Comparative Evaluation of Mechanical Properties, Color Stability, and Surface Roughness of Gingiva-Shaded Composites

This study evaluated the mechanical properties, surface topography, and color stability of a conventional acrylic resin compared to three commercially available gingiva-shaded composites after immersion in common beverages.

Conventional acrylic resin (Major Base 20) was compared with three commercially available pink composites: Shofu Beautifil II (Shofu Inc.), Beauty Gum Gingiva (TuskDent), and Dengen Dent (Dengen Dent). Bar-shaped specimens (n = 10 per material) were tested for flexural strength and elastic modulus using a universal testing machine. Disc-shaped specimens (n = 10 per material) were assessed for Vickers microhardness. Additional disc-shaped specimens (n = 10 per material per solution) were immersed in distilled water, tea, coffee, or Coca-Cola for 28 days. Color stability (ΔE) and surface roughness (Ra) were measured before and after immersion using spectrophotometry and profilometry, respectively. Data were analyzed using one-way ANOVA and post hoc Tukey's test (α = 0.05).

Shofu Beautifil II (92.24 ± 11.67 MPa) and Beauty Gum (99.28 ± 16.05 MPa) composites exhibited flexural strength comparable to that of acrylic resin (98.49 ± 10.84 MPa). However, Dengen Dent (35.24 ± 5.87 MPa) showed significantly (p < 0.001) lower flexural strength compared to the other groups (p < 0.001). Both acrylic resin and Dengen Dent had lower elastic modulus and microhardness values than Shofu and Beauty Gum Pink composites (p < 0.001). Dengen exhibited significant color changes after immersion in coffee and tea compared to the other groups (p < 0.001). In terms of post-immersion surface roughness, no significant differences were found between the tested groups, except for Shofu Beautifil II, which showed increased roughness when immersed in Coca-Cola (p < 0.05).

Shofu Beautifil II and Beauty Gum Gingiva showed higher flexural strength, elastic modulus, and microhardness, as well as superior color stability (ΔE ₀₀ < 2.8) and minimal surface roughness change compared to Dengen Dent and acrylic resin. Dengen Dent exhibited lower mechanical properties and color instability (ΔE ₀₀ > 2.8), while acrylic resin had moderate performance across all tested parameters.

The study underscores the critical need for careful material selection in esthetic dentistry, particularly for gingiva-shaded composites. Clinicians should be aware that not all pink composites perform equally. Furthermore, the potential for certain composites to develop increased surface roughness when exposed to acidic drinks such as cola may influence plaque retention. Therefore, selecting a pink composite with proven durability, color stability, and surface integrity is essential for achieving predictable and long-lasting esthetic restorations.