title: Expanders affect subgingival microbiome
design: Sixteen children with tooth-borne acrylic palatal expanders (+BAPE) in mixed dentition  were compared to sixteen untreated matched controls ( BAPE).  Subgingival biofilm was sampled at baseline (t-1) before start of intervention, after one month of standardized oral hygiene with the start of intervention for cases (t0), and four months later (t+1, day of appliance). Paper-point sampling was performed and bacterial DNA was analyzed using 16S V1-V3 rRNA gene amplicon sequencing with bioinformatic evaluation.