BACKGROUND:Micro-abrasion,at-home whitening combined with infiltration resin have a good effect on dental fluorosis,but the effect of this method on micro-cracks in dental fluorosis is still unclear. OBJECTIVE:To explore the effect of micro-abrasion,at-home whitening combined with infiltration resin on micro-cracked dental fluorosis. METHODS:(1)Clinical research:A total of 23 patients with micro-cracked dental fluorosis,including 255 micro-cracked dental fluorosis,were selected from July 2020 to March 2021 in the Department of Prosthodontics,Stomatology Hospital,Tianjin Medical University.All of them received combined treatment of tooth micro-abrasion,at-home whitening and infiltration resin.The tooth color,tooth sensitivity,and tooth pain threshold were compared before treatment and 1 week and 1 month after treatment.(2)In vitro experiment:60 teeth with fluorosis with at least one crack on the tooth surface were collected and randomly divided into three groups for treatment.The control group was treated without any treatment.The whitening group was treated with micro-abrasion and at-home whitening,and the combined group was treated with micro-abrasion,at-home whitening,and infiltration resin,with 20 teeth in each group.The microhardness of the three groups of teeth samples after treatment was measured. RESULTS AND CONCLUSION:(1)Clinical study:6 months after treatment,among 255 teeth with micro-cracked dental fluorosis,whitening treatment for 207 teeth was significantly effective and whitening treatment for 48 teeth was effective,and the overall treatment efficiency was 100%.With the extension of treatment time,the proportion of moderate and severe dental sensitivity showed a decreasing trend.At 6 months after treatment,255 teeth with dental fluorosis had no severe sensitivity,15 with moderate sensitivity,125 with mild sensitivity,and 115 with no sensitivity,and the difference was significant compared with the sensitivity before treatment(P<0.05).There was no significant difference in the threshold of tooth pain before treatment and 1 week and 6 months after treatment(P>0.05).(2)In vitro experiment:The tooth microhardness of the whitening group was lower than that of the control group and the combined group(P<0.05),but there was no significant difference between the control group and the combined group(P>0.05).(3)The results show that the methods of micro-abrasion,at-home whitening combined with infiltration resin have good clinical efficacy in the treatment of micro-cracked dental fluorosis.

BACKGROUND:Quercetin has anti-inflammatory,anti-cancer,anti-oxidation,anti-aging,anti-depression and other pharmacological effects,and has high medicinal value.Quercetin can promote wound healing in normal rats,but few drugs with quercetin as the main component have been developed,which limits its wide application in clinical practice. OBJECTIVE:To investigate the application effect of quercetin-carboxymethyl chitosan hydrogel on diabetic wound in rats by loading quercetin with hydrogel material. METHODS:(1)Carboxymethyl chitosan hydrogels and quercetin-carboxymethyl chitosan hydrogels were prepared respectively,and the micromorphology and in vitro drug release properties of the hydrogels were characterized.(2)Cell experiment:Mouse L929 fibroblasts were cultured in four groups.The blank control group was cultured conventionally.Carboxymethyl chitosan hydrogel,quercetin solution and quercetin-carboxymethyl chitosan hydrogel were added to pure hydrogel group,drug group,and drug-loaded hydrogel group,respectively,to detect cell proliferation and migration ability.(3)Animal experiments:Diabetic models were established in 80 SD rats.After successful modeling,full-layer skin defect wounds with a diameter of 2 cm were made on the back of rats,and these models were randomly divided into four groups.Normal saline,carboxymethyl chitosan hydrogel,quercetin solution,and quercetin-carboxymethyl chitosan hydrogel were injected into the wounds of blank control group,pure hydrogel group,drug group,and drug-loaded hydrogel group,respectively.Each group contained 20 animals,which were bound with sterile gauze.Wound healing,pathological morphology,expression of inflammatory factors,and angiogenesis were observed after operation. RESULTS AND CONCLUSION:(1)Under scanning electron microscope,the microstructures of the two hydrogels were similar,both showed loose porous network structure,and quercetin-carboxymethyl chitosan hydrogels had good drug release performance in vitro.