title: Diffusion of HEMA from resin cements through different dentin thicknesses in vitro.
abstract: OBJECTIVE
  To evaluate the in vitro diffusion of 2-hydroxyethyl methacrylate (HEMA) from the resin cements through different thicknesses of dentin using high-performance liquid chromatography (HPLC) at two time intervals.
  
  
  METHODS
  60 freshly extracted caries- and restoration-free human third molar teeth were used in this study. Standardized box-shaped Class I inlay cavities (6 mm long, 3 mm wide and 2 mm deep) were prepared in all teeth with a high-speed handpiece mounted on a standard cavity machine. The remaining dentin thickness (RDT) between the pulpal wall of the cavity and the roof of the pulp chamber was measured at multiple points for each tooth so that two main groups of 30 teeth each were prepared with an RDT range 0.5-1.9 and 2.0-3.5 mm, respectively. Each of these main groups was divided into three subgroups (n = 10), according to the resin cements tested (RelyX ARC, Panavia F 2.0, Multilink Automix). Lithium disilicate-based ceramic inlays (IPS Empress 2) were manufactured to restore the prepared cavities. A polypropylene chamber containing 1 ml distilled water was attached to the cemento-enamel junction of each tooth. Then, ceramic inlays were cemented with resin cements according to the manufacturers' instructions. Water elutes were analyzed by HPLC at 4.32 minutes and 24 hours. HEMA diffusion amounts were analyzed using three-way ANOVA and Tukey's HSD tests (P < 0.05).
  
  
  RESULTS
  HEMA was detected in the pulp chamber elutes of all the teeth. The amounts of released HEMA did not significantly differ between time periods. The diffused HEMA amounts were significantly different between the RDT of 0.5-1.9 and 2.0-3.5 mm (P < 0.05) and between resin cements tested (P < 0.05). Decreasing RDT substantially increased the amount of HEMA that diffused through the dentin to the pulp space.
authors.forename: Onjen
authors.initials: O
authors.lastname: Tak
authors.forename: Aslihan
authors.initials: A
authors.lastname: Usumez
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002484:Cementation / Q000379:methods; D002851:Chromatography, High Pressure Liquid; D003737:Dental Cavity Preparation / Q000145:classification; D003776:Dental Porcelain / Q000737:chemistry; D003782:Dental Pulp / Q000033:anatomy & histology; D003786:Dental Pulp Cavity / Q000033:anatomy & histology; D003804:Dentin / Q000033:anatomy & histology*; D004058:Diffusion; D006801:Humans; D007284:Inlays; D018020:Lithium Compounds / Q000737:chemistry; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D058105:Polymerization; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
chemical_list: C118557:Empress 2; D018020:Lithium Compounds; D008689:Methacrylates; C438843:Panavia-Fluoro; D011109:Polymethacrylic Acids; C462240:RelyX ARC; D019279:Resin Cements; C493120:lithia disilicate; C502351:multilink adhesive system; D003776:Dental Porcelain; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C005044:hydroxyethyl methacrylate