The effect of oscillation and low seating forces on pulpward pressure transmission and seating during crown cementation: A laboratory study

Purpose: This study investigated the effects of low seating force (5 N) wit h and without oscillation on pulpward pressure transmission during crown ce mentation. Materials and Methods: Thirty human premolars received standardi zed complete-crown preparations. They were randomly allocated into three ex perimental groups of ten: group 1 = 100-N static load; group 2 = 5-N static load; and group 3 = 5-N load with oscillation. Crowns were constructed of base-metal alloy and attached to a purpose-built loading device. Pulpal pre ssures were recorded using a 0- to 104-kPa pressure transducer that was con nected via the sectioned root of the premolar to the pulp chamber, which wa s perfused with saline driven by nitrogen gas at 83 kPa until a steady rate was achieved. The crowns were cemented using zinc phosphate cement, and po stcementation elevations were measured with a linear variable differential transformer. An amalgam condenser provided oscillation for 1 minute. Result s: The pulpal pressures were: group 1 = 455 Pa; group 2 = 26 Pa; and group 3 = 76 Pa. The postcementation crown elevations were: group 1 = -48 mum; gr oup 2 = 362 mum; and group 3 = 26 mum. Conclusion: Acceptable crown seating can be obtained using low force (5 N) combined with oscillation, and lower pressure pulses are generated compared to using high force (100 N) alone.