Clinical efficacy of mineralized collagen (MC) versus anorganic bovine bone (Bio-Oss) for immediate implant placement in esthetic area: a single-center retrospective study.

BACKGROUND: The purpose of this retrospective study was to evaluate the clinical efficacy of mineralized collagen (MC) versus anorganic bovine bone (Bio-Oss) for immediate implant placement in esthetic area. METHODS: Medical records of Department of Oral and Maxillofacial Surgery of Shandong Provincial Hospital were screened for patients who had been treated with immediate implant implantation in the esthetic area using either MC (Allgens®, Beijing Allgens Medical Science and Technology Co., Ltd., China) or Bio-Oss (Bio-Oss®, Geistlich Biomaterials, Wolhusen, Switzerland), between January 2018 and December 2019. All patients fulfilling the in-/exclusion criteria and following followed for a minimum period of 1 year after surgery were enrolled into the presented study. Implant survival rate, radiographic, esthetic and patient satisfactory evaluations were performed. RESULTS: Altogether, 70 patients were included in the study; a total of 80 implants were inserted. All implants had good initial stability. The survival rate of implants was 100% at 1-year follow-up. The differences in horizontal and vertical bone loss between the MC group (0.72 ± 0.26 mm, 1.62 ± 0.84 mm) and the Bio-Oss group (0.70 ± 0.52 mm, 1.57 ± 0.88 mm) were no significant difference statistically no significant 6 months after permanent restoration. Similar results occurred at 12 months after permanent restoration functional loaded. Clinical acceptability defined by pink esthetic score (PES) ≥ 6 (6.07 ± 1.62 vs. 6.13 ± 1.41) was not significantly different between groups. Patient satisfaction estimated by visual analog scale (VAS) was similar (8.56 ± 1.12 vs. 8.27 ± 1.44), and the difference was no significant difference between the two groups. CONCLUSIONS: The biomimetic MC showed a similar behaviour as Bio-Oss not only in its dimensional tissues changes but also in clinical acceptability and patient satisfaction. Within the limitations of this study, these cases show that MC could be considered as an alternative bone graft in IIP.

Biocompatibility of Mn0.4Zn0.6Fe2O4 Magnetic Nanoparticles and Their Thermotherapy on VX2-Carcinoma-Induced Liver Tumors.

Malignant tumors are the most serious threat to human health. Much research has focused on revealing the characteristics of this disease and developing methods of treatment. Because tumor cells are more sensitive to heat than normal cells, thermotherapy for the treatment of tumors has attracted much attention. In this paper, we presented functional Mn-Zn ferrite nanoparticles with the molecular composition of Mn0.4Zn0.6Fe2O4 as the magnetic response material for the thermotherapy. The suggested Mn-Zn ferrite nanoparticles were with a self-regulation temperature of 43 degrees C which was ideal for tumor thermotherapy. The biocompatibility and anti-tumor effect of this material were well investigated. It was found that the Mn0.4Zn0.6Fe2O4 nanoparticles have no hemolysis activity, no genotoxic effects and cytotoxicity. Its Median Lethal Dose (LD50) arrived at 6.026 g/kg and it did not induce any abnormal clinical signs in laboratory animals. Moreover, the suggested nanoparticles can increase the inhibitory ratio of weight and volume of tumors, cause tumor tissues necrosis and show the therapeutic effect on the xenograft live cancers in vivo. Based on these results, we could envision the valuable application of the Mn0.4Zn0.6Fe2O4 nanoparticles for the practical thermotherapy.

[Biochemical analysis of stress distribution of dental implants with different body shapes after maxillary sinus augmentation].

PURPOSE: To compare the stress distribution of dental implants with different body shapes after maxillary sinus augmentation. MRTHODS: Three different implant models varying in implant shape were investigated in D3-type maxilla. All materials were assumed to be linear elastic, homogenous and isotropic. An oblique force of 150 N was applied to the implant. Maximal equivalent von-Mises of supporting bone around implants were measured. All of the models were measured by Ansys Workbench 14.5. Statistical analysis was performed using SPSS 17.0 software package. RESULTS: Highest stress of supporting bone emerged on the crestal cortical site around the implant neck. There was no significant difference in the maximum EQV of supporting cortical bone between different groups; the maximum EQV of supporting trabecular bone in the tapered implant group was much higher than other groups; application of grafts reduced the maximum EQV of both cortical and trabecular bone in all groups. CONCLUSIONS: Tampered implant can induce elevated stress distribution of the upper trabecular bone, which may promote marginal bone loss. Application of grafts after maxillary sinus augmentation could favors in reducing the stress loading of dental implants.

