Assessment of Photodynamic Inactivation against Periodontal Bacteria Mediated by a Chitosan Hydrogel in a 3D Gingival Model

Abstract

Chitosan hydrogels containing hydroxypropyl methylcellulose (HPMC) and toluidine blue O were prepared and assessed for their mucoadhesive property and antimicrobial efficacy of photodynamic inactivation (PDI). Increased HPMC content in the hydrogels resulted in increased mucoadhesiveness. Furthermore, we developed a simple In Vitro 3D gingival model resembling the oral periodontal pocket to culture the biofilms of Staphylococcus aureus (S. aureus), Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans), and Porphyromonas gingivalis (P. gingivalis). The PDI efficacy of chitosan hydrogel was examined against periodontal biofilms cultured in this 3D gingival model. We found that the PDI effectiveness was limited due to leaving some of the innermost bacteria alive at the non-illuminated site. Using this 3D gingival model, we further optimized PDI procedures with various adjustments of light energy and irradiation sites. The PDI efficacy of the chitosan hydrogel against periodontal biofilms can significantly improve via four sides of irradiation. In conclusion, this study not only showed the clinical applicability of this chitosan hydrogel but also the importance of the light irradiation pattern in performing PDI for periodontal disease.

Novel Bioactive and Therapeutic Dental Polymeric Materials to Inhibit Periodontal Pathogens and Biofilms

“…Recently, a chitosan-based hydrogel containing 0.5% hydroxypropyl methylcellulose and toluidine blue O with high adhesiveness was developed for the treatment of periodontitis [165]. Two major periodontal pathogens, A. actinomycetemcomitans and P. gingivalis biofilms, were used to evaluate the bactericidal effects.…”

“…Two major periodontal pathogens, A. actinomycetemcomitans and P. gingivalis biofilms, were used to evaluate the bactericidal effects. When the irradiation power was higher than 32.4 J·cm −2 using 630 nm light, a significant reduction in survival rate was observed in both single-species periodontal biofilms [165]. Furthermore, when the light dose was increased to 54 and 108 J·cm −2 , A. actinomycetemcomitans and P. gingivalis biofilms were completely eradicated, respectively [165].…”

“…When the irradiation power was higher than 32.4 J·cm −2 using 630 nm light, a significant reduction in survival rate was observed in both single-species periodontal biofilms [165]. Furthermore, when the light dose was increased to 54 and 108 J·cm −2 , A. actinomycetemcomitans and P. gingivalis biofilms were completely eradicated, respectively [165]. Regarding periodontal regeneration, two in-situ curable biomaterials, BioM1 and BioM2, were developed as support for PS and had excellent mechanical and antimicrobial behaviors [15].…”

Hydrogels: soft matters in photomedicine

“…317 Toluidine blue (31) is another phenothiazine PS used in PDT for a long time. 318,319,320 Formulation in liposomes followed by incorporation into carboxymethylcellulose hydrogels (sometimes called a transferosome approach) and in vivo studies on subcutaneous Ehrlich tumor showed an increase in overall survival of mice when compared to treatment with free toluidine blue. 318…”

“…The formulation showed a high PACT efficiency against periodontal biofilms. 319 Moreover, studies showed that toluidine blue containing hydrogels offer a potential for periodontitis treatment. 320 Also, hydrogels based on HEMA incorporated with NO donor [Mn[PaPy 3 )(NO)]ClO 4 ] exhibited an antimicrobial activity against bacterium P. aeruginosa.…”