Humplik A J, Wilson P R
The University of Melbourne, Australia.
Int J Prosthodont. 2001 Jan-Feb;14(1):53-7.
This study investigated the effects of low seating force (5 N) with and without oscillation on pulpward pressure transmission during crown cementation.
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.
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 microm; group 2 = 362 microm; and group 3 = 26 microm.
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.
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