Color consistency, plaque accumulation, and external marginal surface characteristics of the collarless metal-ceramic restoration.

Four techniques for making collarless metal-ceramic restorations were investigated in this study to examine the final color consistency, the bacterial plaque accumulation, and the surface characteristics of the porcelain margin. Twenty crowns were constructed and data revealed the superiority of the platinum foil technique in producing consistent color, whereas the shoulder porcelain technique resulted in the most significant color deviation. Metal surfaces exhibited the greatest in vitro bacterial plaque accumulation (42.43%), and the margins of the platinum foil technique accumulated the least plaque (7.23%). In addition, the wax binder and the platinum foil techniques produced the smoothest surfaces, whereas again the shoulder porcelain technique exhibited pronounced surface roughness. From the obtained results, and with the limitations of this in vitro study, one can speculate that surface roughness is not a predominant factor in the initial process of bacterial plaque accumulation.