The apex locator is an effective electronic device which is used in dental endodontics in the process of accurately determining the length of the space of the root canal i.e. the space found within the root of the tooth. It does this by determining where the apical foramen is positioned. The apical foramen is that opening at the very apex of the root of a tooth, and nerve vessels and blood vessels pass through this apex so as to supply the dental pulp. It is therefore representative of the junction of the pulp tissues and the periodontal tissues.

This area is considered to be particular important in dental endodontics because it is necessary to thoroughly debride the entire pulp space and remove necrotic tissue while minimizing the load of bacteria in the space. Debridement refers to the process whereby dead, damaged or otherwise infected tissue is removed medically in order to optimize on the healing potential of the healthy tissue which is left. With reference to endodontics, it is the removal of calculus and also plaque whose quantities may have built up in the teeth. In an ideal scenario the debridement stops at the exact position of the apical foramen and this is where the apex locator comes in.

Dental practitioners have found that pinpointing the exact location of the apical foramen can be a challenge and quite often problematic. This is made even more complicated by the fact that the tooth may have a number of small accessory canals situated in the area of the root apex and the result is a delta-like structure. The apex locator, available at, works by measuring how resistant the apex of the root is to electrical current. The apex has a very specific resistance and this is measured by employing the basic principle that when a circuit is complete resistance decreases significantly and consequently current begins to flow. This event, when using an apex locator, is signaled by a beep, the flashing of a light, a buzz, or even by a change in the dial.

Dental endodontics in past years faced the challenge of false readings as a result of wetness in the canal as this would work to facilitate the conduction of current. The wetness could have resulted from a hemorrhage or even the application of an irrigant. However, the apex locator devices used currently alternate between two frequencies and facilitate the comparison of two electrical impedances which fluctuate with apical movement. As a result the device has been proven to have an increased accuracy level of between 80% and 95%.

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