title: Effect of chemical surface treatments and repair material on transverse strength of repaired acrylic denture resin.
abstract: OBJECTIVE
  This study was performed to evaluate the transverse strength of a denture base resin (H), repaired with an autopolymerizing acrylic resin (A) or a visible light-curing (VLC) resin (T) following the use of three chemical solvents: methyl methacrylate monomer, aceton or chloroform.
  
  
  METHODS
  Eighty specimens (65.0 x 10.0 x 3.3 mm) of H were fabricated and stored in distilled water at 37 degrees C for seven days. Specimens were divided into eight equal groups of 10. In each group, specimens were sectioned in the middle to create a 10 mm gap. Two groups served as controls and had no surface treatment. They were repaired with A or T materials. In the remaining six experimental groups, specimen surfaces were treated with ac for 30 sec or mma for 180 sec or ch for 5 sec. Then A or T material was placed on the treated surfaces, using the same preparation molds. After seven days' storage at 37 degrees C, the transverse bond strength (MPa) of the specimens was measured using a three-point bending test. A two-way ANOVA and a Tukey HSD were performed to identify significant differences ( P < 0.05). The nature of the failures was noted as adhesive, cohesive or mixed.
  
  
  RESULTS
  Significant differences were found between the controls and experimental groups ( P < 0.05). In the control groups, repair with A showed significantly higher strength (60.3 MPa) than those repaired with T (51.3 MPa). Mean transverse strength of experimental specimens repaired with A was (75.06 MPa) which was significantly greater than those repaired with T (67.9 MPa). Although surface treatment increased repair strength, no significant differences were detected between the effects of the chemical etchants.
  
  
  CONCLUSIONS
  The autopolymerizing resin exhibited significantly higher repair strength than VLC resin. The transverse strength of the repaired specimens was increased significantly after chemical treatments.
authors.affiliation: Department of Prosthodontic, Faculty of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran. vojdanim@sums.ac.ir
authors.forename: Mahroo
authors.initials: M
authors.lastname: Vojdani
authors.forename: Sakineh
authors.initials: S
authors.lastname: Rezaei
authors.forename: Lila
authors.initials: L
authors.lastname: Zareeian
mesh_terms: D000096:Acetone; D000180:Acrylic Resins; D000704:Analysis of Variance; D002725:Chloroform; D045662:Dental Etching; D003799:Dental Stress Analysis; D003819:Denture Bases; D003780:Denture Repair; D020366:Methylmethacrylate; D044367:Phase Transition; D013499:Surface Properties
chemical_list: D000180:Acrylic Resins; C060386:Triad resin; D000096:Acetone; D020366:Methylmethacrylate; D002725:Chloroform