Calcium and phosphorus co-doped carbon dots enhance osteogenic differentiation for calvarial defect repairin situ.

Calvarial bone defect remains a clinical challenge due to the lack of efficient osteo-inductive agent. Herein, a novel calcium and phosphorus codoped carbon dot (Ca/P-CD) for bone regeneration was synthesized using phosphoethanolamine and calcium gluconate as precursors. The resultant Ca/P-CDs exhibited ultra-small size, stable excitation dependent emission spectra and favorable dispersibility in water. Moreover, Ca/P-CDs with good biocompatibility rapidly entered the cytoplasm through endocytosis and increased the expression of bone differentiation genes. After mixing with temperature-sensitive hydrogel, Ca/P-CDs were injectedin situinto calvarial defect and promoted the repair of bone injury. These Ca/P-CDs provide a new treatment method for the bone repair and should be expended the application in the biomedical fields.

[Preliminary study of bonding strength between diatomite-based dental ceramic and veneering porcelains].

PURPOSE: In order to choose the best veneering porcelain for diatomite-based dental ceramic substrate, the bonding strength between diatomite-based dental ceramics and veneering porcelains was measured, and the microstructure and elements distribution of interface were analyzed. METHODS: The coefficient of thermal expansion (CTE) of diatomite-based dental ceramics was detected by dilatometry. Three veneering porcelain materials were selected with the best CTE matching including alumina veneering porcelain (group A), titanium porcelain veneering porcelain (group B), and E-max veneering porcelain (group C). Shear bonding strength was detected. SEM and EDS were used to observe the interface microstructure and element distribution. Statistical analysis was performed using SPSS 17.0 software package. RESULTS: The CTE of diatomite-based dental ceramics at 25-500 degrees centigrade was 8.85×10-6K-1. The diatomite-based substrate ceramics combined best with group C. Shear bonding strength between group A and C and group B and C both showed significant differences(P<0.05). SEM and EDS showed that the interface of group C sintered tightly and elements permeated on both sides of the interface. CONCLUSIONS: The diatomite-based substrate ceramics combines better with E-max porcelain veneer.

[Effects of a zirconia primer and a self-adhesive resin cement on zirconia bonding].

OBJECTIVE: To evaluate the effects of a zirconia primer and a self-adhesive resin cement on the resin bonding zirconia. METHODS: Eighty zirconia blocks were manufactured, alumina-sandblasted, and randomly divided into five groups that received surface-treatments using different resin cements: group C, treated with a conventional bisphenol-A diglycidyl dimethacrylate (Bis-GMA)-based resin cement; group R, treated with a self-adhesive resin cement; group S, silica-coated via a Sol-gel process, conditioned with silane, and then treated with the Bis-GMA-based resin cement; group ZC, conditioned with a zirconia primer (Z-Prime Plus) and subsequently treated with the Bis-GMA-based resin cement; group ZR, conditioned with the zirconia primer and treated with the self-adhesive resin cement. Light-cured composite resin cylinders were prepared and bonded on the prepared zirconia blocks. Half of the specimens in each group were water-stored for 24 hours, whereas the remaining specimens were aged by thermocycling. All specimens were then subjected to shear bond strength (SBS) testing. Fourier transmission infrared (FT-IR) spectroscopy and gas chromatography-mass spectrometry (MS) were performed to characterize the zirconia primer. RESULTS: Group C presented the lowest SBS, whereas groups R, ZC, and ZR presented the highest values. Thermocycling had no effect on SBS. FT-IR results showed that Z-Prime Plus contained a benzene ring and a carbonyl group. MS analysis showed that Z-Prime Plus contained 2-hydroxyethyl methacrylate, triethylamine. CONCLUSION: Zirconia primer and self-adhesive resin cement increase the resin bonding of zirconia.

[Preliminary study of wireless biofeedback therapy for treatment of bruxism].

