The Effect of Oscillation and Low Seating Forces on Pulpward Pressure Transmission and Seating During Crown Cementation: A Laboratory Study

This article is based on the thesis of A. J. Humplik, submitted to the School of Dental Science, The University of Melbourne, in partial fulfillment of the requirements for the degree of Master of Dental Science. Purpose: This study investigated the effects of low seating force (5 N) with and without oscillation on pulpward pressure transmission during crown cementation. Materials and Methods: Thirty human premolars received standardized complete-crown preparations. They were randomly allocated into three experimental 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 pressures were recorded using a 0- to 104-kPa pressure transducer that was connected via the sectioned root of the premolar to the pulp chamber, which was 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 postcementation elevations were measured with a linear variable differential transformer. An amalgam condenser provided oscillation for 1 minute. Results: 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 µm; group 2 = 362 µm; and group 3 = 26 µm. 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.