Use of sharp instruments, handpieces, water-air sprays, and high speed rotary devices during dental cleaning procedures can release oral bacteria, which may cause significant occupational bioaerosol exposure risks. This study aimed at sampling of airborne bacteria and identification of prevalent bacterial genera and testing of overall microbial activity in settled splatter over clinic floors in several US dental clinic rooms during dental cleaning procedures (n = 15). Culturable airborne bacteria were measured by a Biostage impactor and the diversity and relative abundance of the airborne culturable bacterial community were evaluated by pyrosequencing of 16s rRNA genes. ATP levels were determined in swabbed splatter samples collected from floor surfaces for understanding overall microbial activity and estimating the general cleanliness of the clinic surfaces. Concentrations at the beginning, during, and after dental cleaning procedures were 671 +/- 525, 917 +/- 1203, and 899 +/- 823 CFU/m(3), respectively for airborne bacteria and 91 +/- 101, 243 +/- 129, and 139 +/- 77 RLU/sample, respectively for ATP levels on floors. The dominant bacterial phylum was Proteobacteria. A total of 45 bacterial genera were detected, notable among them included Psychrobacter, Pseudomonas, Sporosarcina, and Streptococcus. Several pathogenic bacterial species such as Psychrobacter sp. (including P. pulmonis, and P. faecalis), Streptococcus sp. (including S. thermophiles, S. parasanguinis, and S. oralis), Pseudomonas sp. (including P. graminis) were identified in air samples collected at different stages of the dental cleaning procedures. The concentration of airborne bacteria in dental clinic rooms did not increase significantly during the cleaning procedures. The diversity of culturable bacteria, however, changed. This change in the diversity and the similarity in major taxa detected in our study to the bacterial taxa reported recently from acute or chronic root canal infections and supragingival plaque samples indicate that oral bacteria from patients can significantly contribute to airborne bacterial load in dental clinics during cleaning procedures.