Using thermal energy produced by irradiation of Mn-Zn ferrite magnetic nanoparticles (MZF-NPs) for heat-inducible gene expression.

One of the main advantages of gene therapy over traditional therapy is the potential to target the expression of therapeutic genes in desired cells or tissues. To achieve targeted gene expression, we developed a novel heat-inducible gene expression system in which thermal energy generated by Mn-Zn ferrite magnetic nanoparticles (MZF-NPs) under an alternating magnetic field (AMF) was used to activate gene expression. MZF-NPs, obtained by co-precipitation method, were firstly surface modified with cation poly(ethylenimine) (PEI). Then thermodynamic test of various doses of MZF-NPs was preformed in vivo and in vitro. PEI-MZF-NPs showed good DNA binding ability and high transfection efficiency. In AMF, they could rise to a steady temperature. To analyze the heat-induced gene expression under an AMF, we combined P1730OR vector transfection with hyperthermia produced by irradiation of MZF-NPs. By using LacZ gene as a reporter gene and Hsp70 as a promoter, it was demonstrated that expression of a heterogeneous gene could be elevated to 10 to 500-fold over background by moderate hyperthermia (added 12.24 or 25.81 mg MZF-NPs to growth medium) in tissue cultured cells. When injected with 2.6 or 4.6 mg MZF-NPs, the temperature of tumor-bearing nude mice could rise to 39.5 or 42.8 degrees C, respectively, and the beta-gal concentration could increase up to 3.8 or 8.1 mU/mg proteins accordingly 1 day after hyperthermia treatment. Our results therefore supported hyperthermia produced by irradiation of MZF-NPs under an AMF as a feasible approach for targeted heat-induced gene expression. This novel system made use of the relative low Curie point of MZF-NPs to control the in vivo hyperthermia temperature and therefore acquired safe and effective heat-inducible transgene expression.

A new species of Ophryotrocha (Annelida, Eunicida, Dorvilleidae) from hydrothermal vents on the Southwest Indian Ridge.

Dorvilleids were collected from hydrothermal vents on the Southwest Indian Ridge by manned submersible Jiaolong. These represent a new species of Ophryotrocha that is here described as Ophryotrocha jiaolongisp. n. This is the first dorvilleid described from vents on the Southwest Indian Ridge. It most closely resembles another vent species, Ophryotrocha akessoni Blake, 1985 from the Galapagos Rift, but can be distinguished by its antennae, palps, jaw structure. The new species has particularly distinctive mandibles, which allow it to be easily identified.

[Effect of NaF on proliferation and mineralization of human periodontal ligament cells].

PURPOSE: To investigate the effect of NaF on proliferation and mineralization of human periodontal ligament cells (hPDLCs). METHODS: hPDLCs were isolated and characterized. The proliferation of hPDLCs treated with different concentration of NaF was tested by CCK-8. Four moderate concentrations were chosen for subsequent experiments. The mineralization was investigated using ALP activity assay, Alizarin red S staining and quantitative real-time polymerase chain reaction(RT-PCR). The data were statistically analyzed with SPSS20.0 software package. RESULTS: Immunohistochemistry showed that the isolated cells were hPDLCs. 5×10-5, 1×10-4 and 5×10-4 mol/L NaF had pro-proliferation effects while 5×10-4 mol/L resulted in the best effect (P<0.05). ALP activity and calcium content was significantly enhanced by 1×10-5 mol/L NaF with osteogenic inductive medium (P<0.05). Quantitative RT-PCR data varied in genes as a result of different NaF concentrations and treatment periods. CONCLUSIONS: 5×10-5, 1×10-4, 5×10-4 mol/L NaF can stimulate proliferation in hPDLCs, 1×10-5 mol/L NaF can enhance ALP activity and calcium content formation of hPDLCs.

Influence of cyclic loading on the fracture toughness and load bearing capacities of all-ceramic crowns.

