NIST researchers quantify cellular viability and inflammatory response to dental bonding resins.

Implanted biomaterials frequently evoke inflammatory responses, which are subsequently responsible for biomedical implant failures. NIST researchers have developed a metrology for the analysis and quantitation of cellular inflammatory responses in vitro. The technique will accelerate biomedical device development by minimizing or eliminating the need for expensive in vivo animal testing.

Real-time polymerase chain reaction (RT-PCR) and flow cytometry were used to quantify elevated cytokine production as an indicator of inflammatory responses to four commercial dental resins. (Cytokines are proteins that are responsible for regulating both the duration and intensity of immune responses and for mediating intercellular communication.) Murine macrophages cells exposed to resins containing Bis-GMA (2,2-bis[p-(2'-hydroxy-3'-methacryloxypro-poxy) phenyl]propane) and HEMA (2-hydroxyethyl methacrylate) had the most adverse responses, as indicated by the relative proportion of live cells to dead cells. Moreover, the other resin systems displayed intermediate levels of viability when compared with the untreated control. The results demonstrate that cellular response to toxic leachables follows a distinct pathway, starting with up-regulation (elevated production) of proinflammatory cytokines and, depending on the strength of the response, terminating in extensive necrosis (localized death of living cells).

For additional information, visit the Polymers Division Web site at www.nist.gov/polymers.

CONTACT: Newell Washburn, [phone]; [e-mail] or LeeAnn Bailey, [phone]; [e-mail].