Hidden clasps versus C clasps and I bars: a comparison of retention.

The Hidden clasp system overcomes the problem of poor esthetics of partial denture clasps, but it is not known how well it works as a retainer. This study tested the retention of Hidden clasps compared with that of C clasps and I bars when they function as part of a tooth-supported partial denture framework. Nine standardized frameworks that incorporated one of the three clasp designs on a premolar abutment were tested on a laboratory model. Their retention was recorded on a tensile testing machine. Specimens carrying the Hidden clasp had the greatest variability in retention among the three groups. Statistically significant differences were found between the C clasp and I bar groups.