Effects of Caries Activity on Compositions of Mutans Streptococci in Saliva-Induced Biofilm Formed on Bracket Materials

Bum-Soon Lim,Sug-Joon Ahn,Bo-Hyun Kim,Won-Jun Shon

doi:10.3390/ma13214764

Bum-Soon Lim, Sug-Joon Ahn + Show 2 more

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https://doi.org/10.3390/ma13214764

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Abstract

This study aimed to investigate effects of caries activity on composition of mutans streptococci in saliva-induced biofilms formed on bracket materials. Three bracket materials were used as specimens: ceramic, metal, and plastic. After saliva was collected using a spitting method from caries-active (CA, decayed, missing, filled teeth (DMFT) score ≥ 10) and caries-free (CF, DMFT score = 0) subjects, saliva was mixed with growth media in a proportion of 1:10. The saliva solution was then incubated with each bracket material. After a saliva-induced biofilm was developed on the surface of the bracket material, the amounts of total bacteria and mutans streptococci were determined using real-time polymerase chain reaction. The results showed that biofilms from CA saliva contained more mutans streptococci but less total bacteria than biofilms from CF saliva, regardless of material type. Adhesion of total bacteria to ceramic was higher than to plastic, regardless of caries activity. Mutans streptococci adhered more to ceramic than to metal and plastic in both biofilms from CA and CF saliva, but there was a difference in adhesion between Streptococcus mutans and Streptococcus sobrinus. The amount of S. mutans was higher than that of S. sobrinus in biofilms from CA saliva despite similar amounts of the two strains in biofilms from CF saliva. The stronger adhesion of S. mutans to ceramic than to metal and plastic was more evident in biofilms from CA saliva than in biofilms from CF saliva. This study suggests that caries activity and material type significantly influenced composition of mutans streptococci in biofilms formed on bracket materials.

Highlights

Enamel decalcification around orthodontic appliances is the most common complication of orthodontic treatment with fixed appliances [1]
This study suggests that caries activity and material type significantly influenced composition of mutans streptococci in biofilms formed on bracket materials
When comparing bacterial composition in biofilms formed on bracket materials, caries activity and bracket materials significantly influenced biofilm composition (Table 5)

Summary

Introduction

Enamel decalcification around orthodontic appliances is the most common complication of orthodontic treatment with fixed appliances [1]. Prevalence of enamel decalcification in the orthodontic patients is about 12.6% to 50% per patients [1,2]. Placement of orthodontic brackets alters the oral environment, favoring enamel decalcification on the tooth surface, since it complicates mechanical cleaning around teeth surfaces and provides additional sites for biofilm formation [3]. Despite recent advancement in orthodontic materials and techniques as well as a variety of prevention and therapeutic methods, enamel decalcification during orthodontic treatment has not been overcome [1]. The enamel decalcification is induced by organic acids produced by oral bacteria. Among the various oral bacteria, mutans streptococci (mainly Streptococcus mutans and Streptococcus sobrinus in the human oral cavity) are the most important cariogenic bacteria for enamel decalcification due to their

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