E19. Dental composites have certain shortcomings that may affect their biocompatibility. Identify these shortcomings and discuss their effect on surrounding biological tissues.

(After Rueggeberg et al., 1995)

Incomplete cure may result in residual monomer, and the amount of leachable monomer increases as the bisGMA content increases (see above). Monomers can cause allergic reactions. Resins may also degrade because of the presence of organic solvents in the oral cavity. For example, esterase can break ester linkages and release molecular segments. Such a segment is bisphenol A, which could be released when some dental monomers degrade. 

Bisphenol A is known to have estrogenic effects. Based on existing knowledge, there are no indications today that the minor amounts of bisphenol A that have been released from composites and sealants have caused any harm to patients.  

(Courtesy of Munksgaard et al., 1996)

Today it seems as some of the biggest problem associated with dental resins is their ability to induce allergic reactions. During the past few years, dentists who use latex gloves in combination with dentin bonding agents have developed very painful allergic reactions on their finger tips (see above). These reactions may very well be a synergistic reaction between a latex swelling monomer (e.g. HEMA used in many dentin bonding agents) and some proteins present in latex. It is the latter proteins that cause the latex allergies, which have increased significantly among medical personnel during the past 10 years.