Does the internal surface treatment technique for enhanced bonding affect the color, transparency, and surface roughness of ultra-transparent zirconia?

PURPOSE: To investigate the effects of different surface treatments and thicknesses on the color, transparency, and surface roughness of ultra-transparent zirconia. METHODS: A total of 120 Katana ultra-translucent multi-layered zirconia specimens were divided into 12 groups according to the thickness (0.3, 0.5, and 0.7 mm) and surface treatment (control, airborne particle abrasion [APA], lithium disilicate coating, and glaze on). Color difference (ΔE00) and relative translucency parameter (RTP00) were calculated using a digital spectrophotometer. The surface roughness (Ra, Rq, Sa, and Sq) was measured using a non-contact profile scanner. The surface morphologies and microstructures of the samples were observed using a tungsten filament scanning electron microscope. Statistical analyses were performed by one-way and two-way analysis of variance (ANOVA) followed by post hoc multiple comparisons and Pearson's correlation (α = 0.05). RESULTS: The results showed that the surface treatment, ceramic thickness, and their interactions had significant effects on ΔE00 and RTP00 (p < 0.001). The surface treatment significantly altered the micromorphology and increased the surface roughness of the ceramic samples. APA exhibited the lowest transparency, largest color difference, and highest surface roughness. Zirconia with 0.3 mm and 0.7 mm thicknesses showed strong negative correlations between Sa and RTP00. CONCLUSIONS: The three internal surface treatments significantly altered the surface roughness, color difference, and transparency of ultra-transparent zirconia. As the thickness increased, the influence of the inner surface treatment on the color difference and transparency of zirconia decreased. CLINICAL IMPLICATIONS: For new zirconia internal surface treatment technologies, in addition to considering the enhancement effect on the bonding properties, the potential effects on the color and translucency of high-transparency zirconia should also be considered. Appropriately increasing the thickness of zirconia restorations helps minimize the effect of surface treatment on the optical properties.

Effect of the coloring liquid shade and dipping time on the color, transparency, and flexural strength of monolithic zirconia.

STATEMENT OF PROBLEM: The impact of different coloring liquid shades and dipping times on the color, transparency, and flexural strength of monolithic zirconia ceramics is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effects of different coloring liquid shades (A2, 3M2, and 5M2) and dipping times (no dipping, 30 seconds, 60 seconds, and 90 seconds) on the color difference (ΔE00), relative translucency parameter (ΔRTP00), and 3-point flexural strength (σ) of monolithic zirconia ceramics. MATERIAL AND METHODS: Yttria-stabilized zirconia (3Y-TZP, 3 mol%) was cut into Ø16×1.2-mm plates (n=10) and 25×4×1.2-mm bars (n=15), which were colored using 3 shades of coloring liquid at 4 dipping times. Color coordinates were measured on a gray background by using a digital spectrophotometer with an integrating sphere attachment. The color and translucency differences were evaluated using 50:50% perceptibility (PT00 and TPT00) and acceptability (AT00 and TAT00) thresholds. The 3-point flexural strengths of the bar-shaped specimens were measured using a universal testing machine and analyzed using the Weibull distribution to calculate the Weibull modulus (m) and characteristic fracture strength (σ0). The data were analyzed with the 2-way ANOVA, Kruskal-Wallis, and LSD post hoc tests (α=.05). RESULTS: Both shade and dipping time significantly affected the color and translucency of monolithic zirconia (P<.001). The ΔE00 was above the PT00 for all groups, with only 3M2-90 and A2-60 being below the AT00. The main cause of color differences was the difference in lightness. Only A2 showed ΔRTP00 below the TPT00 (A2-30 (ΔRTP00=0.26), A2-60 (ΔRTP00=0.29), and A2-90 (ΔRTP00=0.46)). All experimental groups showed translucency differences below TAT00. In addition, only the dipping time had a significant effect on the flexural strength of zirconia (P<.001). CONCLUSIONS: The optical properties of monolithic zirconia ceramics were affected by the shade and dipping time of the coloring liquid. The mismatch in lightness was the main reason for the color difference. The dipping time affects the flexural strength of monolithic zirconia, whereas the shade of the coloring liquid did not seem to influence flexural strength.

Effects of Photobiomodulation Therapy on Hard Tissue Healing in Rat Tooth Extraction Sockets.