OBJECTIVE: To access the effect of wireless biofeedback therapy on bruxism. METHODS: Ten voluntary bruxers (seven female and three male, mean age 26.1 years) were invited to participate in this clinical research. An electric resistance strain gauge was embedded in the position of canine of a maxillary splint for monitoring the abnormal clenching or grinding movement of teeth during sleep. The relevant details of bruxism events, including value of relative force, occurring time and duration were recorded and analyzed by the receiver device and monitoring program respectively. Meanwhile, for the purpose of nerve system and muscle relaxation, a watch-style device around the patient's wrist will vibrate to alert the patient of teeth grinding or clenching if the value of biting force and duration exceed the threshold. Total average episodes of bruxism and duration was observed during eight hours sleep, and was analyzed with one-way analysis of variance in SPSS 19.0 by the end of 6th week and three months following biofeedback therapy. RESULTS: The average episodes of bruxism has declined dramatically from (9.8 ± 2.2) times to (3.0 ± 1.2) times during one night (P < 0.05), and the average duration of bruxism events was reduced from (20.7 ± 12.2) s to (10.0 ± 3.4) s (P < 0.05) after six weeks biofeedback therapy. By the end of three months, the average episodes declined to (2.9 ± 1.2) times (P < 0.05), and the average duration decline to (9.2 ± 2.9) s (P < 0.05) with contrast to preliminary night. CONCLUSIONS: The pressure-based wireless biofeedback device is able to monitoring clenching and grinding of bruxism. The results suggest that biofeedback therapy may be an effective, novel and convenient measure for treatment of bruxism according to several months therapy.

[Effect of hot chemical etching on bond strength of zirconia to resin].

OBJECTIVE: This study aims to evaluate the influence of hot chemical etching on short- and long-term shear bond strength (SBS) of zirconia to resin. METHODS: Eighty zirconia ceramic slices were obtained and randomly divided into five groups based on the surface treatment to be applied--group A: H2SO4/(NH4)2SO4 hot solution etching + application of Clearfil; group B: HF/HNO3 hot solution etching + application of Clearfil; group C: H2SO4/HF/HNO3 hot solution etching + Clearfil; group D: alumina sandblasting + application of Clearfil; group E: tribochemical silica coating + application of silane coupling agent. Eighty composite cylinders were bonded to pretreated ceramic slices using a bis-GMA-based resin cement. Specimens in each group were divided into two fractions: the first half received 24 h water storage, and the second half received 40 d water storage. Then, SBS tests were conducted. Morphological analysis of sandblasted alumina and hot chemical-etched zirconia surfaces were performed by scanning electron microscopy(SEM). RESULTS: Group E displayed the highest SBS before artificial aging, and no statistical difference was found among the other groups. After 40 d water storage, groups A, B, and E showed significantly higher SBS than groups C and D. SBS increased significantly after artificial aging in groups A and B. No significant variations were found before and after artificial aging in the other groups. CONCLUSION: The experimental hot chemical etching solution provides enhanced bonding for zirconia than sandblasting, and the bond strengths remain stable after artificial aging.

[Improving bonding of zirconia through deposition of silica layer via collosol-gelatin process, the roles of NaHCO3].

OBJECTIVE: To evaluate the effects of NaHCO3 on gelation of silica sols and shear bond strength of silica coated zirconia via collosol-gelatin (Sol-Gel) process. METHODS: The gelation time of silica sols after being mixed with 1%, 3%, 5%, 7%, 10% concentrations of NaHCO3 was recorded. The one got the shortest gelation time was used for the following tests. Zirconia blocks were prepared and divided into five experimental groups according to surface conditioning methods: group A, alumina sandblasting; group B, sandblasting + tribochemical silica coating + silane; group C, sandblasting + silica coating via Sol-Gel process + silane; group D, sandblasting + silica coating via Sol-Gel process (NaHCO3 was used) + silane; group E, sandblasting + zirconia primer. A composite resin column was bonded on the treated zirconia surface with Bis-GMA based composite resin cement. All specimens were subjected to shear bond strength (SBS) tests. RESULTS: The shortest gelation time of silica sols were found when silica sols was mixed with 10% NaHCO3. Group A showed the lowest SBS values of (4.12 ± 0.52) MPa, which was significant different from SBS of group B [(10.24 ± 2.78) MPa], C [(7.36 ± 1.59) MPa], D [(9.79 ± 2.07) MPa], D [(8.39 ± 0.49) MPa], and no statistical difference was found between group C and D. CONCLUSIONS: The silica coating via Sol-Gel process can significantly improve the bond strength of zirconia, and NaHCO3 would not exert influences to bonding.

