Use rubber dam.
D003723:Dental Amalgam; D003737:Dental Cavity Preparation / Q000009:adverse effects*; D003762:Dental Instruments; D004646:Emphysema / Q000517:prevention & control*; D006801:Humans; D009059:Mouth Diseases / Q000517:prevention & control*; D013352:Subcutaneous Emphysema / Q000517:prevention & control*
D003723:Dental Amalgam