RESUMO
Objective: To develop a type of oral biofilm to treat ora l ulcer.Methods:Chitosan film was prepared with chitosan only,comp osite chitosan film was prepared with chitosan(7 mg/cm 2),aloe (51 mg/cm 2),di caine(0.55 mg/cm 2) and EGF(40 IU/cm 2).Oral ulcer was made by local applicati on of crystal NaOH in 90 SD rats. The rats were divided into 3 groups with 30 in each. The oral ulcer in each group was treated by chitosan film(group C), compo site chitosan film(group CC) or without treatment(control). The ulcer healing wa s obsered by naked eye and examined pathologically. Results:The average healing time(d) of the ulcer in the groups of C,CC and control was 6.2 5 ? 1.29 ,5.58?1.3 and 8.75?2.49 respectively (C or CC vs Control P0.05). 2 days after treatment higher PCNA expression was observ ed in group CC than that in control(P