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1. An upper central incisor in a 7year old child has open apex and needs to undergo root canal treatment the best way to determine the working length in this case is by
- Using an apex locator
- Radiographic determination using LOPA x-ray
- Paper point method
- Tactile method
ANSWER c
Definition of Working Length : The distance between coronal reference point to the point at which the canal preparation and Obturation must End.
Methods of Working Length Determination of Root canal in Endodontic Treatment :
There are 7 methods commonly used in determining the working Length of a Root canal during Root canal Treatment Procedure. In most cases only some of the below mentioned are used, while in some cases a combination of the methods have to be used to get a precise working length.
Radiographical Methods of Working Length determination:
- Grossman Formula
- Ingles method
- Weine’s method
- Xeroradiography
- Radio Visiography
Non-radiographical methods of Working Length determination:
- Tactile Sense
- Apical periodontal sensitivity
- Paper point method
- Electronic Apex Locator
Paper Point:
- Paper points have been used to dry canals before obturation, but you can even measure the apex of the tooth.
- This is useful in cases with Wide Open apex where the Apex Locator can give false readings.
- Have to insert the Paper point into the canal until you reach resistance and take out the Paper point to see the tip of the point, if the tip is bloody it means it has extended beyond the apex.
- It has its limitations, if there is bleeding in the canal, you can get false readings.
- In case the pulp tissue is not completely removed, if paper point is left for prolonged period of time it absorbs the blood
2. Time of application apex locators work on the principle of
- 30 seconds
- 4 minutes
- 2 minutes
- 5 seconds
ANSWER b
3. Second generation apex locators works on the principle of
- Electrical resistance
- Electrical conductance
- Electrical impedance
- Circuit breaker
ANSWER c
Second generation apex locators
- These apex locators use the Impedance method for determining the WL.
- Basically these instruments measure the opposition to the flow of alternating current (impedance) and hence the name Impedance based apex locators.
- These units utilize the current of a single frequency to perform the task.
- Formatron IV[2], Sono Explorer[3] and Endocater are a few examples of this generation, almost all having the similar drawback of inaccurate readings especially in the presence of irritants in the canal.
4. Irrigant of choice in a tooth with an acute pulpal abscess in
- Sodium hypochlorite
- Hydrogen peroxide
- Normal saline
- EDTA
ANSWER c
5. The most important aspect of irrigation is
- Volume of irrigant used
- Chelating action of sodium
- Lumen of needle
- Aspiration of solution
ANSWER a
Irrigation is a key part of successful root canal treatment as it fulfils several important mechanical, chemical and (micro) biological functions including the healing of periapical tissues.
It is the only way to reach and impact those areas of the root canal wall which are not touched by mechanical instrumentation.
Characteristics of an ideal endodontic irrigant
- Does not stain tooth structure.
- Inactivation in a culture medium.
- Does not induce a cell-mediated immune response.
- Is non-antigenic, non-toxic, and non-carcinogenic to tissue cells surrounding the tooth.
- Have no adverse effects on the physical properties of exposed dentin.
- Has no adverse effect on the sealing ability of filling materials.
- Easy to use/apply.
- Inexpensive.
