Antimicrobial and mechanical properties of experimental TCM-loaded dental resin

Abstract

Objectives: Traditional Chinese Medicines (TCM) has been used for more than four thousand years to treat various infectious diseases. Galla chinensis (GC) and Rhizoma coptidis (RC) have been previously demonstrated having antibacterial properties on various oral bacteria. Given this, adding GC and RC into dental resin might give antibacterial function. The objective of this study is to study the antimicrobial and mechanical effects on GC and RC mixed experimental dental resins. Methods: Three groups were prepared as 1) control group, 2) RC-group and 3) GC-group. RC- and GC-groups were added respectively in 1, 2, 3, 4 & 5-wt% of experimental resin (70.6-wt% UEDMA, 27.44-wt% MMA, 0.98-wt% camphorquinone and 0.98-wt% N,N-cyanoethylmethylanine). These resin cements were dispensed and light-cured in various moulds for flexural (2.0×2.0×25.0-mm3) and compressive (Ø3-mm×9-mm) strength tests, and antimicrobial tests with Porphyromonas gingivals, Streptococcus mitis, Streptococcus mutans and Streptococcus sanguis. The data were further analyzed statistically by one-way ANOVA and Tukey post hoc test at α=0.05. Results: The results showed that all the TCM-loaded resin cements had lower flexural strength (70.8-132.1 MPa) than the control (133.3 MPa), but only in certain wt% (i.e. 4 and 5-wt% RC and 4-wt% GC) demonstrated a statistically significantly lower value (p<0.05). For compressive strength, addition of 1-3 wt% GC showed higher compressive strength (19.5-23.8 MPa) than control (19.3 MPa), whilst others showed a lower value. For the antimicrobial properties, there were no differences in inhibition of S.mitis, S. mutans and S.sanguis between control and RC or GC groups. GC had no inhibitory effect on P.gingivalis compared to the control group. However, P.gingivalis was significantly inhibited (p<0.05) in the RC group compared to the control group such that 3- and 5-wt% RC of P.gingivalis bacteria was reduced to 53%±16% and 51%±11%, respectively. Conclusions: In conclusion, 3wt% Rhinzoma coptidis deemed to be the best entity to be added into the dental resin cement formulation without compromising the mechanical properties whilst giving better antimicrobial properties.