Color stability assessment of polyetheretherketone compared with polymethylmethacrylate and alternative dental polymers: a systematic review with meta-analysis

Color stability is critical for aesthetic dental restorations exposed to staining agents. PEEK is a promising alternative to PMMA and other dental polymers, but comparative evidence is inconclusive. This meta-analysis evaluated whether PEEK offers superior color stability to PMMA and other polymers after staining. Five databases (PubMed, Cochrane Library, Web of Science, Google Scholar, Embase) were searched (inception–September 2026) per PRISMA guidance (PROSPERO CRD420250655659). In vitro studies comparing PEEK's color stability with PMMA and other polymers (POM, polyamide, PEKK, Karadent) after immersion in coffee, tea, red wine, cola, or turmeric were included; risk of bias was assessed with the QUIN tool. Analyses used a custom Python 3.14 random-effects (DerSimonian-Laird) model; heterogeneity was quantified with I 2 . Outcomes were mean differences (MD) in ΔE, interpreted against clinical perceptibility (ΔE ≥ 1.0), acceptability (1.0–3.3), noticeable discoloration (3.3–5.5), and unacceptability (> 5.5). Across 11 included studies, the primary PEEK-versus-PMMA subgroup comparison (non-cold-cure) was statistically significant for coffee (MD -1.77; p = 0.032) and distilled water (MD -0.52; p = 0.018) but not for cola (MD -1.24; p = 0.2) or tea (MD 0.11; p = 0.9). PEEK also showed statistically significantly less discoloration than pooled comparators overall (PMMA, POM, polyamide, Karadent) for coffee (MD -4.13; 95%CI -5.69, -2.58; p < 0.001; I 2 = 99%), cola (MD -3.13; -5.24, -1.02; p = 0.004; I 2 = 98%), tea (MD -2.47; -3.57, -1.37; p < 0.001; I 2 = 93%), and distilled water (MD -0.67; -1.06, -0.28; p < 0.001; I 2 = 99%; statistically significant but clinically negligible); red wine showed no overall difference (MD -0.11; -0.71,0.49; p = 0.7; I 2 = 91%). Heterogeneity was high overall (I 2 = 73–100%); tea remained fragile to single-study exclusion, while cola, coffee, and water were robust. The PEEK-versus-PMMA (non-cold-cure) advantage was significant for coffee and distilled water but not cola or tea. PEEK also showed less discoloration than pooled comparators overall for coffee, cola, tea, and distilled water. Given exclusively in vitro data, small per-subgroup numbers, high heterogeneity, and one study's unusually narrow reported variances, these remain directional, comparator-specific trends requiring prospective validation and independent data verification. The study protocol was registered in PROSPERO (CRD420250655659).