This retrospective study evaluated the 5-year cumulative survival rate and complication rates of a 4·0-mm internal connection implant (MicroThread™ Osseospeed™, Astra Tech) installed for single-tooth restoration. The patients who were treated at Asan Medical Center between 2006 and 2007 were included in this study. A life table analysis was used to calculate the 5-year cumulative survival rate. Comparisons of cumulative survival rates among implant position (anterior, premolar and molar), jawbone (maxilla, mandible), gender and prosthesis type (screw-retained, cement-retained) were performed using the log-rank test. Post-loading complications were analysed using Fisher's exact test. Twelve of 136 implants (anterior; 22, premolar; 25, molar; 89) were lost during the loading period, and 11 were removed due to coronal fracture of fixture. The 5-year cumulative survival rate of the whole arch was 91·9%, and that of the molar region was 87·6%. Statistically significant differences were observed in cumulative survival rates among implant position (P = 0·037), whereas no statistically significant differences were observed among gender, jawbone, prosthesis type. Forty-seven of 114 (41·2%) implants in the posterior region showed post-loading complications, including coronal fracture of fixture and abutment screw loosening.

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Within the limitations of this study, the cell attachment of human gingival fibroblasts was correlated with WCA, developed interfacial area ratio and surface slope. When the surfaces with Sa values of ∼ 0.2 μm or less were concerned, only WCA showed a correlation in a third order manner.