The purpose of this study is to evaluate the effect of tetracylcline-hydrochloride(TC-HCl) on the change of implant surface microstructure according to application time. Implants with pure titanium machined surface, SLA surface and porous surface were used in this study. Implant surface was rubbed with sponge soaked in 50mg/ml TC-HCl solution for 1/2 min., 1 min., 1 1/2 min., 2 min., and 2 1/2min. respectively in the test group and with no treatment in the control group. Then, specimens were processed for scanning electron microscopic observation.

1. Both test and control group showed a few shallow grooves and ridges in pure titanium machined surface implants. There were not significant differences between two groups.

2. In the SLA surfaces, the control specimen showed that the macro roughness was achieved by large-grit sandblasting. Subsequently, the acid-etching process created the micro roughness, which thus was superimposed on the macro roughness. Irrespective of the application time of 50mg/ml TC-HCl solution, in general, test specimens were similar to control.

3. In the porous surfaces, the control specimen showed spherical particles of titanium alloy and its surface have a few shallow ridges. The roughness of surfaces conditioned with tetracycline-HCl was lessened and seen crater-like irregular surfaces relative to the application time.

In conclusion, pure titanium machined surfaces and SLA surfaces weren't changed irrespective of the application time of tetracycline-HCl solution. But the porous surfaces conditioned with tetracycline-HCl solution began to be slightly changed from 2 min. This results are expected to be applied to the regenerative procedures for peri-implantitis treatment.