[Treatment of teeth with open canal system using mineral trioxide aggregate as apical barrier under the dental operating microscope].

PURPOSE: To evaluate the effect of closing root apex of permanent teeth with mineral trioxide aggregate to form barricade in root tip under the dental operating microscope. METHODS: 63 teeth treated in our department with open root apex and periapical periodontitis were selected, MTA was used to rigorously close the root apex under microscope, and thermoplastic gutta pertscha was used to fill dental root after formation of barricade in the root tip. All patients revisited regularly for clinical examinations after treatment. RESULTS: Among the 63 treated teeth, only one tooth (23) was insufficiently filled because of the long dental root and unclear field of vision under microscope, the remaining 62 teeth were filled adequately. The postoperative dental film showed 43 teeth were properly filled while 17 had a little over-filling. The patients were rechecked after three months, and the results showed that 2 patients underwent retro-filling because of fistula, 2 patients were lost during follow-up period, and the remaining patients reached the requirement for success including no sensitivity to percussion, improvement or disappearance of pathological changes around the root tip on dental film and regeneration of bone trabecula. The therapeutic effect was not influenced by minor over-filling. The overall success rate was 95%. CONCLUSION: The method of using mineral trioxide aggregate (MTA) to treat teeth with root apex open is accurate and convenient and the effect is pretty good.

[Evaluation of the use of dental operating microscope in the management of blocked canals].

PURPOSE: This study was performed to evaluate the value of dental operating microscope(DOM) in treating blocked canals. METHODS: 161 blocked canals in 113 teeth were treated with ultrasonic instruments under DOM. The etiology of canal blockage included calcification, resinifying therapy and broken instruments. All canals were grouped based on the cause of blockage, teeth site and blockage location in canals, and then the success rates of negotiating ,using SPSS10.0 software package, were analyzed with X(2) test. RESULTS: The results showed that 131 canals were negotiated with a success rate of 81.37%.Blocked canals caused by calcification, resinifying therapy and broken instruments were managed with the success rate of 84.27%, 81.58% and 73.53%, respectively.There were no significant differences in the success rate(P>0.05). Blocked canals of anterior were managed successfully with a success rate of 93.48%,canals of premolar with a success rate of 84.61%,and canals of molar with a success rate of 72.37%. There were significant differences in the success rate between anterior and molar teeth(P<0.01).When the blockage was located in straight canals or above the root canal curvature,canals were negotiated with a success rate of 93.98>.However,the success rate decreased to 21.42> when the blockage located below the root canal curvature,and significant differences were found(P<0.01). CONCLUSIONS: It is an effective way to use dental operating microscope to treat blocked canals, but the therapeutic effects might be affected by sites of the teeth and the blockage location in canals.