Endoweb -- Apex Locators - Clinical Studies


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	Apex Locators and their Uses	Clinical Cases

CASE 1
A 53-year-old patient was undergoing conventional root canal therapy for tooth # 4.5 which was suspected to have sustained an iatrogenic perforation. (fig#3).

Figure 3A

Figure 3B

Figure 3C

Fig#3 Preoperative radiograph (A) indicates a possible type IV canal
(one main canal breading into two separate ones).
Radiograph of a #10 file (B) in the "lingual" canal.
Note how the file follows the curvature of the root
thus appearing to be inside of the canal.
The extracted tooth (C) confirms
iatrogenic perforation of the root.

There was no clear-cut evidence to substantiate this clinical impression. A #10 file connected to an apex locator was inserted into the buccal canal. A graduate increase in the electrical resistance was observed, and when the apical foramen was reached the apex locator gave us a reading indicating it. The canal length was determined to be 15mm. When the file was inserted in the "lingual canal", the apex locator indicated that the foramen had been reached as soon as the file was inserted into the canal opening. This confirmed the clinical impression that a perforation was present in the root canal system. The character and location of the defect precluded a surgical correction. The tooth was extracted, and the perforation was visually verified. I have to add that this case was treated previous to the use of MTA. Nowadays this perforation could have been repaired by using this material!

CASE 2
A 35-year-old patient presented wit a recently completed root canal treatment and a post cemented in the distal root. It was suspected that the post had perforated the middle area of the root. Radiographs failed to provide a definite answer (fig#4).

Fig#4 Radiograph showing suspected post perforation.
Note periapical pathology.

No other clinical signs or symptoms were present. It was decided to connect one of the electrodes of the apex locator to the post in order to demonstrate a communication with the periodontal membrane. The apex locator registered a typical "in canal" reading. This and evidence of total healing after one year confirmed the accuracy of the reading with the apex locator(Fig#5).

Fig#5 One year recall radiograph confirming the apex locator finding
of no perforation. Note intact lamina dura and total healing
of preexisting periradicular lesion.

CASE 3
A 75-year-old patient required endodontic treatment on an upper bicuspid that had been recently crowned. The radiograph revealed that the canals appeared to be calcified (fig #6).

Fig#6 Radiograph showing "calcified" canals.

Endodontic therapy was started using the surgical microscope. The access opening was made through the crown and the tooth was transiluminated in order to find the orifices into the canals. A white dot was seen at high magnification. A #8 file was introduced into what appeared to be a canal and it was connected to one of the electrodes of an apex locator (fig#7).

Fig#7 A file is inserted into the canal that is attached
to one of the electrodes of an apex locator.

The device registered an "in canal" reading. A second canal was found using the same technique. A radiograph was taken to confirm the working length and the location of the canals (fig#8).

Fig#8 Radiographs confirms that the canals were successfully located.

The only way I know to prevent a perforation 100% is by not doing any endodontics. All of us who like doing endodontics take this risk on a daily basis. Careful examination and thorough knowledge of the internal and external anatomy of each tooth can prevent disasters from happening. Techniques that utilize high magnification, transilumination, dyes and ultrasonics can be extremely useful. However, sometimes we can encounter situations where all the anatomical landmarks are gone and the only thing that we can see is a small "red" or "white" dot The question is, how can we tell, if these dots are canals or perforations! If we are able to determine that a perforation has occurred we can proceed to repairing it immediately and thus increase the chances of repair dramatically. Materials such as MTA can be used quite predictably in situations like this one. However, the success of a perforation repair depends on the size of the defect and how quickly the defect is sealed. Prompt diagnosis is then paramount. The use of an apex locator in this scenario can be extremely advantageous.
Dr. Nahmias currently maintains a private practice specializing in endodontics in Oakville, Ontario, Canada. He is also the creator of Endoweb (http://www.endoweb.com) an endodontic electronic magazine. He can be reached at nahmiasoffice@endoweb.com
References

Nahmias Y, Aurelio A and Gerstein H. Expanded Use of the Electronic Canal Length Measuring Devices; J Endo 1983, 9:347-349.

Sunada I. New Method for Measuring the Length of the Root Canal. J Dent Res. 1962, 41:375-387.

Kobayashi C. The Evolution of Apex-Locating Devices. Alpha Omegan. 1997, 90 #4:21-27.

