[Materials properties of zinc phosphate cements after delayed setting on refrigerated slabs]

Two of the zinc phosphate cements commonly used in orthodontics were mixed, with special attention being paid to the longest possible working time, and examined by scientific methods. The results showed that mixing should generally be carried out on frozen slabs (-18 degrees C to -24 degrees C) and for not longer than 5 min. If a maximum compressive strength is required, mixing should be done at refrigerator temperature (+4 degrees C to +8 degrees C) for no more than 1.5 min by accepting a shorter working time. Neither cement shows any notable physicochemical differences, as regards the material.