BACKGROUND:At present,the treatment of infected bone defects has the problems of long course of disease,poor treatment effect and high cost.The osteogenic effect of personalized bone replacement materials in clinical treatment is limited.Therefore,a 3D-printed bone graft material with both good osteogenic effect and antibacterial effect is urgently needed for clinical treatment. OBJECTIVE:To summarize the research status of 3D-printed scaffolds loaded with antimicrobial agents for the treatment of infected bone defects. METHODS:PubMed,Web of Science,Elsevier,and CNKI databases from January 2010 to June 2022 were searched for related articles.The Chinese search terms were"bone defect,3D printing,scaffold material,antibacterial,animal experiments,in vitro experiments".English search terms were"bone defect,3D printing,scaffold,antibiosis,animal experiment,in vitro".Finally,60 articles were included for review and analysis. RESULTS AND CONCLUSION:The 3D scaffolds made of titanium,magnesium,tantalum and other metals and their alloys have certain osteogenic properties,but do not have antibacterial function.Hydroxyapatite and other bioceramic materials have good biocompatibility and are prone to be degraded,whereas due to the lack of strength,they are usually combined with artificial polymer materials to form composite materials,which respectively mimic the inorganic and organic components in natural bone,and play their respective excellent functions.Antibiotics,silver/copper nanoparticles,antimicrobial peptides,gallium and other antibacterial agents play an antibacterial role by destroying bacterial cell membrane,producing reactive oxygen species to interfere with bacterial DNA replication,inhibiting iron absorption and other mechanisms.As a result,the 3D-printed scaffold has both antibacterial and osteogenic effects.However,there are still some problems such as drug resistance and difficult to control effective concentrations.3D-printed scaffolds are often loaded with antibacterial agents by loading drug-loaded microspheres on scaffolds,preparing antibacterial coating on the scaffold surface,and participating in joint 3D printing with drugs.The loading mode of antibacterial coating prepared on the scaffold surface is the most widely used,and its antibacterial effect is more stable.Nonetheless,the selection of the most suitable loading mode for antibacterial agents needs to be further discussed and summarized.It is a future research prospect to optimize the mechanical properties of composite scaffolds and prepare biomimetic bone scaffolds so that the degradation rate is consistent with the bone reconstruction rate in infected bone defects.The ideal antibacterial agents may play a role through a variety of antibacterial mechanisms,thus being expected to play a good antibacterial effect through low antibacterial concentration,which should be a hot spot of anti-bone infection research.After loading antibacterial agents on the surface of the scaffold,antibacterial agents can"intelligently"react to the local microenvironment,achieving controlled release,and regulating the osteogenesis,vascularization and immune response of the microenvironment,which is the focus of current research.

Objective: To investigate the mechanisms by which D-methionine (D-Met) eradicates Porphyromonas gingivalis biofilms by suppressing cyclic dimeric GMP (c-di-GMP) levels. Methods : Cell viability, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured to determine the effective concentrations of D-Met, which were subsequently used in the following experiments. During the P. gingivalis biofilm formation inhibition experiment and the mature biofilm disassembly experiment, biofilm biomass, exopolysaccharide (EPS), biofilm morphology, integrity of the cell membrane, and the level of c-di-GMP were determined. Results : D-Met < 40 mmol/L was biocompatible. During the biofilm formation inhibition and mature biofilm disassembly experiments, D-Met ≥ 20 mmol/L decreased the biofilm biomass and the production of EPS. SEM analysis showed that the extracellular matrix and bacterial density were drastically reduced by D-Met ≥ 20 mmol/L. TEM detection showed that 35 mmol/L D-Met ruptured the cell membrane during biofilm formation and increased the permeability of the cell membrane in the disassembly phase of mature biofilms. C-di-GMP levels decreased with increasing concentrations of D-Met in a concentration-dependent manner. Conclusion D-Met ≥ 20 mmol/L could eradicate P. gingivalis biofilms by suppressing c-di-GMP levels.

Implant dentures have become the main method for the treatment of dentition defects or complete edentulism. However, due to the lack of periodontal ligament and periodontal ligament proprioceptors, implant dentures have very limited cushioning and sensing capabilities and are prone to occlusal overload. As a risk factor for peri-implantitis, occlusal overload seriously threatens the stability and success rate of implant dentures. This paper reviews the occlusal overload of implant dentures, the causal relationship between occlusal overload and plaque biofilms in peri-implantitis, the mechanism by which occlusal overload promotes peri-implantitis, and the effect of reasonable clinical occlusal adjustment on healing. This review shows that occlusal overload is closely related to the occurrence of peri-implantitis. Occlusal overload can promote the process of peri-implantitis by increasing the release of inflammatory factors and mechanical transduction mechanisms. The intervention of the patients’ bad bite habits and occlusal adjustment can promote the healing of peri-implantitis. At present, there is no uniform standard ideal experimental model for occlusal overload. The phenomenon and mechanism of bone resorption around the implant caused by overload force still need further observation and research, which will help determine the intensity, direction and timing of occlusal loading to guide clinical occlusal adjustment.

