Biomedical devices and modified biomaterial surfaces constitute an expanding research domain in the dental
field. However, such oral applications have to face a very particular environment containing specific
physiological conditions and specific enzymes. To evaluate their suitability in the development of novel
oral applications, the degradability of polyelectrolyte multilayer films made of the natural polysaccharides
chitosan and hyaluronan (CHI/HA) was investigated in vitro and in vivo in a rat mouth model. The films
were either native or cross-linked using a water-soluble carbodiimide (EDC) in combination with
N-hydroxysulfosuccinimide. The in vitro degradation of the films by different enzymes present in the oral
environment, such as lysozyme and amylase, was followed by quartz crystal microbalance measurements
and confocal laser scanning microscopy observations after being film labeled with CHIFITC. Whereas native
films were subjected to degradation by all the enzymes, cross-linked films were more resistant to enzymatic
degradation. Films were also put in contact with whole saliva, which induced a slow degradation of the
native films over an 18 h period. The in vivo degradation of the films deposited on polymer disks and
sutured in the rat mouth was followed over a 3 day period. Whereas film degradation is fast for native
films, it is much slower for the cross-linked ones. More than 60% of these films remained on the disks after
3 days in the mouth. Taken together, these results suggest that the multilayer films made of natural
polysaccharides are of high potential interest for oral applications, especially as drug release systems, offering
various degradation rates and consequent release characteristics.