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UBC Theses and Dissertations

Root canal dentin erosion following different irrigation protocols Magnusson, Michael


Objectives: It has been previously shown that root dentin erosion increases if sodium hypochlorite (NaOCl) is used again following final ethylenediaminetetraacetic acid (EDTA). The purpose of this study is to quantitatively examine the erosion of root dentin when alternating these irrigants during instrumentation. Methods: Eight extracted teeth were instrumented to size #40/04, sequentially from #15/04, using Vortex Blue rotary files (Dentsply Tulsa Dental, Tulsa, OK). Teeth were then randomly divided into four groups based on irrigation protocol as follows: Group 1: negative controls, irrigated with saline throughout the instrumentation process and as a final rinse. Group 2: 6% NaOCl was used between files at a flow rate of 5mL/min for 15 seconds. Final irrigation was 2 minutes 6% NaOCl followed by 2 minutes 17% EDTA. Group 3: Same protocol as group 2, plus an additional rinse with 6% NaOCl (2 minutes, 5mL/min) after EDTA. Group 4: Alternating irrigation using NaOCl and EDTA, each for 15 seconds between files during instrumentation. A final rinse was carried out alternating NaOCl, EDTA and NaOCl for 15 seconds each. All teeth were then sectioned into 1mm disks and the dentin element content was analyzed by continuous line scanning up to 300 µm from the canal lumen using energy-dispersive X-ray spectroscopy. Results: Statistically significant differences in atomic percentages of carbon, oxygen and calcium were observed between groups. Group 4 had significantly lower atomic percentages of calcium and significantly higher atomic percentages of carbon than both group 1 and group 2. Significantly lower calcium was also observed in group 3 compared to group 1 while higher levels of carbon and oxygen were observed in group 3 compared to group 2. A trend toward lower levels of calcium and phosphorus was seen in group 4 compared to group 3, however differences were not statistically significant. Conclusion: Alternating NaOCl and EDTA throughout instrumentation resulted in dentin composition with the lowest percentages of Ca and P, indicating higher potential for root dentin erosion.

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