Orthodontic appliances can affect changes in the relationships of members of the oral microbiome. Microbiome imbalance can result in oral infections and complicate treatment. The focus is on the microbiological profile of dental biofilm and its control. The effects of metals released by corrosion of alloys for oral use on the microbiome and the extent to which they modify the effectiveness of gingivitis therapy by mechanical and chemical control of biofilm will be investigated. Early and late colonizers of the tooth surface will be analyzed. The condition of gingiva will be assessed, and the results will show the specifics of biofilm and gingiva exposed and unexposed, and differences in the response of individual bacteria to therapy. Molecular biology techniques will be used to quantify the total bacterial biomass (16s rRNA) and the proportion of specific bacterial species within the dental biofilm.

The aim is:

• to determine the clinical characteristics of gingiva of subjects not exposed to metals of dental alloys and exposed to metals
• characterization of microbiome of dental biofilm in subjects not exposed to metals of dental alloys and exposed to metals and to determine changes in the structure of dental biofilm due to exposure to metals
• examine the extent to which environmental influences modify the effectiveness of treatment of gingivitis by mechanical removal of biofilm and chemical control (chlorhexidine digluconate mouthwash (CHX))
• to examine the behavior of bacteria of early and late colonizers of dental biofilm after chemical control
• to analyze biofilm on metal and non-metal appliance
• to explore patient reported outcome measures Study design is a randomized controlled trial with 4 parallel groups: (I) fixed metal orthodontic appliance with regular oral hygiene, (II) fixed metal orthodontic appliance with CHX, (III) non-metal fixed orthodontic appliance with regular oral hygiene, and (IV) non-metal orthodontic appliance with CHX.

Inclusion Criteria:

• malocclusion with moderate or great need for orthodontic treatment (Index of Orthodontic Treatment Need grades >=3)

Exclusion Criteria:

• neurodevelopmental disorders
• intellectual disability
• oligodontia
• congenital craniofacial anomalies
• orofacial clefts

Individual participant data will be shared on reasonable request.

March 2024

No criteria established

Groups were labeled as I-IV, appliance is fixed on teeth and visible for both participants and care providers. Mouthwash is also visible. Outcome assessor does not know wether patient was in mouthwash group, but he sees the type of appliance. Microbiologist and statisticians are not aware of the group affiliation.