Effect of silica coating on fracture strength of glass-infiltrated alumina ceramic cemented to dentin.

PURPOSE: To examine the availability of sol-gel processed silica coating for alumina-based ceramic bonding, and determine which silica sol concentration was appropriate for silica coating. MATERIALS AND METHODS: Sixty disks of In-Ceram alumina ceramic were fabricated and randomly divided into 5 main groups. The disks received 5 different surface conditioning treatments: Group Al, sandblasted; Group AlC, sandblasted + silane coupling agent applied; Groups Al20C, Al30C, and Al40C, sandblasted, silica coating via sol-gel process prepared using 20 wt%, 30 wt%, and 40 wt% silica sols, and then silane coupling agent applied. Before bonding, one-step adhesives were applied on pre-prepared ceramic surfaces of all groups. Then, 60 dentin specimens were prepared and conditioned with phosphoric acid and one-step adhesive. Ceramic disks of all groups were cemented to dentin specimens with dual-curing resin cements. Fracture strength was determined at 24 h and after 20 days of storage in water. RESULTS: Groups Al20C, Al30C, and Al40C revealed significantly higher fracture strength than groups Al and AlC. No statistically significant difference in fracture strength was found between groups Al and AlC, or among groups Al20C, Al30C, and Al40C. Fracture strength values of all the groups did not change after 20 days of water storage. CONCLUSION: Sol-gel processed silica coating can enhance fracture strength of In-Ceram alumina ceramic after bonding to dentin, and different silica sol concentrations produced the same effects. Twenty days of water storage did not decrease the fracture strength.

Effects of sol-gel processed silica coating on bond strength of resin cements to glass-infiltrated alumina ceramic.

PURPOSE: The aim of this study was to verify the effects of sol-gel processed silica coating on the bond strength between resin cement and glass-infiltrated aluminum oxide ceramic. MATERIALS AND METHODS: Silica coatings were prepared on glass-infiltrated aluminum oxide ceramic surface via the sol-gel process. Atomic Force Microscope (AFM), Fourier Transmission Infrared spectrum (FTIR), and Energy Dispersive X-ray Spectroscopy (EDS) were used for coating characterization. Forty-eight blocks of glass-infiltrated aluminum oxide ceramic were fabricated. The ceramic surfaces were polished following sandblasting. Three groups of specimens (16 for each group) with different surface treatment were prepared. Group P: no treatment; group PO: treated with silane solution; group PTO: silica coating via sol-gel process, followed by silane application. Composite cylinders were luted with resin cement to the test specimens. Half of the specimens in each group were stored in distilled water for 24 h and the other half were stored in distilled water for 30 days before shear loading in a universal testing machine until failure. Selected ceramic surfaces were analyzed to identify the failure mode using a scanning electron microscopy (SEM). RESULTS: Nanostructured silica coatings were prepared on glass-infiltrated aluminum oxide ceramic surfaces by the sol-gel process. The silicon element on the ceramic surface increased significantly after the coating process. The mean shear bond strength values (standard deviation) before artificial aging were: group P: 1.882 +/- 0.156 MPa; group PO: 2.177 +/- 0.226 MPa; group PTO: 3.574 +/- 0.671 MPa. Statistically significant differences existed between group PTO and group P, and group PTO and groups PO. The failure mode for group P and group PO was adhesive, while group PTO was mixed. The mean shear bond strength values (standard deviation) after artificial aging were: group P: 1.594 +/- 0.111 MPa; group PO: 2.120 +/- 0.339 MPa; group PTO: 2.955 +/- 0.113 MPa. Statistically significant differences existed between each two groups after artificial aging, group P had the lowest bond durability, and group PTO had the highest bond durability. CONCLUSION: The sol-gel process is an effective way to prepare silica coating on dental glass-infiltrated alumina ceramic. Sol-gel processed silica coating can improve the resin bond strength of glass-infiltrated alumina ceramic.

[Effect of nano-silica coating prepared by different concentration silica sol on shear bond strength of alumina ceramic].

