Objective      To evaluate the effect of furcal perforation repaired with Portland cement (PC) by comparing to those repaired with mineral trioxide aggregate (MTA).       Methods      Fifty-three newly extracted human molars were collected and randomly divided into 2 experimental groups: group PC (n=24)

group MTA (n=24) and a negative control group (n=5). Perforations in diameter of 2 mm were prepared at the central pulp chamber floor repaired with PC and MTA

respectively. No perforations were created in the control. The furcation appearances were observed under stereomicroscope after repairing. The interfaces between material and dentin were observed with scanning electron microscope (SEM)

and the width of interface gaps was measured. Microleakage was tested by glucose oxidase detection.       Results      The fineness of furcation appearance after repairing was observed. Some discontinuous microgaps between the material and dentin were found in group PC and group MTA under SEM. The gaps in group PC and group MTA were 7.363±2.159 and 8.693±3.551 μm respectively

which was not significantly different (P0.05). In observation period

the value of microleakage in group PC was less than group MTA

but there was no statistical difference (P0.05).       Conclusion      The effect of PC and MTA for repairing furcal perforation was similar. Nevertheless

PC is advantageous for its cheaper price and less coloration of the teeth

which makes it a substitute of MTA in the future study.