A clinical comparison of dentinal slot retention with metallic pin retention

Twenty-two pairs of extensive amalgam restorations were placed in 19 patients. One amalgam of each pair had self-threading pin retention, and the other had dentinal slot retention. Evaluations were done at baseline, at one, and two years. After two years, 17 pairs of amalgams were available for evaluations. The data obtained can be summarized as follows: 100% (17) of the slot-retained amalgams were clinically acceptable, whereas 94.1% (16) of the pin-retained amalgams were acceptable. It can be concluded that, in clinical usage, dentinal slot retention is as effective as self-threading pin retention in extensive amalgam restorations.