The main purpose of this trial is to determine which material, between ceramic and composite, is best to manufacture dental inlays and onlays in the treatment of moderate dental substance losses, generally due to dental caries. Restorations will be done using direct Computer Assisted Design and Manufacturing (CAD-CAM). Another aim of this study is to determine which factors influence the success of these restorations.

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.

Inclusion criteria :

• patient aged 18-70,who tolerates restorative procedures and presents a moderate-sized dental caries or restoration (that needs to be replaced) necessitating an inlay/onlay restoration.

Exclusion criteria :

• allergy to one of the materials employed, bruxism, severe or acute periodontal or carious disease, poor oral hygiene
• Tooth presents a mobility > II, a periodontal socket > 3mm or supports a removable partial denture

Randomization criterium :

• tooth necessitates an inlay-onlay restoration after caries or former restoration removal

Exclusion from randomization criteria :

• subgingival margin after cavity preparation, rubber dam cannot be placed, all tooth cuspids need to be covered by the restoration.