Objective: To investigate the effects of photobiomodulation therapy (PBMT) on hard tissue healing in rat maxillary first molar extraction sockets. Methods: A total of 20 male Wistar rats were used in the study. The right extraction sockets were irradiated with a Ga-Al-As laser (500 mW, 980 nm) for 51.7 J/cm2 every 24 h for 7 days, while the left sockets served as controls. Rats were sacrificed on days 3, 7, 14, and 28 after tooth extraction, and microcomputed tomography (CT) analysis, histopathological evaluation, and enzyme-linked immunosorbent assay (ELISA) were conducted at different time points. Results: Micro-CT analysis showed that the percentage of bone volume/tissue volume (TV) and bone mineral density were significantly higher in the experimental group compared to the control group on day 28 (p < 0.05). Histopathological evaluation revealed that PBMT promoted new bone formation and accelerated bone remodeling. ELISA demonstrated a significant increase in alkaline phosphatase expression in the laser sides on days 7 and 14 (p < 0.05). Conclusions: One application postextraction followed by seven consecutive daily applications of PBMT can effectively promote hard tissue healing in rat maxillary first molar extraction sockets.

Photoassisted Strategy to Promote Glycerol Electrooxidation to Lactic Acid Coupled with Hydrogen Production.

Electrocatalytic oxidation of glycerol (GLY; from a biodiesel byproduct) to lactic acid (LA; the key monomers for polylactic acid; PLA) is considered a sustainable approach for biomass waste upcycling and is coupled with cathodic hydrogen (H2) production. However, current research still suffer from issues of low current density and low LA selectivity. Herein, we reported a photoassisted electrocatalytic strategy to achieve the selective oxidation of GLY to LA over a gold nanowire (Au NW) catalyst, attaining a high current density of 387 mA cm-2 at 0.95 V vs RHE, together with a high LA selectivity of 80%, outperforming most of the reported works in the literature. We reveal that the light-assistance strategy plays a dual role, which can both accelerate the reaction rate through the photothermal effect and also promote the adsorption of the middle hydroxyl of GLY over Au NWs to realize the selective oxidation of GLY to LA. As a proof-of-concept, we realized the direct conversion of crude GLY that was extracted from cooking oil to attain LA and coupled it with H2 production using the developed photoassisted electrooxidation process, revealing the potential of this strategy in practical applications.

Electrocatalytic Upcycling of Biomass and Plastic Wastes to Biodegradable Polymer Monomers and Hydrogen Fuel at High Current Densities.

Transformation of biomass and plastic wastes to value-added chemicals and fuels is considered an upcycling process that is beneficial to resource utilization. Electrocatalysis offers a sustainable approach; however, it remains a huge challenge to increase the current density and deliver market-demanded chemicals with high selectivity. Herein, we demonstrate an electrocatalytic strategy for upcycling glycerol (from biodiesel byproduct) to lactic acid and ethylene glycol (from polyethylene terephthalate waste) to glycolic acid, with both products being as valuable monomers for biodegradable polymer production. By using a nickel hydroxide-supported gold electrocatalyst (Au/Ni(OH)2), we achieve high selectivities of lactic acid and glycolic acid (77 and 91%, respectively) with high current densities at moderate potentials (317.7 mA/cm2 at 0.95 V vs RHE and 326.2 mA/cm2 at 1.15 V vs RHE, respectively). We reveal that glycerol and ethylene glycol can be enriched at the Au/Ni(OH)2 interface through their adjacent hydroxyl groups, substantially increasing local concentrations and thus high current densities. As a proof of concept, we employed a membrane-free flow electrolyzer for upcycling triglyceride and PET bottles, attaining 11.2 g of lactic acid coupled with 9.3 L of H2 and 13.7 g of glycolic acid coupled with 9.4 L of H2, respectively, revealing the potential of coproduction of valuable chemicals and H2 fuel from wastes in a sustainable fashion.

The extract of concentrated growth factor enhances osteogenic activity of osteoblast through PI3K/AKT pathway and promotes bone regeneration in vivo.

BACKGROUND: Concentrated growth factor (CGF) is a third-generation platelet concentrate product; the major source of growth factors in CGF is its extract; however, there are few studies on the overall effects of the extract of CGF (CGF-e). The aim of this study was to investigate the effect and mechanism of CGF-e on MC3T3-E1 cells in vitro and to explore the effect of combination of CGF-e and bone collagen (Bio-Oss Collagen, Geistlich, Switzerland) for bone formation in cranial defect model of rats in vivo. METHODS: The cell proliferation, ALP activity, mineral deposition, osteogenic-related gene, and protein expression were evaluated in vitro; the newly formed bone was evaluated by histological and immunohistochemical analysis through critical-sized cranial defect rat model in vivo. RESULTS: The cell proliferation, ALP activity, mineral deposition, osteogenic-related gene, and protein expression of CGF-e group were significantly increased compared with the control group. In addition, there was significantly more newly formed bone in the CGF-e + bone collagen group, compared to the blank control group and bone collagen only group. CONCLUSIONS: CGF-e activated the PI3K/AKT signaling pathway to enhance osteogenic differentiation and mineralization of MC3T3-E1 cells and promoted the bone formation of rat cranial defect model.

