Fit of three porcelain-fused-to-metal marginal designs in vivo: a scanning electron microscope study.

This study examined the comparative fit in vivo of three types of PFM crown margins. Marginal openings were measured with an SEM on replicas derived from elastomeric impressions. There was no significant difference among beveled metal margins, metal butt margins, or porcelain butt margins either before or after cementation at the 95% confidence level. This study has shown that it is possible under clinical conditions to consistently produce porcelain butt margins with less than 50 micron marginal opening in PFM restorations.