Objective To discuss the influence of thickness on the fit of porcelain fused metal（PFM） of commercial pure titanium（cp Ti） copings. Methods 30 maxillary incisor resin PFM abutments fabricated by machine with the identical standard was divided into six groups, which were waxed- up, invested and cast with cp Ti. For every kind of thickness of copings which was in order of 0.3, 0.5 and 0.7 mm, there were two groups. One group was veneered, the other was not. That was, three groups veneered, three groups not veneered. All the samples were cemented on their own abutments, after completing the vertical marginal gap measurements the same samples were embedded in acrylic resin and cut mid- orolabially, absolute marginal gap and internal gap were measured. Results When the copings were not veneered, there were no significant differences with the vertical marginal gap, labiocentral and linguocentral absolute marginal gap, wall internal gap and incisive internal gap among three groups. When the copings were veneered, the vertical marginal gap of 0.7 mm group was larger than those of 0.3 and 0.5 mm groups（P<0.05）and the labiocentral absolute marginal gap of 0.7 mm group was also larger than those of 0.3 and 0.5 mm groups（P<0.05）. Conclusion The fit of PFM of 0.3, 0.5, 0.7 mm thickness cp Ti copings was accorded with the demands of clinic, and the thickness of 0.5 mm of cp Ti coping was recommended in clinic.
