Dental composite-resin materials and oral-systemic health: clinical toxicology insights

Resin-based dental composites are the most widely placed direct restorative materials globally. Yet, their organic matrix and complex filler system render them a potential source of biologically active compounds. Residual monomers, including Bisphenol A-glycidyl dimethacrylate (Bis-GMA), triethylene glycol dimethacrylate (TEGDMA), 2-hydroxyethyl methacrylate (HEMA), and urethane dimethacrylate (UDMA), are released into the oral environment through incomplete polymerization, material degradation, and wear, and may subsequently reach systemic circulation. Composite matrix breakdown additionally generates micro- and nanoplastic particles (MNPs), representing a distinct emerging exposure pathway. This review synthesizes clinical and translational evidence on the oral-systemic toxicological implications of resin-based composite materials, with emphasis on biomonitoring data, mechanistic pathways, and relevant risk signals.

A structured search was conducted across PubMed/MEDLINE, Embase, Scopus, and Web of Science for studies published between January 1990 and September 2025. Eligible studies reported biomonitoring outcomes (saliva, blood, urine, breast milk, cord blood, or placenta), toxicokinetic profiles, or systemic and generalized hypersensitivity reactions attributable to resin-based restorative materials. Studies on dental amalgam and non-dental polymer exposures were excluded. Data were synthesized narratively in accordance with SANRA principles.

Released monomers exert concentration-dependent cytotoxic, genotoxic, and immunomodulatory effects, primarily through glutathione depletion, reactive oxygen species generation, and apoptosis induction. Local adverse effects, including gingival inflammation, pulp cytotoxicity, and allergic contact stomatitis, are well-documented in vitro and in clinical case reports. Systemically, BPA and its derivatives have been detected in saliva, urine, blood, breast milk, cord blood, and placenta following dental procedures, raising concerns regarding endocrine-disrupting potential, particularly in children and pregnant women. Dental personnel constitute a distinct occupational risk group through dermal monomer exposure. Composite resins also release MNPs through wear and degradation, with preliminary data suggesting inflammatory and genotoxic potential, though clinical significance remains to be established.

Resin composites pose a measurable, if generally low-level, toxicological risk through monomer elution and, increasingly, MNP release. Adequate operative technique substantially reduces patient exposure. Vulnerable populations, including children, pregnant women, and dental personnel, warrant particular attention. Standardized biomonitoring protocols, updated regulatory thresholds, and dedicated in vivo studies are needed to characterize the long-term oral-systemic health implications of these ubiquitous materials.