title: The Effect of Different Water Temperatures on Retention Loss and Material Degradation of Locator Attachments.
abstract: OBJECTIVE
  To examine the changes in Locator attachments after exposure to different water temperatures and cyclic loading.
  
  
  METHODS
  Four groups of pink Locator attachments (3.0 lb. light retention replacement patrix attachments; 10 per group) were soaked for the equivalent of 5 years of use in distilled water at the following temperatures: 20°C, 37°C, 60°C. One group was kept dry to test the effect of water. A universal testing machine was used to measure the retention force of each treated attachment during 5500 insertion and removal cycles, simulating approximately 5 years of use. The results were compared using Kruskal-Wallis one-way ANOVA by ranks. Surface changes of tested attachments were examined using scanning electron microscopy (SEM).
  
  
  RESULTS
  The exposure to 60°C water significantly increased the percentage of retention loss in Locator attachments (p < 0.05) compared to the 20°C water group and significantly reduced the final retention force compared to the other groups (p < 0.05). SEM examinations revealed severe cracking and material degradation in Locator attachments after exposure to 60°C water and cyclic loading, which were not evident in other groups. Cracking was observed after exposure to 60˚C water before cyclic loading.
  
  
  CONCLUSIONS
  Exposure to 60°C water, potentially similar to denture cleansing procedures, could cause cracking in Locator attachments. Cracking is associated with hydrolytic degradation of nylon at 60°C. The change in structure could result in a significant loss of retention.
authors: Prosthodontics Unit, Department of Restorative Dentistry, UCL, Eastman Dental Institute, London, UK.
authors: Lillian Pui Yuk
authors: LPY
authors: Chiu
authors: Prosthodontics Unit, Department of Restorative Dentistry, UCL, Eastman Dental Institute, London, UK.
authors: Nicola Di
authors: ND
authors: Vitale
authors: Prosthodontics Unit, Department of Restorative Dentistry, UCL, Eastman Dental Institute, London, UK.
authors: Haralampos
authors: H
authors: Petridis
authors: Prosthodontics Unit, Department of Restorative Dentistry, UCL, Eastman Dental Institute, London, UK.
authors: Ailbhe
authors: A
authors: McDonald
mesh_terms: D003799:Dental Stress Analysis; D003820:Denture Cleansers; D003781:Denture Retention; D003828:Denture, Overlay; D008422:Materials Testing; D013696:Temperature; D014867:Water
chemical_list: D003820:Denture Cleansers; D014867:Water
keywords: Dental implants; Locator attachment; overdenture attachment; overdentures; retention; water temperature