(2)Compared with blank control group,the cell proliferation and mobility of the other three groups were increased(P<0.05).The cell proliferation and mobility of drug-loaded hydrogel group were higher than those of pure hydrogel group and drug group(P<0.05).(3)The wound healing rate of the drug-loaded hydrogel group was higher than that of the other three groups at 5 and 11 days after operation.The wound healing rate of rats in the hydrogel group,pure hydrogel group,and drug group reached 100%18 days after operation,which was higher than that in the blank control group(P<0.05).Hematoxylin-eosin staining showed that intact skin and skin appendages were visible on the wounds of rats in the drug-loaded hydrogel group 18 days after surgery,while intact skin and skin appendages were visible on the wounds of rats in the blank control group,pure hydrogel group,and drug group 25 days after surgery.The levels of tumor necrosis factor α and interleukin-6 in the drug-loaded hydrogel group were lower than those in the blank control group at 5,11,and 18 days after surgery(P<0.05),and the levels of transforming growth factor β1 at 11 and 18 days after surgery were lower than those in the blank control group(P<0.05).The mRNA expressions of CD31 and vascular endothelial growth factor α in the drug-loaded hydrogel group were higher than those in the other three groups at 11 and 18 days after operation(P<0.05).(4)These findings indicate that quercetin in quercetin carboxymethyl chitosan hydrogel can regulate inflammatory response,accelerate angiogenesis,promote the proliferation and migration of fibroblasts,and enhance the healing of diabetic wounds in rats.

BACKGROUND:Crosslinked sodium hyaluronate gel has good mechanical property,biocompatibility,and biodegradability,and can be used as an isolated protective material in tumor radiation therapy to protect endangered organs from damage caused by excess radiation dose. OBJECTIVE:To investigate the safety and efficacy of crosslinked sodium hyaluronate gel in reducing the dose of radiation to dangerous organs during brachytherapy. METHODS:A total of 16 specific pathogen-free Kunming mice of the same age and similar body weight were selected as experimental subjects and divided into experimental group and control group by the random number table method,with 8 mice in each group.125I seeds were implanted subcutaneously in the back of mice in the experimental group,and then crosslinked sodium hyaluronate gel was injected around the radioactive particles.Only 125I seeds were implanted subcutaneously in the back of mice in the control group.After injection,the distance between the radioactive particles and the epidermis was measured by spiral CT scan,and the surface radiation dose was measured by radiation dosimeter.Within 10 weeks after injection,the growth state,survival rate,skin radiation damage,and gel retention of mice were observed. RESULTS AND CONCLUSION:(1)Spiral CT scan showed that the implanted gel was relatively concentrated and created an effective distance between the radioactive seeds and the epidermis.The body surface radiation dose of the experimental group was significantly lower than that of the control group(P<0.01).(2)During the experimental observation period,mice in both groups survived;mice in the control group showed obvious irritability and other unstable behavior in the late experimental period,and some mice in the experimental group showed similar behavior.The daily food intake of mice in the two groups had no significant change,and the body mass showed the same increasing trend.After implantation of radioactive seeds,the two groups of mice showed different degrees of radioactive skin injury.From day 23 after injection to the end of the experiment,the skin radiation injury score of the experimental group was lower than that of the control group(P<0.01).At week 10 after implantation,6 mice in the experimental group had no obvious gel residue under their skin,and 2 mice had a very small amount of scattered gel-like samples under their skin.(3)Therefore,the crosslinked sodium hyaluronate injection technique can increase the space between the radioactive target area of 125I seeds and the organ at risk outside the target through physical space occupying,which can effectively reduce the dose of the organ at risk,and play a role in the isolation and protection of the organ at risk.

