title: Repairability of CAD/CAM high-density PMMA- and composite-based polymers.
abstract: OBJECTIVE
  The study aimed to analyse the shear bond strength of computer-aided design and computer-aided manufacturing (CAD/CAM) polymethyl methacrylate (PMMA)- and composite-based polymer materials repaired with a conventional methacrylate-based composite after different surface pretreatments.
  
  
  METHODS
  Each 48 specimens was prepared from six different CAD/CAM polymer materials (Ambarino high-class, artBloc Temp, CAD-Temp, Lava Ultimate, Telio CAD, Everest C-Temp) and a conventional dimethacrylate-based composite (Filtek Supreme XTE, control) and aged by thermal cycling (5000 cycles, 5-55 °C). The surfaces were left untreated or were pretreated by mechanical roughening, aluminium oxide air abrasion or silica coating/silanization (each subgroup n = 12). The surfaces were further conditioned with an etch&rinse adhesive (OptiBond FL) before the repair composite (Filtek Supreme XTE) was adhered to the surface. After further thermal cycling, shear bond strength was tested, and failure modes were assessed. Shear bond strength was statistically analysed by two- and one-way ANOVAs and Weibull statistics, failure mode by chi(2) test (p ≤ 0.05).
  
  
  RESULTS
  Shear bond strength was highest for silica coating/silanization > aluminium oxide air abrasion = mechanical roughening > no surface pretreatment. Independently of the repair pretreatment, highest bond strength values were observed in the control group and for the composite-based Everest C-Temp and Ambarino high-class, while PMMA-based materials (artBloc Temp, CAD-Temp and Telio CAD) presented significantly lowest values. For all materials, repair without any surface pretreatment resulted in adhesive failures only, which mostly were reduced when surface pretreatment was performed.
  
  
  CONCLUSIONS
  Repair of CAD/CAM high-density polymers requires surface pretreatment prior to adhesive and composite application. However, four out of six of the tested CAD/CAM materials did not achieve the repair bond strength of a conventional dimethacrylate-based composite.
  
  
  CONCLUSIONS
  Repair of PMMA- and composite-based polymers can be achieved by surface pretreatment followed by application of an adhesive and a conventional methacrylate-based composite.
authors: Department of Preventive Dentistry, Periodontology and Cariology, University of Göttingen, Robert-Koch-Str. 40, D-37075, Göttingen, Germany. annette.wiegand@med.uni-goettingen.de.
authors: Annette
authors: A
authors: Wiegand
authors: Clinic for Preventive Dentistry, Periodontology and Cariology, University of Zurich, Zurich, Switzerland.
authors: Lukas
authors: L
authors: Stucki
authors: Department of Preventive Dentistry, Periodontology and Cariology, University of Göttingen, Robert-Koch-Str. 40, D-37075, Göttingen, Germany.
authors: Robin
authors: R
authors: Hoffmann
authors: Clinic for Preventive Dentistry, Periodontology and Cariology, University of Zurich, Zurich, Switzerland.
authors: Thomas
authors: T
authors: Attin
authors: Department of Prosthodontics, Ludwig-Maximilians University, Munich, Germany.
authors: Bogna
authors: B
authors: Stawarczyk
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D008422:Materials Testing; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D011140:Polyurethanes / Q000737:chemistry*; D013314:Stress, Mechanical
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D011140:Polyurethanes; D019904:Polymethyl Methacrylate
keywords: Adhesive; CAD/CAM polymer; Composite; Failure; PMMA; Repair; Shear bond strength
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