Rotating vs. oszilating preparation of oval root canals

Methods: N=77 extracted teeth with oval root canals were embedded in polyacrylate blocks. The blocks were sawed 5mm and 10mm away from the apex. The cross-sections were digitally photographed under microscopical magnification and the blocks were rebuilt. Crowns were removed and the teeth were divided randomly in two groups. After preparation of the coronal and middle part using the respective sequences of the two systems the slices were separated and photographs were taken again. By superimposition of pre- and post-pictures, the following data was assessed: Difference in x-coordinate of the root canal (DifX), difference in y-coordinate of the root canal (DifY) showing how the original root canal was preserved. Furthermore the difference in area of the root canal (DifAr) standing for the absolute amount of removed dentin was measured. The data was statistically analysed by using Mann-Whitney-U-Test.

Results: Regarding the center of the root canal there was a significant difference between the two systems in the lower section (5mm from apex) for the x- and y-coordinate (median values) DifX:0,098mm(FM),0,044mm(EE),p=0,03; DifY:0,070mm(FM),0,042mm(EE),p=0,02, but no significant difference for the higher section (10mm from apex): DifX:0,096mm(FM),0,098(EE),p=0,38, DifY:0,062mm(FM),0,058mm(EE),p=0,30. Considering the difference in area there was a significant difference in the lower section (DifAr: 0,14mm2(FM),0,08mm2(EE),p=0,01) but also no difference in the higher section.

Conclusions: Within the limits of this study it can be concluded that an oszilating system can be superior in the lower coronal part of oval root canals compared to a rotating system. Further studies should investigate the cleaning ability of both systems.