title: How much do resin-based dental materials release? A meta-analytical approach.
abstract: OBJECTIVE
  Resin-based dental materials are not inert in the oral environment, and may release components, initially due to incomplete polymerization, and later due to degradation. Since there are concerns regarding potential toxicity, more precise knowledge of the actual quantity of released eluates is necessary. However, due to a great variety in analytical methodology employed in different studies and in the presentation of the results, it is still unclear to which quantities of components a patient may be exposed. The objective of this meta-analytical study was to review the literature on the short- and long-term release of components from resin-based dental materials, and to determine how much (order of magnitude) of those components may leach out in the oral cavity.
  
  
  METHODS
  Out of an initial set of 71 studies, 22 were included. In spite of the large statistical incertitude due to the great variety in methodology and lack of complete information (detection limits were seldom mentioned), a meta-analytical mean for the evaluated eluates was calculated. To relate the amount of potentially released material components with the size of restorations, the mean size of standard composite restorations was estimated using a 3D graphical program.
  
  
  RESULTS
  While the release of monomers was analyzed in many studies, that of additives, such as initiators, inhibitors and stabilizers, was seldom investigated. Significantly more components were found to be released in organic than in water-based media. Resin-based dental materials might account for the total burden of orally ingested bisphenol A, but they may release even higher amounts of monomers, such as HEMA, TEGDMA, BisGMA and UDMA. Compared to these monomers, similar or even higher amounts of additives may elute, even though composites generally only contain very small amounts of additives. A positive correlation was found between the total quantity of released eluates and the volume of extraction solution.
  
  
  CONCLUSIONS
  There is a clear need for more accurate and standardized analytical research to determine the long-term release from resin-based materials. Several guidelines for standardization are proposed.
authors.affiliation: Leuven BIOMAT Research Cluster, Department of Conservative Dentistry, School of Dentistry, Oral Pathology and Maxillo-Facial Surgery, Catholic University of Leuven, Kapucijnenvoer 7, B-3000 Leuven, Belgium. kirsten.vanlanduyt@med.kuleuven.be
authors.forename: K L
authors.initials: KL
authors.lastname: Van Landuyt
authors.forename: Tim
authors.initials: T
authors.lastname: Nawrot
authors.forename: B
authors.initials: B
authors.lastname: Geebelen
authors.forename: J
authors.initials: J
authors.lastname: De Munck
authors.forename: J
authors.initials: J
authors.lastname: Snauwaert
authors.forename: K
authors.initials: K
authors.lastname: Yoshihara
authors.forename: Hans
authors.initials: H
authors.lastname: Scheers
authors.forename: Lode
authors.initials: L
authors.lastname: Godderis
authors.forename: P
authors.initials: P
authors.lastname: Hoet
authors.forename: B
authors.initials: B
authors.lastname: Van Meerbeek
mesh_terms: D001559:Benzhydryl Compounds; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D055598:Chemical Phenomena; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent; D006801:Humans; D008689:Methacrylates / Q000737:chemistry; D010636:Phenols / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D058105:Polymerization; D011109:Polymethacrylic Acids / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors; D000098826:Bisphenol A Compounds
chemical_list: D001559:Benzhydryl Compounds; D017438:Bisphenol A-Glycidyl Methacrylate; D003188:Composite Resins; D003764:Dental Materials; D008689:Methacrylates; D010636:Phenols; D011092:Polyethylene Glycols; D011109:Polymethacrylic Acids; D011140:Polyurethanes; C029824:urethane dimethacrylate luting resin; C020946:triethylene glycol dimethacrylate; C005044:hydroxyethyl methacrylate; C006780:bisphenol A; D000098826:Bisphenol A Compounds