Dynamics of the oral microbiome during orthodontic treatment and antimicrobial advances for orthodontic appliances

Abstract

The oral microbiome plays an important role in human health, and an imbalance of the oral microbiome could lead to oral and systemic diseases. Orthodontic treatment is an effective method to correct malocclusion. However, it is associated with many adverse effects, including white spot lesions, caries, gingivitis, periodontitis, halitosis, and even some systematic diseases. Undoubtedly, increased difficulty in oral hygiene maintenance and oral microbial disturbances are the main factors in developing these adverse effects. The present article briefly illustrates the characteristics of different ecological niches (including saliva, soft tissue surfaces of the oral mucosa, and hard tissue surfaces of the teeth) inhabited by oral microorganisms. According to the investigations conducted since 2014, we comprehensively elucidate the alterations of the oral microbiome in saliva, dental plaque, and other ecological niches after the introduction of orthodontic appliances. Finally, we provide a detailed review of recent advances in the antimicrobial properties of different orthodontic appliances. This article will provide researchers with a profound understanding of the underlying mechanisms of the effects of orthodontic appliances on human health and provide direction for further research on the antimicrobial properties of orthodontic appliances.

Keywords: Applied sciences; Health sciences; Natural sciences.

Graphical abstract

Figure 1

The figure illustrates that different types of orthodontic appliances placed in the oral cavity cause changes in the oral microbiota at different ecological sites in the oral cavity, which may increase the possibility of dental caries, periodontitis, and halitosis

Figure 2

Major habitats within the mouth including saliva, soft tissue surfaces of the oral mucosa (buccal mucosa, keratinized gingiva, palate, tonsils, throat, and tongue soft tissues), and hard tissue surfaces of the teeth (supragingival and subgingival dental plaque (tooth biofilm above and below the gum) Adapted with permission from. Copyright 2024, Oxford University Press.

Figure 3

Schematic illustrations of alterations of the oral microbiome in orthodontic patients with fixed appliances (A) (a) Overview of study design illustrating the visit events at each time point during 3months orthodontics; (b) Plaque species taxonomic profiles by visit (T0, baseline, day of bonding; T1, 1-week postbonding; T2, 6-week postbonding; T3, 12-week postbonding). (B) Comparison of salivary microbial diversity before (T0) and 3 months (T1) and 6 months (T2) after treatment. (C) Comparison of microbial composition in supragingival plaque between white spot lesions (WSLs) and health group after 6–12 months orthodontic treatment. Adapted with permission from.^,, Copyright 2024, SAGE Publications.

Figure 4

Schematic illustrations of alterations of the oral microbiome in orthodontic patients with clear aligners (CAs) (A) (a) Boxplots of alpha diversity of salivary microbiota in the control and white spot lesion groups. Left: Chao1 and Observed_species indices; right: Shannon and Simpson indices (∗∗p < 0.01, Kruskal-Wallis). (b) PCoA plot based on the unweighted UniFrac and Bray-Curtis distances. A certain trend of clustering and separation of samples was identified when comparing the control and white spot lesion groups (p < 0.05, PERMANOVA). (B) Percentage relative abundance of genera in supragingival plaque exhibiting differences in association with (a) plaque index in FAs (left) and CAs (right) and with (b) gingival index in FAs (left) and CAs (right). (C) Analysis of the change of subgingival microbial structure at the genus level in female adult patients with clear aligners. (a) Heatmap of relative abundance of subgingival bacteria at genus level at three different time points: before orthodontic treatment (T0), one month after orthodontic treatment (T1), and three months after orthodontic treatment (T2). (b) Genus-level taxon distribution at T0, T1, and T2. (c) The relative abundance of eight periodontal pathogens at the genus level within three different time points. Adapted with permission from.^,, Copyright 2024, Elsevier.