The Efficacy of The Coloring Agents from Black Glutinous Rice on Dental Biofilm Staining

Abstract

The use of disclosing agents is recommended to identify the degree and location of dental biofilm which will facilitate oral hygiene practice and contribute to oral disease prevention. To search for an alternative disclosing agent with good staining ability and biocompatibility from natural products, this study aimed to investigate the efficacy of coloring agents made from black glutinous rice (BGR) on dental biofilm staining. BGR solution was prepared by boiling rice in water and frozen dry to get the dark purple powder, which was later mixed with water at ratio 1:2 before application. The crossover clinical trial was conducted in 36 volunteers who were classified into 3 groups (n=12/group) according to their ages (18-26, 27-46, and 47-66 years old). Within the same age, the volunteers were randomly divided into 2 subgroups to apply either with erythrosine dye (ED) or BGR solution. After a 2-week washout period, the volunteers switched to apply another coloring agent. The stained dental biofilm was recorded 4 sites/tooth as staining, not staining or could not identify, by the examiner and the volunteers. The results showed that BGR solution specifically stained dental biofilm in dark purple colour, it did not stain adjacent gingival or oral tissues as well as tooth-colored restorations. The volunteers could see and completely detect the stained teeth within 15 minutes before color started gradually fading. Kappa coefficients demonstrated the interrater reliability between the examiner and the volunteers from ED and BGR solution were 0.34 and 0.30, respectively. This indicated the same interval of agreement of both disclosing agents. There was no statistically significant difference between both agents among different aged groups. The analysis of tooth surfaces and tooth locations demonstrated the significant difference between both agents on the mesial surface and lower posterior teeth, respectively (Paired t-test; p<0.05). In conclusion, the coloring agents from BGR can stain dental biofilm with desirable properties. Its efficacy is marginally less than ED but it has some superior features regarding being natural, safe, and specific staining. In the form of powder, it is convenient for households to promote oral hygiene care.