A Quantitative Notion of Persistency of Excitation and the Robust Fundamental Lemma

As already known, orthodontic treatment presents a factor of plaque retention, promoting an in-crease of bacterial growth in the oral cavity. Nevertheless, after orthodontic debonding an alteration of the previous microbiological status may occur. The present study was designed to assess varia-tions among six bacterial species in the oral cavity and the status of oral health after orthodontic debonding. At the end of the fixed orthodontic treatment, 30 patients were divided into three groups based on the type of retention: I -10 patients were treated with upper and lower fixed retention devices, II -10 with upper and lower removable retention devices, and III -10 with lower fixed and upper removable retention devices. To assess the alterations of oral microbiota after ortho-dontic debonding, two salivary swabs were collected for each individual: the first immediately after debonding (T0) and the other one 6 weeks later (T1). Six species, the ones most correlated with the development of caries and periodontal disease, were selected for microbiological analysis with Real-time PCR: Streptococcus mutans, Aggregatibacter actinomycetemcomitans, Porphyromonas gin-givalis, Tannerella forsythia, Treponema denticola, and Fusobacterium nucleatum. Furthermore, in order to correlate the microbiological outcomes with the clinical condition, oral health indexes at T0 and T1 were assessed for all patients. Six weeks after debonding, the salivary levels of the bacteria investigated tend to decrease and the values of the oral health indexes tend to improve with all types of treatment considered (p <.05). Salivary bacteria levels and oral health are similarly influenced by fixed and/or removable orthodontic retentions.