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Apex Locators and their Uses

Clinical Cases

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CASE 1 A 53-year-old patient was undergoing conventional root canal therapy for tooth # 4.5 which was suspected to have sustained an iatrogenic perforation. (fig#3).






Fig#3 Preoperative radiograph (A) indicates a possible type IV canal (one main canal breading into two separate ones). Radiograph of a #10 file (B) in the "lingual" canal. Note how the file follows the curvature of the root thus appearing to be inside of the canal. The extracted tooth (C) confirms iatrogenic perforation of the root.

There was no clear-cut evidence to substantiate this clinical impression. A #10 file connected to an apex locator was inserted into the buccal canal. A graduate increase in the electrical resistance was observed, and when the apical foramen was reached the apex locator gave us a reading indicating it. The canal length was determined to be 15mm. When the file was inserted in the "lingual canal", the apex locator indicated that the foramen had been reached as soon as the file was inserted into the canal opening. This confirmed the clinical impression that a perforation was present in the root canal system. The character and location of the defect precluded a surgical correction. The tooth was extracted, and the perforation was visually verified. I have to add that this case was treated previous to the use of MTA. Nowadays this perforation could have been repaired by using this material!

CASE 2 A 35-year-old patient presented wit a recently completed root canal treatment and a post cemented in the distal root. It was suspected that the post had perforated the middle area of the root. Radiographs failed to provide a definite answer (fig#4).

Fig#4 Radiograph showing suspected post perforation. Note periapical pathology.

No other clinical signs or symptoms were present. It was decided to connect one of the electrodes of the apex locator to the post in order to demonstrate a communication with the periodontal membrane. The apex locator registered a typical "in canal" reading. This and evidence of total healing after one year confirmed the accuracy of the reading with the apex locator(Fig#5).

Fig#5 One year recall radiograph confirming the apex locator finding of no perforation. Note intact lamina dura and total healing of preexisting periradicular lesion.

CASE 3 A 75-year-old patient required endodontic treatment on an upper bicuspid that had been recently crowned. The radiograph revealed that the canals appeared to be calcified (fig #6).

Fig#6 Radiograph showing "calcified" canals.

Endodontic therapy was started using the surgical microscope. The access opening was made through the crown and the tooth was transiluminated in order to find the orifices into the canals. A white dot was seen at high magnification. A #8 file was introduced into what appeared to be a canal and it was connected to one of the electrodes of an apex locator (fig#7).

Fig#7 A file is inserted into the canal that is attached to one of the electrodes of an apex locator.

The device registered an "in canal" reading. A second canal was found using the same technique. A radiograph was taken to confirm the working length and the location of the canals (fig#8).

Fig#8 Radiographs confirms that the canals were successfully located.

The only way I know to prevent a perforation 100% is by not doing any endodontics. All of us who like doing endodontics take this risk on a daily basis. Careful examination and thorough knowledge of the internal and external anatomy of each tooth can prevent disasters from happening. Techniques that utilize high magnification, transilumination, dyes and ultrasonics can be extremely useful. However, sometimes we can encounter situations where all the anatomical landmarks are gone and the only thing that we can see is a small "red" or "white" dot The question is, how can we tell, if these dots are canals or perforations! If we are able to determine that a perforation has occurred we can proceed to repairing it immediately and thus increase the chances of repair dramatically. Materials such as MTA can be used quite predictably in situations like this one. However, the success of a perforation repair depends on the size of the defect and how quickly the defect is sealed. Prompt diagnosis is then paramount. The use of an apex locator in this scenario can be extremely advantageous. Dr. Nahmias currently maintains a private practice specializing in endodontics in Oakville, Ontario, Canada. He is also the creator of Endoweb (http://www.endoweb.com) an endodontic electronic magazine. He can be reached at nahmiasoffice@endoweb.com References Nahmias Y, Aurelio A and Gerstein H. Expanded Use of the Electronic Canal Length Measuring Devices; J Endo 1983, 9:347-349. Sunada I. New Method for Measuring the Length of the Root Canal. J Dent Res. 1962, 41:375-387. Kobayashi C. The Evolution of Apex-Locating Devices. Alpha Omegan. 1997, 90 #4:21-27.


	Apex Locators in the diagnosis of perforations		Back to Intro


	*The First Electronic Endodontic Magazine*
	Back to: www.endoweb.com Home Page Email: nahmiasoffice@endoweb.com