|Year : 2021 | Volume
| Issue : 2 | Page : 75-79
Chitosan biomaterials: Natural resources for dentistry
Khooshbu Gayen, Sagar Pabale, Supreet Shirolkar, Subir Sarkar, Somen Roychowdhury
Department of Pedodontics and Preventive Dentistry, Dr. R. Ahmed Dental College and Hospital, Kolkata, West Bengal, India
|Date of Submission||12-Jul-2021|
|Date of Decision||16-Sep-2021|
|Date of Acceptance||28-Sep-2021|
|Date of Web Publication||11-Feb-2022|
Dr. Supreet Shirolkar
Department of Pedodontics and Preventive Dentistry (2C), Dr. R. Ahmed Dental College and Hospital, Kolkata - 700 014, West Bengal
Source of Support: None, Conflict of Interest: None
In the quest for discovering ideal dental materials, biomaterials or those derived from biological sources play a special role because of their varied usages and inherent biocompatibility. Chitosan has been a rather recent material derived primarily from exoskeletons of life that forms mainly anthropods and fungi, etc. Evolving technology and understanding has made it possible for us to employ more biomaterials that are easy to adapt for uses in humans with less side effects and more therapeutic effects. With increasing applications that chitosan has found in medicine, exploring the dental applications of chitosan needs to be started with more vigor as well. Chitosan owing to its properties of being antimicrobial, biocompatible, biodegradable, osteoconduction, etc., either de novo or on being modified can be a real blessing in disguise for dentistry and find application in therapies from preventive to regenerative dentistry in various of its specialties.
Keywords: Antimicrobial activity, chitosan, guided tissue regeneration
|How to cite this article:|
Gayen K, Pabale S, Shirolkar S, Sarkar S, Roychowdhury S. Chitosan biomaterials: Natural resources for dentistry. Int J Oral Health Sci 2021;11:75-9
| Introduction|| |
After cellulose, chitin is the most abundant biopolymer found in the natural world. Chitin is an amino polysaccharide, cationic polymer, and has a rigid crystalline structure due to hydrogen interactions between acetamide and hydroxyl groups. The main source of chitin is exoskeleton of arthropods and other sources are fungi, insects, and mushrooms. Natural biomaterials are recognized for their biological properties such as biodegradation, biocompatibility, and bioadhesion which have applications in biomedical fields. Other examples of natural biomaterials are fibrin, collagen, and natural silk.
Chitosan, a natural polysaccharide, is the most important product of chitin. It has increased and enhanced properties and is a safe microbial agent. Chitosan is derived from alkaline deacetylation (70%) of chitin after almost 50% deacetylation [Figure 1].
| Structure|| |
Chitosan is composed of copolymer of glucosamine and N-acetylglucosamine and has a linear structure. It has different active regions:
- Three different functional groups of amido and amino groups in C-2 location
- Hydroxyl groups in C-3 and C-6.
| Properties|| |
Chitosan has a wide range of unique and favorable properties which have led to a number of generous opportunities.
- It has a wide spectrum of antibacterial properties
- No toxicity
- High viscosity
- High water binding capacity
- Resistant to digestive enzymes so humans are unable to digest it. However, some bacteria can do fragmentation of it
- After combining with various kinds of bioactive molecules, it can possess the property of osteoconductivity
- It shows pH-dependent versatility. In low pH, it exhibits polycationic nature, and in higher pH, it promotes intermolecular interactions and advances the formation of films, fibers, porous scaffolds, and gels
- It has high chelating ability for various metal ions such as iron, magnesium, zinc, cobalt, and copper ions
- What makes the material unique is that depending upon the manner of application, the properties can be tailored as favorable
- Some structural parameters such as molecular weight and degree of acetylation are responsible for the modulation of characteristics of chitosan. Degree of acetylation can strongly influence the biological, physical, and chemical properties
- Through various chemical modifications like cross-linking, few properties can be altered such as biodegradability and mechanical strength.
| Uses of Chitosan|| |
Chitosan has ample uses in several branches such as:
- Pharmaceutical – Weight loss, cosmetics, acne treatment, hair care products in creating capsules for enhancing absorption
- Biomedical – Gene therapy, tissue regeneration
- Agriculture – Accelerate growth of foods and vegetables
- Water purification – Used as a flocculator
- In the field of dentistry:
Chitosan offers huge potential in this arena of developing an innovative biodental material. Through this article, we try to review the current and future prospects of chitosan in dentistry [Figure 2].
