Antimicrobial Resistance in Dental Bioaerosols: Insights from Microbiological Analysis of Face Shield Masks

Bioaerosols are airborne particles that may carry microorganisms and are frequently generated during dental procedures. This study aimed to analyze the microbiological profile of isolates found on face shields masks used by dental students during restorations with conventional restorative procedures (CRP) and atraumatic restorative treatment (ART), and to assess the antimicrobial susceptibility of the most frequent isolates. Samples were collected from the face shields of 30 students (15 CRP and 15 ART) using Rodac TSA contact plates after use. Plates were incubated at 36 ± 1 °C for 48 h, colonies counted, and microorganisms identified by MALDI-TOF mass spectrometry. The mean colony count was 35.9 CFU/plate for CRP and 28.6 CFU/plate for ART. In total, 49 microorganisms were isolated, predominantly Staphylococcus spp. (55.1%), including S. epidermidis, S. warneri, S. capitis, and S. saprophyticus. Among the 27 Staphylococcus isolates, non-susceptibility rates were highest for levofloxacin (100%), erythromycin (74.1%), and clindamycin (48.1%), while all were susceptible to chloramphenicol, linezolid, rifampicin, and sulfamethoxazole. Multidrug resistance was observed in 70.4% of isolates. Both procedures posed comparable risks of microbial dispersion through bioaerosol generation, including multidrug-resistant bacteria. These findings reinforce the need for strict biosafety and disinfection measures in dental practice to minimize infection risks.