Dentin permeability and eugenol diffusion after full crown preparation

To compare teeth prepared to receive a metallic versus a metal-ceramic crown with respect to (1) in vitro dentin permeability before and after using a desensitizing agent and (2) pulpal eugenol concentration after sealing a temporary crown with a zinc oxide-eugenol based cement.

The roots of 20 human mandibular molars were separated and the crowns were prepared to receive a metallic crown. The hydraulic conductance was recorded before and after using Protect dentin desensitizer. The crowns were then further reduced to receive a metal-ceramic crown and the hydraulic conductance was recorded under the same conditions, on deeper dentin, before and after using the desensitizing agent. Twenty additional teeth were prepared: 10 to receive a metallic crown and 10 teeth to receive a metal-ceramic crown. A tube filled with 1 mL phosphate buffered saline (PBS) was sealed to the cementoenamel junction. A temporary crown was sealed onto the preparation with Temp Bond. The amount of eugenol that diffused across dentin into PBS was spectrofluorimetrically measured at Day 1 and Day 7. The crown preparations were vertically sectioned and the dentin remaining thickness was recorded.

The hydraulic conductance of teeth prepared for a metal-ceramic crown was twice as high as teeth prepared for a metallic crown (P < 0.001). The desensitizing agent reduced the hydraulic conductance in both groups (P< 0.001). The two groups showed the same hydraulic conductance after using Protect (ns). No significant difference was found in the amount of eugenol diffusion between the two groups of teeth although eugenol diffusion decreased with time (P < 0.01). No correlation was found between eugenol diffusion and remaining dentin thickness.