ROEN0110

40 I I research _ working length indicatedbeforetheforamen.Therecordedvaluesare reviewed in Table 1. The first group of values indicates the moment at which the position of the tip of the finger spreader switched from beyond the apex to the mark apex, 0.0 or red segment (all indicating anatomical or major foramen). These variations are likely due to fine vari- ationsinthepositionofthetipofthefingerspreader, since positioning of the plastic plate could not have been identical in each case. The second group of values indicates the moment at which the reading switched from the mark indicating the anatomical foramen to the first mark coronal to this one: 0.1 (ProPex I and ApexPointer+), 0.25 (MedicNRG-XFR), lowest green line (Dentaport ZX) and lowest yellow square (Raypex 5). The red figures in the last column indicate the EFLs’ precision in measuring the same distance, in other words, the level of resolution. The blue figures are from previous tests. Together they present the EFLs’ ability to make fine distinctions. Therefore, the answer to our question is that dif- ferentEFLsshowdifferentvalueswithdifferentlevels of resolution for the same distance in the same root canal. However, and fortunately, all deviations are far below the range of clinically acceptable tolerance of approximately 0.5mm (about 0.3mm and less), and therefore do not significantly influence the precision and accuracy of EFLs in locating anatomical foramen. _In vivo studies In vivo studies are generally conducted on ex- tracted teeth, offering much more realistic, relevant, reliable, and thus useful data for practitioners. There are several factors that can affect the readings and, consequently, the results achieved in clinical condi- tions. These factors are: 1. status of pulp tissue (vital, necrotic, infected, etc.); 2. pre-flaring of the coronal and/or middle third of the canal; 3. statusofthediameteroftheminorandmajorfora- men(preservedinitsnaturaldimensionordeviated by pathological resorption or instrumentation); 4. size of measuring file; 5. file material; 6. canal content (empty and dry, or inflamed pulp tis- sue,pus,necrotictissueandbacterialdetritus,etc.); 7. electroconductive properties and ion concentra- tion of irrigating solution used; and 8. type of tooth (anterior, posterior, single, multi- rooted, etc.). Anumberofstudieshaveconfirmedthatsomefac- torsfacilitatemoreconsistent,straightforward,faster and precise readings. These beneficial factors are: 1.pre-flaringofthecoronalandmiddleportionofthe root canal; 2. removing of the pulp tissue and debris from the canal; 3. foramen not enlarged by instrumentation or peri- apical pathosis; 4. size of the measuring file coincides with the lumen of the apical portion of the canal; and 5. application of moderately conductive irrigating solutionssuchas2%NaOCl,chlorhexidine,orEDTA solution. The type of the tooth and file material have been provennottoaffectthereadingsandaccuracyofEFLs. roots1_2010 Fig. 8_The tip of the finger spreader #15 was introduced into the canal until it reached the plastic plate barrier firmly placed at the plane of the anatomical foramen. Fig. 9_Microscopic image of the distance from the file tip to the line tangent to the anatomical foramen (L1). Fig. 10_Post-op radiograph of tooth #46. Fig. 8 Fig. 9 Fig. 10