Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

APD > Apex locator > Flashcards

Apex locator Flashcards

1
Q

To effectively undertake a RC treatment, what should the clinician determine?

A

The apical limit of the root canal system

The position of the canal terminus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Why is it important to determine the apical limit of the root canal system and The position of the canal terminus

A

Studies have shown the root fillings which have extended beyond the apex or are more than 2mm short of the apex are associated with a higher chance of failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the anatomical apex?

A

The end of the root as determined from a macro perspective - end of the root as you can visualise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why is the anatomical apex not useful?

A

it doesnt take into account the micro-anatomy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the radiographic apex?

A

Determined by the radiograph

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why is the radiographic apex inaccurate?

A

As take 0.5mm and use this as a measurement
As the foramen is often located to one side of the radiograpic apex
This varies from 0.3-0.6mm but can be up to 3mm
Deposition of the cementum at the apex can cause further discrepancies
pathology - External resorption can change the position of the foramen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the major apical constriction

A

The widest point of the foramen where it exits the root

Considered to be entirely within the cementum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the problem with using the major apical constriction as the point of finish?

A

Doesn’t produce a natural stop for the filling material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the minor apical constriction?

A

The narrowest point of the foramen
The cementum narrows up from the major apical foramen
The location is variable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Where is the minor apical constriction?

A

usually 0.5-1mm short of the apex at the point where the cementum fuses with the dentine (CDJ)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the CDJ?

A

The point where the cementum fuses with radicular dentine

The point where the root canal finishes and the periodontium begins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the CDJ considered to be?

A

The ideal limit of a root canal treatment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why is CDJ not a landmark to be used in endodontics?

A

It can only be detected histologically

Can be irregular - one side 3mm higher than the other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which landmark should we use?

Why?

A

Minor apical constriction
Narrowest part of the root canal system and forms a good natural barrier
Consistent anatomical reference point
Most practical landmark

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the different methods for determining working length?

A

Tactile feedback from instruments
The paper point technique
Radiographic determination of WL
Electronic apex locator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why not just rely on tactile feedback?

A

Most experienced endodontists could only detect apical constriction in 60% of cases by tactile sensation alone
Made more complicated by sclerosis, resorption and anatomical differences

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does the paper point technique rely on?

A

root canal system of an uninfected tooth in dry whilst whilst the periodontium is wet (hydrated tissue)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do you carry out the paper point technique?

A

Paper points placed at incrementally shorted lengths until no moisture is detected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

When is the paper point technique useful?

A

open apices or abnormal anatomy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

When is the paper point technique not useful?

A

apical exudate in infected cases and when patency is not achieved

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the radiographic determination of WL?

What does it rely on?

A

Undertaken with paralleling technique

Uses the premise that the apical constriction ia 0.5-1mm short of the radiographic apex

22
Q

What is the problem with using radiographic determination?

A

The apical constriction can be significantly further away in over-instrumentation of the apex - can under and over prepare
Can be difficult to determine due to overlying structures or superimposition of canals
Exposes the patient to radiation

23
Q

What do apex locators use to identify where the apex is?

A

Uses resistance/impedance of the RC and PDL to determine where the RC finishes and the PDL begins

24
Q

How does the apex locator work?

A

An electrical circuit is formed, starting at the AL running through a clip on the file, through the RC, through the AC, out the PDL, and through the mucosa and to clip on the patients lip and back to the AL
To do with resistance and impendence - changes when the file enters and leaves the canal

25
Q

How do first gen AL’s work?

A

Resistance-based
Set up to detect the value: resistance between endodontic instument at the apical foramen and an electrode on the oral mucosa

26
Q

What is the resistance between endodontic instument at the apical foramen and an electrode on the oral mucosa

A

6.5 kW

27
Q

What are the problems with the 1st gen apex locator?

A

Accurate when dry, but affected by the exudate, pulp tissue. haemorrhage or electrolytes
Sometimes result in a small electric shock

28
Q

What do second gen apex locators rely on?

