The purpose of this study was to observe the minim pins of Link plus (which has buttress thread and shoulder stop design) inserted into dentin and the dentin surrounding pin. The gingival walls of class II cavity were prepared with high speed handpiece in molar teeth not elapsed time after teeth were extracted, and pinhole of 2mm in depth was positioned about 1 mm to the dentinoenamel junction and minim pin was inserted with wrench. After initial examination of the specimens, the specimens were sectioned longitudinally and horizontally to the pins with carborundum disc and low speed diamond saw (Isomet Buehler Ltd) All specimens were coated Au of 250-300${AA}$ in thickness with Ion Sputter JFC 100 and observed under Scanning Electron Microscope (JSM-35) The following results were obtained. 1. The shoulder stop was seated on the enterance of pinhole in gingival wall, and there were the irregular space between the pin and dentin at the enterance to the pin hole and flakes of dentin lifting from the dentin floor. 2. In case of section to pin horizontally or longitudinally, the dentin debris were observed in gap between pin and dentin, and small cracks were often seen in the dentin surrounding minim pins.