Abstract To determine how silica nanoparticle (NanoSi) content modulates polymerization kinetics, dentin bonding, and interfacial adaptation in self-adhesive flowable resin composites (SAFRCs). Five UDMA/PPGDMA/10-MDP SAFRCs containing 0, 2. 5, 5, 7. 5, or 10 wt% NanoSi were compared to a commercial reference (Vertise Flow, VF). Real-time ATR-FTIR provided t 0. 5, Rp max, delay time, and DC max ; viscosity was measured under controlled shear. Shear bond strength (SBS) was tested at 24 h. Masson’s trichrome and environmental SEM (E-SEM) assessed interfaces. Two-way MANOVA examined formulation and exposure time (20 vs 40 s) effects on kinetics; one-way ANOVA analyzed µSBS (ɑ = 0. 05). Formulation and time significantly affected the multivariate kinetic response (Wilks’ λformulation = 0. 1905, p = 0. 0099; Wilks’ λₜime = 0. 4296, p = 0. 0045), with no interaction. NanoSi₂. 5 polymerized fastest (Rp max 3. 17 ± 0. 43%·s⁻ 1) ; NanoSi₅ was slowest (1. 61 ± 0. 26%·s⁻ 1). DC max increased with filler, peaking at NanoSi₁0 (78. 77 ± 2. 64%) ; extending exposure from 20 to 40 s raised DC max by 10. 23 ± 2. 16% without altering kinetics. All pastes were shear-thinning, with viscosity rising monotonically with NanoSi. SBS differed among materials (ANOVA F = 3. 14, p = 0. 02): VF was highest (8. 6 ± 2. 2 MPa) ; NanoSi₀ reached 6. 0 ± 1. 1 MPa (NS vs VF) ; NanoSi₂. 5–5 clustered lower (~ 3–4 MPa) and NanoSi₇. 5 reached the minimum. Trichrome and E-SEM showed thin, continuous interfaces at 0–2. 5 wt% and increasing porosity/thin separations at 7. 5–10 wt%. Nanosilica altered cure, flow and interfacial quality trade-offs; faster early kinetics and higher final conversion did not translate into higher SBS, emphasizing the need to optimize interfacial wetting/adaptation alongside mechanical parameters in SAFRC design. A formulation window may exist in which flow, cure, and bonding are balanced to enhance the clinical potential of self-adhesive composites.
Alves et al. (2026) studied this question.