Purpose: This case-controlled study examined clinical and microbiological parameters in Brazilian children and adolescents receiving orthodontic treatment using fixed orthodontic appliances or removable orthodontic appliances.
Methods: The plaque index, gingival index, number of decayed, missing and filled teeth, and probing pocket depth was measured on each fully erupted tooth in 30 patients treated with fixed orthodontic appliances and an equal number of age and sex-matched control subjects. The same parameters were also measured in 18 patients treated with removable orthodontic appliances and an equal number of age and sex-matched control subjects. In the patients treated with fixed orthodontic appliances, subgingival plaque samples were collected from four teeth with orthodontic brackets and from four teeth with orthodontic bands. In the patients with removable appliances, subgingival plaque samples were collected from clasped maxillary permanent first molar teeth and from four unclasped permanent teeth. Samples of unstimulated whole saliva and samples from the dorsal surface of the tongue were also obtained from each subject. Each sample was analyzed for the presence of 19 target bacteria by dot blot. A subset of samples was examined by direct amplification of bacterial nucleic acids.
Results: Compared to their respective age and sex-matched controls, whole mouth means for plaque index and gingival index were significantly elevated in both the fixed and removable orthodontic groups. There was no difference in the DMFT. Subjects with fixed orthodontic appliances had a higher prevalence of each of the target species except for L. fermentum, Neisseriaceae and S. mutans. The prevalence of A. naeslundii and Streptococcus sp. was significantly higher on teeth with orthodontic brackets alone compared to teeth with both orthodontic bands and brackets. Subjects with removable orthodontic appliances had a higher prevalence of A. actinomycetemcomitans, C. rectus, E. corrodens, L. fermentum, Neisseriaceae, and spirochetes. The prevalence of Neisseriaceae was significantly higher on unclasped teeth compared to clasped teeth. There was no difference between sample sites for the target bacteria except for A. actinomycetemcomitans that was detected less frequently in saliva. Orthodontic patients demonstrated higher proportions of gram negative species by direct amplification of nucleic acids including species frequently associated with periodontal disease as well as rarely cultivable or non-cultivable species such as Abiotrophia defectiva, Gemella haemolysans, Granulicatella adiacens, Lautropia sp., Terrahaemophilus aromaticivorans, and TM7 bacterium.