Public transparency and physicochemical standardization in the regulation of PMMA dermal fillers: a comparative analysis of FDA, EU MDR, and ANVISA frameworks.

Permanent dermal fillers based on poly (methyl methacrylate) (PMMA) offer durable aesthetic correction but introduce lifelong patient risk due to their non-resorbable nature. This risk profile raises the question of whether existing regulatory frameworks adequately address the material determinants of long-term biocompatibility. This study presents a comparative analysis of publicly accessible regulatory documentation governing PMMA dermal fillers across three major jurisdictions: the U.S. Food and Drug Administration (FDA), the European Union under the Medical Device Regulation (MDR), and Brazil's National Health Regulatory Agency (ANVISA). Across the public-facing documentation examined, we did not identify consistently accessible, class-wide physicochemical acceptance criteria for key material attributes such as microsphere size distribution, morphology, or residual monomer content. Instead, regulatory frameworks rely primarily on manufacturer-defined specifications evaluated within confidential premarket submissions. This limits the extent to which material safety parameters are externally verifiable and comparable across products. While this approach is well established and effective for many medical devices, its suitability for permanent, micro-particulate implants remains uncertain. Using Brazil, where publicly available documentation enabled direct comparison of two registered PMMA dermal fillers, as an empirical illustration, this study shows how variability in publicly disclosed information may complicate clinician-level interpretation and cross-product comparison. In response, we propose a complementary "material-first" regulatory perspective in which physicochemical parameters are defined through publicly accessible standards, such as pharmacopeial-style monographs. These standards are presented as a conceptual framework to enhance transparency and consistency in risk assessment, rather than as a replacement for existing process-based regulatory systems. For permanent implantable biomaterials, integrating material-level benchmarks with current regulatory practices may improve transparency, comparability, and long-term risk assessment.