title: Level of residual monomer released from orthodontic acrylic materials.
abstract: OBJECTIVE
  To quantify, with high-pressure liquid chromatography (HPLC), the amount of residual monomer leached from different orthodontic acrylic materials prepared with two different manipulation methods.
  
  
  METHODS
  Eighty cylindrical specimens (5 × 25 mm) were divided into eight groups (n  =  10). The specimens were prepared with four acrylic materials-Orthocryl Neon Blue (Dentaurum), Orthocryl EQ (Dentaurum), Orthoplast (Vertex), and O-80 (Imicryl)-and with two different manipulation methods: doughing and spray-on. HPLC measurements were made at intervals of 2 hours, 6 hours, 1 day, 1 week, and 3 months. One-way analysis of variance (ANOVA) and Tukey's honestly significant difference multiple-comparison test were used to assess the amount of monomer eluted from the various groups. To assess the differences within each group over the various periods, repeated-measures ANOVA and paired t-tests were used.
  
  
  RESULTS
  Statistically significant differences were found within the groups in the amount of residual monomer in the specimens at different time intervals (P < .001). HPLC showed statistically significant differences among the groups (P < .05) in the amount of eluted monomer. Evaluation of the manipulation techniques showed that the monomer release rate was higher in the specimens prepared with the doughing method. When the four acrylic materials were compared, the specimens made from Orthoplast (Vertex) showed the highest rate of monomer release with both manipulation techniques.
  
  
  CONCLUSIONS
  The spray-on method can be recommended to clinicians for the preparation of orthodontic appliances.
authors.affiliation: a  Research Assistant, Inonu University, Faculty of Dentistry, Department of Orthodontics, Malatya, Turkey.
authors.forename: R Betul
authors.initials: RB
authors.lastname: Iça
authors.forename: Fırat
authors.initials: F
authors.lastname: Öztürk
authors.forename: Burhan
authors.initials: B
authors.lastname: Ates
authors.forename: Meral Arslan
authors.initials: MA
authors.lastname: Malkoc
authors.forename: Ünzile
authors.initials: Ü
authors.lastname: Kelestemur
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000336:Aerosols; D002851:Chromatography, High Pressure Liquid; D003432:Cross-Linking Reagents / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D020366:Methylmethacrylate / Q000737:chemistry; D008768:Methylmethacrylates / Q000737:chemistry; D009967:Orthodontic Appliances; D058105:Polymerization; D011108:Polymers / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000737:chemistry; D013696:Temperature; D013729:Terpenes / Q000737:chemistry; D013997:Time Factors; D014783:Viscosity
chemical_list: D000180:Acrylic Resins; D000336:Aerosols; D003432:Cross-Linking Reagents; D003764:Dental Materials; D008689:Methacrylates; D008768:Methylmethacrylates; C091936:Orthocryl; D011108:Polymers; D013729:Terpenes; D020366:Methylmethacrylate; C008715:orthoplast; C004919:ethylene dimethacrylate; D019904:Polymethyl Methacrylate
keywords: Acrylic material; Manipulation methods; Monomer release