Biofilm formation on the surface of dental restoratives may lead to secondary caries, which is the main reason for the replacement of composite fillings. Dental materials with antimicrobial properties may reduce biofilm formation. The present study aimed to investigate the biofilm inhibitory effect of methacrylated chitosan, an antimicrobial polymer, covalently incorporated into the polymeric network of an experimental dental adhesive.


Methacrylated chitosan was synthesized by reacting low molecular weight chitosan with methacryloyl chloride under acidic conditions. An experimental dental adhesive (49% Bis-GMA, 24% TEGDMA, 24% HEMA, 1% camphorquinone, 1% butylated hydroxytoluene, 1% ethyl 4-(dimethylamino)benzoate) was prepared. Methacrylated chitosan (20 wt%) was mixed with the experimental dental adhesive and homogenous sample disks were prepared upon curing. The biofilm inhibitory effect was investigated using Streptococcus mutans UA159, grown in BHI (pH 7.0) for 24 hours before quantification of the biofilm was performed using resazurin (1% solution). The effect of the modified material was compared to dental adhesive without methacrylated chitosan (control). The effect of incorporating methacrylated chitosan on the adhesive’s bonding properties was investigated using the notched-edge shear bond strength test (ISO 29022:2013).


Biofilm studies showed that dental adhesive containing methacrylated chitosan (20 wt%) halved biofilm formation of S. mutans compared to control. The notched-edge shear bond strength test showed comparable bond strength to dentin for the two adhesives investigated.


An experimental dental adhesive incorporated with methacrylated chitosan significantly reduced biofilm formation compared to control, and it may be useful in prevention of secondary caries development.

Ida Sofia Stenhagen (Presenter) NIOM – Nordic Institute of Dental Materials
Håkon Valen, NIOM – Nordic Institute of Dental Materials
Inger Sofie Dragland, NIOM – Nordic Institute of Dental Materials
Hilde Kopperud, NIOM – Nordic Institute of Dental Materials