorated with ZnO on cell functions, a response surface mathematical model was used to optimize the concentration of ZnO incorporation into the Ti nanotubes for stem cell differentiation and antibacterial properties for the first time. Both experimental and modeling results confirmed (R (2) values of 0.8873-0.9138 and 0.9596-0.9941, respectively) that Ti incorporated with appropriate concentrations (with an initial concentration of Zn(NO3)2 at 0.015 M) of ZnO can provide exceptional osteogenic properties for stem cell differentiation in bone cells with strong antibacterial effects, properties important for improving dental and orthopedic implant efficacy.

Synthesis of TiO2 nanotubes with ZnO nanoparticles to achieve antibacterial properties and stem cell compatibility.

To endow titanium (Ti) with antibacterial properties, different concentrations of zinc oxide (ZnO) nanoparticles were decorated on anodized titanium dioxide (TiO2) nanotubes by a simple hydrothermal treatment method. The particle sizes of ZnO, which were evenly distributed and tightly adherent to the walls of the Ti nanotubes, ranged from 20-50 nm. Results from this study showed that Zn was released from the TiO2 nanotubes in a constant, slow, and biologically inspired manner. Importantly, the results showed that the ZnO decorated TiO2 nanotubular samples inhibited Streptococcus mutants and Porphyromonas gingivalis growth compared to control unmodified Ti samples. Specifically, S. mutants and P. gingivalis growth were both reduced 45-85% on the ZnO decorated Ti samples compared to Ti controls after 7 days of culture. When examining the mechanism of action, it has been further found for the first time that the ZnO decorated Ti samples inhibited the expression of Streptococcus mutans bacterial adhesion genes. Lastly, the results showed that the same samples which decreased bacterial growth the most (0.015 M precursor Zn(NO3)2 samples) did not inhibit mesenchymal stem cell growth compared to Ti controls for up to 7 days. In summary, results from this study showed that compared to plain TiO2 nanotubes, TiO2 decorated with 0.015 M ZnO provided unprecedented antibacterial properties while maintaining the stem cell proliferation capacity necessary for enhancing the use of Ti in numerous medical applications, particularly in dentistry.

[Effect of platelet-rich plasma on cell proliferation and osteogenic activity of pulp stem cells].

OBJECTIVE: To evaluate the effects of different concentrations of platelet-rich plasma (PRP) on human dental pulp stem cells (hDPSC) proliferation and osteogenic differentiation activity so as to provide basis for future application of dental pulp stem cells and PRP in tissue engineering and bone repair therapy. METHODS: hDPSC were isolated and cultivated in vitro. Flow cytometric analysis was carried out to test the expression of STRO-1.hDPSC were cultured in various concentrations of PRP (1%, 5%, 10%, 20%). At the 2nd and 6th day 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) was tested. Osteogenic differentiation of hDPSC was assessed using alkaline phosphatase (ALP) staining and Alizarin Red staining at the 7th and 14th day. RESULTS: Flow cytometric analysis demonstrated that 14.82% of hDPSC were STRO-1 positive. One percent to 20% PRP showed significant effect of promoting hDPSC proliferation. One percent to 10% PRP showed significant effect of promoting hDPSC osteogenic differentiation. CONCLUSIONS: Certain concentrations of PRP can promote hDPSC proliferate and osteogenic differentiate, and this finding suggests future application of dental pulp stem cells and PRP in bone tissue engineering.