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Dr Arvind Sharma Non surgical root canal



Dr Arvind Sharma Non-surgical root canal re-treatment of the mandibular left first premolar (LL4)

Dr Arvind Sharma qualified in 1996 from the University of Dundee and works in Edinburgh as an Associate providing General Dentistry and Advanced Endodontics. Dr Sharma is committed to postgraduate education and is an active member of the British Endodontic Society and The Royal Odonto-Chirurgical of Scotland.

Dr Arvind Sharma Non surgical root canal re-treatment – The modern dental microscope provides enhanced visualisation and unprecedented access to the oral cavity. What follows is a case that exemplifies the significance of using superior magnification to aid in modern dentistry.

The patient is a 49-year-old male, non-smoker (as from March 2011), and has a moderate alcohol intake. Well motivated about his dental health, he regularly attends six monthly examinations, hygienist appointments and is registered with NHS Scotland.
Figure one - intercuspal position upFigure two - upper occlusal viewFigure three - lower occlusal view




Having experienced pain in the lower left quadrant for several days – especially with biting and pressure – the patient presented for an emergency appointment. At this time, the tooth area had also become swollen, but no sleep loss or high temperature was reported. The patient was able to identify tooth LL4 as the source of complaint, noting that analgesics had been taken to ease what he described as a dull throbbing pain.
Although the patient had received primary root canal treatment on tooth LL4 whilst on holiday in Las Vegas in 2003, he had remained symptom-free until recently. On returning to Scotland at that time, a temporary restoration had been placed, with a composite onlay provided as a definitive coronal restoration. No other relevant medical history or long-term medications were noted.

Intraoral and extraoral
During the extraoral examination, apart from minor submandibular swelling to the left mandible, no other significant findings were noted.  The intraoral examination revealed that gingival swelling was palpable buccal to tooth LL4 with it appearing both tender to percussion and to have a small degree of mobility. Oral mucosa, tongue, sublingual tissue and soft/hard palate, however, appeared within normal limits with no lingual swelling noted.
Periodontal condition
A basic periodontal examination was recorded as shown below:
Table one: Periodontal examination
2      1      4
4      3      3

Occlusal examination
Angles Class I anterior relationship showed a Class I molar relationship on the left and a Class I canine relationship on the right. The left and right lateral excursions were canine guided and protrusive guidance was provided by palatal surfaces of the maxillary incisors.
The dentition was heavily restored posteriorly on the left and with one occlusal restoration present on the right. The upper anterior incisors had porcelain-bonded crowns in situ.
Table two: Dentition
7       4 3 2 1     1 2 3 4 5 6 7
7 6 5 4 3 2 1     1 2 3 4 5 6 7

Specific examination of the problem site (LL4)
Tooth LL4 was previously restored with a composite onlay in situ. Fitted in 2009, it had a good marginal seal and good occlusal relationship with the maxillary teeth. Intercuspal relationship was noted and the buccal cusp was involved in left lateral excursions. There were no isolated periodontal probing defects, no signs of coronal or root fracture and the tooth was tender to percussion.
Table three: Special tests
Special Test    LL4    LR4
Digital axial/horizontal pressure    Yes    No
TTP-axial/horizontal    Axial    No
Digital palpation-buccal/lingual    Buccal/lingual    No
Endo-Frost    No    Yes
EPT    No    Yes
Periodontal probing     Within normal limits    Within normal limits

Radiographic examination
A periapical radiograph taken at the emergency appointment revealed a marginally sound coronal restoration. A dentine pin appeared to be present in the distal of the tooth, with further evidence of some horizontal bone loss. A radio-opaque material was present in the root canal, which appeared sub-optimal and short of the radiographic apex, whilst the root appeared wide and a ledge was visible mid root with the obturating material. This suggested that two root canals were present with only one obturated. A periapical radiolucency was also apparent with some widening of the periodontal ligament space.
Figure four - pre-operative radiograph





Strictly speaking, a definitive diagnosis is only possible with a histological analysis of the infected area. However, the resources and facilities for this were not available. The diagnosis for the patient’s pain showed moderate, non-suppurative, localised, chronic apical periodontitis with a non-obturated root canal (a failed primary root canal treatment).
After discussing the benefits, limitations and risks of various treatment options including root canal treatment, extraction of teeth with prosthetic replacement and reducing infection with further observation, the patient opted for root canal retreatment under a private contract. Thereafter, consent was given and two subsequent appointments were made.

