Effect Of Rat Direct Pulp Capping With Metformin-loaded Carbon Point Hydroxyapatite Hollow Microspheres

Background:Young permanent teeth with pulpal diseases brought on by caries,trauma,etc.are frequently observed in clinical practice.It is not appropriate for standard cultivation since the apical foramen is not closed and the root needs to develop further.In order to encourage the establishment of a reparative dentin barrier,pulp is typically protected during root canal procedures by being covered with pulp-capping material.Unfortunately,the current pulp-capping agents have their own benefits and drawbacks,and they fall short of the ideal pulp-capping agent specifications,necessitating the creation of new pulp-capping materials.Carbon dots are carbon-based,zero-dimensional nanomaterials having an abundance of amino,carboxyl,and hydroxyl groups on their surface.It has been widely used in sensing,bioimaging,drug transport,antibacterial,and osteogenic sectors and is one of the most promising nanomaterials in the future.They also have good biocompatibility,optical properties,and are simple to functionalize.Because of their enormous specific surface area,high affinity,and superior biocompatibility,spherical hydroxylapatites are frequently utilized in drug administration and environmental adsorption.Hollow hydroxylapatite microspheres are now a reliable pulp capping agent carrier.After previous experiments,our team has prepared metformin carbon point and hydroxylapatite hollow microspheres,and found that appropriate concentrations of metformin carbon dots could promote the differentiation of human dental pulp stem cells into odontoblasts by activating autophagy in vitro,but with increasing concentrations over time;The metformin carbon spot has a negative effect on the proliferative activity of dental pulp stem cells,so we consider using hydroxylapatite hollow microspheres as a good carrier of metformin carbon spot to construct a sustained-release systemObjective:The creation of metformin-loaded carbon-point hydroxyapatite hollow microspheres,characterization of the drug delivery system and assessment of its impact on the proliferation of human dental pulp stem cells,impact of direct pulp capping on dentin formation,and inflammatory restoration of rat first molars were all assessed in vivo using H&E and immunohistochemical staining.Methods:1.hollow hydroxyapatite microsphere preparation using metformin carbon point.The sustained-release effect in vitro was evaluated after the surface morphology,drug loading rate,and entrapment efficiency were investigated.2.Human dental pulp stem cells were isolated and subcultured from removed third molars.3.Cell counting was used to assess the cytotoxicity of metformin carbon point loaded hollow hydroxylapatite microspheres.4.The rats were divided into six groups: blank control group,metformin loaded carbon point hydroxyapatite hollow microsphere group,calcium dihydroxide group.The rats were put to death 14 and 28 days after the operation.Using the H&E stain and immunohistochemical stain,the development of dentin and the resolution of inflammation in the third stage of the molar were studied.Results:1.High resolution scanning electron microscopy was used to show how metformin was successfully added to create hydroxylapatite with a diameter of 4.81±0.74 m.(HRSEM).The highest drug loading rate was 21.26± 0.38%,and the highest entrapment rate was 76.77 ± 0.18%.In vitro release experiments revealed that metformin continued to leak after 30 days,with a cumulative release rate of 60.01%.2.The initial arrangement of the primary human dental pulp stem cells inside the tissue mass was asymmetrical;however,upon passage,the cells took on a long,fusiform,"Vortex-like," or bundle-like shape.3.The results of CCK-8 demonstrated that the amount and timing of metforminloaded carbon point hydroxyapatite hollow microspheres had an impact on the proliferation activity of human dental pulp stem cells.4.The H&E stain results showed that at 14 days,more reparative dentin was produced in the metformin-loaded c-hydroxyapatite hollow microspheres group than in the calcium dihydroxide group(p < 0.05),at day 28,the area of the reparative dentin was slightly higher than that of the calcium dihydroxide,but there was no significant difference,on the 28 th day,the anti-inflammatory effect of metformin loaded carbon point hydroxyapatite hollow microspheres group was not significantly different from that of the calcium dihydroxide group,but was stronger than that of the other three groups(p < 0.05).The results of immunohistochemistry showed that DMP-1 was strongly positive in MCDs-HHAM Group and Dycal Group at the 14 th day.and there was no significant difference among the groups on the 28 th day.Conclusion:It offers hope for the investigation and creation of new pulp capping agents because metformin loaded carbon point hydroxyapatite hollow microspheres have a high drug loading rate and entrapment efficiency,good slow release performance,biological safety,the capacity to promote the formation of the third dentin,and good anti-inflammatory ability.