Clinical, microbiological and immunological effects of natural compounds-containing mouthrinses in patients with fixed orthodontic appliance therapy

Abstract

Malocclusion and orthodontic treatment can give rise to bacteria and nonbacterial induced gingival inflammations. Previous studies have shown that some natural compounds-containing mouthrinses (NCCMs) have clinical benefits for maintaining gingival health. The aim of the present study was to investigate the effectiveness of NCCMs in the management of dental plaque and gingivitis among orthodontic patients.

The present study consisted of three parts: 1) a systematic review on the effectiveness of NCCMs as an adjunct to unsupervised oral hygiene in the management of dental plaque and gingivitis; 2) an in vitro study to evaluate the antimicrobial and antioxidant effects of Fructus mume (FM) extract; 3) a clinical study to test the clinical, microbiological and immunological effects of a NCCM (FM extract containing) among orthodontic patients.

Firstly, an electronic search for clinical studies of NCCMs was conducted in Medline-PubMed, the Cochrane Central Register of Controlled Trials and EMBASE from the inception of these databases to February 2013. Plaque index (PI), gingival index (GI) and gingival bleeding index (BI) were selected as primary outcome measures. The result identified 11 clinical trials which tested 13 different NCCMs; however, the heterogeneity and limited number of studies on any individual NCCM precluded a meta-analysis, which indicated that substantial evidence of NCCM is still lacking.

Secondly, the antimicrobial effect of FM extract on oral pathogens was tested by agar diffusion assay, broth micro-dilution assay, XTT reduction assay and fluorescence microscopy; the antioxidant effect of FM extract was tested by total antioxidant capacity assay. The results showed: 1) a significant bacteria inhibition effects of FM extract on oral pathogens; 2) a significant difference in the biofilm’s cell viability between FM extract and the negative control exposure (p<0.01); 3) FM extract significantly increased the amount of dead bacteria on the biofilms from microscope images; 4) the antioxidant capacities of FM extracts were 2.91 ± 0.03 uric acid equivalents (UAE).

Thirdly, a six-month randomized, parallel controlled clinical trial consisted of 90 orthodontic patients who were allocated to: 1) negative control group: oral hygiene instruction (OHI) alone; 2) positive control group: OHI plus an essential oils (EO) mouthrinse; 3) experiment group: OHI plus a two-stage NCCM (stage 1: FM extract solution, stage 2: sodium bicarbonate solution). Clinical assessments of PI, BI and modified gingival index (MGI) were obtained. Salivary microbial quantification of aerobic and anaerobic bacteria, streptococci and lactobacilli counts was conducted. Salivary Interleukin-1beta (IL-1β) and macrophage migration inhibitory factor (MIF) levels were detected by ELISA assay. BI was significantly reduced in the two-stage NCCM group compared to the negative control group at 6-months (p<0.05). There was no significant inter-group differences in salivary bacteria counts (p>0.05). The salivary IL-1β level was significantly correlated with salivary aerobic and anaerobic bacteria counts (r 0.34-0.61, p<0.01).

In conclusion: 1) evidence of the effectiveness of NCCM as an adjunct to unsupervised oral hygiene for plaque and gingivitis control is insufficient; 2) FM extract has a significant antimicrobial effect on oral pathogens in vitro; 3) the two-stage NCCM has moderate gingival health benefits among orthodontic patients.