title: Effect of repair resin type and surface treatment on the repair strength of heat-polymerized denture base resin.
abstract: BACKGROUND
  Acrylic resin denture fracture is common in prosthodontic practice. When fractured denture bases are repaired, recurrent fractures frequently occur at the repair surface interface or adjacent areas.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the effect of different surface treatments on the flexural strength of the acrylic resin denture base repaired with heat-polymerized acrylic resin, autopolymerizing resin, and light-polymerized acrylic resin.
  
  
  METHODS
  Ninety-six specimens of heat-polymerized acrylic resin were prepared according to the American Dental Association Specification No. 12 (65.0 × 10.0 × 2.5 mm) and sectioned into halves to create a repair gap (3.0 × 10 × 2.5 mm). The sectioned specimens were divided into 3 groups according to their repair materials. The specimens from each group were divided into 4 subgroups according to their surface treatments: a control group without any surface treatment; an experimental group treated with methyl methacrylate monomer (MMA group); an experimental group treated with airborne-particle abrasion with aluminum oxide particles of 250-μm particle size (abrasion group); and an experimental group treated with erbium:yttrium-aluminum-garnet laser (laser group). After the surface treatments, the 3 materials were placed into the repair gaps and then polymerized. After all of the specimens had been ground and polished, they were stored in distilled water at 37°C for 1 week and subjected to a 3-point bend test. Data were analyzed with a 2-way analysis of variance, and the Tukey honestly significant difference test was performed to identify significant differences (α=.05). The effects of the surface treatments and repair resins on the surface of the denture base resin were examined with scanning electron microscopy.
  
  
  RESULTS
  Significant differences were found among the groups in terms of repair resin type (P<.001). All surface-treated specimens had higher flexural strength than controls, except the surface treated with the methyl methacrylate in the heat-polymerized group. A significant difference between the control and abrasion groups (P=.013) was found. The scanning electron microscopy observations showed that the application of surface treatments modified the surface of the denture base resin.
  
  
  CONCLUSIONS
  The repair procedure with heat-polymerized resin exhibited significantly higher flexural strength than that of the autopolymerized and light-polymerized resins. In addition, the airborne-particle abrasion with aluminum oxide particles of 250-μm particle size improved the flexural strength of the specimens tested.
authors.affiliation: Research Assistant, Department of Prosthodontics, Faculty of Dentistry, Atatürk University, Erzurum, Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Alkurt
authors.affiliation: Professor, Department of Prosthodontics, Faculty of Dentistry, Recep Tayyip Erdoğan University, Rize, Turkey. Electronic address: zyesilz@hotmail.com.
authors.forename: Zeynep
authors.initials: Z
authors.lastname: Yeşil Duymuş
authors.affiliation: Research Assistant, Department of Prosthodontics, Faculty of Dentistry, Atatürk University, Erzurum, Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Gundogdu
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000537:Aluminum Oxide / Q000737:chemistry; D045662:Dental Etching / Q000379:methods; D003764:Dental Materials / Q000737:chemistry*; D003775:Dental Polishing / Q000379:methods; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D003819:Denture Bases; D003780:Denture Repair; D006358:Hot Temperature; D006801:Humans; D053844:Lasers, Solid-State; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D020366:Methylmethacrylate / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D018583:Pliability; D058105:Polymerization; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D003764:Dental Materials; D014867:Water; D020366:Methylmethacrylate; D000537:Aluminum Oxide