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

Abstract

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.

Influence of Immediate Dentin Sealing on the Shear Bond Strength of Pressed Ceramic Luted to Dentin with Self-Etch Resin Cement

“…The claimed benefits include minimizing pulp irritation and less need for anesthesia on removal of the provisional crown, as well as an increase in bond strength. This latter finding following final cementation is in agreement with the work of Cherkasski and Wilson [6]. …”

Effect of the use of die spacer on the marginal fit of copings cast in NiCr, NiCrBe and commercially pure titanium

“…The use of only one layer of die spacer produced an intermediate value (131.07 μm) with no significant difference in relation to the higher and lower values. These results are consistent with those of previous studies, and highlight the importance of using this technical resource to ensure a lower discrepancy of prosthetic castings fabricated with alternative alloys (3,17,19).…”

“…In addition, it promotes an internal relief for the luting agent, thus preventing the cement layer from interfering on the crown's complete seating and helps compensating for the alloy's casting shrinkage by adding to the thermal expansion of the refractory material (13,16). The internal relief promoted by die spacers has been shown to reduce the intrapulpar tensions and the force required at the moment of crown cementation (17,18), in addition to ensuring a better marginal fit and increasing the restoration's retention in 25% (19,20).…”

In vitro vertical misfit evaluation of cast frameworks for cement-retained implant-supported partial prostheses

“…In the latter, vertical gap may be due to implant misalignment, impression technique, wax contraction, alloy composition, type of investment, framework design, casting and veneering method, 10-12 luting procedure, or operator experience. [13][14][15][16][17][18] Given the complexity in achieving a completely passive fit with current casting technologies, this study aimed at evaluating the vertical misfit of three-unit cast structures for implant-fixed restorations luted over machined dental implant abutments. The null hypotheses tested were that: (1) there are no differences in the vertical fit of bridge structures independently from the alloy type (cobalt-chromium, titanium, palladium-gold) and their specific investing and casting procedures, and (2) there are no differences in the marginal discrepancy achieved on anterior and posterior bridge abutments.…”