title: Mechanical Properties and Simulated Aging of Silicone Maxillofacial Elastomers: Advancements in the Past 45 Years.
abstract: OBJECTIVE
  To identify and discuss the findings of publications on mechanical behavior of maxillofacial prosthetic materials published since 1969.
  
  
  METHODS
  Original experimental articles reporting on mechanical properties of maxillofacial prosthetic materials were included. A two-stage search of the literature, electronic and hand search, identified relevant published studies up to May 2015. An extensive electronic search was conducted of databases including PubMed, Embase, Scopus, and Google Scholar. Included primary studies (n = 63) reported on tensile strength, tear strength, and hardness of maxillofacial prosthetic materials at baseline and after aging.
  
  
  RESULTS
  The search revealed 63 papers, with more than 28 papers being published in the past 10 years, which shows an increased number of publications when compared to only 6 papers published in the 1970s. The increase is linear with significant correlation (r = 0.85). Such an increase reflects great awareness and continued developments and warrants more research in the field of maxillofacial prosthetic materials properties; however, it is difficult to directly compare results, as studies varied in maxillofacial prosthetic materials tested with various silicone elastomers being heavily investigated, standards followed in preparing test specimens, experimental testing protocols, and parameters used in setting simulated aging conditionings.
  
  
  CONCLUSIONS
  It is imperative to overcome the existing variability by establishing unified national or international standards/specifications for maxillofacial prosthetic materials. Standardization organizations or bodies, the scientific community, and academia need to be coordinated to achieve this goal. In the meantime and despite all of these theoretically significant alternatives, clinical practice still faces problems with serviceability of maxillofacial prostheses.
authors.affiliation: Cranio-Maxillofacial Prosthetics Unit, King's College Hospital, King's College London Denmark Hill Campus, London, UK.
authors.forename: Muhanad M
authors.initials: MM
authors.lastname: Hatamleh
authors.affiliation: Department of Prosthodontics, Dental School, University of Athens, Greece.
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Polyzois
authors.affiliation: Facutly of Medicine, Jordan University of Science and Technology, King Abdullah University Hospital, Irbid, Jordan.
authors.forename: Amjad
authors.initials: A
authors.lastname: Nuseir
authors.affiliation: University of Jordan-School of Dentistry, Amman, Jordan.
authors.forename: Khaldoun
authors.initials: K
authors.lastname: Hatamleh
authors.affiliation: Department of Substitutive Dental Science, Faculty of Dentistry, Taibah University, Madinah, Saudi Arabia.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Alnazzawi
mesh_terms: D004548:Elasticity; D006801:Humans; D008422:Materials Testing; D008447:Maxillofacial Prosthesis; D012826:Silicone Elastomers; D013718:Tensile Strength
chemical_list: D012826:Silicone Elastomers
keywords: Silicone elastomer; artificial aging; facial silicone; mechanical properties