It is the most important activity of chitosan which is against viruses, bacteria, fungi, and even algae. Different mechanisms are there to prove the antimicrobial activity of chitosan [Figure 3]:
- Interaction of ionic surface leads to cell wall leakage
- After invading into the nuclei of microorganisms, it inhibits the mRNA and protein synthesis
- It forms a barrier to suppress microbial growth.
Studies have found that chitosan has higher antimicrobial activity toward Gram-positive bacteria than Gram-negative bacteria. In vitro studies have shown chitosan has an antibacterial effect on Streptococcus mutans, Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitans. Fujiwara et al. were the first to report in their study that chitosan showed an inhibitory effect on S. mutans in relation to caries [Figure 4].
- Chitosan shows antioxidant activity mainly due to hydroxyl group (OH) and amino groups (NH) through:
- Neutralization of free radicles
- Binding to free ions.
- The antitumor activity of chitosan is mainly due to the ability of inducing cytokine production by enhancing T-cell proliferation. As per Tokoro et al. observation, the effect is due to increase in secretion of interleukin-1 and 2. Other investigations showed chitosan to have a role in inducing apoptosis in tumor cells.
| Oral Drug Delivery|| |
Chitosan is a potential oral drug carrier and reduces the side effects of systemic administration and also bypassing the first-pass effect, it delivers the drug to specific sites. By using chitosan base composites, a booming local drug delivery system can be made with desirable properties such as maintaining a close contact to oral mucosa, contact time, and a continuous release profile, thus it enhances the bioaccumulation to treat oral pathologies. The nanoparticle form, which has a higher surface area, is used to deliver several antibiotics such as chlorhexidine, metronidazole, and nystatin to treat infections and inflammations in periodontal tissues in situ. The antimicrobial nature can also be used here in case of quaternized chitosan in dental implants and as an wound dressing material in surgeries.
Guided tissue regeneration
As the regenerative periodontal therapy is continuously developing, there is an increase of interest in guided tissue regeneration (GTR) or guided bone regeneration. The strategy behind GTR is the isolation of periodontal defect by a membrane to form a barrier for gingival tissue infiltration and encourage bone regeneration in the defects. Chitosan has been chosen as a favorable material because of having the desirable properties of comprehensive GTR membrane – smart, conducive, and bio-integrative. However, to increase the bioactivity, chitosan is combined with various osteogenic materials. Researchers have combined it with various inorganic materials such as hydroxyapatite, silica, tricalcium phosphate, and bioactive glass to improve osteogenic properties and mechanical resistance. Functionally graded membrane is a concept described by a number of studies where the graded structure is used at the defect site around tooth and/or implant surface. Qasim et al. in their study reported the development of chitosan–hydroxyapatite membrane using solvents – acetic acid and ascorbic acid.
Degree of osseointegration is an important assessing parameter of clinical success of dental implants. Studies have found that chitosan coating may alter the surface properties of bone–implant interface such as it changes the elastic modulus and reduces the area of stress concentration and thus gives promising results.
Modification of dentifrices
Chitosan additive is found to enhance the efficacy of dentifrices in tackling oral tissue loss in acidic environment by imparting anti-abrasive and anti-erosive effects. Addition of chitosan has improved the effectivity of tin-based toothpaste in reducing dental hard tissue loss by enhancing the anti-wear effect.
Cationic nature of chitosan + low pH
High affinity for binding with structures with negative potential such as enamel and salivary pellicle
Protective multilayer of organic matrix formation over mineralized surfaces.
Prevention of caries
Chitosan can be added in chewing gum and mouthwashes which eventually reduces the load of cariogenic bacteria and stimulates the salivary flow. Low-molecular-weight chitosan has a major role in disrupting the colonization of pathogenic bacterial strains (S. mutans) from tooth surface without hampering the normal oral flora. Studies have found chitosan as an effective material in reducing the number of cariogenic groups by doing a comparison between two groups, one which took the chewing gum and another group that did not. As a mouthwash, when it is used, it shows antiplaque effects also. Chitosan and thiolated chitosan shows synergic antibacterial activity and higher mucoadhesion without cytotoxicity. Thus, chitosan has a potential role in protecting oral hygiene.
