6 Generation of retentive force by electroformed telescope crowns

Abstract

We measured the retentive force and negative pressure generated between the inner and outer crowns of electroformed telescope crowns having 0°, 2°, 4° and 6° taper with glycerin solutions of different viscosities. The peak retentive force was significantly greater at a glycerin concentration of 20% or more, when compared with no solution. The increase in maximum negative pressure was greater at 0° or 2° than at 4° or 6°, and greater increases were observed with glycerin concentrations of 60% and 80% compared with lower concentrations. At 2°, the retentive force did not increase significantly as the glycerin concentration increased when holes were present in the outer crowns. The above findings suggest that the viscosity of saliva and the negative pressure generated between the inner and outer crowns effectively increases the retentive force in a 2° tapered electroformed telescope crown.