TBU # 011: Deep Margin Elevation and Subgingival Defects

deep margin elevation meryem alhalid reel matrix Mar 09, 2022

Subgingival margins are a common clinical challenge, that is because of the difficulty in obtaining sufficient restorative access and a moisture-free field for bonding. Restoring proximal class 2 caries lesions is a very common procedure in our practice, It also comes with its concerns especially if the margins are reaching subgingivally below the cementoenamel junction: concerns here are isolation, weaker bond strength in cervical areas, difficulty in recording an impression as well as the delivery of the final restoration, and therefore failure in providing good contact and contours of the restoration. Placing a defective proximal restoration whether it's direct or indirect, can cause serious periodontal issues as well as secondary caries. Traditional restorative and surgical approaches such as crown lengthening and surgical extrusion are quite invasive and time-consuming. The deep margin elevation procedure has a lot of potentials to expand the conservative restoration and also minimise the use of crowns. The concept of deep margin elevation was first presented by Dietschi and Spreafico in 1998. Followed by the paper ‘Deep margin elevation: a paradigm shift’ by Pascal Magne and Roberto Spreafico in 2012.

Before we start discussing this topic let's focus on understanding the terminologies behind it: Open sandwich technique, CMR (Cervical margin relocation), and lastly moving to our current topic deep margin elevation. Cervical margin relocation CMR was presented by Dietschi and Spreafico, in 1998 and it suggested that instead of the traditional methods of treating subgingival caries, an elevation of the existing proximal margin from a subgingival cavity to a more supragingival level can be obtained by using an adequate layer of resin composite if moisture control is possible. This technique was known before as an open sandwich technique. Deep margin elevation was a term given to this technique by Pascal Magne and Roberto Spreafico in 2012. It is a term that can combine cervical margin relocation and open sandwich technique.

So what is deep margin elevation (DME)? It simply means an elevation of the proximal gingival margin to an equigingival or supragingival location by using a direct resin restoration. This procedure depends on isolation, In subgingival defects, we have the choice of doing a deep margin elevation or keeping the preparation as it is and following the traditional methods. If you cant isolate a tooth then this treatment option is undoubtedly contraindicated. Selecting the right choice of treatment is very important to ensure successful outcomes. DME is a predictable, and reliable clinical procedure. It appears to be well tolerated by the periodontium if it was applied with a proper isolation and a well adapted matrix system.

As mentioned before the main objective of DME is to eliminate the challenges that come with placing a restoration in a deep subgingival margin. In such lesions indirect bonded restorations are preferred because of the preparation size, these defects are usually associated with the use of inlays and onlays, especially those fabricated using a chairside computer-aided design/computer-assisted manufacturing (CAD/CAM). Indirect restorations come with a set of challenges that were mentioned above. You need to isolate the tooth properly, All margins should appear clearly. If you can achieve that then you can have a proper impression or a scan of the preparation, luting would be way easier with moisture control that will aid in bonding strength and you will be able to clean the excess luting composite resin before curing it. All that can offer more predictable long term results. It is impossible to have a complete moisture-free environment in a subgingival margin. It is advised to relocate your margin more coronally so you can eliminate the risk of compromising your bonding seal.

Rubber dam isolation is extremely critical because we are working in an area that contains gingival curricular fluid and most likely gingival inflammation in that area is present which is prone to bleeding. So rubber dam isolation is the thing that indicates or contraindicates this technique. Without ideal rubber dam isolation, you will not be able to perform DME, if you don’t have good isolation, Bleeding will occur during the placing of the matrix and therefore contaminating the bonding area and affecting it negatively. So deep margin elevation is indicated only when I can achieve perfect isolation along with a proper application of the matrix system.

Adapting the matrix band to the base of the restoration can be challenging. Some specially designed matrix systems are found based on this technique (ex: Reel matrix by Garrison). A specially designed margin elevation matrix will provide you with the best gingival adaptation and contour for the deep margin areas. That is because it is usually trimmed in height to allow improved adaptation to deep margin areas. You can modify the normal matrix system that is available in your clinic by reducing the height of it. Many materials can help achieve a good seal such as Wedges, Teflon tape, and light-cured rubber dam materials.

Deep margin elevation can be performed using a direct resin composite ( traditional restorative or flowable). we can achieve this technique using a modified curved Tofflemire matrix or a special matrix system to elevate the gingival margin to a level where it can be sealed under rubber dam isolation, As I said before it can only be performed under good isolation and well-adapted matrix. Otherwise, this technique is not preferable and might cause more harm than good. A Bitewing radiograph should be taken at the end of the procedure before placing an indirect restoration to make sure that the new composite margin is well adapted and free from any gaps and overhangs. If everything is under control proceeding with the final restoration can be done. It is also necessary to follow up on the soft tissue reaction to the procedure, in a case where unsuccessful DME has been performed, you will find persistent bleeding during and after the procedure.

Some fundamental steps to obtain a successful DME:

Find a good matrix system, and train well on using it. the traditional matrixes do not usually work best for a lesion below the cementoenamel junction, in the worst case you can modify the traditional matrix.
Make sure your matrix is stabilized by the remaining structure of the tooth.
Reduce the matrix height to 2-3mm so it can slide in the sub-gingival area (in case you are using the traditional matrix system).
Make sure that no tissue or rubber dam is remaining between the tooth margin and the matrix. The matrix should completely seal the margin.
Re prepare your margin gently before bonding, this tip here is used to eliminate debris and other contamination.
Immediate dentin sealing should be applied before the deep margin elevation.
Preheat the restorative resin material you are using to minimise the risk of interlayer gaps. Also, the air blocking final step in polymerization is usually recommended.
After you elevate the margin by approximately 2 mm. Remove the excess of composite around the tooth by using a no.12 blade or a sickle scaler. This step is to ensure a smooth external layer as well as the absence of overhangs.
Bitewing radiograph is an essential step after you finish the procedure.

DME is a very useful clinical tool and it supports the goal of restorative dentistry which is the conservation of the tooth structure, It can also be used before endodontic treatment to ensure better isolation during the treatment. If this technique is used in the right way it can improve the bond and marginal seal as well as reinforce undermined cusps, filling the undercuts and providing the necessary structure for indirect restorations. The deep margin elevation approach is suitable for a wide range of clinical situations, where the subgingival defects are limited to the junctional epithelium and have not invaded the connective tissue attachment (The gingival margin of the future restoration is estimated clinically to be at least at 1-1.5mm distance from the alveolar crest).