Prosthetic treatment aims to provide functional rehabilitation of the stomatognathic system, which is also associated with an improvement in the overall functioning of the entire organism. Permanent restorations – crowns, bridges, as well as posts, are the most commonly used restorations in modern dental prosthodontics. The significant risk of complications arises from the fact, that clinical procedures require the reduction of the hard tooth tissues. At every stage of treatment, both during the single tooth recontruction with a prostethic crown and when complete occlusal recontrucion is necessary, it is essential to consider and ensure, optimal function of all components of the stomatognathic system. The objective of this article was to present the most common errors made during clinical stages, and the resulting complication when using permanent dentures based on the natural teeth. In the first part of the article, complications and their most frequent causes were gathered and presented. In the second part of the paper, errors at various clinical stages during treatment with conventional fixed prostheses- crowns, bridges and posts were analyzed.