Synthesis And In Vitro Release Of Dexamethasone Sustained-Release System Of Hollow Carbonated Hydroxyapatite Microspheres

Caries and dental trauma are the most common oral diseases in humans.Deep caries proximal pulp and dental trauma can cause dental pulp damage.The dental pulp not only provides nutrition for the teeth,but also plays a crucial role i n the development of the roots of the young permanent teeth and the heali ng process of the apical foramen.Meanwhi le,it can respond to pathological stimulation to produce restorative denti n and maintai n normal function of teeth.At present,the clinical treatment of dental pulp i njury is mainly root canal therapy and vital pulp therapy(VPT).Although the root canal therapy has the advantage of higher success rate i n clinical observation,the dental tissue after removing the pulp is easily discolored and becomes brittle,causi ng serious damage to the tooth.The preservation of the dental pulp from external bad stimulation and promotes odontoblast-like differentiation of dental pulp cells is the current oral conventional treatment.Therefore,vital pulp therapy has become a research hotspot for many scholars.In addition,the search for a new type of high survi val rate,low-trauma pulp preparation will also become one of the trends in dental care in the future.Dexamethasone(DEX),a synthetic glucocorticoid that has anti-i nflammatory,anti-endotoxin,immunosuppressive,anti-shock,and enhanced stress response,is widely used in the treatment of autoimmune diseases,inflammation,asthma,and dermatology,eye disease.Studies have found that DEX not only promotes the osteogenic differentiation of mesenchymal cells,but also adds 10-8 mol/L DEX to human dental pulp cells culture medi um,which shows that it stimulates odontogenic differentiation of progenitors derived from human dental pulp cells.Dental pulp degeneration and necrosis are caused by caries and injury through persistent chronic inflammation to pulp tissue.Glucocorticoids can exert anti-inflammatory effects by i nhibiting decompose of arachidonic acid to block the formation of inflammatory mediators.Therefore,it can be considered to construct a sustai ned-release system so that DEX is not rapidly released i n the dental pulp surgery site and can be released continuously for a long period of time at a low concentration.In that way it not only plays an anti-inflammatory role,but also promotes the self-repair of the dental pulp to achieve the best effect of protecting the dental pulp.The nano-hydroxyapatite can be attached to with the hard tissues of the teeth through the complete affi nity bonding,and has good biocompatibility,and can also i nduce the generation of denti n bridges and repair hard tissue defects.Hollow hydroxyapatite microspheres,with their special internal hollow structure and porous shell,make them the most promising carriers for drug molecules,proteins,and bioactive factors.When used as a drug carrier,it can effecti vely increase the storage of drugs and prolong the time of sustai ned release.The mai n features of the sustained-release system are safety,effectiveness,stability,long duration of dr ug action,stable plasma concentrations,and reduced side effects.The purpose of this experimental study: According to the pri nciple of biomimetic minerali zation,through the hydrothermal precipitation method and under atmospheric pressure,simple synthesis carbonated hydroxyapatite,similar to bone-like and dental primary inorganic compounds,using organic small molecule glyci ne and surfactant sodium dodecyl sulphonate as additives.The product was characteri zed: The prepared hydroxyapatite was a microsphere composed of acicular nanoparticles with a diameter of 2-4 ?m,characterized by field emission scanni ng electron microscopy.In partially damaged microspheres,it exhibited a hollow structure.X-ray powder diffraction,Fourier Transform Infrared Spectrometer analysis confirmed it belong to carbonated hydroxyapatite.Nitrogen adsorption and desorption analysis,the specific surface area of the microspheres were 37.30 m2/g and mainly pore size distributed in 10~100nm.D ue to the good physicochemical properties of the microspheres,this study loaded dexamethasone i nto the microspheres to construct an in vitro sustained-release system,and tested the system's drug loadi ng rate,encapsulation efficiency,and sustai ned release performance in vitro.