The effect of oscillation, low seating force and dentine surface treatment on pulpward pressure transmission during crown cementation: a laboratory study.

The aim of the present research was to evaluate intra-pulpal pressure with respect to a combination of factors that are known to reduce pulpward pressure transmission in the laboratory while maintaining acceptable seating of the crowns. Thirty premolars were prepared for full crowns and individual crowns were cast. Ten teeth were etched prior to crown cementation with 100 N seating force. Crowns of groups 2 and 3 were cemented with 10 N force, after dentine sealing with bonding agent. Group two received, in addition, oscillating seating force during cementation. Pulp chamber pressure during cementation and marginal seating discrepancy after cementation were recorded. Group 1 showed significantly higher pressure mean 600 Pa and better crown seating (mean -22 microm) compared with group two (mean 144 Pa and 24 microm) and group 3 (mean 102 Pa and 44 microm) (P=0.001). Low seating forces combined with die spacer and sealing of dentinal tubules resulted in significant reduction of pressure transmitted into the pulp chamber during crown cementation. It is suggested that pre-impression sealing of dentine be considered for crown preparations on vital teeth.