Electronic length measurement using small and large files in enlarged canals

Area of Science:

• Endodontics
• Dental Technology
• Root Canal Anatomy

Background:

• Electronic apex locators (EALs) are standard tools in endodontics.
• The impact of file size relative to canal diameter on EAL accuracy is not fully understood.
• Accurate electronic length control is crucial during root canal preparation.

Purpose of the Study:

• To investigate discrepancies in root canal length measurements using small versus appropriately sized endodontic files.
• To assess the accuracy of EALs for electronic length control during rotary file preparation.
• To evaluate the reliability of the Root ZX apex locator in determining apical constriction location.

Main Methods:

• 21 single-rooted teeth were used; actual length (AL) was determined with a size 10 file.
• Initial length (IL) was measured with a size 10 file using the Root ZX apex locator.
• Canals were enlarged to size 60 with rotary files, with continuous EAL monitoring.
• Final lengths were measured with size 10 (FL-10) and size 60 (FL-60) files.
• Histomorphometric analysis confirmed file tip positions relative to the apical anatomy.

Main Results:

• Initial length (IL) was significantly shorter than actual length (AL) by 0.45 mm.
• No statistically significant difference was found between IL, FL-10, and FL-60.
• Histomorphometry revealed that file tips remained within the root confines, despite the absence of natural apical constriction in some teeth.
• The Root ZX indicated an apical constriction location even when it was anatomically absent.

Conclusions:

• The Root ZX apex locator can indicate an apical constriction's location even after it has been eliminated by instrumentation.
• Length measurements obtained using both small (size 10) and large (size 60) files are comparable in enlarged root canals.
• EALs provide reliable electronic length control during rotary canal preparation, regardless of file size relative to the canal.