[In vitro studies on two types of alloys with respect to their effect on the predisposition to secondary caries after obturations].

The authors studied two types of powdered alloy for amalgam without phase "Gamma-2"--"Stom-Am non gamma-2", production of TIC "Pharmachim", Bulgaria. They made obturations from the amalgams on trial to 45 healthy, extracted according to orthodontic indications, human teeth, preserved for 12 weeks in 10% gelatin solution with pH = 4.5 with lactic acid added to the solution in accordance to the international standard for studies on caries and periodontal diseases. On the base of the results from the studies the following conclusions could be drawn: 1. The transversal width of the lesions on the walls in case of amalgam obturations from the two alloys studied is considerably smaller versus that of obturations from the standard (ordinary) alloy for amalgam. 2. The difference in the effect of the two Bulgarian types of alloy tested is not significant, the number of the lesions in case of obturations with them being smaller. 3. The preamalgamation improves definitely only the possibility of shifting of the chips. 4. The amalgam obturations from the alloys without phase "gamma-2" tested, show a likely lower disposition to secondary caries than the obturations from the ordinary alloy for the amalgam.