In Vivo Biodegradation of bisGMA and Urethane-Modified bisGMA-Based Resin Composite Materials

Area of Science:

• Dental Materials Science
• Polymer Chemistry
• Biomaterials

Background:

• Resin composites are widely used in dental restorations.
• Concerns exist regarding the in vivo chemical degradation of resin composites and potential release of harmful substances.
• Bisphenol A glycidyl dimethacrylate (bisGMA) is a common monomer in dental composites, and its degradation products are of interest.

Purpose of the Study:

• To compare the in vivo chemical degradation of bisGMA-based and urethane-modified bisGMA-based resin composites.
• To assess the release of bisphenol A (BPA) and bishydroxypropoxyphenylpropane (bisHPPP), a bisGMA breakdown product.
• To investigate the correlation between human salivary esterase activity (HSDE) and the release of degradation products.

Main Methods:

• A cohort of 58 patients received either a traditional bisGMA-based (Z250) or a urethane-modified bisGMA-based (TPH Spectra) composite restoration.
• Human salivary esterase activity (HSDE) was measured prior to restoration placement.
• Rinse samples collected before, immediately after, and 7 days after restoration were analyzed for BPA and bisHPPP using HPLC-MS.

Main Results:

• Bisphenol A (BPA) was not detected in any rinse samples.
• Bishydroxypropoxyphenylpropane (bisHPPP) was detected only in samples immediately after restoration placement for both composite types.
• No statistically significant difference in bisHPPP levels was observed between the two composite groups or a correlation with HSDE.
• The release of bisHPPP was short-term and rapidly diluted below detection limits.

Conclusions:

• Conventional and urethane-modified bisGMA-based resin composites exhibit limited in vivo chemical degradation.
• No detectable BPA release occurred, and bisHPPP release was transient and not influenced by material type or salivary esterase levels.
• These findings suggest that current resin composite materials do not pose a significant risk of releasing harmful degradation products in the oral cavity.