The purpose of this study was to investigate how cyclic loading influenced the fracture toughness of hot-press lithium disilicate and zirconia core materials and whether there was an increase in the propensity for crown failure. Two types of all-ceramic crowns including the IPS e.max Press system (n=24) and the Lava zirconia system (n=24), were selected. Sectioned specimens were subjected to cyclic loading with the maximum magnitude of 200 N (R=0.1) until two million cycles. The material properties including Young's modulus (E) and hardness (H) and the fracture toughness (KIC) of the core materials were evaluated using indentation methods (n=12 each). The load-bearing capacities of the specimens were examined by means of monotonic load to fracture (n=12 each). It was found that the material properties, including E, H and KIC, of the two types of dental ceramics, were reduced. Statistical analysis indicated that there were no significant influences of fatigue loading on material properties E and H for both types of dental ceramics or KIC for zirconia, while for the IPS e.max Press core, KIC, which was parallel to the direction of the lithium disilicate crystals, was significantly reduced (P=0.001). A conclusion was drawn that zirconia possesses high mechanical reliability and sustainable capacity to resist fatigue loading, while fatigue loading remarkably degraded the anisotropic mechanical behaviour of hot-press lithium disilicate ceramics.

A study on the preparation and characterization of plasmid DNA and drug-containing magnetic nanoliposomes for the treatment of tumors.

PURPOSE: To explore the preparation and characterization of a novel nanosized magnetic liposome containing the PEI-As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) complex. METHODS: Mn(0.5)Zn(0.5)Fe(2)O(4) and As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) nanoparticles were prepared by chemical coprecipitation and loaded with PEI. The PEI- As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) complex was characterized using transmission electron and scanning electron microscopy, X-ray diffraction, energy dispersive spectrometry, and Fourier transform infrared spectroscopy. Cell transfection experiments were performed to evaluate the transfect efficiency. Magnetic nanoliposomes were prepared by rotatory evaporation and their shape, diameter, and thermodynamic characteristics were observed. RESULTS: Mn(0.5)Zn(0.5)Fe(2)O(4) and PEI-As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) nanoparticles were spherical, with an average diameter of 20-40 nm. PEI-As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) was an appropriate carrier for the delivery of a foreign gene to HepG2 cells. Energy dispersive spectrometry results confirmed the presence of the elements nitrogen and arsenic. Nanoliposomes of approximately 100 nm were observed under a transmission electron microscope. Upon exposure to an alternating magnetic field, they also had good magnetic responsiveness, even though Mn(0.5)Zn(0.5)Fe(2)O(4)was modified by PEI and encased in liposomes. Temperatures increased to 37°C-54°C depending on different concentrations of PEI-As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4)and remained stable thereafter. CONCLUSION: Our results suggest that PEI-As(2)O(3)/Mn(0.5)Zn(0.5)Fe(2)O(4) magnetic nanoliposomes are an excellent biomaterial, which has multiple benefits in tumor thermotherapy, gene therapy, and chemotherapy.

Effects of a new shape-memory alloy interspinous process device on pressure distribution of the intervertebral disc and zygapophyseal joints in vitro.

OBJECTIVE: To quantify the pressure distribution of lumbar intervertebral discs and zygapophyseal joints with different degrees of distraction of the interspinous processes by using a new shape-memory interspinous process stabilization device, and to research the relationship between changing disc and zygapophyseal joint loads and the degree of distraction of interspinous processes, and thus optimize usage of the implant. METHODS: Six cadaver lumbar specimens (L(2)-L(5)) were loaded. The loads in disc and zygapophyseal joints were recorded at each L(3-4) disc level. Implants with different spacer heights were then placed by turn and the pressure measurements repeated. RESULTS: An implant with 10 mm spacer height does not significantly share the load. A 12 mm implant reduces the posterior annulus load, and meanwhile decreases the zygapophyseal joints pressure, but only in extension. A 14 mm implant shares the loads of posterior annulus, nucleus, and zygapophyseal joints in extension and the neutral position, but slightly increases the anterior annulus' load. Though 16-20 mm implants do decrease the loads in the posterior annulus and zygapophyseal joints, the anterior annulus' load was apparently increased. CONCLUSION: Different degrees of distraction of the interspinous processes lead to different load distribution on the intervertebral disc. The implant tested is not appropriate in cases of serious spinal stenosis because of the contradiction that, while over-distraction of the interspinous processes decreases the posterior annulus and the zygapophyseal joints load and distracts the intervertebral foramina, it leads to a marked increase in the load of the anterior annulus, which is recognized to accelerate disc degeneration.