BACKGROUND:How to effectively promote bone regeneration and bone reconstruction after bone injury has always been a key issue in clinical bone repair research.The use of biological and degradable materials loaded with bioactive factors to treat bone defects has excellent application prospects in bone repair. OBJECTIVE:To investigate the effect of polylactic acid-glycolic acid copolymer(PLGA)composite scaffold modified by lysine-grafted graphene oxide nanoparticles(LGA-g-GO)on osteogenic differentiation and new bone formation. METHODS:PLGA was dissolved in dichloromethane and PLGA scaffold was prepared by solvent evaporation method.PLGA/GO composite scaffolds were prepared by dispersing graphene oxide uniformly in PLGA solution.LGA-g-GO nanoparticles were prepared by chemical grafting method,and the PLGA/LGA-g-GO composite scaffolds were constructed by blending LGA-g-GO nanoparticles at different mass ratios(1%,2%,and 3%)with PLGA.The micromorphology,hydrophilicity,and protein adsorption capacity of scaffolds of five groups were characterized.MC3T3 cells were inoculated on the surface of scaffolds of five groups to detect cell proliferation and osteogenic differentiation. RESULTS AND CONCLUSION:(1)The surface of PLGA scaffolds was smooth and flat under scanning electron microscope,while the surface of the other four scaffolds was rough.The surface roughness of the composite scaffolds increased with the increase of the addition of LGA-g-GO nanoparticles.The water contact angle of PLGA/LGA-g-GO(3%)composite scaffolds was lower than that of the other four groups(P<0.05).The protein adsorption capacity of PLGA/LGA-g-GO(1%,2%,and 3%)composite scaffolds was stronger than PLGA and PLGA/GO scaffolds(P<0.05).(2)CCK-8 assay showed that PLGA/LGA-g-GO(2%,3%)composite scaffold could promote the proliferation of MC3T3 cells.Alkaline phosphatase staining and alizarin red staining showed that the cell alkaline phosphatase activity in PLGA/LGA-g-GO(2%,3%)group was higher than that in the other three groups(P<0.05).The calcium deposition in the PLGA/GO and PLGA/LGA-g-GO(1%,2%,and 3%)groups was higher than that in the PLGA group(P<0.05).(3)In summary,PLGA/LGA-g-GO composite scaffold can promote the proliferation and osteogenic differentiation of osteoblasts,and is conducive to bone regeneration and bone reconstruction after bone injury.

BACKGROUND:We have successfully established an animal model of small ear pig in southern Yunnan province with internal tension relieving technique combined with autologous Achilles tendon for anterior cruciate ligament reconstruction,and verified the stability and reliability of the model.However,whether internal tension relieving technique can promote the ligamentalization process of autologous Achilles tendon graft has not been studied. OBJECTIVE:To investigate the differences in the process of ligamentalization between conventional reconstruction and internal reduction reconstruction of the anterior cruciate ligament by gross view,histology and electron microscopy. METHODS:Thirty adult female small ear pigs in southern Yunnan province were selected.Anterior cruciate ligament reconstruction was performed on the left knee joint with the ipsilateral knee Achilles tendon(n=30 in the normal group),and anterior cruciate ligament reconstruction was performed on the right knee joint with the ipsilateral knee Achilles tendon combined with the internal relaxation and enhancement system(n=30 in the relaxation group).The autogenous right forelimb was used as the control group;the anterior cruciate ligament was exposed but not severed or surgically treated.At 12,24,and 48 weeks after surgery,10 animals were sacrificed,respectively.The left and right knee joint specimens were taken for gross morphological observation to evaluate the graft morphology.MAS score was used to evaluate the excellent and good rate of the ligament at each time point.Hematoxylin-eosin staining was used to evaluate the degree of ligament graft vascularization.Collagen fibers and nuclear morphology were observed,and nuclear morphology was scored.Ultrastructural remodeling was evaluated by scanning electron microscopy and transmission electron microscopy. RESULTS AND CONCLUSION:(1)The ligament healing shape of the relaxation group was better at various time points after surgery,and the excellent and good rate of MAS score was higher(P<0.05).Moreover,the relaxation group could obtain higher ligament vascularization score(P<0.05).(2)The arrangement of collagen bundles and fiber bundles in the two groups gradually tended to be orderly,and the transverse fiber connections between collagen gradually increased and thickened,suggesting that the strength and shape degree of the grafts were gradually improved,but the ligament remodeling in the relaxation group was always faster than that in the normal group at various time points after surgery.(3)The diameter,distribution density,and arrangement degree of collagen fibers in the relaxation group were better than those in the normal group at all time points,especially in the comparison of collagen fiber diameter between and within the relaxation group(P<0.05).

