Apex Locators Flashcards
Define apex locator and its components.
Apex Locators are the instruments used in Endodontics to determine the Working length(Working length is defined as the distance from a coronal reference point to the point at which canal preparation and obturation should terminate) in Root Canal Treatment as an adjunct to Radiography. They are used to locate the Apical foramen by determining the Apical constriction AC or Cementodentinal junction
A- Lip clip B- File clip C- Electronic device D- Cord which connects above three parts
Describe now Apex locator works and their uses.
A probe , such as a file, is attached to an electronic instrument with an electric cord and is inserted through the root canal until it contacts the surrounding PDL.
When the probe touches the soft tissues of the PDL, the electrical resistance gauges for both gingiva and PDL would have similar readings.
By measuring the depth of insertion of the probe, one may determine the exact working length of root canal
They are useful in conditions where apical portion of canal system is obstructed by:
a) impacted teeth,
b) zygomatic arch,
c) excessive bone density,
d) tori,
e) overlapping roots,
f) shallow palatal vault.
In such cases, they can provide information which radiographs cannot.
- They are useful in patient who cannot tolerate X-ray film placement because of gag reflex.
- In case of pregnant patients, to reduce the radiation exposure, they can be valuable tool.
- They can also be used in children who may not tolerate taking radiographs, disabled patients and patients who are heavily sedated.
- They are helpful in root canal treatment of teeth with incomplete root formation, requiring apexification and to determine working length in primary tooth.
What are contra indications of Al?
The use of apex locators and other electrical devices such as pulp testers, electrosurgical instruments and desensitizing equipment, is contraindicated for patients who have cardiac pacemakers.
- Electrical stimulation to the pacemaker patient can interfere with pacemaker function. The severity of the interference depends on the specific type of pacemaker and the patient’s dependence on it.
- In special cases, an apexlocator may be used on a patient with a pacemaker when it’s done in close consultation with the patient’s cardiologist.
What are advantages (6) and dis advantages (3) of Al?
Advantages of EAL
- Devices are mobile, light weight and easy to use
- Much less time required
- Additional radiation to the patient can be reduced (particularly useful in cases of pregnancy)
- 80 - 97 % accuracy observed
- Provide objective information with high degree of accuracy.
- Some apex locators are also available in combination with pulp tester, or with rotary system, so can be used in combination
Disadvantages of EAL
a) Can provide inaccurate readings in following cases:-
a. Presence of pulp tissue in canal
b. Too wet or too dry canal
c. Use of narrow file
d. Blockage of canal
e. Incomplete circuit
f. Low battery
b) Chances of over estimation
c) May pose problem in teeth with immature apex
Describe gen 1 Al and its advantages and disadvantagesz.
Resistance Apex locators.
- It is based on the principle that resistance offered by periodontal ligament and oral mucous membrane It is called as Sonoexplorer.
- These apex locators give false readings in the presence of Blood, pus, chelating agents, irrigants in the root canal.
Advantages of 1st generation Apex locators
- Easily operated
- Digital read out
- Audible indication
- Detects perforation
- Can be used with K-file
- May incorporate pulp tester
Disadvantages of 1st generation Apex locators
- Requires a dry field
- Patient sensitivity
- Requires calibration
- Requires good contact with lip clip
- Cannot estimate beyond 2mm Examples: Neosono
Describe gen 2 and 3 examples
- : It works on the principles of Impedance,
- A major disadvantage of second generation apex locator is that root canal has to be free of electro-conductive materials to obtain accurate readings.
- Presence of electro-conductive irrigants changes the electric characteristics and lead to inaccurate readings
- Examples of Second generation apex locators.
o Endocater o Sono explorer o Apex finder endoanalyzer it is a combination of Apex locator and pulp tester o Digipex o Extract a pex o Foramatron IV o Pio apex locator
Write advantages and dis advantages of gen 2 apex locators
Advantages of 2nd generation Apex locators
- Does not require lip clip
- No patient sensitivity
- Analog method
Disadvantages of 2nd generation Apex locators:
- No digital read out
- Difficult to operate
- Canal should be free of elecro-conductive irrigants and tissue fluids
Describe gen 3 apex-locators and 3 examples.
They are also called as Frequency dependent apex locator.
- Works on the principle of frequency or Comparitive impedence. They are based on the fact that different sites in canal give difference in impedance between high (8 KHz) and low (400 Hz) frequencies.
- The difference in impedance is least in the coronal part of canal. As the probe goes deeper into canal, difference increases. It is the greatest at cemento dentinal junction.
- Endex
- Root ZX
- Neosono Ultima
- Mark V plus
- Justwo or Justy II
- Apex finder A.F.A
What are advantages and dis advantages of gen 3 apex locators?
- Easy to operate
- Uses K-type file
- Audible indication
- Can operate in presence of fluids
- Analog read out
Disadvantages of 3rd generation apex locator:
- Requires lip clip
- Chances of short circuit
Describe 4th generation apex locators?
• These measure the resistance and capacitance separately rather than the resultant impedance value.
• There can be difference in the combination of values of capacitance and resistance that provides the same impedance, thus the same foraminal reading. But by using 4th generation apex locators this can be broken down into primary components and measures saperately for better accuracy and thus less chances of occurance of errors
Describe gen 5 apex locators,
• It uses multiple frequencies rather than dual frequency as in third and fourth generation of apex locators, so it works in dry and wet canal and requires no calibration (e.g. Raypex)
Describe 6th gen apex locators
Sixth generation:
• Also called adaptive apex locators, multifrequency operating system. Sound operated device can produce different kinds of sound to indicate the difference position of the file in the root canal. Dry and wet conditions are also available for accurate reading.
