Evaluation Of The Dental Operating Microscope In The Management Of Blocked Canals

Objective Existence of blocked canals influences the completion of root canal therapy successfully. We should remove it completely. This study was performed to evaluate the value of dental operating microscope in treating blocked canals. Methods 51 blocked canals in 46 teeth were treated with ultrasonic instruments under operating microscope. The etiology on the cause of blockage, teeth site and blockage location in molar canals, and the success rates of negotiating and average time for preparation of blocked canals which were managed, using SPSS15.0 software package , were analyzed withχ2 test and t test. Results The results showed that 51 canals were negotiated with the total success rate of 74.50%.Blocked canals caused by separated instruments and calcification were managed with the success rate of 72.41% and 77.27%, respectively.And average time for preparation of separated instruments and calcification which were managed were 50.95±21.52min and 36.39±9.36min , respectively. There was significant difference in average time(P<0.01). In the blocked canals caused by separated instruments, canals of anterior,premolar and molar were managed with a success rate of 100% and 61.90%. There was no significant difference in success rate(p>0.05); the average time of successful ones were 26.36±6.83min and 60.33±17.26min, respectively. There was significant difference in average time (p<0.01); All of 21 molar separated instruments which located in top 1/3,medium 1/3 and foot 1/3 of root canals were managed with a success rate of 71.43% and 57.14%. There was no significant difference in success rate(p>0.05); the average time of successful ones were 44.98±18.38min和68.00±10.60min,respectively. There was significant difference in average time (p<0.05). In the blocked canals caused by calcification, canals of anterior,premolar and molar were managed with a success rate of 100% and 73.68%. There was no significant difference in success rate (p>0.05); the average time of successful ones were 23.94±3.68min and 38.36±8.40min, respectively. There was significant difference in average time (p<0.01); All of 19 molar calcification which located in top 1/3,medium 1/3 and foot 1/3 of root canals were managed with a success rate of 83.33% and 57.14%. There was no significant difference in success rate (p>0.05); the average time of successful ones were 34.52±5.16min and 44.94±9.12min, respectively. There was significant difference in average time (p<0.01). Conclusion The use of dental operating microscope is proved to be an effective way in the management of blocked canals, but the therapeutic effects might be affected by sites of the teeth and the blockage location in canals.