Deep margin elevation and placement of an onlay using warmed resin composite

Case by Max Andrup

The maxillary right first premolar of this patient had a huge defect on the lingual aspect extending subgingivally. In order to facilitate proper working field isolation for the placement of an onlay, it was decided to elevate the margin using the deep margin elevation (DME) technique. Moisture control is more easily handled with a matrix and composite compared to trying to keep a deep box dry at the placement of an indirect restoration. The preferred method used to maximize the bond strength to dentin was immediate dentin sealing combined with resin coating, while the luting material of choice was warmed light-curing resin composite (CLEARFIL™ AP-X). It shows a superior performance compared to dual-cure luting materials e.g. in terms of conversion of monomers to polymers, time available for excess removal, bio-mechanical properties and polymerization shrinkage stress.

Fig. 1. Pre-operative situaton with clearly visible deep distal margin. In reality, it was even deeper than the picture reveals. The Brinker Rubber Dam Clamp B4 placed here is a life saver in cases with subgingival margins. The buccal wall was still intact. We planned to reduce it to allow the onlay to cover it completely, allowing it to work under compression and thus increasing the fracture resistance.

Fig. 2. Situation after placement of a sectional matrix on thedistal aspect of the tooth. In order to retract the rubber dam mesially, PTFE tape was placed in this area. This allowed me to seal the dentin in a perfectly dry environment. For immediate dentin sealing, the smear layer developed on the dentin immediately after tooth preparation was compacted with the aid of air abrasion (50 μm alumina particles) to provide for the best possible bonding conditions, followed by the application of the bonding agent (CLEARFIL™ SE Protect). Afterwards, the bonded dentin was covered with a thin layer of flowable resin composite (CLEARFIL MAJESTY™ ES Flow). This resin coating ensures that the hybrid layer is thick enough and that the dentin is perfectly sealed.

Fig. 3. After immediate dentin sealing and resin coating. The hybrid layer was left to mature for approximately five minutes. This measure leads to an increased bond strength to dentin, which prevents issues that might occur due to the polymerization shrinkage stress occurring after composite placement. Subsequently, CLEARFIL™ AP-X was applied in small increments, starting in the distal box. In this way, the biobase was built up to the desired height. The main arguments for using CLEARFIL™ AP-X as a replacement for deep dentin are that the modulus of elasticity is within the same range as that of dentin and it exhibits an extraordinarily low polymerization shrinkage.

Fig. 4. Lateral view of the tooth at the day of delivery. View of the tooth at the day of delivery after rubber dam placement and prior to air-abrasion treatment of the biobase, which was performed to remove any remaining temporary cement. Following try-in, the lithium disilicate onlay was cleaned with KATANA™ Cleaner and pretreated with CLEARFIL™ Ceramic Primer. The biobase was sandblasted again for cleaning.

Fig. 5. Onlay in place after selective etching of the enamel with 35 % phosphoric acid etchant, and application of CLEARFIL™ SE Bond to the biobase and the intaglio of the onlay as well as luting with heated CLEARFIL™ AP-X. Excess composite was removed and the composite light cured.

FINAL SITUATION

Fig. 6. Occlusial view of the luted restoration.

Dentist:

Max Andrup graduated from the University of Umeå in 2010 and today runs his private practice in the city of Hudiksvall, Sweden. He has a passion for restorative dentistry with a biomimetic approach.