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the importance of the coronal seal, my feeling from talking to colleagues is that this concept is largely misinterpreted. The coronal seal is considered by many to be synonymous with the post-endodontic crown, and the significance of establishing a sound coronal seal (preventing bacterial ingress) early on in the procedure is being overlooked.

Bacteria Dental decay and periapical inflammation are bacterial driven processes. It seems sensible, therefore, to eliminate bacterial ingress into the space we are trying to disinfect, and for this reason I am zealous about starting endodontic cases by establishing the coronal seal.

The significance of ‘coronal seal’ on the success of endodontic treatment is well accepted and a widely endorsed endodontic priority. I have a suspicion, however, that the real meaning of this concept might be being obscured.

As an undergraduate, Ray and Trope’s paper (1995) on the periapical status of endodontically treated teeth was one of the few I had memorised gearing up for my finals. It didn’t come up, and instead we chatted about the structures derived from the first pharyngeal arch. I scraped a pass!

That paper will probably be familiar to all – but a quick recap: hundreds of orthopantomograms (OPG) were scrutinised on a light box for teeth with root fillings. The quality of the root fillings and the quality of the coronal restorations in those teeth were assessed and the influence of both aspects on periapical health was considered.

A rather alarming 60% of root filled teeth had apical areas but a sound coronal restoration was the greater predictor for a healthy periapex than a sound root filling.

Most papers are quickly distilled down to a single message, with this one being 'coronal seal is more important than apical seal'. Despite the spotlight being shone on

I am frequently asked by enthusiastic colleagues for opinions on their endodontic cases-in-progress. Although I am usually being asked about optimal taper or a snazzy new file system, all too often I can see leaking restorations that have been overlooked or coronal caries that have been missed.

Peter RafteryPeter is the endodontist at 3dental clinic in Dublin. He is a registered endodontic specialist with the GDC (UK) and graduated from Dublin Dental School in 2003.

Figures 1 and 2: In this case, the restoration was found both clinically (fractured at the distolingual aspect) and radiographically (radiolucency at distocervical) wanting. It all has to be removed

Figures 3-5: Decay noted under distal restoration. Once cleared, the missed mesiobuccal canal was scouted for (the file’s parachute safety chain not seen). Cavit placed over the orifices to prevent the tooth-coloured restorative material from flowing into the orifices, which would make subsequent canal access difficult. At the same time, a maximal ‘band’ of clean, hard dentine is needed for bonding

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THE REAL SIGNIFICANCE OF ESTABLISHING A CORONAL SEAL

EARLY ON IS BEING OVERLOOKED

October 2016 IRISH DENTISTRY www.irishdentistry.ie30

CLINICAL ENDODONTICS

Peter Raftery discusses the significance of coronal seals in endodontic treatment

Fears for the coronal seal

pulp chamber. In this instance, I was able to locate the previously undiscovered and unfilled mesiobuccal canal. I then place a damp cotton pledget, cut to size, onto the pulp floor, and a same sized increment of Cavit over that, before engaging a matrix band around the tooth.

It is important only to cover the pulp floor with cotton and Cavit, and not to allow it to spread onto the cervical dentine. The maximal clean dentine surface area must be available for bonding so that a robust, solid restoration can be placed. The matrix band was then removed and the normal occlusal scheme was established into the restoration using polishing burs and articulating paper. The rubber dam was then placed and the pulp chamber reaccessed. The paper-white Cavit serves as an early warning system because when the bur hits the soft temporary filling material, I can then use a hand instrument to hook out the soft Cavit and cotton from below. I am then instantly back in business, and my subsequent endodontic treatment flows better.

The four-walled access cavity better allows pooling of irrigant in the pulp chamber throughout the procedure for improved disinfection, and the already restored tooth allows for better rubber dam clamp adaptation. The occlusally adjusted restoration allows for the quickest of temporisations at the end of

Case study With the significance of coronal seal in mind, this case is useful for explaining the typical way I approach cases: if the existing coronal restoration is either clinically or radiographically imperfect, I will remove the whole thing as an opening gambit. I have yet to regret removing a suspect restoration at the outset for not having found leakage or caries beneath. Under local anaesthesia (but not rubber dam) I will cut out the old restoration before using a large rosehead bur to be confident that what dentine I am leaving behind is sound.

Having removed all the caries, I will take the opportunity to scout for the root canals at this stage by extending my drilling into the

the appointment when both local anaesthesia (and patient cooperation) can be wearing thin.

Conclusion Getting the coronal seal correct at the outset of endodontic treatment paves the way for slicker, more successful endodontic treatment. The concept of the coronal seal ought not to be thought of as a postoperative consideration.

ReferencesRay HA, Trope M (1995) Periapical status of

endodontically treated teeth in relation to the technical quality of the root filling and the coronal restoration. Int Endod J 28(1):12-8

Figure 11: Postoperative radiograph

Figures 6-10: In this instance, Dentsply’s Surefil SDR bulk fill composite is used. Once finished with articulating paper, the rubber dam was placed and reaccessed back through the restoration. Note the thick, robust four-walled access cavity

Comments to Irish Dentistry@IrishDentistry

KEY POINTS

• A coronal seal must be established early on to eliminate bacteria

• Getting the coronal seal right at the start of endodontic treatment leads to a more successful outcome

• Coronal seals should not be thought of as a ‘postoperative consideration’.

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