Myrrh mixed with silver nanoparticles demonstrates superior antimicrobial activity against Porphyromonas gingivalis compared to myrrh and silver nanoparticles alone

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Myrrh mouthwash (MM) is used against an oral health microbe that causes gingivitis.

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Adding silver nanoparticles (SN) may increase antimicrobial activity (AA).

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Our laboratory analysis compared AA between MM with and without SN.

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After 48 h, AA between MM with and without SN was similar.

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Adding SN to MM does not increase antimicrobial activity.

Introduction

Gingivitis is an oral condition characterized by inflammation and bleeding of the gingiva (gums), largely caused by Porphyromonas gingivalis. Oral hygiene options for controlling P. gingivalis include mouthwash containing Commiphora myrrha (myrrh), which has been shown to be effective against the microbe. Silver nanoparticles (SN) have been studied for their antibacterial effect in different oral health applications, including mouthwash. This was an in vitro laboratory study of the anti-microbial actions of myrrh and SN against P. gingivalis.

Methods

We compared the anti-microbial properties against P. gingivalis of four solutions: a) placebo solution, b) myrrh solution (MS), c) MS mixed with silver nanoparticles (MSN), and d) SN suspension alone. Sixteen agar plates were divided into four groups of four plates, and each group was treated with one of the solutions/suspensions. The solution/suspension was administered on the agar disc diffusion method, and inhibition zones (IZs) were measured after 24 (time 1), 48 (time 2), and 72 h (time 3). To characterize MSN and SN, Fourier-transform infrared spectroscopy (FT-IR) was used. UV–Vis spectroscopy and energy dispersive X-ray (EDX) were used to further characterize MSN.

Results

After 24 h, the median IZ for the MS plates was 16 mm, and the median IZ for MSN plates was 15 mm. At time 2, the MS median IZ was 15 mm, but the MSN median IZ increased to 18 mm, and the interquartile ranges (IQRs) did not overlap. At time 3, the median IZs was similar again, with MSN and MS having IZs of 16 mm and 15 mm, respectively. SN alone showed no anti-microbial activity.

Conclusions

Our findings show that MSN displayed superior anti-microbial activity against P. gingivalis compared to MS and SN after 48 h of incubation, but not after 24 h. Also, the increased anti-microbial activity had ceased by 72 h.