Endodontic Retreatment

This patient came in with RCT #29 completed 7 years earlier. She reported dull ache, had a gold onlay and obvious apical lesion. Clinically, tooth was mildly sensitive to percussion, normal probing depths. Diagnosis: Prior RCT with Phoenix Abscess. Retreatment indicated.

During retreatment, a lateral canal was opened, irrigated & obturated. No fractures seen under the microscope.

At 3 months, the patient was asymptomatic and apical healing noted. This lesion is classified as "healing" due to the decrease in apical lucency since the retreatment.

At 15 month recall, the patient is asymptomatic and lesion is "healed", despite failure to place coronal restoration.

Swartz, Skidmore & Griffin (1983) in an evaluation of 1007 endodontically treated teeth found that the #1 reason for failure was inadequate restorations. They also found that overfills caused 4 times as many failures.

This patient was encouraged to get coronal coverage on this tooth ASAP.

Separated File Removed

Look closely and you can see a separated file in the mesial root.


The contrast feature makes the separated instrument a little more obvious.

For more information about removing a separated instrument, click here.

For information about PREVENTING a separated instrument, click here.

Length Determination with Radiographs

Apex locators have become commonplace in the clinical practice of endodontics. They have shown remarkable accuracy and reliability. Part of the skill in using an apex locator is understanding when the reading is reliable or not. There are certain conditions where an apex locator may not give a reliable reading and traditional length determination using radiographs is required.

For radiographic length determination we rely upon our files and radiographs. For a quick review of terms, the radiographic apex is where the apex appears on the film. The anatomic apex is where the apical foramen is positioned, which may or may not be at the most apical part of the root. When using radiographs to determine the length of the root, it is recommended that we estimate the length of the root from 0.5mm-1.0mm from the radiographic apex.

The reason for this estimation goes back to the early 1970's.

Palmer, Weine & Healy 1971 showed that when teeth are filled to the radiographic apex, the gutta percha is extruded out of the canal 50% of the time.

Burch & Hulen 1972 found that the apical foramen deviated from the anatomic apex 78%-99% of the time.

Because of these early length studies, it is recommended to estimate your length short by 0.5-1.0mm.

Here is an interesting case that demonstrates how filling to the radiographic apex may actually be filling long.


Here is a post operative film following RCT of #3. I think most people would assume that the obturation looks pretty good.

1 year recall looks good radiographically, however the patient continues to reports some sensitivity.

After some of the extruded sealer has resorbed, its easier to see that there is a slight over fill. Since the patient's symptom persist, the tooth is treated surgically

Surgical exposure of the root apices shows the extruded gutta percha and sealer.

Simple apicoectomy removes the extruded gutta percha.

This case shows how easy it is to overfill a root canal. Length determination using apex locaters as well as radiographs is an important skill for any clinician performing endodontic therapy.

Horizontal Root Fracture?

This tooth was referred to an oral surgeon for extraction and immediate implant placement on #11. A void between the post and the root canal filling is noted and it appears there may be some widening of the periodontal ligament adjacent to that void. There was purulence noted from the sulcus and the attached gingival tissue was inflammed. The tooth was otherwise asymptomatic. I was asked to do a consultation to confirm the horizontal fracture before the tooth was extracted. As I have mentioned in previous posts, root fractures are very difficult to diagnose.

A second radiograph of the tooth appears normal. No sign of fracture or change in the periodontal ligament from this view. It does appear that there may be some coronal leakage on the distal margin of the crown.

Another radiographic shift reveals that the post preparation was off center slightly with the canal. I explained to the patient and my oral surgeon colleague that the only way to know for sure would be to examine the tooth surgically or by removing the post and examining the tooth internally using the microscope.

When given the option to evaluate the tooth microscopically and potentially retain the natural tooth, the patient elected to disassemble the post & crown and evaluate it. Microscopic examination as well as additional radiographs revealed no sign of horizontal fracture. Endodontic retreatment was completed and a post and core build up was completed. There is plenty of supracrestal bone to get a good ferrule for the new crown.
Proper endodontic consultation allowed this patient to retain his natural tooth, save considerable time and money and be back to complete function in a matter of a few weeks.
The endodontic part of the "multi-disciplinary" approach to implant treatment planning is often lacking. Diagnosis of root fracture rarely can be made by looking at a single film. Endodontic consultation is an important part of implant treatment planning.