Temperature changes during ultrasonic irrigation with different inserts and modes of activation

This study evaluated temperature changes during passive ultrasonic irrigation. Root canals of three extracted maxillary canines were enlarged to size #45. Thermocouples were mounted 3, 6, and 9 mm from the apical foramen. Teeth were placed in a water bath at 37 degrees C. Distilled water (20 degrees C) was continuously delivered through an ultrasonic unit (group 1) or deposited into the root canal before ultrasonic activation (group 2); for activation, noncutting nickel-titanium (NiTi) inserts or stainless steel K-files #15, #25, and #35 were used. Before and during ultrasonic activation, temperatures were continuously measured for 210 seconds. Statistical analysis was performed using analysis of variance and Scheffé post hoc tests. Temperatures initially decreased by up to 7.4 degrees C; these drops were significantly smaller in group 1 than in group 2 (p < 0.001) in the middle and apical root canal third. The decreases were followed by temperature rises for all inserts in group 2. However, in group 1, temperatures just reached baseline values in middle and apical thirds; in the coronal root canal third, lower temperatures were measured. In group 2, mean temperature rises were 7.7 degrees , 7.5 degrees , and 4.2 degrees C in coronal, middle, and apical root canal thirds. Here, K-file type inserts size #35 generated highest and inserts size #15 the lowest temperatures rises; NiTi inserts were more effective than size #15 K-files and less effective than #35 K-files. Continuous flow negated the potential of ultrasonic activation to heat irrigation solutions. Noncutting NiTi instruments and large K-files were more effective than small K-files in warming deposited irrigants. Temperature changes during ultrasonic irrigation with different inserts and modes of activation Zeltner M (med dent), Peters OA (PD Dr med dent MS), Paqué F (Dr med dent) 1 University of Zurich Dental School, Division of Endodontology, Zurich, Switzerland 2 University of The Pacific, Arthur A. Dugoni School of Dentistry, Department of Endodontics, San Francisco, USA Correspondence: Dr. Frank Paqué University of Zurich Dental School Plattenstr. 11 CH-8028 Zurich Phone: +41 44 6343468 Fax: + 41 44 634 43 08 e-mail: frank.paque@zzmk.uzh. ch Acknowledgement We would like to thank Dipl. Ing. Thomas Reich for expert technical support with the experimental setup. Abstract Introduction This study evaluated temperature changes during passive ultrasonic irrigation (PUI) of intracanal solutions. Methods Non-cutting Nickel Titanium inserts or stainless steel K-Files #15, #25 and #35 were used. Root canals of three extracted human maxillary canines were enlarged to apical size #45. Thermocouples were mounted inside root canals 3, 6 and 9 mm from the apical foramen. Teeth were placed in a water bath at 37°C. Distilled water (20°C) was continuously delivered through the ultrasonic unit (Group 1) or deposited into the root canal prior to ultrasonic activation (Group 2). Baseline temperatures were determined before irrigation and averaged. Ultrasonic activation was subsequently performed; fifteen measurements were done with each insert. Temperatures were recorded every second and expressed as differences to baseline values. Statistical analysis was done using ANOVA and Scheffé post-hoc tests. Results Initially, temperature decreased by up to 7.4°C; these drops were significantly smaller in Group 1 than in Group 2 (p<0.001) in the middle and apical root canal third. The decreases were followed by temperature rises for all inserts in Group 2. However, in Group 1, temperatures just reached baseline values in middle and apical thirds; in the coronal root canal third lower temperatures were measured. In Group 2, mean maximum temperature rises over baseline were 7.7, 7.5 and 4.2°C in coronal, middle and canal thirds, respectively. There were significant differences between activation modes for all inserts (p<0.001). In Group 2, K-file type inserts size #35 generated highest and insert size #15 the lowest temperatures; the NiTi inserts was more effective than size #15 K-files and less effective than #35 K-files. Conclusions Continuous flow negated the potential of ultrasonic activation to heat irrigation solutions inside root canals. Non-cutting NiTi instruments and large K-files were more effective than small K-files in warming the irrigation solution.Introduction This study evaluated temperature changes during passive ultrasonic irrigation (PUI) of intracanal solutions. Methods Non-cutting Nickel Titanium inserts or stainless steel K-Files #15, #25 and #35 were used. Root canals of three extracted human maxillary canines were enlarged to apical size #45. Thermocouples were mounted inside root canals 3, 6 and 9 mm from the apical foramen. Teeth were placed in a water bath at 37°C. Distilled water (20°C) was continuously delivered through the ultrasonic unit (Group 1) or deposited into the root canal prior to ultrasonic activation (Group 2). Baseline temperatures were determined before irrigation and averaged. Ultrasonic activation was subsequently performed; fifteen measurements were done with each insert. Temperatures were recorded every second and expressed as differences to baseline values. Statistical analysis was done using ANOVA and Scheffé post-hoc tests. Results Initially, temperature decreased by up to 7.4°C; these drops were significantly smaller in Group 1 than in Group 2 (p<0.001) in the middle and apical root canal third. The decreases were followed by temperature rises for all inserts in Group 2. However, in Group 1, temperatures just reached baseline values in middle and apical thirds; in the coronal root canal third lower temperatures were measured. In Group 2, mean maximum temperature rises over baseline were 7.7, 7.5 and 4.2°C in coronal, middle and canal thirds, respectively. There were significant differences between activation modes for all inserts (p<0.001). In Group 2, K-file type inserts size #35 generated highest and insert size #15 the lowest temperatures; the NiTi inserts was more effective than size #15 K-files and less effective than #35 K-files. Conclusions Continuous flow negated the potential of ultrasonic activation to heat irrigation solutions inside root canals. Non-cutting NiTi instruments and large K-files were more effective than small K-files in warming the irrigation solution.