chitosan nanoparticles in endodontics

Deeksha Aggarwal; Jagat Bhushan; Kitty Sidhu; Manoj Rao

Research - (2023) Volume 11, Issue 3

chitosan nanoparticles in endodontics

Deeksha Aggarwal^*, Jagat Bhushan, Kitty Sidhu and Manoj Rao

^*Correspondence: Deeksha Aggarwal, Department of conservative dentistry and endodontics, Harvansh Singh jundge institute of dental science and hospital Panjab University Chandigarh, India, Email:

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Abstract

Chitosan is a white color, biodegradable polymer discovered in 1811. It has cytocompatibility with most of mammalian tissue. Chitosan interacts with positive charge cell membrane of bacteria, causes cell lysis and leakage of intercellular products. It has chelating property with dentinal surface with no effect on microhardness of dentin. It can be potential drug delivery agent because of its effect epithelial tight junction. Present review article focuses on benefits of chitosan in endodontics.

Keywords

Chitosan, Dental materials

Introduction

Chitosan is biopolymer derived by deacetylation of chitin. It consists of N-acetyl glucosamine & glucosamine units. It is white in colour, non-toxic and biodegradable polysaccharide [1]. Chitin was first discovered in 1811 by Henri Branconnot in a study on mushroom. Prof. C.Rouget in 1859 found that alkaline chitin can be dissolved in acids and Hoppe seiler named this substance as chitosan [2].

Chitin is 2nd most abundant in nature cellulose. It is found in cuticle of insects, cell wall of fungi, yeast, shrimp shells, chitosan on the other hand found in certain fungi only [3].

Physical Structure of Chitosan

Chitin consists of (1, 4)-linked N-acetyl glucosamine. Hydrolysis of amide group of chitin forms chitosan. Chitosan is produced from chitin by 2 different methods

Heterogenous deacetylation of solid chitin.

Heterogenous deacetylation of pre-swollen chitin under vacuum.

Heterogenous deacetylation is more preferred in industries where preferential deacetylation occur in chain, leaving an intact long parent chain whereas homogenous occur in alkaline medium at 20-400C for 12- 24 hrs. Alkali act on pre-swollen chitin [4]. Chitosan can be molded into various shapes like resins, microspheres, hydrogel membrane etc [5].

Chitosan is a polymer of N-acetyl glucosamine and glucosamine containing one amino group and two hydroxyl group on sixth carbon atom. It consists of positively charged amino group which interact with negatively charged cell membrane [6].

Biological Property

Chitosan is non-toxic, natural biodegradable molecule which binds to mammalian and microbial cells. It enhances osteoblast formation in bone regeneration. Chitosan has cytocompatibility with most of the mammalian’s cells. Chitosan and the cells interaction increases as the positive charge of the polymer increases due to presence of free amino groups. Chitosan also has homeostatic and fungi static property [7].

Chemical Property

Chitosan contains free positive charge amino groups and hydroxyl groups. Plaque formation on tooth surface is prevented by positively charge amino groups of chitosan. Chitosan reacts with hydrochloric acid, glutamic acid and forms water soluble salts. In acidic medium, chitosan gets protonated due to free amino acids. Most of the chemical properties of chitosan are dependent on pH of surrounding and degree of deacetylation of molecule [8].

Chitosan has been used in dentistry mainly in form of nanoparticles. These nanoparticles can be formed by Ionotropic gelation.

Micro emulsion method.

Emulsification solvent diffusion method.

Polyelectrolyte complexes.

Reverse micellar method [9].

Now a day’s chitosan is gaining importance in Endodontics because of the following advantages.

Antimicrobial Efficacy of Chitosan

Chitosan particles attach to negatively charged cell wall of bacteria, release cellular content and cell death [10]. Also, it is a chelating agent and chelates the metal ions present in bacteria and hence interrupting many bacterial enzymes and metabolism [11]. It has muco adhesive property and opens the epithelial tight junction of bacteria contributing to antimicrobial efficacy [12]. Chitosan exerts anti-fungal effect by suppressing sporulation and spore germination [13]. At lower pH electrostatic effect is mainly responsible for antimicrobial efficacy and at high pH; hydrophobic and chelating effect is responsible for antimicrobial efficacy. The use of chlorhexidine with chitosan provides a synergistic effect against E.faecalis [14].

Factors affecting the antimicrobial efficacy

Molecular weight of chitosan.

pH of chitosan.

Positive charge carried by particles.

Hydrophilic or hydrophobic nature.

Type of microorganism.

Ionic strength.

Chelating potential of particles.

Physical state of particles.

pH of particles.

Temperature and time of contact [15].

Chitosan interrupts the bacterial adhesion to dentin surface and prevent biofilm formation by bacteria [16].

In root canal therapy calcium hydroxide has been traditionally used as intracranial medicament for 7 days [17]. Chitosan along with calcium hydroxide causes sustained release of calcium from calcium hydroxide and maintenance of alkaline environment for a period of 30 days [18]. Incorporation of chitosan into zinc oxide eugenol as temporary restorative material improves its efficacy against staphylococcus epidermis, streptococcus mutans and E.faecalis. Chitosan also improves antibacterial efficacy [19] and inhibit biofilm formation at dentin sealer interface when zinc oxide eugenol used as a sealer [20].

Chelating Property of Chitosan

Chitosan has chelating potential with dentinal surface and hence produce surface roughness similar to that produced by EDTA. Mechanism of action of adsorption, ion exchange and chelation by chitosan particles depends on

Bridge Model: Bridge model state that amino groups in chitosan attack similar metal ions.