Nanosized As2O3/Fe2O3 complexes combined with magnetic fluid hyperthermia selectively target liver cancer cells.

AIM: To study the methods of preparing the magnetic nano-microspheres of Fe(2)O(3) and As(2)O(3)/Fe(2)O(3) complexes and their therapeutic effects with magnetic fluid hyperthermia (MFH). METHODS: Nanospheres were prepared by chemical co-precipitation and their shape and diameter were observed. Hemolysis, micronucleus, cell viability, and LD(50) along with other in vivo tests were performed to evaluate the Fe(2)O(3) microsphere biocompatibility. The inhibition ratio of tumors after Fe(2)O(3) and As(2)O(3)/Fe(2)O(3) injections combined with induced hyperthermia in xenograft human hepatocarcinoma was calculated. RESULTS: Fe(2)O(3) and As(2)O(3)/Fe(2)O(3) particles were round with an average diameter of 20 nm and 100 nm as observed under transmission electron microscope. Upon exposure to an alternating magnetic field (AMF), the temperature of the suspension of magnetic particles increased to 41-51 degrees C, depending on different particle concentrations, and remained stable thereafter. Nanosized Fe(2)O(3) microspheres are a new kind of biomaterial without cytotoxic effects. The LD(50) of both Fe(2)O(3) and As(2)O(3)/Fe(2)O(3) in mice was higher than 5 g/kg. One to four weeks after Fe(2)O(3) and As(2)O(3)/Fe(2)O(3) complex injections into healthy pig livers, no significant differences were found in serum AST, ALT, BUN and Cr levels among the pigs of all groups (P > 0.05), and no obvious pathological alterations were observed. After exposure to alternating magnetic fields, the inhibition ratio of the tumors was significantly different from controls in the Fe(2)O(3) and As(2)O(3)/Fe(2)O(3) groups (68.74% and 82.79%, respectively; P < 0.01). Tumors of mice in treatment groups showed obvious necrosis, while normal tissues adjoining the tumor and internal organs did not. CONCLUSION: Fe(2)O(3) and As(2)O(3)/Fe(2)O(3) complexes exerted radiofrequency-induced hyperthermia and drug toxicity on tumors without any liver or kidney damage. Therefore, nanospheres are ideal carriers for tumor-targeted therapy.

[Stress analysis of the all-ceramic crown with a numerical approach].

OBJECTIVE: To analyze the stress distribution in all-ceramic crowns when it was subjected to load. METHODS: A 3D numerical model of the all-ceramic crown of the right mandibular first molar was generated from scanned CT images. Finite element analysis (FEA) was used to evaluate the stress distribution in the all-ceramic crown when it was subjected to 5 load conditions. RESULTS: Stress distributions under 5 loading conditions were obtained. Stress concentrations were generally found near the loading areas at the veneer and at the lower surface of the core beneath the loading areas. In the 5 loading conditions, it was found that when the crown was loaded with vertical concentrated load, the tensile stresses around the shoulder areas were uniform, while stress concentration with maximum of 32.25 MPa was found at the shoulder areas in lingual-buccal direction when loads were applied at an angle of 10 degrees with the tooth axis on the buccal side. The masticatory load which was applied at 20 degrees with the tooth axis on the buccal side would cause stress concentration at the shoulder in mesial-distal direction. The maximum value could reach 11.29 MPa. CONCLUSIONS: The occlusal surface of the all-ceramic crown must be trimmed to increase multiple contact zones with the opposite surfaces in antagonist teeth to avoid excessive concentrated stress that may cause crown failure.

[Study on fracture mechanism of human dentin].

OBJECTIVE: To study the influence of moisture on the mechanical behavior of human dentin and fracture mechanism with crack extension in dentin. METHODS: A loading system that was suitable for biological materials was presented in this paper. With the help of digital image correlation (DIC), the surface deformation of wet samples was analyzed. Miniature compact tensile specimens were made from molars extracted from human beings. The fracture mechanism of human dentin was studied with compact tension (CT). RESULTS: Hydrated dentin behaved like visco-elastic material while dehydrated dentin became brittle. The bridged tissue behind the crack tip and the blunting effect at the crack tip resisted the extension of crack in dentin. CONCLUSIONS: Hydration plays an important role in mechanical properties of dentin. Dentin tissue has the ability to resist within extension of crack, however this ability decreases with aging.