In vitro quantification of the apical sealing ability of retrograde amalgam fillings

Retrograde amalgam fillings were placed in 12 extracted human canines. The microleakage from the both directions (coronally and apically) was determined using pressurized fluid filtration at 90 min, 6 h, 1 day, 2 days, and 1,2,4, and 8 wk after amalgam filling. Leakage from either direction decreased markedly in the 90-min to 6-h interval after filling. At intervals between 1 day and 8 wk, only small changes in leakage were noted. After any time period, leakage from the coronal direction was greater than leakage from the apical direction. However, this difference was not statistically significant except at 90 min when the coronal leakage was significantly greater. This experimental system was shown to reliably measure microleakage in retrograde amalgam fillings.