Dental periodontal procedures: a systematic review of contamination (splatter, droplets and aerosol) in relation to COVID-19

The COVID-19 pandemic significantly impacted dental care delivery, particularly periodontal care. The primary transmission routes of SARS-CoV-2 are considered direct contact, droplets, and fomites, with increasing evidence of aerosol transmission. Standard infection control precautions in UK dentistry were based on the premise that any patient could be infectious. The WHO recommends droplet and contact precautions for COVID-19 patients and airborne precautions during aerosol-generating procedures (AGPs). Periodontal care is common, and understanding which procedures generate aerosols is crucial for infection control. This review aims to characterize splatter, droplet, and aerosol spread during periodontal procedures, record outcomes and measures of contamination, explore the influence of procedural delivery on aerosol generation, and identify evidence gaps.

Previous studies have reviewed aerosol generation in dentistry, but lacked detailed analysis of periodontal care procedures. The definition of aerosol used in this review considers particles <5 µm. Larger droplets (>50 µm) are defined as spatter. Aerosols can remain airborne for hours, while spatter settles quickly. AGPs are defined as procedures using high-speed devices that generate droplets and aerosols. Standard infection control is recommended for all procedures, but uncertainties about the safety of periodontal care during the pandemic led to professional organization guidance. This guidance has attempted to address anxieties around providing safe periodontal care, particularly in light of its high prevalence across age groups within the UK population. However, further evidence is needed to inform appropriate infection control measures and address uncertainties regarding risk.

This systematic review, registered with the International Prospective Register of Systematic Reviews (ID number 193058), searched Medline (OVID), Embase (OVID), Cochrane Central Register of Controlled Trials, Scopus, Web of Science, and LILACS, and ClinicalTrials.gov. Keywords and MeSH terms were used. Studies measuring aerosol, droplets, or splatter linked to periodontal treatment were included. Studies were excluded if aerosol generation wasn't linked to a specific procedure. Data extraction was conducted using a standardized form. Studies were assessed for methodological quality and sensitivity using a traffic light system. Narrative synthesis was undertaken.

Fifty studies were included, examining ultrasonic scaling (n=44), air polishing (n=4), prophylaxis (n=2), and hand scaling (n=3). Contamination was found in all studies, even with suction, and increased with higher power settings. Contamination was identified on operators (head, neck, body), patients (head, neck, chest), and assistants. Settled spatter was found 30 minutes after treatment in some studies. Microbiological studies measured colony-forming units (CFUs). Air polishing studies indicated greater contamination on the patient in some cases, while hand scaling produced minimal contamination. Environmental contamination decreased with distance from the patient. Air contamination was detected in several studies. The variability in methodology and the measurement methods limited direct comparisons between studies.

This review demonstrates that all periodontal procedures examined produce contamination (splatter, droplets, aerosol), even with suction. Higher power settings and operator position influence contamination amount and spread. Ultrasonic scaling produced significant contamination, while hand scaling produced minimal contamination. Contamination persisted for up to an hour post-treatment. The findings highlight the importance of infection control, appropriate PPE (including respiratory, facial, and body protection), and the use of lower power settings. The limited number of studies investigating contamination beyond 30 min post-treatment highlights the need for further research. The heterogeneity in methodologies limits direct comparisons and suggests that studies may have underestimated the amount and spread of contamination. The lack of studies investigating a wider range of locations for contamination in the clinical environment also limits the generalizability of this review's findings.

Ultrasonic scaling, air polishing, and prophylaxis generate contamination (splatter, droplets, and aerosols), even with suction. Hand scaling produces minimal contamination. Appropriate PPE, particularly respiratory, facial, and body protection, is crucial for these procedures. Lower power settings should be considered to reduce contamination. Future research using comparable methodologies is needed to clarify the extent of contamination, the risk of transmission, and the impact of environmental factors.

The heterogeneity of study methodologies and measurement techniques limited direct comparisons between studies. The sensitivity of some microbiological methods may have underestimated contamination levels. Many studies didn't report suction use at baseline. Limited data exist on contamination beyond 30 minutes post-treatment and on specific pathogen transmission. Most studies focused on operator and patient contamination, with limited data on the wider clinical environment.