Reliability of electronic measuring devices in endodontic therapy

By Blank L, Tenca J, Pelleu G

Date: 01/1975
Journal: JOE


  • Purpose: To clinically evaluate two types of commercial devices currently available for electronically locating the apical foramen of a root canal as an aid in determining canal length. (audible VS. meter type).
  • Materials/Methods:

  • 65 teeth with 103 canals (planned for extraction)
  • Local anesthesia, RD isolation, Access, Pulpal debridement.
  • WL determined using with two commercially available electronic measuring devices (Fig).
  • With the lead clips of each unit attached, the file was inserted into the canal until the unit indicated that the apical foramen had been reached:
  • Sono-Explorer: when a single steady tone was heard and when the needle of the meter entered the red zone and registered its highest reading.
  • Endometer: this occurred when the meter read 40.
  • Direct file measurements were made after teeth extraction.
  • The difference between measurements obtained electrically and directly was determined as the error.
  • Most highlighted Results:

  • Both electronic devices performed within acceptable limits in 85% (Endometer) and 89% (Sono-Explorer) of the canals tested.
  • acceptable limits: a difference up to 0.2 mm from the control measurements.
  • No significant difference between the two devices.

Clinical significance:

Such measuring devices have a definite place in the armamentarium of dentists engaged in endodontic therapy