Direct post-endodontic restorations with a tight seal

Contents:

• The need for a high-quality coronal restoration to ensure long-term success and apical periodontal health
• Scientific insights into direct post-endodontic restorations 
• The real deal is a proper seal 
• Create direct post-endodontic restorations with a tight seal 

Regardless of the clinical situation, there is one thing that all endodontic treatments have in common: They need a high-quality coronal restoration to ensure long-term success and apical periodontal health. Ray and Trope¹ found evidence on the strong link between marginal integrity of the coronal restoration and the absence of apical periodontitis back in 1995, which has been confirmed by several more recent studies^2,3,4. When planning for an endodontic treatment, it therefore is paramount to also consider the appropriate type of coronal restoration, and the final choice for the case at hand might not always be the same.

This seems to go against the classic recommendation of always putting a crown on endodontically treated teeth but is actually in line with science. In their 2019 paper on evidence-based treatment planning for endodontically treated teeth⁵, Alan Atlas, Simone Grandini and Marco Martignoni conclude that “[…]with classic crowning, […] a significant amount of residual tooth structure is sacrificed in the preparation. Moreover, crowning often involves creating a subgingival perparation margin and therefore a significantly less hygienic margin region. For those reasons and in the light of recent research results, the almost habitual, reflex-like decision in favor of crowning single teeth regardless of the coronal cavity configuration must be considered questionable.”⁵

Among other options, a direct post-endodontic restoration might therefore be the treatment of choice to prevent unnecessary loss of tooth structure and complications during the restorative procedure. It also might cut the treatment cost for the patient by a significant amount, depending on local insurance- and health system. But are there viable options that ensure a long-term success of the endo treatment?

This conclusion finds support in several other reviews and retrospective studies^7,8, leading to the conclusion by Atlas et al. that “[…] in ETT [endodontically treated teeth] with three or four coronal walls left, that is, at least one marginal ridge remaining, and no undermined cavity walls, direct adhesive restoration may be considered as an alternative to cuspal coverage.”⁵ Figure 2 provides a clinical example of both a Class I and II cavity in endodontically treated teeth, that are matching these criteria, allowing dental practitioners to place a less invasive and more cost effective direct restoration.

Figure 2: Endodontically treated posterior teeth with four and three coronal walls, and barely undermined residual tooth structure before and after direct restoration

(Courtesy of Dr. Marcus Holzmeier, Germany)

The real deal is a proper seal

Ray and Trope¹ already highlighted the importance of maintaining marginal integrity of the coronal restoration for the long-term success of an endo and the prevention of apical periodontitis. Regarding direct post-endodontic restorations on posterior teeth, this means that dental practitioners are facing the same challenge as in Class I and II restorations on vital teeth: Preventing microleakage by achieving a proper seal and creating a gap-free restoration.

But because of their depth and shape, endodontic Class I and II cavities are even more challenging than regular posterior cavities. They require placement of more filling material than usual, and not only do so gap-free but also at the right layer thickness to ensure a proper management of shrinkage stress and maintain a seamless adaptation to the cavity walls during curing.

The importance of managing shrinkage stress through proper placement in post-endodontic restorations cannot be overstated, as most surfaces of a post-endodontic restoration are bonded to cavity walls. At the same time, the root canal orifices can make it difficult to determine the actual depth of the cavity and the layer thickness of already placed composite.

Figure 3: Large quantities of filling material need to be placed in posterior post-endodontic cavities

This can create significant shrinkage stress through the amount of bonded surfaces. In addition, it is hard to visually determine the depth of the cavity including root canal orifices, and place Universal Composites and Flowables in the right layer thickness (clinical picture by Paqué F., 2014).

SDR^® flow+ Bulk Fill Flowable from Dentsply Sirona is an excellent choice to deal with the challenge of achieving a proper seal in post-endodontic restorations, as it provides an extremely low polymerization stress as well as excellent flowability and self-levelling without manipulation. This not only mitigates the risk of creating too much shrinkage stress, but also makes material placement easier and can even save time during treatment. As shown in the clinical case below, placing two layers of SDR^® flow+ composite can be enough to fill the bulk of the post-endodontic cavity.

The result is a tightly sealed coronal restoration, as shown in the micro-CT image of Figure 4, which shows the adaptation of the initial SDR^® flow+ composite layer in a post-endodontic Class I cavity. SDR^® flow+ Bulk Fill Flowable has adapted itself seamlessly to both the cavity walls and the root canal obturation material, creating the ideal conditions to achieve a proper coronal seal.

Figure 4: Analysis of the initial SDR® flow+ composite layer in a post-endodontic Class I cavity, using a micro-CT.

The SDR^® flow+ composite layer (grey) shows a tight seal to the cavity walls as well as an excellent adaptation to the obturation material (red). (Image source: Paqué F., 2014 (ref. 14.1483))

Dealing with shrinkage stress works equally well, when using SDR^® flow+ Bulk Fill Flowable, as the SDR^® bulk fill technology enables the formation of a more relaxed network, minimizing the build-up of stress. This low-stress chemistry is able to deal even with the large amount of bonded surfaces in a post-endodontic cavity, as Van Ende⁹ has shown in 2016, proving that SDR^® bulk fill flowable technology can deal with high C-factors, leading to a tight coronal seal even for post-endodontic cavities.

Figure 5: Shrinkage stress: Shown as a ratio of SDR® flow+ Bulk Fill Flowable in comparisson with other Direct Restoratives¹⁰

Create direct post-endodontic restorations with a tight seal

There are many reasons that can make direct coronal restorations the go-to option in an endodontic treatment – from the desire to preserve as much of the natural tooth as possible to financial considerations by the patient. And given the right clinical situation of a posterior Class I or II with three or more cavity walls remaining, scientific data indicates that this treatment option can lead to high quality outcomes with long-term success.

Achieving a proper coronal seal by creating gap-free adaptation and managing shrinkage stress however is paramount to reach that goal, and what would be a better material to get there than one that also makes placement faster and easier: SDR^® flow+ Bulk Fill Flowable from Dentsply Sirona.

Please contact a Dentsply Sirona representative to find out more about SDR^® flow+ Bulk Fill Flowable.