Purpose This study aimed to compare the long-term survival rate and peri-implant marginal bone loss between different types of dental implant–abutment connections. Methods Implants with external or internal abutment connections, which were fitted at Gangneung-Wonju National University Dental Hospital from November 2011 to December 2015 and followed up for >5 years, were retrospectively investigated. Cumulative survival rates were evaluated for >5 years, and peri-implant marginal bone loss was evaluated at 1- and 5-year follow-up examinations after functional loading. Results The 8-year cumulative survival rates were 93.3% and 90.7% in the external and internal connection types, respectively ( P =0.353). The mean values of marginal bone loss were 1.23 mm (external) and 0.72 mm (internal) ( P <0.001) after 1 year of loading, and 1.20 mm and 1.00 mm for external and internal abutment connections, respectively ( P= 0.137) after 5 years. Implant length (longer, P =0.018), smoking status (heavy, P =0.001), and prosthetic type (bridge, P =0.004) were associated with significantly greater marginal bone loss, and the use of screw–cement-retained prosthesis was significantly associated ( P =0.027) with less marginal bone loss. Conclusions There was no significant difference in the cumulative survival rate between implants with external and internal abutment connections. After 1 year of loading, marginal bone loss was greater around the implants with an external abutment connection. However, no significant difference between the external and internal connection groups was found after 5 years. Both types of abutment connections are viable treatment options for the reconstruction of partially edentulous ridges.