title: Hardness and surface roughness of enamel and base layers of resin denture teeth after long-term repeated chemical disinfection.
abstract: To evaluate the effect of successive cycles of disinfection in different denture cleansers on the surface roughness and the Vickers hardness of two layers of acrylic resin (base-BL and enamel-EL) of two commercial cross-linked artificial teeth.
  
  
  
  The occlusal surfaces of 60 acrylic resin denture posterior teeth (Trilux-TLX and SR Orthosit PE-SRO) embedded in autopolymerizing acrylic resin were ground fat with 1200-grit silicon carbide paper. Specimens were stored in distilled water at 37°C and then submitted to the microhardness (VHN) and roughness (μm) tests. Specimens were stored in distilled water at 37°C for 90 days and submitted to 720 disinfection cycles in sodium hypochlorite at 0.5%, 30% vinegar solution or distilled water (control). Afterward, micro-hardness and roughness tests were again performed. Data were analyzed using two-way ANOVA and Tukey's test (α=0.05).
  
  
  
  Hypochlorite immersion decreased the hardness of BL and EL of SRO teeth, with an average reduction of 10.11% (p<0.008). TLX teeth demonstrated a hardness reduction of 28.96% of both layers for all solutions including water (p<0.0000). The roughness of both teeth was not affected by denture cleansers (p>0.37).
  
  
  
  Hypochlorite promoted deleterious effects on the hardness of both layers of the artificial teeth tested. Immersion in vinegar and water also resulted in reduction of hardness of TLX teeth.
  
  
  
  The surface hardness of the different layers of cross-linked artificial teeth can be altered by daily disinfection in denture cleansers commonly indicated for removable dentures.
authors: Assistant Professor, Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, São Paulo, Brazil, Phone: 551432358245, e-mail: khnepp@yahoo.com.br.
authors: Karin Hermana
authors: KH
authors: Neppelenbroek
authors: Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors: Luciana Ayumi
authors: LA
authors: Kurokawa
authors: Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors: Andréa Lemos Falcão
authors: AL
authors: Procópio
authors: Department of Prosthodontics, Sagrado Coração University, São Paulo, Brazil.
authors: Thiago Amadei
authors: TA
authors: Pegoraro
authors: Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors: Juliana
authors: J
authors: Hotta
authors: Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, São Paulo, Brazil.
authors: Jozely Francisca
authors: JF
authors: Mello Lima
authors: Department of Dentistry, Ponta Grossa State University, Parané, Brazil.
authors: Vanessa Migliorini
authors: VM
authors: Urban
mesh_terms: D019342:Acetic Acid / Q000737:chemistry; D000180:Acrylic Resins / Q000737:chemistry*; D017554:Carbon Compounds, Inorganic / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003820:Denture Cleansers / Q000737:chemistry*; D004203:Disinfection / Q000379:methods*; D006244:Hardness; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry; D017655:Silicon Compounds / Q000737:chemistry; D012973:Sodium Hypochlorite / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014093:Tooth, Artificial; D014867:Water / Q000737:chemistry
chemical_list: D000180:Acrylic Resins; D017554:Carbon Compounds, Inorganic; D003188:Composite Resins; D003764:Dental Materials; D003820:Denture Cleansers; D008689:Methacrylates; D011140:Polyurethanes; D017655:Silicon Compounds; D014867:Water; C029824:urethane dimethacrylate luting resin; C004919:ethylene dimethacrylate; D019904:Polymethyl Methacrylate; D012973:Sodium Hypochlorite; D019342:Acetic Acid; C022088:silicon carbide
keywords: Laboratory research; Artificial tooth; Hardness; Disinfectants; Surface properties; Polymers.