As the world’s population ages, age-related cognitive decline and dementia are becoming important challenges for geriatric care. Despite the ongoing search for solutions to address cognitive decline, effective interventions have not yet been established. There is increasing evidence from clinical, epidemiological, and animal studies that masticatory dysfunction due to occlusal disharmony is a risk factor for cognitive decline and an increased incidence of dementia. The mechanisms may involve altered nutritional intake, decreased cerebral blood flow, chronic stress, and hippocampal morphological function. These findings suggest that maintaining and adequately restoring the entire masticatory system has a positive impact for the prevention of cognitive decline.

Occlusal disorder is an abnormal condition in which the static and dynamic relations between the upper and lower teeth are not well aligned . The most common occlusal disorder in clinical practice is the inability to reach the intercuspal position due to early contact of individual points or occlusal interference due to occlusal high points, which can lead to periodontal tissue damage, decreased masticatory function, temporomandibular joint and muscle discomfort; these results can occur through the overactivation of the locus coeruleus-sympathetic-adrenal medullary system and hypothalamic-pituitary-adrenal axis induce elevated serum corticosteroid levels, which leads to chronic stress in the body. This article reviews the effects of chronic stress caused by occlusal disorder on bone tissue, stomatognathic system, emotional health and cognitive function. It has been found that occlusal disorders not only result in the loss of bone in the oral cavity, the reduction of bone mass in the whole body and damage to the local function of the stomatognathic system but also negatively affect the body’s anxiety, sleep, cognitive function and spatial memory ability as a result of the neuroendocrine changes . In recent years, concern about occlusal disorders has been on the rise. Early detection and timely adjustment of uncoordinated occlusion has become an issue that cannot be ignored in the clinic.

BACKGROUND: Accurate serum total thyroxine (TT4) measurement is important for thyroid disorder diagnosis and management. We compared the performance of six automated immunoassays with that of isotope-diluted liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) as the reference method. We also evaluated the correlation of thyroid stimulating hormone (TSH) with TT4 measured by ID-LC-MS/MS and immunoassays. METHODS: Serum was collected from 156 patients between October 2015 and January 2016. TT4 was measured by immunoassays from Abbott (Architect), Siemens (ADVIA Centaur XP), Roche (E601), Beckman-Coulter (Dxi800), Autobio (Autolumo A2000), and Mindray (CL-1000i), and by ID-LC-MS/MS. Results were analyzed using Passing-Bablok regression and Bland-Altman plots. Minimum requirements based on biological variation were as follows: a mean bias of ≤4.5% and total imprecision (CV) of ≤3.7%. RESULTS: All immunoassays showed a correlation >0.945 with ID-LC-MS/MS; however, the slope of the Passing-Bablok regression line varied from 0.886 (Mindray) to 1.23 (Siemens) and the intercept from −12.8 (Siemens) to 4.61 (Mindray). Only Autobio, Beckman-Coulter, and Roche included the value of one in the 95% confidence interval for slope. The mean bias ranged from −10.8% (Abbott) to 9.0% (Siemens), with the lowest value noted for Roche (3.5%) and the highest for Abbott (−10.8%). Only Abbott and Roche showed within-run and total CV ≤3.7%. CONCLUSIONS: Though all immunoassays correlated strongly with ID-LC-MS/MS, most did not meet the minimum clinical requirement. Laboratories and immunoassay manufacturers must be aware of these limitations.
Bias (Epidemiology) ; Diagnosis ; Humans ; Immunoassay ; Mass Spectrometry ; Methods ; Thyroid Gland ; Thyrotropin ; Thyroxine

Objective Preparation of aqueous reference materials for cholesterol and glycerol.Methods Study on reference materials.The certified reference materials GBW09203b and GBW09149 were weighed accurately and dissolved into 20% of methyl cyclodextrin aqueous solution to prepare six kinds of candidate reference materials of cholesterol and glycerol according to the concentration.The materials were tested for homogeneity and stability using routine methods.The reference methods of isotope dilution liquid chromatography tandem mass spectrometry (ID-LC/MS/MS) were used to determine the concentration of cholesterol and glycerol to evaluate the accuracy of the certified values.Meanwhile, the blank verification test was carried out.The expanded uncertainty was the combination of standard uncertainty of measurement, unhomogeneity and instability.Results It showed that the six candidate reference materials were homogeneous and stable for at least 1 year at-70 ℃ and-20 ℃.The certified values (reference value ± expanded uncertainty,mmol/L) were as follows,for cholesterol:0.65±0.01,1.31 ±0.01,2.57±0.02,5.21±0.06,7.71±0.08,10.24±0.06;for glycerol:0.29±0.01,0.58±0.01,1.22±0.02,2.24±0.02,3.46±0.04,4.52 ±0.04.The results of reference methods were consistent with the certified values.Blank validation tests showed that the concentration of the analytes would not be affected by the reagent and the blank matrix.Conclusions Certified reference materials for cholesterol and glycerol in aqueous solution have been prepared successfully.These materials are homogeneous and stable, and the certified values are reliable.Therefore the materials have been approved to be the Certificate Reference Materials of GBW 09823, GBW 09824, GBW 09825, GBW09826, GBW09827 and GBW 09828.