BACKGROUND:The regeneration and remodeling of Achilles tendon rupture after surgery are difficulties in clinical treatment.Tissue engineering hydrogels afford the possibility on the healing of postoperative Achilles tendon. OBJECTIVE:To investigate the effect of tannic acid modified interpenetrating network hydrogel on tissue regeneration and remodeling of ruptured Achilles tendon in rats. METHODS:(1)The interpenetrating network hydrogel was prepared under the blue light and the immersion of CaSO4 solution.The micromorphology,mechanical properties,adhesion properties,in vitro drug release properties,and biocompatibility of hydrogels were characterized.(2)Thirty Sprague-Dawley rats were randomly divided into sham operation group,operation group,and hydrogel group,with 10 rats in each group.The animal model of Achilles tendon rupture was established in the latter two groups.In the operation group,the ruptured Achilles tendon was sutured using the modified Kessler method.In the hydrogel group,the ruptured Achilles tendon was repaired by the same method,and the tannic acid modified interpenetrating network hydrogel patch was completely wrapped around the joint of the broken end.Four weeks after the operation,imaging examination,histological evaluation,biomechanical test,and the level test of inflammatory factors were performed. RESULTS AND CONCLUSION:(1)Scanning electron microscope showed that tannic acid modified interpenetrating network hydrogels had porous microstructure with pore size of 3-10 μm,and the hydrogels had good in vitro drug release properties,adhesion strength and tensile strength.CCK-8 assay and live/dead staining showed that the hydrogel had no significant effect on the proliferation activity of rat bone marrow mesenchymal stem cells,and had good biocompatibility.(2)MRI imaging showed that compared with the operation group,the Achilles tendon in the hydrogel group showed uniform low signal,the thickness of the anteroposterior diameter of the Achilles tendon was reduced,and the boundary between the Achilles tendon and the surrounding tissue was more clear,and the performance was more similar to that of the sham operation group.Hematoxylin-eosin staining and Masson staining showed that the tendon fibers in the operation group were arranged in a loose and chaotic manner,with increased cell density and disordered arrangement,accompanied by obvious inflammatory cell infiltration,and intratendinous ossification appeared in some areas.In the hydrogel group,the tendon fibers were arranged in an orderly manner;the cell density was reduced and arranged orderly;the inflammatory cell infiltration was significantly reduced.The tensile strength of Achilles tendon in the operation group was lower than that in the sham operation group(P<0.05).The tensile strength of Achilles tendon in the hydrogel group was higher than that in the operation group(P<0.05).Compared with sham operation group,the mass concentration and mRNA expression of interleukin-1β,interleukin-6,and tumor necrosis factor α in Achilles tendon of rats were increased in the operation group(P<0.05).Compared with the operation group,the level and mRNA expression of three inflammatory factors were decreased in the hydrogel group.(3)It is concluded that tannic acid modified interpenetrating network hydrogel can inhibit the local inflammatory response and promote the tendon remodeling.

