Ceramic Versus Composite in the Treatment of Posterior Teeth by Inlays or Onlays (CECOIA)

• FDI criteria for dental restorations assessment [ Time Frame: at 2 years ] [ Designated as safety issue: Yes ]
  2 independent evaluators The primary outcome will consist in the FDI instrument for dental restorations assessment, as it was published after consensus in 2007 and updated in 2010 . This instrument is composed of three dimensions (biological, functional and esthetic), each consisting of several items that are assessed by clinical and radiographic examination according to Likert scales of 5 terms. Some items are evaluated quantitatively, others visually.The worst score of all items is retained as the overall score of the restoration, thus resulting in a single (ordinal) primary outcome.
  
  

• Restoration survival analysis [ Time Frame: at 2 years ] [ Designated as safety issue: No ]
  The primary outcome will consist in the FDI instrument for dental restorations assessment, as it was published after consensus in 2007 and updated in 2010 . This instrument is composed of three dimensions (biological, functional and esthetic), each consisting of several items that are assessed by clinical and radiographic examination according to Likert scales of 5 terms. Some items are evaluated quantitatively, others visually.The worst score of all items is retained as the overall score of the restoration, thus resulting in a single (ordinal) primary outcome.
  
  
• wear [ Time Frame: at 2 years ] [ Designated as safety issue: No ]
  The primary outcome will consist in the FDI instrument for dental restorations assessment, as it was published after consensus in 2007 and updated in 2010 . This instrument is composed of three dimensions (biological, functional and esthetic), each consisting of several items that are assessed by clinical and radiographic examination according to Likert scales of 5 terms. Some items are evaluated quantitatively, others visually.The worst score of all items is retained as the overall score of the restoration, thus resulting in a single (ordinal) primary outcome.
  
  
• overall quality of the restoration [ Time Frame: at 2 years ] [ Designated as safety issue: No ]
  The primary outcome will consist in the FDI instrument for dental restorations assessment, as it was published after consensus in 2007 and updated in 2010 . This instrument is composed of three dimensions (biological, functional and esthetic), each consisting of several items that are assessed by clinical and radiographic examination according to Likert scales of 5 terms. Some items are evaluated quantitatively, others visually.The worst score of all items is retained as the overall score of the restoration, thus resulting in a single (ordinal) primary outcome.
  
  
• FDI instrument validity data [ Time Frame: at 2 years ] [ Designated as safety issue: No ]
  The primary outcome will consist in the FDI instrument for dental restorations assessment, as it was published after consensus in 2007 and updated in 2010 . This instrument is composed of three dimensions (biological, functional and esthetic), each consisting of several items that are assessed by clinical and radiographic examination according to Likert scales of 5 terms. Some items are evaluated quantitatively, others visually.The worst score of all items is retained as the overall score of the restoration, thus resulting in a single (ordinal) primary outcome.
  
  

WHO estimates dental caries prevalence to be over 90% adults worldwide. When tooth substance loss due to the decayed tissue is small, a filling is done by the dentist directly. When the substance loss is important, dentists often treat it with a crown, which presents the disadvantage of further mutilating the tooth. An intermediate technique consists in manufacturing an inlay or an onlay: these restorations become more and more common since they are a minimally invasive solution in such cases. Inlays and onlays can be made of metal, ceramic or composite. Patients tend to refuse metallic restorations, so that dentists generally have to choose between composite and ceramic. Composite wears whereas ceramics fracture. Published in vitro studies provide possible answers to which material is most effective but very few clinical studies have been conducted to confirm them. Material\'s choice for inlay manufacturing is thus more country-based than evidence-based (Most french dentists choose composite while US dentists prefer ceramics for example). The main objective of this trial is to compare the clinical performance of ceramic and composite inlays/onlays. Other objectives include looking for the prognostic factors of these restorations and validating the criteria proposed by the World Dental Federation (FDI) to evaluate dental restorations.