Objective:To compare the changes of marginal bone resportion between immediate implantation and delayed implantation after 12 to 24 months of definitive prostheses finished.Methods:41 patients were recruited and divided into immediate implant placement group(n =20) and delayed implant placement group(n =21).All implants were evaluated via radiograph after surgery,6 months after implantion,1 year and 2 years after prostheses placement respectively,the height of marginal bone was measured 6 month after implation,1 year and 2 years after prostheses placement.Results:After 6 month,1 year and 2 year the mesial marginal bone attachement (MBA) of immediate implant placement group increased by (1.35 ± 1.12),(2.16 ± 1.73) and (2.53 ± 1.65) mm,the distal by (1.46 ± 1.17),(1.94 ± 1.16) and (2.32 ± 1.68) mm,respectively (among the 3 time points of examination,P ＜ 0.05).As for the delayed implantation group,in the mesial area MBA increased by (-0.52 ± 0.47),(-0.69 ± 0.58) and (-0.97 ± 0.78) mm,in the distal area by (-0.46 ± 0.44),(-0.60 ± 0.45) and (-0.72 ± 0.63) mm (among 3 time points,P ＞ 0.05).Conclusion:Immediate implantation is superior to delayed implantation for marginal bone attachement of dental implant.

Objective:To study the attachment and collagen deposition of human gingival firbroblasts (HGFs) on titanium surface with different topography.Methods:Titanium surfaces created by machining(group M),electrolytic etching(group ECE) and electrolytic etching and acid etching(group ECA) were observed by SEM.HGFs cultured on the titanium surfaces were observed by laser scanning confocal microscope.Attachment of the cells was examined by comparing the numbers of attached to detached cells,respectively.Collagen production and deposition were examined via a Sirius red-based stain assay and confocal laser scaning microscopy.Results:The surface rouphness (μm) of group M,ECE and ECA was 0.867 5 ± 0.136 8,1.749 8 ± 0.355 1 and 1.671 4 ± 0.297 0 (P＜ 0.05) respectively,Cell attachment was significantly weaker on machined surface than on ECE and ECA surfaces,while which was weaker on ECE surface than on ECA surface.Collagen production was the highest on the machined surface,followed by that on ECE and ECA surface,Collagen deposition displayed a parallel pattern on the machined surface,while it was multidirectional on the ECE and ECA surfaces.Conclusion:The ECA surface of titanium may be beneficial to HGFs attachment,the machined surface may promote collagen deposition.

Objective: To evaluate the effect of platelet-rich fibrin extract (PRFe) on the adhesion, proliferation and differentiation of MC3T3-E1 cells cultured on the titanium discs. Methods: Samples were divided into experimental group (P) and control group (D). Group P used the α-minimal essential medium (α-MEM) containing PRFe (0.5%), while group D used only the α-MEM. Cell adhesion and cytoskeleton were observed using scanning electron microscopy (SEM) and laser scanning confocal microscopy (LSCM). Methyl thiazolyl tetrazolium (MTT) assay to detect the number of the osteoblasts at 1, 3, 5, 7 d; the activity of alkaline phosphatase (ALP) to detect the differentiation of osteoblast at 1, 3, 5, 7 d; the level of osteogenetic biomarkers core-binding factorα1 (cbfα1) and osteocalcin (OCN) were quantified by quantitative real-time PCR (qRT-PCR) at 3 and 7 d. Results: SEM and LSCM showed that the adhesion and filaments of group P were higher than those of group D at each time point. MTT assay showed that the absorbance were significantly increased in group P (1 d: 0.299±0.002, 3 d: 0.517±0.004, 5 d: 0.810±0.002, 7 d: 1.203±0.011) compared with group D (1 d: 0.198±0.003, 3 d: 0.399±0.002, 5 d: 0.588±0.002, 7 d: 0.897±0.005) at each time points (P<0.05). Furthermore, the ALP activity of group P (1 d: 0.162±0.004, 3 d: 0.289±0.001, 5 d: 0.491±0.006, 7 d: 0.647±0.005) was significantly higher than that of group D (1 d: 0.121±0.003, 3 d: 0.191± 0.006, 5 d: 0.252±0.004, 7 d: 0.365±0.012), (P<0.05). Moreover, the qRT-PCR showed that the Cbfα1 and OCN gene expression in group P (Cfbα1, 3 d: 1.50±0.04, 7 d: 1.94±0.06; OCN, 3 d: 3.37±0.17, 7 d: 3.92± 0.04) were significantly higher than that in group D(Cfbα1, 3 d: 1, 7 d: 1.18±0.13; OCN, 3 d: 1, 7 d: 2.34± 0.09) (P<0.05). Conclusions PRFe promoted the adhension, proliferation and differentiation of MC3T3-E1 cells on the titanium discs.