The purpose of this comprehensive review was to evaluate and identify the performance of composite/ceramic onlays versus crowns. The strength of the evidence is based on published trials, systematic reviews and observational studies. Methods:The dental literature was reviewed for controlled clinical studies and retrospective cross-sectional studies from 1966 to 2013. Longevity of onlay or crown is dependent upon many different factors, including material, patient-and dentist-related. Principal reasons for failure were secondary caries fractures, marginal deficiencies, wear and postoperative sensitivity.Minimally invasive dentistry, in cases in which it is appropriate, is a concept that preserves dentition, supports structures and involves low cost therapy.