Delamination of the maxillofacial silicone elastomer away from the commercially pure titanium (cpTi)-encapsulated magnets affects the long-term performance of the facial restoration.The purposes of this in vitro study were to investigate the interfacial microleakage patterns of 2 maxillofacial silicone elastomers with cpTi when 3 different primers were used and to evaluate the porosity of the 2 elastomers tested.To test the interfacial microleakage patterns of the 2 elastomers MDX4-4210 (EL1) and A-2006 (EL2) with cpTi when 3 metal primers, A-304 (PR1), A-320 bonding enhancer (PR2), Super-Bond C&B monomer (PR3), and ethyl-cyanoacrylate (Super Glue) were used, the bonded interfaces were observed using reflected light microscopy, and the percentage of the linear extent of leakage along the interface (%microleakage) was measured. High-resolution x-ray computed microtomography scanning was used to investigate the percentage of void volume fraction (%VF) for both silicone EL1 and EL2. The data were analyzed with 2-way ANOVA and post hoc tests (α=.05).No statistically significant differences were found among the percentages of PR1, PR2, and PR3 microleakage, whereas ethyl-cyanoacrylate showed a statistically significant higher percentage of microleakage than either of the silicone elastomers (P<.001). EL1 medical grade elastomer groups have always had a statistically significantly higher percentage of microleakage than the EL2 platinum silicone elastomer groups (P<.001). For both elastomers, no statistically significant differences were found in %VF (P=.056).Differences in mechanical properties, chemical composition, and manipulations during handling of the maxillofacial silicone elastomers can affect the linear microleakage along the cpTi-silicone elastomer bonding interface and the porosity of the silicone elastomer.