A

Impedence based locators

29
Q

What is the problem with second gen apex locators?

A

Still affected by presence of electrolytes and tended to be variable between teeth

30
Q

How do 3rd gen AL’s work?

A

Use multiple frequencies to determine the distance between an endontic instrument and the end of the canal
Calibrated to detect the apical constriction

31
Q

What is good about 3rd gen AL’s?

A

Improved in accuracy by the presence of electrolytes and accuracy is decreased if the canal is dry
Have an accuracy of 83-100%
Can be attached to rotary instruments to give instant readings - this makes it less accurate

32
Q

How do 4th gen AL’s work? What makes them more accurate?

A

Use 2 frequencies to detect the apical constriction, but only uses one at a time - this reduces the noise from using multiple frequencies and therefore negates the need for a filter - makes them more accurate

33
Q

What are the problems with apex locactors?

A

Metallic restorations will short-circuit the apex locator reading leading to a mis-reading - need to be replaced or ensure the file does not touch the restoration and the pulp chamber isn’t flooded with irrigating solution
Perforations will trigger an apex response when the file touches the perforation - good as tells you perforation but give inaccurate reading
Large lateral canals - may cause misreading - get reading too soon

34
Q

What 8 things lead to clinical success?

A
  1. Radiographs
  2. The access cavity
  3. The irrigating media
  4. The endodontic file
  5. The apex of 0 reading
  6. Re-checking WL
  7. The battery
  8. Unstable readings
35
Q

Why are pre-op radiographs important?

A

To obtain information about the root canal shape and anatomy

36
Q

What needs to be done to the access cavity before

A

Ideally remove any metallic restorations prior to treatment
No fluid in the pulp chamber - gentle drying with 3 in 1
Modern apex locators work best in the moist canal

37
Q

What is special about the irrigating solution?

A

do not impact on the performance of modern apex locators

38
Q

What is significant about the endodontic file?

A

Should be in contact with all the walls of the RC
A file which is too narrow will be less accurate
The metal which the file is made of (SS and NiTi) does not affect the accuracy

39
Q

When is the AL most accurate?

A

When it is giving an apex or 0 reading and contacting the PDL

40
Q

What do earlier readings from the AL not give an indication of?

A

0.5 or 1 do not indicate the distance from the apex

41
Q

What is the best way to use the AL?

A

Advance the file until the display reads ‘apex’ or ‘0’ reading and subtract 0.5mm from the length

42
Q

What are commercial AL calibrated to?

What does a 0 reading mean?

A

The apex, 0 reading means 0mm from the apex

43
Q

When should the WL be re-checked when using a AL

Why will the WL now decrease?

A

After the coronal 2/3 of the canal have been shaped

The WL will decrease because of a decrease in the curvature of the canal

44
Q

When should the re-checking happen?

A

prior to shaping the apical terminus

45
Q

What do low voltages cause?

A

electronic errors , ensure the apex locators batteries are well charges before use

46
Q

When are the only times apex readings should be accepted?

A

When the scale bar is stable and moves in sympathy with the movements of the file

47
Q

when should the apex readings not be accepted?

A

If flashes intermittently
Moves erratically
Displays no bars

48
Q

What may unstable readings be due to?

A

faulty machine
Obliterated anatomy
Excessive exudate

49
Q

What do you do if you get unstable readings?

A

dress the canal, and re-check at next visit

50
Q

What is needed to locate the apex?

A

Careful study of high quality radiographs
Magnification of radiographs and blocking out extraneous light
Keeping apical anatomy in your mind
Use tactile sense to locate apical constriction
Observe blood/fluids on instrument tip or anywhere on a paper point
Use and understand your apex locator

51
Q

What are the main advantages of using a apex locator?

A

Can reduce the need for mid-treatment radiographs and therefore reduce the time taken to complete the procedure

APD (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions