Deep Margin Elevation: Indications and Clinical Protocol

Deep margin elevation moves a subgingival proximal margin coronally with a small layer of bonded composite, so that an inlay, onlay or partial crown can be bonded under rubber dam instead of chasing a margin below the gingiva. Used correctly, it can spare the patient crown lengthening; used outside its limits, it leaves an overhang in the sulcus. This article explains the indications, the three conditions that decide success, a step-by-step protocol and what the in vitro and clinical evidence actually shows.

What deep margin elevation is

The idea was described by Dietschi and Spreafico in 1998 as part of a protocol for the adhesive cementation of tooth-coloured posterior restorations. Instead of preparing the indirect restoration down to a deep proximal margin, a base of composite is placed over the existing margin to bring it to a level where isolation, impression and cementation become predictable. The same procedure appears in the literature as cervical margin relocation, coronal margin relocation and proximal box elevation (Juloski et al. 2018; Samartzi et al. 2022).

Deep margin elevation is usually combined with immediate dentine sealing and with what Dietschi and Spreafico call cavity design optimisation: filling undercuts and correcting the cavity geometry with composite before the impression (Dietschi and Spreafico 2015). The result is a more conservative preparation for the indirect restoration and easier clinical steps.

Indications and contraindications

Deep margin elevation is mainly used for posterior teeth with deep proximal lesions or old restorations that extend below the cemento-enamel junction (CEJ) and that will receive a bonded indirect restoration. Typical situations:

• Class II cavities in premolars and molars with one or both proximal boxes ending in dentine or cementum below the CEJ.
• Replacement of a deep proximal filling before an onlay or partial crown.
• Endodontically treated teeth that will receive an adhesive overlay or endocrown, where the proximal margin is deep but can still be isolated.

The decision against crown lengthening depends less on the depth in millimetres than on whether the area can be isolated. Samartzi and colleagues summarise three criteria that must all be met:

1. The working field can be completely isolated with rubber dam.
2. The matrix seals the cervical margin accurately.
3. The matrix does not invade the connective tissue compartment of the supracrestal tissue attachment.

If any of these fails, surgical exposure of the margin, orthodontic extrusion or a combination is the more appropriate route. Where the lesion reaches bone level, the review by Samartzi and colleagues (2022) cites a recommendation to combine surgical crown lengthening with deep margin elevation.

Clinical protocol step by step

The protocol below follows the review by Samartzi and colleagues (2022), which draws largely on the description by Magne and Spreafico (2012), combined with the in vitro data on layering.

1. Isolation. Place rubber dam. Remove caries and old restorations. The margin must be visible and dry.
2. Matrix. Place a circumferential stainless steel matrix around the tooth so that it seals below the margin. Curved matrices give a better emergence profile than straight bands. The band should be higher than the planned elevation but narrow enough to slide into the sulcus; reducing its height by 2 to 3 mm with scissors often helps. For very deep localised defects, a sectional matrix can be slid vertically into the sulcus inside a loosened circumferential matrix ("matrix in a matrix") before the outer band is tightened.
3. Wedge. Insert a wedge that supports the matrix without deforming its profile. Where a wedge would distort the band, PTFE tape can be packed instead.
4. Check the seal. Neither rubber dam nor gingiva may lie between the cavity margin and the matrix. If the matrix is unstable, the technique has failed and the treatment plan needs to change.
5. Margin and bonding. Refresh the margin with fine diamonds or oscillating tips, apply the adhesive to the exposed dentine (immediate dentine sealing) and light-cure according to the manufacturer.
6. Elevation. Build up the box floor with composite in thin layers until the margin sits at a level that allows reliable isolation and impression. Use only as much composite as needed.
7. Finishing. Remove the matrix, finish the cervical transition and remove excess with a sickle or a No. 12 blade.
8. Bitewing radiograph. A post-operative bitewing is essential to confirm that there is no gap or overhang before the final preparation and impression or scan (Samartzi et al. 2022).

Layering and material choice: what the in vitro studies show

Two in vitro studies from the same group, one of them co-authored by Dr. Hajtó, examined how the elevation is built up. Roggendorf and colleagues (2012) elevated deep proximal boxes in extracted third molars by 3 mm before luting composite inlays. Elevation with restorative composite in three consecutive layers produced margins in dentine comparable to bonding the inlay directly to dentine. Self-adhesive resin cements used as elevation material produced significantly more gaps.