Concentrate Growth Factors Regulate Osteogenic Dysfunction of MC3T3-E1 Cells Induced by High Glucose Through PI3K/Akt Signaling Pathway.

INTRODUCTION: The aim of this study is to investigate the effects of Concentrate Growth Factors Extract (CGF-e) on the proliferation and osteogenic differentiation of MC3T3-E1 cells under high glucose condition. MATERIALS AND METHODS: MC3T3-E1 cells were divided into 4 groups including normal glucose (5.5-mM) group (control), high glucose (25.5-mM) group, normal glucose + CGF-e group, and high glucose + CGF-e group. The proliferation, osteogenic differentiation and mineralization of osteoblasts were evaluated, respectively, by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, cytoskeleton analysis, alkaline phosphatase activity assay, alizarin red staining, and real-time polymerase chain reaction. Western blots analysis was used to explore the role of PI3K/Akt pathway. RESULTS: The viability, osteogenic differentiation, and mineralization of MC3T3-E1 cells were significantly decreased by high glucose. All observed osteogenic dysfunction were inhibited by CGF-e. Moreover, the PI3K/Akt pathway was activated by CGF-e. CONCLUSIONS: It was concluded that the soluble factors released by CGF could significantly attenuate high glucose-mediated MC3T3-E1 cells osteogenic dysfunction through the PI3K/Akt pathway.

Alpha-Lipoic Acid Alleviates High-Glucose Suppressed Osteogenic Differentiation of MC3T3-E1 Cells via Antioxidant Effect and PI3K/Akt Signaling Pathway.

BACKGROUND/AIMS: Patients with diabetes mellitus have a higher risk of dental implant failure. One major cause is high-glucose induced oxidative stress. Alpha-lipoic acid (ALA), a naturally occurring compound and dietary supplement, has been established as a potent antioxidant that is a strong scavenger of free radicals. However, few studies have yet investigated the effect of ALA on osteogenic differentiation of osteoblasts cultured with high glucose medium. The aim of this study is to investigate the effects of ALA on the osteoblastic differentiation in MC3T3-E1 cells under high glucose condition. METHODS: MC3T3-E1 cells were divided into 4 groups including normal glucose (5.5 mM) group (control), high glucose (25.5 mM) group, high glucose + 0.1 mM ALA group, and high glucose + 0.2 mM ALA group. The proliferation, osteogenic differentiation and mineralization of cells were evaluated by MTT assay, alkaline phosphatase (ALP) activity assay, alizarin red staining and real time-polymerase chain reaction. High-glucose induced oxidative damage was also assessed by the production of reactive oxygen species (ROS) and superoxide dismutase (SOD). Western blots were performed to examine the role of PI3K/Akt pathway. RESULTS: The proliferation, osteogenic differentiation and mineralization of MC3T3-E1 cells were significantly decreased by the ROS induced by high-glucose. All observed oxidative damage and osteogenic dysfunction induced were inhibited by ALA. Moreover, the PI3K/Akt pathway was activated by ALA. CONCLUSIONS: We demonstrate that ALA may attenuate high-glucose mediated MC3T3-E1 cells dysfunction through antioxidant effect and modulation of PI3K/Akt pathway.

Hyperlipidemia compromises homing efficiency of systemically transplanted BMSCs and inhibits bone regeneration.

