title: A study to investigate and compare the physicomechanical properties of experimental and commercial temporary crown and bridge materials.
abstract: OBJECTIVE
  To develop two experimental temporary crown and bridge materials with improved physicomechanical properties.
  
  
  METHODS
  Commercial materials: Trim (TR, monomethacrylate, Bosworth) and Quicktemp2 (QT, dimethacrylate, Schottlander).
  
  
  METHODS
  isobutyl methacrylate/poly(ethyl methacrylate) (IBMA/PEM) and n-butyl methacrylate/PEM (nBMA/PEM), both monomethacrylates. For water absorption/desorption studies rectangular samples (40 mm × 10 mm × 1 mm) of each material were prepared, immersed in deionized water (DW, control) and artificial saliva (AS), and weighed at regular time intervals. %solubility and diffusion coefficients (D) for uptake/loss processes were calculated and compared with theoretical predictions. Polymerization exotherm (cylindrical samples 10 mm × 18 mm) and flexural moduli were measured (three point bending; rectangular samples 80 mm × 10 mm × 4 mm, dry and after 9 days storage in DW). The data were compared statistically.
  
  
  RESULTS
  QT and nBMA/PEM had lower %equilibrium uptakes/loss in DW (0.68%/0.884% and 0.64%/0.895% respectively). QT had the lowest water absorption/desorption D (P<0.05) compared to the three monomethacrylates, in DW and AS. %solubility for all systems showed no differences in DW (P>0.05), but a difference for QT in AS (P<0.05). QT reached its maximum temperature rapidly (∼2 min; 3 monomethacrylates ∼7-13 min). The commercial materials exhibited high peak temperatures (∼51°C, P<0.05; experimental materials ∼43°C). QT had a higher flexural modulus (∼4 GPa; 3 monomethacrylates ∼0.7-1 GPa) for dry and wet samples. The moduli for commercial materials reduced significantly after immersion in DW; there was no difference between the dry and wet experimental materials samples (P>0.05).
  
  
  CONCLUSIONS
  The experimental materials merit further studies since they presented with lower setting exotherms, and contained no phthalate plasticizer, thus being less of a risk to patients.
authors.affiliation: Centre of Oral Health Research, School of Dental Sciences, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4BW, UK. Electronic address: bana.abdulmohsen@ncl.ac.uk.
authors.forename: Bana
authors.initials: B
authors.lastname: Abdulmohsen
authors.affiliation: Centre for Oral Growth and Development (Dental Physical Sciences), Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 4NS, UK.
authors.forename: Sandra
authors.initials: S
authors.lastname: Parker
authors.affiliation: Centre for Oral Growth and Development (Dental Physical Sciences), Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 4NS, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Braden
authors.affiliation: Centre for Oral Growth and Development (Dental Physical Sciences), Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 4NS, UK.
authors.forename: Mangala P
authors.initials: MP
authors.lastname: Patel
mesh_terms: D003442:Crowns; D003764:Dental Materials / Q000737:chemistry*; D003794:Dental Restoration, Temporary; D003799:Dental Stress Analysis; D003829:Denture, Partial; D055119:Elastic Modulus; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D058105:Polymerization; D011109:Polymethacrylic Acids / Q000737:chemistry*; D012995:Solubility
chemical_list: D003764:Dental Materials; D008689:Methacrylates; D011109:Polymethacrylic Acids; C488491:Quicktemp; C091347:vinyl ethyl methacrylate; C008968:poly(isobutyl methacrylate); C016284:butyl methacrylate
keywords: Diffusion coefficient; Equilibrium uptake/loss; Exothermic reaction; Mechanical properties; Plasticizer; Polymers; Provisional restoration materials; Solubility; Temporary crown and bridge materials; Water absorption/desorption