Frankenberger and colleagues (2013) repeated the design with CAD/CAM glass-ceramic inlays and thermomechanical loading. Bonding the ceramic directly to dentine gave the highest proportion of gap-free margins in dentine (92 %). Three layers of bonded restorative composite reached 84 %. Self-adhesive resin cements again performed significantly worse. The authors concluded that, with a meticulous layering technique and bonded composite, proximal box elevation may be an alternative to bonding ceramic directly to dentine, and that self-adhesive cements are not suitable for this indication.

Practical consequences:

• Build the elevation in several thin increments of bonded restorative composite rather than in one thick layer.
• Do not use self-adhesive resin cements as the elevation material.
• Keep the elevation as small as possible: its only purpose is to move the margin to a level where the rest of the procedure can be done under control.

Samartzi and colleagues note that there is no consensus on the best material for the elevation itself. Flowable, conventional and preheated composites have all been used.

Periodontal response: what clinical data show

The obvious concern is that a composite margin left subgingivally may harm the periodontium. The clinical evidence is limited but more reassuring than the old dogma suggests, provided the margin is well adapted.

• Ferrari et al. (2018): In a controlled trial with 35 posterior teeth restored with lithium disilicate crowns, sites with cervical margin relocation showed more bleeding on probing after 12 months than shoulder preparations (53.0 % versus 31.5 % per site). Higher bleeding was expected where the deep margin was at or closer than 2 mm to the bone crest. The authors describe the technique as sensitive, especially on deep subgingival margins.
• Bertoldi et al. (2020): In 29 patients, the gingiva adjacent to subgingival composite showed a level of histological inflammation similar to that next to natural root surfaces after 3 months. Plaque scores, bleeding scores and probing depth decreased.
• Muscholl et al. (2022): In 63 patients with restorations about 2.7 years old on average, bleeding on probing and gingival bleeding did not differ from sound control teeth. Gingival bleeding was higher on test teeth in patients who did not use interdental brushes daily.

Frese, Wolff and Staehle (2014) also argue for a critical view of the biological width dogma when margins are placed below the CEJ, as long as moisture control is possible. The systematic review by Srirama and colleagues (2024) found no deleterious effect of deep margin elevation on pulp or periodontium in the included studies, while rating the overall level of evidence as low.

Long-term survival of restorations with deep margin elevation

The largest clinical dataset so far comes from Bresser and colleagues (2019). They evaluated 197 partial indirect restorations with deep margin elevation in 120 patients, placed between 2007 and 2016. With eight absolute failures, the cumulative survival rate was 95.9 % up to 12 years, with a mean observation time of 57.7 months. Indirect composite restorations showed more degradation than ceramic ones, and endodontic treatment was associated with fractures of restorations and teeth.

These numbers are encouraging, but the context matters. Juloski and colleagues (2018) concluded in their review that there was no strong evidence either for or against cervical margin relocation and called for randomised controlled trials. Samartzi and colleagues (2022) note that the literature is still mainly in vitro. Deep margin elevation is therefore a well-founded option, not a technique without limits.

Where deep margin elevation fits in the restorative plan

Deep margin elevation changes the preparation for the indirect restoration: the margin now sits on composite rather than on dentine or cementum, and the cavity geometry can be optimised at the same time. The choice of material for the onlay or partial crown and the design of the preparation remain separate decisions. The principles of margin design for ceramic restorations are covered in the article on crown prep guidelines for all-ceramic restorations, and the material question is discussed in e.max vs zirconia. In worn dentitions with many compromised teeth, deep margin elevation is one of several tools for keeping preparations conservative, as described in the article on full mouth rehabilitation for the worn dentition.

Summary

Deep margin elevation relocates a deep proximal margin coronally with bonded composite so that an indirect restoration can be bonded under controlled conditions. It works when three conditions are met: complete isolation, a matrix that seals the margin, and no invasion of the connective tissue attachment. Thin increments of bonded restorative composite give the best margins in vitro, self-adhesive cements are not suitable, and a bitewing radiograph checks the result. Clinical data show acceptable periodontal responses and high survival, with the reservation that randomised trials are still scarce. Hands-on training in adhesive and prosthodontic techniques is listed in the course overview.

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