Deep Margin Elevation (DME)

What Is Deep Margin Elevation?

Deep Margin Elevation (DME) — also called Cervical Margin Relocation (CMR) — is a pre-restorative technique in which a subgingival preparation margin is built up with composite resin to a position at or above the gingival margin before taking an impression or scan for an indirect ceramic restoration (inlay, onlay, overlay, or crown).

The problem it solves is fundamental: impression materials, scanning optics, and rubber dam clamps all perform poorly below the gingival sulcus. Margins that sit 1–3 mm below the gumline cannot be accurately captured, reliably sealed at cementation, or maintained in long-term health without surgical modification of the surrounding periodontium.

Conventional treatment of deep subgingival margins requires osseous crown lengthening surgery: a periodontal surgeon cuts the gum tissue and reshapes the alveolar bone to expose the margin. This is an invasive, expensive ($1,500–$3,000), recovery-intensive procedure that permanently alters the patient's periodontal anatomy. DME replaces this surgery in the majority of eligible cases.

When Is DME Needed?

DME is indicated when the apical extent of the cavity preparation or the failing existing restoration margin sits below the crest of the free gingival margin — typically more than 0.5 mm subgingivally. This occurs most commonly in:

• Large Class II carious lesions extending below the interproximal bone crest.
• Existing crown margins that have receded or are associated with subgingival secondary decay.
• Root fractures extending just below the gumline where composite elevation can create a buildable margin.
• Previous deep restorations where the preparation walls extend into the subgingival zone.

The DME Technique

Gaining Access

The first challenge is tissue management: achieving dry, isolated access to the subgingival margin without causing irreversible soft tissue damage. Options include retraction cord with hemostatic agent, electrosurgical troughing, or laser gingivoplasty to temporarily displace or remove a thin band of sulcular tissue around the margin. The choice depends on the tissue biotype, sulcus depth, and operator preference.

Conditioning and Sealing the Deep Margin

Once the deep margin is accessible and dry, the root surface or deep dentin is conditioned with a self-etch adhesive system (phosphoric acid etching of root dentin is generally avoided to prevent collagen damage at the cementum-dentin junction). A thin layer of bonding agent is applied and light-cured.

Composite Elevation

A low-shrinkage, high-viscosity composite is incrementally placed over the deep margin, building it up to a position 0.5–1 mm above the free gingival margin. This creates a new, supragingival margin that can be cleanly finished, accurately scanned or impressed, and subsequently bonded to at cementation. The elevated composite wall becomes the new cervical margin of the tooth preparation to which the ceramic restoration will bond.

Final Preparation and Impression

With the margin now supragingival, the preparation is completed to final form, IDS is applied to exposed dentin, and the impression or intraoral scan captures a clean, dry, clearly visible margin — the prerequisite for a well-fitted, properly sealed indirect restoration.

Evidence and Clinical Performance

DME has accumulated substantial clinical evidence over the past decade. A landmark systematic review by Bresser et al. (2019) examined 1,154 teeth treated with cervical margin relocation over periods up to 10 years and found survival rates of 87.5% — comparable to conventionally prepared indirect restorations without deep margins. Marginal quality, periodontal health indices, and cementation quality were all clinically acceptable across the majority of included studies.

The key variable in DME success is isolation quality. Cases where optimal rubber dam or field isolation cannot be achieved have higher rates of marginal gap and early cement failure. Practitioners should not attempt DME without adequate isolation.

Credentials to Verify

• AOBMD
  Academy of Biomimetic Dentistry Fellowship — DME is covered in the biomimetic curriculum as a core pre-restorative adjunct protocol. AOBMD fellows demonstrate competency in cervical margin management as part of the posterior adhesive case documentation requirement.
• ALLEMAN
  Alleman Center Six Lessons — deep margin management and subgingival bonding are addressed in the curriculum's coverage of adhesive protocol adaptations for complex cavity geometries.

Frequently Asked Questions