Enamel repair and regeneration
Repair and regeneration is still a challenging part in the field of dentistry. Chitosan-based restorative materials are under consideration here for successfully conveying organic amelogenin at the enamel defects sites. Ruan et al. used a chitosan-based hydrogel for the delivery of amelogenin with the purpose of reinvigorating the crystalline structure. Chitosan renders a dual effect–protective effect against caries and enamel crystal orientation. However, further researches are needed to enlighten on the role of chitosan in the regeneration of enamel.
Adhesion and dentin bonding
Technique sensitivity is an issue in the present dentin replacement materials in the process of acid etching and removal of smear layer. Chitosan antioxidant gel application on dentin has an additive effect on impermeability as it enhances the bonding of composite resins. In some studies, chitosan hydrogel was reported to increase shear bond strength and deliver a strong dentin bonding system. To support cell adhesion, collagen is added to enhance the biological properties of chitosan.
Hemostasis and pulpotomy
Chitosan is one of the most effectively used hemostatic agents. The positive charge in it binds to the negative charge of erythrocytes and induces a reaction when it comes into the contact of blood. Chitosan granules contain majority of assistive properties of an ideal hemostatic agent and interact directly with red blood cells and thrombocytes and form a cross-linked clot barrier.
Chitosan is also used in pulpotomy procedure of primary teeth as a hemostatic agent. Chitosan is diluted with sterile saline and after removal of coronal pulp, it is placed over the pulp chamber for 15–20 s and hemostasis is achieved. Chitosan enhances the formation of reparative dentin and that is why it is reported as an ideal material for pulpotomy.
Modification of glass ionomer cement
Although glass ionomer cement (GIC) is one of the most favorable biomimetic restorative materials due to its certain properties such as biocompatibility, sustained fluoride release, and very less microleakage, it has some drawbacks too. Mostly in case of bulk filling, GIC lacks flexural strength and fracture toughness. Petri et al. in their study found that when chitosan is added to GIC, the flexural strength of GIC increases much higher than conventional GIC and in addition to this, the rate of fluoride ion release also increases. Chitosan in conjunction with GIC has additional benefits of protein and growth factor release and is primarily used in vital pulp therapy. Chitosan interacts with the poly(acrylic) acid in GIC and forms a polymer complex phase which enhances the protein release profile. This property enlightens the path of dental pulp regeneration with chitosan. Limapornvanich et al. studied the relation of bovine serum albumin release from chitosan modified GIC and found a longer release of bovine serum albumin and no cytotoxic effects on pulp cell. The combined effect of chitosan and albumin boosts the antiapoptotic activity of pulp cells and advocate remineralization. This guides us in discovering a dental pulp-friendly restorative material which will protect us from the toxic effect of residual acid in GIC.
Research studies related to chitosan
- In a study, human dental pulp cells were cultured on chitosan membranes. The growing cells on chitosan membrane recommend a promising method in tissue regeneration and therapeutic applications
- Another study concluded that in the field of regeneration when chitosan hydrogel is combined with growth factors and human dental pulp stem cells, it contributes by the formation of dentin–pulp-like tissue
- Based on the chelating and antibacterial properties of chitosan nanoparticles (CNP), a comparative study was done using NaOCl, NaOCl-EDTA, NaOCl-EDTA-CNPs, or NaOCl-CNPs. They concluded that during root canal treatment, CNPs can be used as a final irrigant, as they have dual benefits of removal of smear layer and inhibition of bacterial colonization
- A Scanning electron microscope (SEM) study by Mittal et al was carried for assessing the effectiveness of smear layer removal from the root canal wall, it was found that even in low concentrations the most efficient solution for removing the smear layer and smear plug with minimal erosive effect was 0.2% chitosan in comparison to 15% EDTA and apple cider vinegar
- A study revealed that a 3–5-min application of 0.2% chitosan is the most viable combination to be used on root dentin.
| Conclusion|| |
Year after year, extraction of hidden treasures of nature is done by humans and after combining them with active compounds, the field of medicine and dentistry is constantly evolving. Current commercially available dental materials offer immense room for progress which makes it a challenging task and an area of active research to develop better materials. Chitosan has emerged as a promising material in this field due to its availability, biocompatibility, and biodegradable nature, antimicrobial properties, safe delivery of drugs, etc. Further researches are needed to explore the excellent potential of this biomaterial and to expand its biological applications in future.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]