Analysis of the misfit of dental implant-supported prostheses made with three manufacturing processes

The microgap between implant components has been associated with complications such as screw loosening or adverse biologic responses.

The purpose of this study was to quantify the microroughness of the mating surfaces of implant components manufactured with different processes, to quantify the microgap between implant components, and to determine whether a correlation exists between microroughness and the microgap.

Nine dental implants with a standard external connection were paired with 3 milled, 3 cast, and 3 sintered compatible cobalt-chromium alloy abutments. The abutment surface was examined, and the roughness parameter Sz was measured by using a white-light interferometric microscope at ×10 to ×100 magnification. The abutment surface and the microgap of the implant-abutment connection were observed with scanning electron microscopy, and the microgap width was quantified from micrographs made of each implant-abutment pair. The mean and standard deviation of roughness and microgap were evaluated. A 1-way ANOVA (α=.05) was used to assess the influence of the manufacturing process on roughness and microgap. The Pearson correlation was used to check dependence between roughness and microgap.

The milled abutments possessed a connection geometry with defined edges and a mean roughness of 29 μm, sintered abutments showed a blurred but functional connection with a roughness of 115 μm, and cast abutments showed a connection with a loss of axial symmetry and a roughness of 98 μm. A strong correlation was found between the roughness values on the mating surfaces and the microgap width.

The milled components were smoother than the cast or sintered components. A correlation was found between surface roughness and microgap width.