BACKGROUND:Our previous studies have found that poly(vinylidene fluoride)bionic periosteum prepared by electrospinning has good cytocompatibility,but its biocompatibility is unknown. OBJECTIVE:To evaluate the biocompatibility of poly(vinylidene fluoride)bionic periosteum doped with Zn2+and Mg2+. METHODS:Poly(vinylidene fluoride),poly(vinylidene fluoride)bionic periosteum doped with 1％Zn2+,doped with 1％Mg2+,and doped with 1％(Zn2++Mg2+)were prepared by electrospinning to make bionic periosteum extract.SD rats were selected as the experimental subjects for hemolysis test,short-term systemic toxicity test,and heat source test.Guinea pigs were selected as the experimental subjects for skin sensitization test.The biocompatibility of bionic periosteum of four groups was tested. RESULTS AND CONCLUSION:(1)The hemolysis test results showed that the hemolysis rates of 1％Zn2+poly(vinylidene fluoride),1％Mg2+poly(vinylidene fluoride),1％Zn2++1％Mg2+poly(vinylidene fluoride)bionic periosteum and poly(vinylidene fluoride)extract were(0.130±0.013)％,(0.149±0.020)％,(0.466±0.018)％,and(0.037±0.018)％,respectively,which met the hemocompatibility standard of biomaterials.(2)The results of short-term systemic toxicity test showed that the four groups of bionic periosteal extract had no toxic signs such as body mass reduction,food intake changes,and dyspnea in SD rats,and had no toxic effects on major organs of rats.(3)Heat source test results showed that after intervention with poly(vinylidene fluoride)bionic periosteum doped with 1％Zn2+,doped with 1％Mg2+,and doped with 1％(Zn2++Mg2+),and poly(vinylidene fluoride)bionic periosteum extract,the elevated body temperature values of SD rats were(0.133±0.058),(0.100±0.010),(0.300±0.010),and(0.300±0.017)℃respectively.All were less than 0.6 ℃and the total temperature increase was less than 1.4 ℃.(4)The results of skin sensitization test showed that no erythema or edema was observed under the skin of guinea pigs after the intervention of bionic periosteum extract of four groups.(5)The results showed that poly(vinylidene fluoride)and poly(vinylidene fluoride)bionic periosteum doped with Zn2+and Mg2+had good biocompatibility.

BACKGROUND:Computer-assisted implant surgery can improve implantation accuracy,but the use of implant template in the posterior tooth area is limited for patients with small opening and small interocclusal distance.Therefore,the digital guide has been improved. OBJECTIVE:To study the effect of modified implant template on the accuracy of assisted implantation in missing second molars. METHODS:From July 2020 to July 2023,40 patients who received digital guide plate implantation or free hand implantation to repair missing second molars were selected from First Affiliated Hospital of Guangzhou Medical University.According to the coin toss method,patients were randomly divided into a trial group(n=22;modified digital guide assisted implantation)and a control group(n=18;free hand implantation).The data of neck deviation,tip deviation,depth deviation,and angle deviation were compared between groups for preoperative and postoperative cone beam CT overlap analysis.One week after the operation,the patients'satisfaction with the operation was assessed by visual analog scale score. RESULTS AND CONCLUSION:(1)The trial group included 25 implants(12 in the upper jaw and 13 in the lower jaw);the control group included 23 implants(8 in the upper jaw and 15 in the lower jaw).The neck deviation,tip deviation,depth deviation,and angle deviation of the trial group were all smaller than those of the control group(P<0.05,P<0.001).There was no significant difference in accuracy between the maxillary and mandibular implant site in the trial group(P>0.05).(2)There was no significant difference in satisfaction with the operation between the two groups(P>0.05).(3)The results showed that improving the digital guide plate for assisted implantation for missing second molar can improve surgical accuracy and is suitable for patients with small opening and small interocclusal distance in the posterior tooth area.

