Cochran 1989.

Study characteristics
Methods	Trial design: RCT ‐ split mouth Location: Indiana University School of Dentistry, Michigan, Indianapolis, USA Setting: closed operatory separate from other clinical facilities Language: English Number of centres: 1 Study period: not mentioned Funding source: grant from Hygiene corp. Akron, OH Study protocol: not available
Participants	Age: not mentioned Total number of participants: part 1: n = 16; part 2: n = 10 Inclusion criteria: For part 1: Adults who required restorations on adjacent anterior or posterior teeth (4 needing restorations in anterior maxilla, 4 needing restorations in anterior mandible, 4 needing restorations in posterior maxilla and 4 needing restorations in posterior mandible) No dental prophylaxis or antibiotic therapy in past 6 months For part 2: Participants who do not require restorative procedures (5 maxillary and 5 mandibular areas from second molar to opposite canine for spraying procedure were selected) No dental prophylaxis or antibiotic therapy in past 6 months Exclusion criteria: not mentioned Number randomized: For part 1: 32 sites (16 in intervention and 16 in control) "Selection of isolation method, lesion and appointment was randomised". For part 2: 10 (5 in intervention and 5 in control) Number evaluated (withdrawals/missing participants): part 1: 16; part 2: 10 (no missing participants)
Interventions	Comparision: rubber dam + HVE versus cotton roll (without rubber dam) + HVE Intervention: Group name: rubber dam + HVE Number of intervention groups: 1 (but study done in 2 parts using 2 different procedures) Number randomized to intervention group: 16 for part 1; 5 for part 2 Description of intervention: For part 1: rubber dam + HVE during restorative procedure (n = 16). 1 lesion of each pair (anterior and posterior) was restored using rubber dam isolation and HVE. Aerosol particle sampling was done during preparation, cleaning and restoration of all lesions and time required was recorded. Microbial samples were collected throughout the procedure time, which ranged from 11.8 to 23.8 minutes. For part 2: rubber dam + HVE during spraying procedure (n = 5). At appointments 1 week apart, the area from second molar to canine in each participant‐assigned arch was sprayed for 2 minutes with high‐speed handpiece spray followed by spray from air water syringe for 2 minutes. For the intervention group, the teeth were isolated during this procedure with rubber dam and HVE was also used. Microbial samples were collected throughout the procedure time, which was 8 minutes. Any co‐interventions: no Comparator: Group name: cotton roll (without rubber dam) + HVE Number of control groups: 1 (study done in 2 parts using 2 different procedures) Number randomized to control group: 16 for part 1; 5 for part 2 Description of control: For part 1: cotton roll (without rubber dam) + HVE during restorative procedure: (n = 16). 1 lesion of each pair (anterior and posterior) was restored using cotton roll isolation and high‐volume evacuation. Aerosol particle sampling was done during preparation, cleaning and restoration of all lesions and time required was recorded. For part 2: cotton roll (without rubber dam) + HVE during spraying procedure (n = 5). At appointments 1 week apart, the area from second molar to canine in each participant‐assigned arch was sprayed for 2 minutes with high‐speed handpiece spray followed by spray from air water syringe for 2 minutes. Teeth were isolated using cotton rolls and HVE was also used.
Outcomes	Outcome name: reduction in contamination of aerosols (in 2 areas – at dental unit light and 24 inches from mouth and particpant’s chest) (measured by reduction in CFU) Outcome measurement: CFU Effect estimate: mean + SE Key conclusions: "routine use of rubber dam combined with other accepted barrier techniques can contribute significantly to overall infection control program".
Notes	We had hoped to contact the study author for the method of random sequence generation, allocation concealment and for the study protocol; however, no contact details were available.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No details available
Allocation concealment (selection bias)	Unclear risk	No details available
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Not mentioned. 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	High risk	Outcomes measured is CFU using stereomicroscopy (manual counting), which is a subjective method and thus may be affected by lack of assessor blinding.
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