CATEGORY 72 AUSTRALASIAN DENTIST A Case Study: Handling a Subgingival MOD by Using the Deep Margin Elevation Technique followed by the Use of a Sectional Matrix There are times when, as a practitioner, our desire to do “ideal dentistry” bumps up against the “realities” of a patient’s circumstances. When a patient presents with a posterior tooth that has deep cervical decay, perhaps even approaching the crest of bone, one’s first instinct may be to recommend crownlengthening periodontal surgery, followed by an indirect (lab-fabricated) restoration such as an onlay or full crown. One or more “realities” however may get in the way. A patient’s finances might not readily allow for such costly treatment. Certain medical conditions may be contraindications for an invasive surgical procedure. Some patients may be fearful or simply be reluctant to undergo what they consider to be an “aggressive” approach, but would be willing to entertain what they perceive to be more conservative measures. The technique known as Deep Margin Elevation (DME) or cervical margin relocation has been evolving since at least the 1990’s. Numerous authors (Dietschi and Spreafico, 19981; Magne and Spreafico, 20122) introduced and refined the technique, primarily as a precursor to the placement of an indirect restoration, to improve isolation and reduce contamination at the time of cementation. DME involves the excavation of subgingival caries and then the surrounding of the deep preparation with a band to isolate and shape the placement of a dentin adhesive followed by an initial layer of composite resin, up to a more manageable height at or just above the gingiva. But, as has been pointed out, the technique has also proven useful in the placement of large direct composite restorations. “DME may facilitate the positioning of separating rings and generate improved contours and tight proximal contacts in three, four and five surface direct restorations that are used increasingly for socioeconomic reasons.”3 Over the years, it has been well documented that excellent interproximal contact and contours with direct composite resin can be obtained using systems that employ precurved sectional matrix bands with separating rings. A few examples would be the ComposiTight system by Garrison Dental or the Triodent system (also known as Palodent Plus, Dentsply Sirona). Each one may struggle, however, with a preparation that extends well subgingivally. The convex shape that these systems can produce to create ideal contour at the contact area is less suited in the cervical region, where the root may be flatter or even have concavities. The band may bump into the height of contour of the adjacent tooth, which makes it harder for the cervical portion to adapt to the shape of the root. (Fig. 1 A and B)) As a result, over the years a number of different matrix band systems have been devised to optimize the technique. In the following case studies, I will highlight the use of the Margin Elevation Band system from Garrison Dental. The band’s reduced height eliminates interference from the neighboring tooth, and allows the band to be drawn more subgingivally and snugger on the tooth to get good adaptation. It is available for use with a traditional Tofflemire matrix holder, or as part of Garrison’s Reel Matrix system (Fig. 2 A and B). After recreating the cervical portion of the tooth, the remainder of the restoration can be performed with the regular sectional band and ring to obtain ideal results. The use of certain materials and protocols has been recommended to accomplish the best results.4 As a newcomer to this technique, my material choices varied somewhat on my first go around, but the technique still allowed me to obtain results that would otherwise have been difficult or impossible to achieve. Case Study A 46 year old male was found, on radiographicexamination, tohaverecurrent decay beneath a large MOD amalgam restoration (fig. 3). It was discussed that, given the size of the restoration, it might ultimately serve as a core for a full coverage indirect restoration in the near future. Removal of the amalgam and excavation revealed that the decay extended quite far subgingivally on both the mesial and distal (fig. 4). It became apparent that, were a crown preparation to be planned, it would be next to impossible to place retraction cord to record a finish line this deep, and at crown delivery it would be impossible to isolate to allow predictable bonding of the crown. Since the crown preparation was not anticipated this day, my goal was to place a direct restoration, with good contact on the mesial to prevent food impaction. Robert S. Rosenfeld, DDS By Robert S. Rosenfeld, DDS Figure 1a Figure 2a Figure 1b Figure 2b LINICAL
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