Abstract: Objective This study aimed to investigate the influence of coping material and porcelain firing on the marginal and internal fit of computer-aided design/computer-aided manufacturing (CAD/CAM) of zirconia ceramic implant-and titanium ceramic implant-supported crowns. Methods Zirconia ceramic implant (group A, n=8) and titanium metal ceramic implantsupported crowns (group B, n=8) were produced from copings using the CAD/CAM system. The marginal and internal gaps of the copings and crowns were measured by using a light-body silicone replica technique combined with micro-computed tomog-raphy scanning to obtain a three-dimensional image. Marginal gap (MG), horizontal marginal discrepancy (HMD), and axial wall (AW) were measured. Statistical analyses were performed using SPSS 17.0. Results Prior to porcelain firing, the measurements for MG, HMD, and AW of copings in group A were significantly larger than those in group B (P<0.05). After porcelain firing, the measurements for MG of crowns in group A were smaller than those in group B (P<0.05), whereas HMD and AW showed no significant difference between the two groups (P>0.05). Porcelain firing significantly reduced MG (P<0.05) in group A but significantly increased MG, HMD, and AW in group B (P<0.05). HMD and AW were not influenced by porcelain firing in group A (P>0.05). Conclusion The marginal fits of CAD/CAM zirconia ceramic implant-supported crowns were superior to those of CAD/CAM titanium ceramic-supported crowns. The fits of both the CAD/CAM zirconia ceramic implant-and titanium ceramic implant-supported crowns were obviously influenced by porcelain firing.

Key words: fit, implant-supported crown, porcelain firing, titanium, zirconia