Microbiological assessment of aerosol generated during debond of fixed orthodontic appliances.

INTRODUCTION: The aims of this study were to describe bacterial load and diversity of the aerosol created during enamel cleanup after the removal of fixed orthodontic appliances and to assess the effect of a preprocedural mouth rinse. METHODS: The study involved the sampling of ambient air adjacent to the patient's mouth during adhesive removal using a slow-speed handpiece and a spiral fluted tungsten carbide bur without water irrigation. Sampling was carried out during enamel cleanup with or without a preprocedural mouth rinse of either sterile water or chlorhexidine. Airborne particles were collected using a viable inertial impactor simulating the human respiratory tree. The bacteria collected were analyzed using both culture and molecular techniques. RESULTS: Bacteria produced during debond and enamel cleanup can reach all levels of the respiratory tree. The use of a preprocedural mouth rinse, either sterile water or chlorhexidine, increased the numbers and diversity of the bacteria in the air. CONCLUSIONS: When using a slow-speed handpiece and a spiral fluted tungsten carbide bur for enamel cleanup after orthodontic treatment, the bacterial load and diversity of the aerosol produced are lower when a preprocedural mouth rinse is not used.

Axenic culture of a candidate division TM7 bacterium from the human oral cavity and biofilm interactions with other oral bacteria.

The diversity of bacterial species in the human oral cavity is well recognized, but a high proportion of them are presently uncultivable. Candidate division TM7 bacteria are almost always detected in metagenomic studies but have not yet been cultivated. In this paper, we identified candidate division TM7 bacterial phylotypes in mature plaque samples from around orthodontic bonds in subjects undergoing orthodontic treatment. Successive rounds of enrichment in laboratory media led to the isolation of a pure culture of one of these candidate division TM7 phylotypes. The bacteria formed filaments of 20 to 200 µm in length within agar plate colonies and in monospecies biofilms on salivary pellicle and exhibited some unusual morphological characteristics by transmission electron microscopy, including a trilaminated cell surface layer and dense cytoplasmic deposits. Proteomic analyses of cell wall protein extracts identified abundant polypeptides predicted from the TM7 partial genomic sequence. Pleiomorphic phenotypes were observed when the candidate division TM7 bacterium was grown in dual-species biofilms with representatives of six different oral bacterial genera. The TM7 bacterium formed long filaments in dual-species biofilm communities with Actinomyces oris or Fusobacterium nucleatum. However, the TM7 isolate grew as short rods or cocci in dual-species biofilms with Porphyromonas gingivalis, Prevotella intermedia, Parvimonas micra, or Streptococcus gordonii, forming notably robust biofilms with the latter two species. The ability to cultivate TM7 axenically should majorly advance understanding of the physiology, genetics, and virulence properties of this novel candidate division oral bacterium.

Microbial contamination of "as received" and "clinic exposed" orthodontic materials.

INTRODUCTION: Our objective was to determine whether components of fixed orthodontic appliances as received from the manufacturers and after exposure to the clinical environment are free from microbial contamination before clinical use. A pilot molecular microbiologic laboratory study was undertaken at a dental hospital in the United Kingdom. METHODS: A range of orthodontic materials "as received" from the manufacturers and materials "exposed" to the clinical environment were studied for bacterial contamination. After growth on blood-rich media, cultured bacteria were identified by 16S rDNA polymerase chain reaction amplification and sequence phylogeny. RESULTS: Bacteria were isolated from "as received" bands, archwires, and impression trays, but the level of contamination was low (0.5 × 10(1) to 1.825 × 10(2) CFU/mL(-1)). Various bacterial species were isolated from "clinic exposed" bands, archwires, impression trays, coil springs, and elastomeric modules, but the level of contamination was low (0.5 × 10(1) to 8.0 × 10(1) CFU/mL(-1)). The most commonly identified bacterial species was Staphylococcus epidermidis, followed by Kocuria, Moraxella, and Micrococcus species. CONCLUSIONS: New materials "as received" from the manufacturers and those exposed to the clinical environment are not free from bacterial contamination before use in patients, but this contamination is low considering the potential for aerosol and operator contamination and could be considered insignificant. Further studies would be required to determine the level of risk that this poses.