ROEN0110

I 37 research _ working length I roots1_2010 File size with respect to the diameter of the apical constriction and foramen can also affect precision. Since the measurements are repeated a number of timesonthesametooth,itiswisetousesmoothcanal instruments (for example, small size finger spreader for lateral condensation) that cause less damage to the fine apical structures than endodontic files. TheEFLmodelusedcanalsoaffecttheresults.The majorityofstudiesconductedonthishaveconfirmed that with newer and improved models, higher preci- sion and more consistent results can be obtained. Pre-flaring of the coronal third of the root canal improves determination of the apical diameter. The firstfilethatbindsattheapicalconstriction,stabilises andincreasestheprecisionofthereadingsinanytype of EFL. The range of tolerance, which varies from approximately 0.1 to 0.5mm, and sometimes 2mm, significantly affects the EFLs’ accuracy; the wider the rangeis,thehigherthepercentageofEFLprecisionis. From a number of articles, we concluded that the method and the apical landmark selected to deter- minetherealoractuallengthofthetoothalsosignif- icantly influences the results. The apical end-points selected varied greatly, from the anatomical apex to the anatomical foramen, and in some cases to the cemento-dentinal junction. Additionally, only vague explanationsforthemethodandobtainedresultswere offeredattimes,makingtheresultsincomparable. It is generally believed that in vitro studies offer valuable and useful facts and results for the clinical practice. However, most of the currently available studies are on single-rooted or single-canal teeth. Many of these studies also have too many variables, resulting in confusion rather than leaving the reader with clear and appropriate conclusions. Owing to the apparent lack of precise and reliable information, Prof Joshua Moshonov (Hadassah Uni- versity, Jerusalem) and a team of researchers from MedicNRG, which we accompanied at a later stage, tested several of the newer EFL models, namely ProPexI(DENTSPLYMaillefer),DentaportZX(J.Morita), Raypex 5 (VDW) and ApexPointer+ (MICRO-MEGA). Figs. 2a & b_The difference between the real values and those shown on the Dentaport ZX (a) and ProPex I (b) is approximately 300 µm. Fig. 3_A difference of 200 µm between the real value and that shown on the ApexPointer+. Fig. 2a Fig. 2b Fig. 3