Dental high-speed handpiece and ultrasonic scaler aerosol generation levels and the effect of suction and air supply.

OBJECTIVE: Exposure to aerosol spray generated by high-speed handpieces (HSHs) and ultrasonic scalers poses a significant health risk to oral health practitioners from airborne pathogens. Aerosol generation varies with different HSH designs, but to date, no study has measured this. MATERIALS AND METHODS: We measured and compared aerosol generation by (1) dental HSHs with 3 different coolant port designs and (2) ultrasonic scalers with no suction, low-volume evacuation (LVE) or high-volume evacuation (HVE). Measurements used a particle counter placed near the operator's face in a single-chair, mechanically ventilated dental surgery. Volume concentrations of aerosol, totaled across a 0.3-25-µm size range, were compared for each test condition. RESULTS: HSH drilling and scaling produced significantly high aerosol levels (P < .001) with total volume concentrations 4.73×108µm3/m3 and 4.18×107µm3/m3, respectively. For scaling, mean volume of aerosol was highest with no suction followed by LVE and HVE (P < .001). We detected a negative correlation with both LVE and HVE, indicating that scaling with suction improved operator safety. For drilling, simulated cavity preparation with a 1-port HSH generated the most aerosol (P < .01), followed by a 4-port HSH. Independent of the number of cooling ports, lack of suction caused higher aerosol volume (1.98×107 µm3/m3) whereas HVE significantly reduced volume to -4.47×105 µm3/m3. CONCLUSIONS: High concentrations of dental aerosol found during HSH cavity preparation or ultrasonic scaling present a risk of infection, confirming the advice to use respiratory PPE. HVE and LVE both effectively reduced aerosol generation during scaling, whereas the new aerosol-reducing 'no air' function was highly effective and can be recommended for HSH drilling.

Airborne transmission: a new paradigm with major implications for infection control and public health.

Recognition of airborne transmission of SARS-CoV-2 and other respiratory viruses is a paradigm shift in the Infection Prevention and Control (IPC) field, contributed to by New Zealand's experience in Managed Isolation Quarantine Facilities (MIQF). Slowness to embrace this shift by the World Health Organization (WHO) and other international bodies highlights the importance of applying the precautionary principle and subjecting established theories to the same level of critical scrutiny as those challenging the status quo. Improving indoor air quality to reduce infection risk and provide other health benefits is a new frontier, requiring much additional work at both grassroots and policy levels. Existing technologies such as masks, air cleaners and opening windows can improve air quality of many environments now. To achieve sustained, comprehensive improvements in air quality that provide meaningful protection, we also need additional actions that do not rely on individual human's behaviour.