Muzzin 1999.

Study characteristics
Methods	Trial design: RCT – split‐mouth design Location: Baylor College of Dentistry, Dallas, USA Setting: 2 separate enclosed dental operatories Language: English Number of centres: 1 Study period: not mentioned Funding source: not mentioned Study protocol: not available
Participants	Age: 21 to 57 years – mean age 30 years Total number of participants: 30 (7 male, 23 female) Inclusion criteria: minimum of 20 permanent teeth (10 on each side of the mouth). Exclusion criteria: hypertension; diseases that require a sodium‐restricted diet; respiratory infections; or rheumatic heart disease, presence of heart murmur or prosthetic replacement requiring antibiotic premedication. being treated with immunosuppressive or anticoagulant medications with acute gingival inflammation, generalized gingival recession, full‐mouth crown and bridge, or more than 1 composite restoration. Number randomized: 30 Number evaluated (withdrawals/missing participants): 30
Interventions	Comparison: HVE versus no HVE Intervention: Group name: with aerosol reduction device (ARD) Number of intervention groups: 1 Number randomized to intervention group: 30 Description of intervention: split mouth – 1 side (maxillary and mandibular) of the mouth was scaled by using an air polisher without the aerosol reduction device (control); and the opposing side, air polisher was used with the aerosol reduction device (intervention). Any co‐interventions: no Comparator: Group name: without ARD Number of control groups: 1 Number randomized to control group: 30 Description of control: as above
Outcomes	Outcome name: reduction in contamination of aerosol (at 2 areas – 12 inches from mouth and on face mask) Outcome measurement: CFU (using blood agar plates) Effect estimate: mean (SD) Key conclusions: the results of this investigation suggest that the aerosol reduction device attached to the air polisher is effective in reducing the amount of microbially contaminated aerosol and spatter that are generated during air polishing.
Notes	We wanted to contact the study author for method of randomisation, allocation concealment, blinding of participants and study protocol, but their e‐mail details were not available.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No details about method of randomisation: "We randomly assigned the order of use of the air polisher with and without the aerosol reduction device as well as sampling of the right and left sides of the subject’s mouth."
Allocation concealment (selection bias)	Unclear risk	No details given
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Blinding is not possible. However, participants and personnel will not be able to alter their behaviour even if they know the received intervention.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Assessor blinded. Quote: "Three microbiologists (C.B. and two others), blinded to each treatment group assignment, counted the number of CFUs on each plate using the Quebec Colony Counter and a hand‐tally counter."
Incomplete outcome data (attrition bias) All outcomes	Low risk	No dropouts
Selective reporting (reporting bias)	Unclear risk	We are not sure of reporting selective outcomes as there is no protocol available.
Other bias	Low risk	None