The in vivo evaluation of hand/rotary/ultrasound instrumentation in necrotic, human mandibular molars.

This in vivo, prospective, randomized, single-blinded study histologically compared biofilm/necrotic debridement efficiency of a hand/rotary technique versus a hand/rotary/1 min ultrasound technique in the mesial roots of necrotic, human mandibular molars. The hand/rotary group consisted of 20 mesial roots. The hand/rotary/ultrasound group consisted of 20 mesial roots prepared with the same hand/rotary technique followed by 1 min of ultrasonic irrigation, per canal, utilizing an ultrasonic needle in a MiniEndo unit. Following extraction, histologic preparation and staining, 0.2 mum cross-sections from the 1- to 3-mm apical levels were evaluated for percentage of biofilm/necrotic debris removal. Cleanliness results at the 1-, 2- and 3-mm levels for the hand/rotary and hand/rotary/ultrasound techniques, respectively, were: Canals, 80% versus 95%, 92% versus 99%, and 95% versus 100%; Isthmuses, 33% versus 83%, 31% versus 86%, 45% versus 91%. Statistical analysis revealed mean percent canal and isthmus cleanliness values to be significantly higher for hand/rotary/ultrasound technique at all levels evaluated.