Carious LR7 The LR7 is carious

The signs and symptoms indicate an irreversible pulpitis.

The caries is removed and the tooth is provisionally restored with a glass ionomer core. This is to prevent the ingress of salivary bacteria during the endodontic treatment.

The prognosis for endodontic treatment in the presence of caries at the time of root filling is reduced. It is important to remove all the caries before starting any endodontic treatments.

Access To Pulp Chamber X10

Access is made through the GIC core to the pulp space. The pulp chamber was disinfected with hot 5% NaOCl for one minute to reduce the bacterial load.

Two canals are identified: A C-shaped dito-lingual canal extending mesially, and a conventional disto-buccal canal.

To facilitate vision: The canals are debrided of necrotic pulp tissue with micro-debriders [Maillefer].

Notice the "bubbling" of the NaOCl solution

Identification Of Mesio-Buccal Canal X10

Judicious removal of the roof of the pulp horn reveals an further canal.

Without the microscope the chances of being able to identify such anomalous anatomy is slim.

It is important to resist the temptation to rush towards the apex. Time spent identifying canals and refining the access cavity outline now will facilitate instrumentation and obturation later.

Furthermore it allows time for good penetration the of disinfecting solutions into the coronal and middle thirds of the root canal system. Together with the pulp space, these are the most heavily contaminated portions.

Identification of 2nd Mesio-Buccal Canal X16

The careful shaping of the mesio-buccal pulp horn without spoiling the walls and floor of the pulp chamber has enabled another canal orifice to be located! Injudicious use of instruments can damage the natural anatomy of the floor of the pulp chamber. This makes orifice location far more demanding - even with a microscope. Even if the first mesio-buccal canal had been located without a microscope; it would have been highly unlikely that this second canal could have been found. The canal is gently enlarged with micro-openers and micro-debriders.

Establishing An MB2 Glide Path X 10

Whilst it might be appealing to attempt to navigate such complex root canals with NiTi instruments: This temptation must be avoided.

The first step is to provide a glide path for the rotary instruments. The instrument of choice is a K-type, stainless steel file. Stainless steel files are more resistant to sudden catastrophic failure than rotary NiTi instruments.

Stainless steel will undergo plastic deformation prior to breaking. This can be seen clinically by examining the file carefully for elongation of the flutes. Such checks should be made before introducing a file into a canal.

Any files showing plastic deformation should be discarded.

Establishing The Working Length

The working length [WL] is established using a combination of paper points, an electronic apex locator, radiographs, and from tactile feedback of the apical constriction if present.

In order to avoid confusion only two files were introduced for the working length radiograph. These were in the MB1 and DB canals. This prevents uncertainty when files are superimposed radiographically. The other canal WL are determined from the aforementioned techniques.

Notice the superior seal obtained distally by the GIC provisional core.

Post Shaping X10

Following the completion of the shaping and cleaning, the final morphology of the root canal system can be visualised clealry with the microscope.

There is a distinct disto-buccal canal. The lingual canal is C-shaped extending from the disto-lingual towards the centre of the root mass. The exploration to confirm the absence of a genuine separate mesio-liniugal canal can also be seen.

Due to access, unfortunately it was not possible to simultaneously photograph both mesial canals within this image, without radically enlarging the access cavity to improve visibility. This would structurally weaken the tooth. For the sake of a photograph this was not considered clinically justifiable.

Post-operative Radiograph

Interpretation of the post-operative radiograph requires some appreciation of the root canal morphology negotiated.

MB1 can be clearly identified as the most mesial canal. Just to left of this is the MB2. Distally the MB2 silhouette is superimposed by the mass of the C-shaped lingual canal. The distal canal can only be identified in its apical extent as it curves distally. This can be confirmed by the working length radiograph.

It is unlikely that this tooth could have been successfully treated without the use of a dental operating microscope