[Influence of cavity lining on marginal leakage beneath cast restoration]

This study investigated the effect of a cavity lining on marginal leakage of a cast restoration.

MOD cavities were prepared on human extracted upper third molars. Additional hemispherical cavities (1.6 mm diameter), simulating deep caries, were prepared on axial walls, and they were restored with lining materials including a glass-ionomer, a resin-modified glass-ionomer, and a low viscosity composite for a lined group. Metal inlays were cast with a 12% Au-Ag-Pd alloy and luted with four luting agents including a zinc phosphate(HZ), a conventional glass ionomer (FI), a resin-modified glass ionomer (VL), and an adhesive resin (SB). The specimens were stored in 37 degrees C distilled water for 24 hours and subjected to 5,000 thermo-cycles, and then, dye penetration was evaluated after 24 hr immersion in 2% erythrosine solution. Metal disks were luted to dentin disks, which have the same-sized spherical cavities in the central area, with the same luting agents. Shear bond strengths were evaluated for both lined and non-lined specimens after the same storing and thermo-cycle processes.

The inlay specimens luted with SB exhibited no dye penetration, while the specimens luted with HZ presented dye penetration reaching to the pulp chamber. The specimens luted with FI and VL showed moderate dye penetration and the values of dye penetration for the cavity-lined group were significantly less compared to those for the lined group (p<0.05). The shear bond strength of the specimens luted with SB and VL was significantly affected by the lining material. The shear bond strength of the specimens luted with HZ or FI was 0 MPa.

The marginal leakage of a cast restoration is affected by the cavity lining but can be improved by using adhesive resin.