Oral microbiome in orthodontic patients = Il microbioma orale nel paziente ortodontico

OBJECTIVES The study of the microbiota is gain ing overwhelming importance in recent years. The orthodontic treatment may be associated with an increased cariogenic risk and a worsening of preexisting periodontal diseases. The aim of this review is to investigate the available evidence regarding the correlation between the use of orthodontic devices and changes in the oral microbiome. MATERIALS AND METHODS A search was carried out to identify articles of interest on the PubMed database, using the following keywords: “oral microbiome in orthodontic patients”, “fixed orthodontic appliance”, “clear aligners”, “microbiological colonization”, “oral microbiome”, “periodontal pathogen”. The articles published up to February 2021 about patients in fixed orthodontic therapy or with aligners were included. RESULTS Orthodontic fixed appliance in creased the accumulation of bacte rial plaque; this is mainly due to the presence of retentive areas on the dental surface, but also to the difficulty in oral hygiene home procedure. Supragingival plaque accumulation influences subgingival microbial composition, favoring the transition to more periodontal pathogenic species. Fixed appliance insertion is followed by a qualitative change in the composition of the subgingival bacterial population, with an increase of some periodontal pathogenic bacteria, such as Campylobactor rectus, Prevotella nigrescens, Pseudomonas spp., Tannerella forsythia, Porphyromonas gingivalis. However these microbial changes in subgingival plaques appear to be transient, returning to the pretreatment levels at the end of the orthodontic treatment, when the appliances are removed. In patients treated with aligners, the composition of the microbial flora does not change significantly after 6 months of use of this type of device. CONCLUSIONS Based on our narrative review the levels of subgingival periodontopathogens temporarily increased after placement of an orthodontic fixed appliance, and decreased and returned to the pretreatment levels several months later. Fixed orthodontic appliances can still promote a transient condition of plaque-related gingivitis. Aligners allows a better oral hygiene at home, therefore are associated to a reduced risk of periodontal inflammation and caries, than fixed devices. CLINICAL SIGNIFICANCE Orthodontic fixed appliance may provide sites for bacterial adhesion and biofilms formation, because of some aspects related to the orthodontic devices features (es. the presence of plaque retentive areas and consequential greater difficulties in home oral hygiene measures). The use of these devices can favor the ap pearance of gingivitis plaque-re lated, while it does not seem to represent a risk factor for the development of periodontal disease. For this reason, especially in patients on fixed therapy, maintaining good oral hygiene at home and scheduling regular check-ups are essential. On the other hand, in patients treated with aligner, no significant changes in the composition of the microbial flora may seem to occur. The use of aligners allows adequate oral hygiene and reduces the risk of developing caries or gingivitis compared to fixed orthodontic therapy. These devices may be preferred, if clinically appropriate, in those adults at high risk of developing gingivitis and caries.