Indiana University-Purdue University Indianapolis (IUPUI) / The purpose of this investigation was to compare the histopathologic effects of kinetic cavity preparation to the histopathologic effects of conventional high-speed handpiece preparation on the human dental pulp. The objective was to test the following hypothesis: kinetic cavity preparation results in significantly fewer pulpal effects than does conventional preparation using the high-speed handpiece. Class V cavity preparations were made in 26 teeth of seven patients who required extraction of these teeth for orthodontic purposes. Thirteen teeth were prepared using kinetic cavity preparation, using 27-um aluminum oxide particles at 160 pounds per square inch pressure. Thirteen were prepared using the high-speed handpiece and 330bur. Glass ionomer restorations were placed in all teeth. Extractions were done 10 to 15days after preparation. On teeth with closed apices, the apical one-third of the root was removed. All teeth were placed in 10 percent formalin solution. Teeth were sectioned and selected slides stained with hematoxylin and eosin for histologic evaluation. Microscopic findings indicated that the amount of remaining dentin was of significant thickness to be protective to the pulp. Pulpal responses ranged from no response in 22 specimens to a mild response in 4 specimens. Based on the results of this study, it was concluded that shallow preparation into the dentin does not cause pulpal damage at 10 to 15 days post-preparation, when using either kinetic cavity preparation or high-speed handpiece preparation. The hypothesis that kinetic cavity preparation causes significantly fewer pulpal effects than does conventional preparation with the high-speed handpiece was rejected.

Indiana University-Purdue University Indianapolis (IUPUI) / This in-vitro, prospective, randomized study microscopically compared the debridement efficacy of passive ultrasonic irrigation (PUI) using the Ultrasonic Bypass System and different irrigating protocols. Eighty extracted maxillary anterior teeth were randomly assigned to four groups. Teeth were instrumented using EndoSequence rotary instrument system and treated with passive ultrasonic irrigation with different irrigating regimens for one minute. Group one (control) was treated with hand/rotary instrumentation. Group two was treated with hand/rotary instrumentation followed by a one-minute PUI using the Ultrasonic Bypass System with 6.0-percent NaOCl. Group three was treated with hand/rotary instrumentation followed by a one-minute PUI using the Ultrasonic Bypass System with 17-percent EDTA. Group four was treated with hand/rotary instrumentation followed by a one-minute PUI using the Ultrasonic Bypass System with 30 seconds of 6.0-percent NaOCl and 30 seconds of 17-percent EDTA. Teeth were sectioned longitudinally and each half was divided into three equal parts from the anatomic apex. The half with the most visible part of the apex was used for SEM evaluation. A scoring system for debris and smear layer removal was used. Statistical analysis was performed using a Kruskal-Wallis test, which determines if there are any differences among the four groups. Following this test, a Wilcoxon Rank Sum test was used to compare each pair of groups. The addition of a one-minute PUI with the Ultrasonic Bypass System significantly enhanced the removal of smear layer when compared with the hand/rotary instrumentation with conventional irrigating solutions. The Ultrasonic Bypass System when used with the combination of 6.0-percent NaOCl and 17-percent EDTA after hand/rotary instrumentation significantly removed smear layer at the coronal, middle, and apical areas of a tooth when compared with all other groups. A one-minute PUI with the Ultrasonic Bypass System combined with NaOCl and EDTA is significantly better in smear removal and ultimately will result cleaner canal wall.