bridge it is imperative that the gingival sulcus tissue 21 be retracted in order for the dentist to make an accurate impression of the prepared tooth 20 in accordance with this invention and to control any excessive gingival bleeding an application of a liquid hemostatic agent 22 e g aluminum chloride ferric sulfate or other suitable astringent is applied to the cut tissue in the area of the gingival sulcus the astringent can be applied with centrix 39 s benda micro applicator 23 as seen in fig1 or by any other suitable applicator e g centrix inc 39 s benda u00ae brush softstix u2122 disposable applicator or syringe and the like the astringent 22 is applied with moderate pressure and by rubbing the astringent solution against the cut tissue to infuse the astringent solution into the cut capillaries after the bleeding is under control a dam 24 is adjusted and fitted to the prepared tooth 20 and to at least one tooth mescal and distal beyond the prepared tooth or teeth 20 in accordance with this invention the dam 24 is formed of a porous foam or sponge type material which may be either natural or synthetic the dam 24 as shown in fig4 is formed for use on posterior teeth as shown the dam 24 may be formed as an elongated block of a sponge foam or other type of porous material it will be understood that the block of foam or sponge may be of any desired length from which the dentist may sever therefrom the desired length necessary to dam one or more teeth being worked upon conversely the dam 24.