Adhesives influence colour stability of composite veneers

Dental Tribune International

Thu. 5 March 2026

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DAMMAM, Saudi Arabia: Aesthetic longevity remains a central concern in anterior composite restorations, where colour change is a frequent reason for replacement. While composite material properties have been well studied, far less is known about the contribution of adhesive systems—especially experimental adhesives containing bioactive fillers—to long-term shade stability. A recent in vitro study by researchers in Saudi Arabia has investigated whether different commercial and experimental adhesives influence the colour of direct composite veneers after exposure to common beverages.

The authors compared a fourth-generation total-etch adhesive system, a seventh-generation universal self-etch adhesive system, and two experimental bioactive adhesive systems, one incorporating nano-hydroxyapatite and the other nano-bioactive glass. Composite veneers fabricated from IPS Empress Direct (Ivoclar) A2 nano-hybrid composite of increasing standard thickness from the cervical to incisal thirds were placed on typodont maxillary incisors and immersed daily in coffee, cola or deionised water for 60 days. Colour change was measured at the incisal, middle and cervical thirds, allowing assessment of both adhesive type and regional composite thickness.

Overall, coffee produced the greatest colour change, and cola also produced notable colour change relative to deionised water in many conditions, although the magnitude of staining depended on the adhesive system and tooth region. The hydroxyapatite-based adhesive showed the lowest overall colour change across most regions and solutions, whereas the bioactive glass-based adhesive exhibited significantly greater discoloration than the hydroxyapatite formulation but less than the commercial systems. The fourth-generation adhesive demonstrated better colour stability than the seventh-generation adhesive in the middle and cervical thirds. The middle and incisal thirds were generally more prone to colour change than the cervical third.

The findings suggest that adhesive selection can meaningfully influence the long-term aesthetic outcome of direct composite veneers. While universal adhesives offer clinical convenience, their colour stability may be inferior to multi-step systems in aesthetic zones. The experimental adhesives demonstrated promising resistance to discoloration, supporting the concept that bioactive fillers may help stabilise the resin–tooth interface and limit stain uptake. However, the higher discoloration observed with the bioactive glass formulation highlights that not all bioactive approaches confer the same optical performance. Clinicians should therefore consider both adhesive choice when planning highly aesthetic anterior restorations, especially for patients with frequent exposure to staining beverages.

The study, titled “The effect of adhesive systems on shade matching of composite veneer”, was published online on 3 February 2026 in Dentistry Journal.