BACKGROUND:It has been confirmed that the mixing of decellularized matrix and polymer electrospinning can not only improve the structural properties of fibers,but also preserve the biological decellularized of decellularized matrix.However,there is no relevant report on the preparation of skin tissue engineering scaffolds by electrospinning polyurethane and decellularized skin matrix. OBJECTIVE:To investigate the reparative effect of a decellularized skin matrix/polyurethane blended fibrous scaffold on rat skin defects. METHODS:Polyurethane electrospun fibrous scaffold and decellularized skin matrix/polyurethane blended fibrous scaffold were fabricated using the electrospinning technique.The fiber structure was observed under scanning electron microscope.Rat adipose mesenchymal stem cells were inoculated on two kinds of scaffolds respectively.The morphology of the scaffolds was observed under scanning electron microscope.Three full-thickness skin defects of 1 cm×1 cm were fabricated on the back of 10 SD rats.Polyurethane electrospun fibrous scaffolds(control group)and decellularized skin matrix/polyurethane blended fibrous scaffolds(experimental group)were implanted in two of the defects,and no material was implanted in the remaining defects(blank control group).The skin wound healing was observed at 1,2,and 3 weeks after operation.At 3 weeks after implantation,the wound was stained with hematoxylin and eosin and the scar area was calculated. RESULTS AND CONCLUSION:(1)Under scanning electron microscope,the two kinds of electrospun fibers were reticulated,and the rat adipose mesenchymal stem cells attached to the fibers on the two kinds of scaffolds,and the adhesion was good.(2)With the extension of the postoperative time,the skin wounds of each group gradually healed.By week 3 after the operation,the skin wounds of the experimental group and the control group were basically healed,and small ulcers could be seen on the wounds of the blank control group.Hematoxylin-eosin staining of skin wounds showed that the epidermal coverage of the wound was basically complete in the control group and the experimental group,and fibroblast growth and inflammatory cell infiltration could be seen in the dermis.In addition,the collagen fibers of the wound in the experimental group were abundant and arranged in a regular order,basically parallel to the epidermal surface.The wound epidermis of blank control group was still defective.The scar area of the experimental group was smaller than that of the other two groups(P<0.05,P<0.01).(3)These results indicate that the decellularized skin matrix/polyurethane blended fibrous scaffold can effectively repair full-thickness skin defects and improve scar formation in rats.

BACKGROUND:Research on carbon nanomaterials in the biomedical field is booming,and related scientific research results are increasing year by year.However,visualization analysis of the annual number of publications,the research status of countries,institutions,authors,and research hotspots and trends in this field is relatively scarce. OBJECTIVE:To present the research status of carbon nanomaterials in biomedical field,reveal the main research subjects,explore the research hotspots and development trends,and provide a reference for the future development of this field. METHODS:The core data set of Web of Science was used as the literature source to search the relevant researches on carbon nanomaterials in the biomedical field from 2012 to 2023.The knowledge map was generated by using Citespace software with countries,institutions,authors,keywords,and co-citations as nodes and for visualization analysis. RESULTS AND CONCLUSION:(1)A total of 2 932 papers were included in this study.In the medical field,carbon nanomaterials had a large number of papers and a fast growth rate.The United States has a large number of papers;China is an emerging force in this field,although the number of papers is the largest,but the level of research and influence need to be improved.The Chinese Academy of Sciences is the largest cooperative network institution,which mainly targets domestic institutions and lacks cooperation with well-known foreign institutions.(2)Keyword analysis displays that the green synthesis method and application of displaying carbon points have been the focus of research,followed by the new method of combining carbon nanomaterials with cancer phototherapy and immunotherapy,the key direction of future research.(3)The dynamic development trend of co-citations suggests that tissue engineering is a hot research topic of carbon nanomaterials in the field of biomedicine,mainly including the research of carbon nanomaterials for the repair and regeneration of heart and nerve tissue and as a bio-ink additive for 3D and 4D bioprinting.(4)In the future,with the development of the biomedical field in the direction of precision and treatment,researchers should speed up the creation of carbon-based systems formed by the combination of scientific and effective carbon nanomaterials with science and technology,new polymers or organic molecules,and new therapeutic methods,so as to give full play to the maximum effect of carbon nanomaterials.