The clinical concepts regarding the restoration of root canal treated teeth are not clear today and often based on conjecture due to a lack of sound empirical data. The diversity of published opinions is confusing and may lead to less-than-optimal treatment selections. There is also emerging debate whether or not a post is necessary. The purpose of the present article is to organize this topic in evidence-based principles and provide dental practitioners with clear guidelines about restorative therapy for premolar and molar teeth. Two clinical reports are presented, to exemplify the different clinical situations. The first case highlights a conservative restoration of an endodontically treated molar, maintaining an adequate quantity of healthy residual tissue and only covering the cusp with restoration material, which was not sustained by healthy dentin. In the second case, the fact that the premolar was so badly damaged by carious pathology meant that it was necessary to use a pin to anchor the composite material, and the cusp was covered completely. Based on the two presented clinical reports and a literature review, the concept of fiber post application is explained. Searches by hand and MEDLINE were employed to identify peer-reviewed articles on reconstruction of endodontically treated posterior teeth. A total of 70 articles published between 1967 and 2008 were reviewed.