Tooth bleaching improves dental esthetics but may cause color mismatch with existing resin composite restorations and complicate restorative treatment planning because tooth color may change during the post-bleaching stabilization period, sometimes requiring delayed restoration placement or replacement of existing restorations. Universal shade resin composite (UC) has been introduced to simplify shade selection; however, its ability to adapt to dynamic tooth color changes associated with bleaching has not been sufficiently documented. A 61-year-old male patient underwent tooth bleaching for esthetic improvement. One year later, secondary caries was detected on tooth #22 and restored using a UC. The restoration was placed prior to additional bleaching procedures. Clinical follow-up indicated that the UC restoration appeared to maintain shade adaptation after bleaching. Furthermore, at the two-year follow-up, generalized tooth discoloration was observed; however, the restoration remained harmonized with the surrounding tooth structure. Subsequent additional bleaching resulted in further lightening of the tooth structure while shade harmony with the restoration was preserved. Favorable shade adaptation was maintained throughout the three-year follow-up. This case suggests that a UC restoration placed before bleaching appeared to maintain shade compatibility over long-term follow-up, despite bleaching-induced color improvement and subsequent intrinsic and extrinsic discoloration.

Self-adhering flowable composites (SAFCs) were developed to simplify restorative procedures by eliminating separate adhesive steps; however, their bonding performance, mechanical properties, and biological properties remain controversial. This study evaluated a newly developed SAFC (SA-100R) compared with three commercial SAFCs (Fusio Liquid Dentin, Constic, and Vertise Flow) and a conventional composite (Clearfil AP-X used with a two-step self-etch adhesive). Microtensile bond strength (μTBS) to dentin, failure modes, Knoop microhardness, resin–dentin interfacial morphology (SEM), elemental composition (EDX), and cytocompatibility (CCK-8, LIVE/DEAD staining) were assessed. The conventional composite system exhibited significantly higher µTBS than all SAFCs (p < 0.05). Among SAFCs, SA-100R showed the highest bond strength and no pre-testing failures. SEM revealed abundant resin tag formation only in the conventional system, while all SAFCs showed interfacial gaps, with SA-100R exhibiting the least pronounced gaps. SA-100R showed no significant cytotoxic effects across all tested concentrations. Within the limitations of this short-term in vitro investigation, SA-100R demonstrated improved bonding performance and favorable biocompatibility compared with existing SAFCs, suggesting its potential as a simplified restorative material. However, the conventional adhesive/composite system remains the reference standard for dentin bond strength, and long-term clinical performance remains to be established through further studies.