Re-Treatment of a Failing Posterior Amalgam Restoration
Immediate dentin sealing improves the longevity of adhesively bonded crowns
Nikhil Sethi, BDS
The development of new adhesive materials and techniques has resulted in preparations that are more conservative in design, facilitating greater preservation of sound tooth structure. These developments not only allow clinicians to perform more conservative adhesive direct restorations but also more conservative adhesive indirect restorations, which are defined as partial crown restorations made from composite or ceramic that have to be seated passively and adhesively cemented in a preparation characterized by special attributes.1
Partial coverage preparations in posterior teeth that are restored with all-ceramic materials, such as lithium disilicate, have been shown to demonstrate similar fracture resistance to that of natural teeth,2 and if morphology-driven preparation technique guidelines1 are followed, the restoration will demonstrate predictable clinical results.
From a bonding perspective, immediate dentin sealing is a technique that has been widely recommended and used for the past 15 years.3 The benefits of using this technique include better bond strength to freshly cut dentin, less marginal gaps, less bacterial leakage, reduced sensitivity, and more. All of these principles are applied in the following clinical case.
Case Report
A patient presented to the office with a failing amalgam restoration and fractured distobuccal cusp on the upper right first molar (Figure 1). Following the history and examination, an esthetic analysis was performed to determine the ideal location for the margins (Figure 2). The failing amalgam restoration was then removed in a conservative manner (Figure 3). After final amalgam removal, a deep discolored dentin base with minor undercuts was revealed in an area close to the pulp. The immediate dentin sealing technique3 was performed to protect it from contamination and promote adhesion, and then the final preparation was completed (Figure 4). Next, a self-etch bonding technique was performed using a light-cured dental adhesive (All-Bond Universal®, BISCO, Inc.), and the core was reconstructed using a nanohybrid universal composite (Venus® Diamond, Kulzer) (Figure 5). This step helps reduce the esthetic challenges for both the laboratory and the clinician. After the preparation and core reconstruction were complete, an impression was taken and sent to the laboratory for the fabrication of a lithium disilicate crown (Figure 6).
At the seating appointment, the restoration was tried-in to check for proper fit and occlusion. The preparation was kept as conservative as possible, avoiding the unnecessary removal of tooth structure in order to place the crown (Figure 7). In combination with a proper bonding technique, this conservative approach provides a durable and predictable restoration.1,4
The restoration was cemented using a dual-cure resin luting cement system (Duo-Link Universal™, BISCO, Inc.). After the margins were tack-cured for 3 seconds to facilitate proper cleaning and the removal of excess cement, a final light activation was performed for 20 seconds on each surface of the tooth (ie, buccal, lingual, occlusal). Complete poly-merization of the material was achieved via chemical curing (Figure 8). At a 14-month follow-up consultation, the restoration exhibited excellent marginal adaptation and proper occlusal function (Figure 9).
About the Author
Nikhil Sethi, BDS
Private Practice
London, England
References
1. Veneziani M. Posterior indirect adhesive restorations: updated indications and the Morphology Driven Preparation Technique. Int J Esthet Den. 2017;12(2):
204-230.
2. Stappert CF, Att W, Gerds T, et al. Fracture resistance of different partial-coverage ceramic molar restorations: an in vitro investigation. J Am Dent Assoc. 2006;
137(4):514-522.
3. Magne P. Immediate dentin sealing: a fundamental procedure for indirect bonded restorations. J Esthet Restor Dent. 2005;17(3):144-154; discussion 155.
4. Banks RG. Conservative posterior ceramic restorations: a literature review. J Prosthet Dent. 1990;63(6):
619-626.
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