Endodontic retreatment of a lower right first molar with WaveOne®

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Dr. David C. Baker uses a technique that facilitates quick and predictable results

Patient history

The patient is a 34-year-old female who was referred by a local colleague. She had broken her lower right first molar and complained of some general discomfort. The tooth had received root canal treatment some years earlier. The patient was fit and well, but was a little anxious about the treatment.



Upon examination, it was found that LR6 had a fractured restoration, with a silver point sitting proud out of the fracture. The tooth was slightly tender to percussion and had mild buccal tenderness. Circumferential pocket probing revealed a maximum of 2-mm pocketing.

Extraoral and intraoral examination showed no swelling or obvious lymphadenopathy. The soft tissues were of normal texture and color, oral hygiene was good, and the teeth were generally well maintained.

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Images were taken using indirect digital radiographs with a beam-aiming device (Figure 1). The radiograph identified a root-filled, lower first molar tooth. The two mesial canals had been obturated with silver points, and the distal suggested a short gutta-percha filling. There were apical radiolucencies associated with both roots and possibly some apical resorption on the distal root. The marginal bone was sound, and both roots had a slight curvature.


Diagnosis of a fractured tooth with chronic apical periodontitis due to a failed root treatment was established.

Treatment options

Several treatment options were discussed with the patient:

  • Extraction and/or replacement with an immediate denture, bridge, or implant.
  • Root canal retreatment followed by provision of a cuspal coverage protective restoration.

As the patient wished to save the tooth, success rates of root canal retreatment and the difficulties associated with removing silver points were discussed. One of the silver points was so proud that it was removed then and there with tissue forceps. A new angled periapical radiograph (Figure 2) was taken, showing the more difficult remaining silver point.

Treatment details

After an inferior alveolar dental block with a buccal infiltration, the tooth was isolated using a rubber dam, with a single number seven molar clamp on LR7 and a reversed premolar clamp on LR5. Access to the three canals was established with a high-speed air turbine under magnification with a microscope. The pulp chamber was refined and tidied up with a No. 2 Start-X Dentsply ultrasonic tip (Figure 3).

The access cavity was flooded passively using a side-venting monoject needle with 3% sodium hypochlorite. Using a No. 3 Start-X tip, space was made around the remaining silver point in the mesiobuccal canal. Once space was made, a Hedstrom file was able to slide alongside the silver point and help tease it out completely. 

A size 10 stainless steel K-file was used to gently scout each of the three canals. The size 10 file moved fairly easily in all three canals to approximately two-thirds of the estimated length. A WaveOne® Primary 25:08 file was selected and mounted on a WaveOne motor. The WaveOne program was selected (Figure 4) for each of the three canals.

Initially working the file into the coronal half of each canal, slight pressure was applied apically for three or four motions before removing the file for cleaning, irrigation, and recapitulation. The file removed the coronal gutta percha in the distal canal. With copious irrigation and recapitulation, the size 10 file was able to slowly approach the estimated canal length from the preoperative radiographs. 

An Apex locator zero reading was used to establish the position of the apical foramen, with the chosen working length in each canal 0.5 mm from this. The glide paths were confirmed to the working lengths of each canal. The working lengths were 19.5 mm for the mesial canals, and 19 mm for the distal canal. The mesial canals merged into the apical 2 mm.

A WaveOne Primary file was used again in each canal, this time to the full working lengths. The WaveOne file reaches working lengths in this sort of canal fairly easily, but is best removed after three to four progressive motions to clear the debris from the file and irrigate the canal with recapitulation. Apical patency was maintained throughout with a size 10 hand file. The gutta percha from the distal canal was removed uneventfully,* and no solvents were required.

At this stage, the tooth was medicated with non-setting calcium hydroxide and dressed with PTFE and a glass ionomer temporary restoration. 

The patient returned 10 days later to have the treatment finished. She reported mild discomfort for a day or so after the first appointment, but this had since settled. Once again local anesthetic was administered, and the rubber dam was applied as before.

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The temporary dressing was removed, and the canals were irrigated as they were previously. A size 10 K-file confirmed patency once more, and a size 25 hand K-file was checked for the previously agreed length and for apical gauging. Tug back was confirmed with matching gutta-percha points, and a cone fit radiograph was taken to confirm the prepared lengths (Figure 5).

Once again the canals were irrigated with 3% sodium hypochlorite. This was followed by sonic irrigation with the EndoActivator®, using the number 2 red tip. The canals were washed with 17% EDTA for 1 minute, dried, and irrigated with 2% chlorhexidine gluconate before being dried for a final time.

The canals were obturated with warm vertical compaction using AH Plus® (Dentsply) (Figure 6) and the Calamus® Dual Filling system (Figure 7) with matching WaveOne gutta-percha points (Figure 8). The black tip 40:30 was chosen for the mesial canals and the yellow tip 05:50 for the distal canal.

140506 C DrBaker 03After obturation, excess sealer and gutta percha was removed from the access cavity, and the tooth was sealed with glass ionomer. The occlusion was checked. Two appropriately angled radiographs (Figures 9 and 10) were taken to confirm an adequate obturation with a small distal puff of sealer. The obturation showed a continuous taper of all canals. The patient was given postoperative advice regarding pain relief and advised to contact her referring dentist. The dentist was advised to provide a crown to the tooth to maintain a sound coronal seal and prevent future fracture as soon as possible.

The patient was reviewed 3 months later, and a new periapical radiograph (Figure 11) showed good signs of healing. The patient has since been asymptomatic. 


This treatment was carried out and completed using just one reciprocating file. WaveOne offers a simple technique that provides quick and predictable results. The complete system ensures that matching paper points and gutta percha are available in either obturators or cones. Although there are three files to choose from in the system (Small 21:06, Primary 25:08 and Large 40:08), the majority of cases can be completed with a single WaveOne Primary file 25:08.

The reciprocating motion of the rotary file massively reduces the risks of cyclic fatigue. The instruments, which are manufactured out of M-Wire NiTi, are also more resilient to fracture.


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