PURPOSE: Mesenchymal stem cells (MSCs) can selectively home to bone defects and play an essential role in promoting bone regeneration. As an adverse effect factor for bone metabolism, hyperlipidemia significantly impairs bone regeneration. In this study, bone marrow stromal cells (BMSCs) were systemically transplanted into a hyperlipidemic mouse model to explore the effect of hyperlipidemia on stem cell recruitment and bone regeneration. METHODS: Hyperlipidemia was established in ApoE-/- mice (on C57BL/6J background) fed with a high fat diet (HFD) for five weeks. C57BL/6 mice fed with the same diet served as controls. BMSCs labeled with the green fluorescent protein (GFP) were then injected via the tail vein and bone defects were created in the mandibles. The animals were sacrificed at weeks 1, 2 and 4 after surgery, and the fate of the transplanted BMSCs was monitored with a fluorescence microscope and immunohistochemical analysis. After hematoxylin and eosin (HE) staining and Masson's Trichrome (MT) staining, histomorphometric analysis was performed to evaluate bone regeneration. RESULTS: In both groups transplanted with BMSCs, the number of GFP-positive BMSCs detected in the bone defects reached its peak at 1 week after surgery and was decreased thereafter. However, at all time points, less GFP+ cells were detected in the ApoE-/- mice than in the corresponding control mice. BMSCs transplantation significantly enhanced new bone formation, but to a lesser degree in the ApoE-/- mice when compared with the control mice. CONCLUSIONS: Hyperlipidemia compromises homing efficiency of systemically transplanted BMSCs and inhibits bone regeneration.

Effect of umbilical cord mesenchymal stem cell in peri-implant bone defect after immediate implant: an experiment study in beagle dogs.

BACKGROUND: For the sake of reducing post extraction resorption, getting optimal positioning of the implant and shortening treatment time, immediate implant placement following tooth extraction has been proposed as a treatment option. However, the large bone defect peri-implant has a negative influence on the process of bone healing. In this study, umbilical cord mesenchymal stem cells (UCMSCs) were transplanted into the bone defect peri-implant inbeagle dogs and the effect of UCMSCs on bone regeneration in peri-implant were assessed. METHODS: The mandibular second, third and fourth premolars of 8 beagle dogs were extracted bilaterally. The defects in one side were filled with platelet-rich fibrin (PRF) and then UCMSCs were injected into the defect area, while the defects in the other side were filled with PRF only as control group. The titanium implant was placed into the distal root socket of each extracted tooth. The animals were sacrificed at week 2, 4 and 8 post operative. The bone defects adjacent to the implant which are 4 mm in height, 4 mm in the mesio-distal direction and 3.5 mm in the bucco-lingual direction were made after immediate implant. Histomorphometric analysis was performed using methylene blue-fuchsin acid staining and hematoxylin and eosin (HE) staining to evaluate bone regeneration. RESULTS: The direct bone-to-implant contact (BIC) in the experiment after 4 and 8 weeks was 56.47±1.18% and 76.23±2.08%; and in the control group was40.79±0.65% and 61.17±2.79%, respectively. The percentage of newly formed bone after 2, 4 and 8 weeks was 17.60±1.5%, 49.82±4.02% and 67.16±2.1% in experiment group; and in control group 14.30±1.25%, 37.04±2.29% and 58.83±3.36%, respectively. These results represented significant differences statistically. CONCLUSION: Intra-bone marrow injection of UCMSCs can promote new bone formation. UCMSCs can be used to as excellent seed cells to repair the large defect peri-implant after immediate implant.

Effect of umbilical cord mesenchymal stem cell in peri-implant bone defect after immediate implant: an experiment study in beagle dogs.

BACKGROUND: For the sake of reducing post extraction resorption, getting optimal positioning of the implant and shortening treatment time, immediate implant placement following tooth extraction has been proposed as a treatment option. However, the large bone defect peri-implant has a negative influence on the process of bone healing. In this study, umbilical cord mesenchymal stem cells (UCMSCs) were transplanted into the bone defect peri-implant in beagle dogs and the effect of UCMSCs on bone regeneration in peri-implant were assessed. METHODS: The mandibular second, third and fourth premolars of 8 beagle dogs were extracted bilaterally. The defects in one side were filled with platelet-rich fibrin (PRF) and then UCMSCs were injected into the defect area, while the defects in the other side were filled with PRF only as control group. The titanium implant was placed into the distal root socket of each extracted tooth. The animals were sacrificed at week 2, 4 and 8 post operation. The bone defects adjacent to the implant which are 4 mm in height, 4 mm in the mesio-distal direction and 3.5 mm in the bucco-lingual direction were made after immediate implant. Histomorphometric analysis was performed using methylene blue-fuchsin acid staining and hematoxylin and eosin (HE) staining to evaluate bone regeneration. RESULTS: The direct bone-to-implant contact (BIC) in the experiment after 4 and 8 weeks was 56.47 ± 1.18% and 76.23 ± 2.08%; and in the control group was40.79 ± 0.65% and 61.17 ± 2.79%, respectively. The percentage of newly formed bone after 2, 4 and 8 weeks was 17.60 ± 1.5%, 49.82 ± 4.02% and 67.16 ± 2.1% in experiment group; and in control group 14.30 ± 1.25%, 37.04 ± 2.29% and 58.83 ± 3.36%, respectively. These results represented significant differences statistically. CONCLUSION: Intra-bone marrow injection of UCMSCs can promote new bone formation. UCMSCs can be used to as excellent seed cells to repair the large defect peri-implant after immediate implant.

