INVESTIGATION OF ROOT CANAL ENLARGING AND SHAPING TIMES, FORCES, SHAPING REGIONS, AND TRANSPORTATION AMOUNTS BY THE RECIPROC Ni-Ti ROTARY FILE WITH A SPECIAL-PURPOSE MOTOR AND BY RECIPROC DIRECT

抄録

Single-file enlarging and shaping of curved root canals was performed using RECIPROC, a Ni-Ti rotary file with reciprocating motion imparted by a special-purpose motor, and using the RECIPROC direct handpiece designed especially for the RECIPROC and linkable to a dental unit, with comparisons between the two systems of operating time, forces, shaping regions, and transportation amounts, at a rotary speed setting of 15,000 rpm. The results showed no significant differences in total enlargement and shaping time, pulling force average, average values for shaping amounts of inside or outside curvature region after root canal enlargement and shaping, or root canal transportation. The average pushing force was significantly higher with RECIPROC direct. With use of RECIPROC with the torque control function of its special-purpose motor, the operator can lessen the force setting with a warning alarm on reaching the torque limit, but no warning alarm is issued by RECIPROC direct, and this may be the reason for the significant difference found in pushing force. With either system, however, no file fracture, step formation, or other complication, and no file deformation were found. These results show that proper root canal enlargement and shaping similar to that of RECIPROC attached to the special-purpose motor can be obtained with RECIPROC direct at a speed setting of 15,000 rpm, provided care is used to avoid excessive force application.