Smart Dentin Replacement Plus (SDR+): Composition, Polymerization Behaviour, Mechanical Properties, and Clinical Evidence: A Narrative Review

Abstract

Smart Dentin Replacement Plus (SDR+) is a bulk-fill flowable composite designed for use as a dentin replacement material in posterior restorations. This narrative review aimed to summarise the composition, polymerisation behaviour, mechanical properties, clinical applications, and the available scientific evidence for SDR+. A literature search was conducted using PubMed, Scopus, and Google Scholar to identify relevant in vitro studies, clinical trials, and review articles on SDR+ and bulk-fill resin composites. SDR+ is based on a modified urethane dimethacrylate (UDMA) resin system that incorporates stress-modulating polymerisation technology. Available evidence suggests that SDR+ demonstrates reduced polymerization shrinkage stress, adequate depth of cure up to 4 mm, and satisfactory mechanical properties for use as a dentin replacement material. Clinical studies have reported favourable marginal adaptation, low postoperative sensitivity, and clinical performance comparable to conventional incremental composite techniques. In addition, optimised resin–filler balance improves handling characteristics and radiopacity without altering the material’s fundamental stress-reducing mechanism. Within the limitations of currently available evidence, SDR+ appears to be a reliable and simplified alternative to incremental composite placement techniques in posterior restorations. However, further long-term clinical studies are required to confirm its durability and long-term clinical success.