[The activity of osteoclast in peri-implant tissues in Beagle dogs].

PURPOSE: To observe the quantity and activity of osteoclast in peri-implant tissues dynamically. METHODS: An animal model of dental implants was established in 6 male Beagle dogs of 1-2 years old. Bone remodeling was tested at 3-, 7-,15-,30-,60- and 90-day after placement of implants. The mandibular bones were taken out and the morphological changes were observed under X-ray examination.Bone tissue samples underwent HE staining. The data were analyzed with SPSS13.0 software package. RESULTS: The most prominent period of osteoclasts occurred at 7-day after placement of implants. After 7 days of implantation, the activity of osteoclast gradually decreased. CONCLUSIONS: The active stage for bone remodelling in peri-implant tissues during unloading period is about 7 days after implantation.

[Expression of receptor activator of NF-κB ligand and osteoprotegerin in peri-implant tissues during unloading period].

OBJECTIVE: To observe the expression of receptor activator of NF-κB ligand (RANKL) and its decoy receptor osteoprotegerin (OPG) during unloading period of dental implants. METHODS: An animal model of dental implants was established in Beagle dogs. Bone remodeling was tested at 3, 7, 15, 30, 60 and 90 days after the placement of implants. RANKL and OPG mRNA expression were quantified by real-time PCR. Then mandibular bones were resected and some sections were observed. RESULTS: The most prominent period of bone remodeling occurred at 7 day after the placement of implants (OPG/RANKL mRNA, 2.15 ± 0.1). The expression of RANKL and OPG increased in a time-dependent manner in both soft and hard tissue. After 7 days they gradually decreased. CONCLUSIONS: Both OPG and RANKL were expressed in peri-implant tissues, and the changing tendency of RANKL and OPGmRNA was consistent with the change of bone remodeling. The active stage for bone remodelling in peri-implant tissues during unloading period is about 7 days after implantation.

[Expression of receptor activator nuclear factor kappa B ligand and osteoprotegerin in peri-implant soft tissue and bone tissue].

OBJECTIVE: To study mRNA expression of receptor activator nuclear factor kappa B ligand (RANKL) and its decoy receptor, osteoprotegerin (OPG) in peri-implant tissue during unloading period. METHODS: An animal model of dental implant was established in 6 male Beagle dogs of 1-2 years old. Bone remodeling was tested at 3, 7, 15, 30, 60 and 90 days since the placement of implants. RANKL and OPG mRNA expression were quantified by real-time polymerase chain reaction (PCR). Then mandibular bones were taken out and the morphological changes were observed by X-ray, bone tissue was tested by immunohistochemistry stain. RESULTS: The most prominent period of bone remodeling occurred at 7th day after the placement of implants. The expression of RANKL and OPG increased in a time-dependent manner in both soft and hard tissue. After 7 days they gradually decreased. CONCLUSION: RANKL and OPG can express in soft tissue, and the changing tendency is consistent with the change of bone remodeling, it indicates that RANKL and OPG play an important role in the bone remodeling.

[Comparison of cytotoxicity between chemical retraction agents on human gingival fibroblasts in vitro].

OBJECTIVE: To choose the best retraction agent for the clinic by evaluating cytotoxic effects of six chemical retraction agents on human gingival fibroblasts (HGF) in vitro. METHODS: HGF were treated with six chemical retraction agents which included 20% Al2(SO4)3, 5% Al2(SO4)3, 15.5% Fe2(SO4)3, 13.3% Fe2(SO4)3, 0.1% HCl-epinephrine and 0.01% HCl-epinephrine. The damage of direct contact and proliferation inhibit were observed by methyl thiazolyl tetrazolium (MTT) colorimetric assay, the ultra structure was observed under transmission electron microscope (TEM). RESULTS: All of chemical retraction agents caused cell damage and proliferation inhibit. The ability of cytotoxic effect increased in an order of 0.01% HCl-epinephrine<0.1% HCl-epinephrine<5% Al2(SO4)3<20% Al2(SO4)3