Free Arm Model: Chitosan is composed of chitin dimers. Free electrons present on nitrogen are responsible for interaction between metal and chelating surface. Only metal ions attached to amino group interact with material structure [21].

Chitosan provides surface roughness and smear layer removal similar to those produced by EDTA but less than that of NaOCL [22]. Chitosan penetrates deep inside the dentinal tubules due to its smaller size and hydrophilic property. Chitosan has large number of hydroxyl ions and free amino groups which help in ionic interaction between dentin calcium and chelating agent [23]. Chelating potential depends on application time, concentration of solution and amount of solution.

Chitosan is better chelating agent than EDTA because EDTA is a stronger chelating agent and alter the calcium phosphate ratio of dentin causing absorption of peritubular and inter-tubular dentin thereby, decreasing the micro-hardness of dentin [24,25]. On other hand chitosan causes removal of smear layer but also remineralization of demineralized dentin by providing phosphate ions which attract calcium and provide a nidus for calcium hydroxyapatite crystals [26,27]. It interacts with collagenase and metallic metalloproteinases and protect dentinal surface from their action [28]. So, because of all these properties it can be used as final irritant in place of NaOCL.

Anti-Oxidant Property

Chitosan monomer has 2 amino groups and 1 hydroxyl group. These groups scavenge the free radicals. Depolymerization of chitosan lead to formation of low molecular weight chitooligossachride which significantly interfere with nitric oxide production. Low molecular weight chitosan activates Nf-ĸß and enhance iNos expression by binding to CR3 and TLR4 receptors. Antioxidant property is inversely proportional to molecular weight as less intramolecular hydroxy bond is present in small chains resulting in more reactive hydroxyl and amino groups [29,30].

Adhesive Potential

An interconnected porous structure is formed when chitosan is hydrophilized. There is increase in cohesive energy with increase in contact time with adhesive surface. This can be explained by potential rearrangement of molecular structure and formation of extended 2- fold helix from relaxed 2-fold helix which has more potential for forming hydrogen bond and hydrophobic interaction [31].

Chitosan inculcated into direct bonding agent and composite inhibit growth of bacteria and help in attaining bond stability when added into direct bonding agent [32]. These composites have better mechanical property like bond strength.

Effect on Bond Strength: Final irrigation with chitosan improves dentinal surface wettability on substrate by forming calcium phosphate layer. Chitosan forms crosslinks with collagen fibers and prevent degradation of dentinal organic matrix. Decrease in bond strength of sealers is due to action of metalloproteinases on dentinal surface. Chitosan forms crosslink with metalloproteinases and inhibit it action on dentinal surface. Metalloproteinases are major cause of decrease in bond strength over time. Hence chitosan helps in improvement of bond strength with time. It helps in improving bond strength of epoxy resin to dentinal surface [33]. Also, chitosan is hydrophilic in nature containing large number of hydroxyl and amino groups. In acidic medium these amino acids make cationic interactions with dentinal surface which in turn attract other groups for better penetration inside dentinal tubules [34]. Although its effect smear layer removal is dependent on concentration and contact time with dentinal surface and presence of smear layer has a negative influence on push out bond strength [35].

Drug Delivery Agent: Chitosan has been widely used in medical science as effective drug delivery agent. The potential explanation behind this could be its effect on epithelial tight junction. In dentistry, it is used along with calcium hydroxide and triple antibiotic paste because it provides slow and controlled drug release, stability, enhancing efficacy and reduce toxicity. Calcium hydroxide has low solubility, diffusibility and limited ability to invade inside dentinal tubules. It also has dentin buffering potential which reduces its antibacterial efficacy against E. faecalis which is major pathogen in persistent secondary endodontic infection [36].

When calcium hydroxide and chitosan come in contact with bacteria NH3 group from glucosamine of chitosan attack the bacterial cell wall causing leakage of intercellular substance of bacteria. Calcium hydroxide prevents the recolonization of dentinal surface by candida albicans and E.faecalis [37].

Regenerative Endodontics: Regenerative endodontics deals with ability of bioactive materials for pulpal regeneration and vascularization. Cellularized fibrin hydrogel with chitosan as a scaffold support dentine pulp formation and provide good antibacterial efficacy. Addition of chitosan in fibrin does not affect morphology and viability of collagen matrix and promotes pulpal tissue formation [38].

Biocompatibility: Process of wound involves a series of events including adhesion, differentiation & proliferation [39]. Direct pulp capping in endodontics is to initiate formation of reparative dentin by process of wound healing. Study is Subhi et al in 2018, showed that chitosan as direct pulp capping agent improve cell viability [40]. It has improved mechanical property, odontogenic potential and biocompatibility when used as direct pulp capping agent [41].

Conclusion

Chitosan owing to its antibacterial property, biocompatibility has come to forefront in developing dental materials. Most studies highlight’s its noncytotoxic potential, odontogenic cell differentiation potential, antimicrobial potential. In light of above advantages, chitosan can be beneficial material for advancement in field of Conservative dentistry and Endodontics and other areas of dentistry.

References

Kou SG, Peters LM, Mucalo MR. Chitosan: A review of sources and preparation methods. Int J Biol Macromol 2021; 169:85-94.

chitosan nanoparticles in endodontics

Abstract

Keywords

Introduction

Conclusion

References

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