Evaluation of methodologies and additive efficacy on maxillofacial color longevity research: A systematic review and meta-analysis.

Chung, Se Hun, Chamberlain, Kathryn, Winwood, Keith and Coward, Trevor J (2025) Evaluation of methodologies and additive efficacy on maxillofacial color longevity research: A systematic review and meta-analysis. The Journal of Prosthetic Dentistry. ISSN 0022-3913

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Abstract

The lifespan of maxillofacial silicone elastomer-based prostheses can be as short as 6 months, primarily because of sunlight-induced color degradation. Efforts to enhance color stability have led to incorporating additives that include nanoparticles, opacifiers, and ultraviolet (UV) blockers. However, variability in testing methods and the absence of standardized protocols have led to inconsistent findings, underscoring the need for uniform testing to evaluate the color stability of these materials effectively. The purpose of this systematic review and meta-analysis was to assess the methodologies used in maxillofacial color longevity research and to synthesize findings on the effectiveness of additives in enhancing the color stability of pigmented silicone formulations exposed to solar radiation. This systematic review, adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, evaluated the impact of additives on color stability under solar radiation. Searches across PubMed, Web of Science, Embase, Scopus, and Cochrane databases (up to October 2024) followed the Population, Intervention, Comparator, Outcomes (PICO) criteria, limited to English-language studies. Articles were evaluated using a modified Consolidated Standards of Reporting Trials (CONSORT) guideline and quality-assessed with the Newcastle-Ottawa Scale, with high-quality studies (scoring 6 to 9) eligible for meta-analysis. A random-effects model in the RevMan Web tool was used, with heterogeneity assessed via the I² test and results presented in forest plots with 95% confidence intervals. A lack of standardized protocols persists in methodologies concerning specimen dimensions and pigmentation formulations, despite established weathering methods for both outdoor and artificial conditions. The meta-analysis demonstrated consistent improvements in color stability with additives under artificial weathering (P<.001), while no significant improvement was observed during a 3-month period of outdoor weathering (P=.120). High heterogeneity across studies was observed, largely associated with variability in silicone pigmentation formulations. Additives including nanoparticles, opacifiers, and UV blockers enhance the color stability of maxillofacial prostheses; however, the inherent stability of pigments remains a critical factor. Future research should focus on developing standardized testing methods tailored to maxillofacial applications, ensuring representativeness for prostheses and accounting for silicone formulation parameters relative to UV penetration.