After the patient was questioned about known allergies, amoxicillin 500mgs tds was prescribed for five days. At the next appointment – which was 16 days later due to his work commitments – the restorability of tooth LL4 was discussed. Since the present restoration was well fitting and functional, it was decided to maintain this onlay and perform the root canal re-treatment through the occlusal surface. The patient was warned, however, that in the event that the onlay suffered damage as a result of the access cavity, he would require a new restoration. The possibility of a future full coverage crown was also discussed, and once the procedure was explained again for clarification, the patient consented to treatment.
For the treatment itself, topical anaesthesia was first applied. After 60 seconds, a buccal and lingual infiltration was administered and a rubber dam was placed and sealed. An access cavity was then prepared through the existing composite onlay with the aid of x2 magnification surgical loupes. The obturation material was located buccally and identified as pink gutta-percha and subsequently removed with the aid of Gates Glidden burs, stainless steel files sizes 25 and 30 and solvent (chloroform).
The canal was irrigated copiously with 5.25% heated (50oC) sodium hypochlorite (NaOCl). A radiograph was then taken to verify the working length (20mm from the occlusal surface) and to confirm gutta-percha removal – since a zero reading had been achieved – with an electronic apex locator. Patency had also been achieved in the buccal canal.
Figure five - working length radiograph of buccal canal




The tooth was then assessed with the aid of a Carl Zeiss OPMI ® Pico operating microscope at x10 magnification and the remaining gutta-percha was removed. After locating the lingual canal, which was apparent on the initial radiograph, root dentine was removed with ultrasonic instruments. A working length was established as before and measured with an electronic apex locator, which was then verified with another radiograph. The lingual canal was again patent and had a working length of 19mm from the occlusal surface reference point.
Figure six - working length radiograph of lingual canal



To achieve straight-line access, being careful not to remove excessive dentine and restoration material, Gates Glidden burs were again used. Copious irrigation with 5.25% heated NaOCl was performed and a glide path was established with 2% taper K files, 10-20 with patency being confirmed by recapitulating with a size 10 stainless steel K file. The files were then used with a watch-winding action and finished with a push-pull motion until a smooth glide path was created.
Canals were dried and a temporary dressing of calcium hydroxide paste placed in each canal with 1mm of the working length. A foam pellet was placed in the pulp chamber and a temporary restoration placed in the access cavity.
Two weeks later at the second appointment, the patient reported LL4 to be completely symptom-free. Upon clinical examination, no submandibular, buccal or lingual swelling was noted, the tooth was not tender to percussion and the temporary dressing was in situ.
After topical aesthetic was applied and local anaesthetic administered, a rubber dam was placed as before and the temporary dressing removed. The canals were irrigated and prepared with reciprocating rotary files using an endodontic motor and both canals were prepared to length with a pecking motion as per the manufacturers guidelines. A master apical cone radiograph was also taken to verify GP lengths after gauging each canal to an apical width size 25 (MAF).
Figure seven - master apical cone radiograph



A final rinse was performed with 5.25% heated sodium hypochlorite with sonic agitation for 30 seconds in each canal. Each canal was again irrigated with NaOCl and then irrigated with 17% ethylenediaminetetraacetic acid for a further 30 seconds with a final flush with NaOCl. The canals were then dried with paper points until the tips of the points were withdrawn from the canals dry.

Obturation was performed with gutta-percha cones, which used sealer via continuous wave and heated backfill. The heated gutta-percha was condensed with a size 2 plugger and Gooseneck burs were then used to level and smooth it to the canal orifice level. The chamber was cleansed with isopropyl alcohol and sealed with light-cured flowable composite after applying 37% hydrophosphoric acid for 20 seconds, washing with water for 20 seconds, drying with air and applying a dentine bonding agent. The remainder of the access cavity was restored with composite resin and light cured for 20 seconds. The rubber dam was then removed, the occlusion checked in intercuspation position and lateral excursions and the surface polished with rubber cups and diamond polishing paste. A final radiograph was taken showing a well-condensed obturation with good coronal, mid and apical seal. Some sealer extrusion was noted.

At a one-year review appointment the patient reported no symptoms and he was delighted at how quickly the tooth had settled post-treatment. Clinical examination reported no significant findings and the radiograph taken showed signs of radiographic healing. The definitive restoration was also functioning well.
See figure eight

Root canal treatment can be a very challenging dental discipline due to the complexity of the root canal system. Root canal re-treatment adds another dimension because the clinician has to dismantle another clinician’s work and orientate himself according to the radiographic evidence available. Fortunately in this case, the radiographic view available was sufficient enough to obtain the necessary canal anatomy. Upon reflection, another five degree angled view periapical radiograph may have given a better image of the additional root. The decision was made, however, according to ionising radiation medical exposure regulations (IRMER 2000 and IRR99), not to expose the patient to further radiation, as the available radiograph was sufficient for diagnostic purposes.
This case also demonstrates the importance of using scanning optical microscopy (SOM). The lingual canal could be seen with the SOM but was not visible with x2 magnification surgical loupes. The SOM certainly enhanced the operative procedure and enabled me to treat this case more effectively and with greater precision.