OBJECTIVE: To evaluate the effect of nano-silica coating prepared by different concentration silica sol on shear bond strength between alumina ceramic and resin cement. METHODS: Silica coating was prepared with colloidal silica sol on alumina ceramic surface that was treated with air particle abrasion. Infrared spectrum (IR), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) were used to analyze the silica coating. A total of 32 alumina ceramic discs were randomly divided into 4 groups with 8 discs per group, which received different surface treatments as silane couple agent (control group), 20% silica sol + silane (group A), 30% silica sol + silane (group B), 40% silica sol + silane (group C). Each ceramic disc was bonded to composite with resin cement, and then shear bond strength of these samples was tested. RESULTS: It was observed from the IR pictures that symmetrically flexible vibration absorption kurtosis, anti-symmetrically flexible vibration absorption kurtosis, and bending vibration absorption kurtosis of Si-O-Si enhanced after heat treatment. SEM pictures showed that nanoparticles in coating gel were well distributed and some of them conglomerated after heat treatment. There was a little conglomeration in 20% coating, more in 30%, and the most in 40%. Contents of surface silicon increased after modification with silica coating prepared by sol-gel method. Bond strength of three groups with silica coating was significantly higher than that of the group with only silane couple agent [(1.881 +/- 0.156) MPa] (P < 0.05). Group B gained the highest strength [(4.852 +/- 0.178) MPa] compared with group A [(3.196 +/- 0.171) MPa] and group C [(3.576 +/- 0.671) MPa] (P < 0.05). CONCLUSIONS: Surface silicon contents all increased after surface modification with different concentration silica sol. Silica coating followed with silane couple agent could significantly enforce bond strength of alumina ceramic, with 30% silica sol group gaining the highest bond strength.

[Surface modification of dental alumina ceramic with silica coating].

OBJECTIVE: To make silica coating through sol-gel process, and to evaluate the wettability of dental alumina ceramic with or without coating. METHODS: Silica coating was prepared with colloidal silica sol on In-Ceram alumina ceramic surface which had been treated with air particle abrasion. Coating gel after heat treatment was observed with atomic force microscope (AFM), and was analyzed by infrared spectrum (IR) with gel without sintered as control. Contact angles of oleic acid to be finished, sandblasted and coated ceramic surface of were measured. RESULTS: AFM pictures showed that some parts of nano-particles in coating gel conglomerated after heat treatment. It can be seen from the IR picture that bending vibration absorption kurtosis of Si-OH also vanished after heat treatment. Among contact angles of three treated surface, the ones on polished surface were the biggest (P = 0.000, P = 0.000), and sandblasting+silica coating surface the smallest (P = 0.000, P = 0.003). CONCLUSION: Silica coating can be made with sol-gel process successfully. Heat treatment may reinforce Si-O-Si net structure of coating gel. Wettability of dental alumina ceramic with silica coating is higher than with sandblasting and polishing.

Effect of layering feldspathic porcelain on resulting veneer color with aluminum oxide core.

OBJECTIVE: To evaluate the resulting color of veneers affected by adding a layer of veneering porcelain on Procera aluminium oxide core. METHODS: Fifteen aluminium oxide disks were randomized into three groups. Each of five disks was veneered with porcelain of the Vita shade Al, A2 and B4 respectively. The color of the substrate covered with non-veneered disks and the veneered disks was measured separately and the color differences were calculated. RESULTS: Statistically significant differences (P < 0.01) in color coordinates of dark substrate were recorded between the substrate covered by an aluminium oxide disks and the addition of veneering porcelain to aluminium oxide disks. Mean coordinates color difference (DeltaE, DeltaL *, Deltaa *, Deltab *) after adding the three shades of veneering porcelain showed increase from Al (2.311) to A2 (4.313) to B4 (8.778) in DeltaE, decrease from Al (-1.530) to A2 (-3.369) and B4 (-3.358) in DeltaL *, and increase from Al (-1.440) to A2 (2.198) to B4 (7.955) in Deltab *. The direction of the color modification correlated with values obtained from the liberation. The resulting color was also affected by the color of the underlying structure. CONCLUSION: This study illustrates that color of aluminium oxide shell could be modified with feldspathic veneering porcelain, which may be used by practitioners to alter the esthetic outcome of porcelain veneers.