The issue of complete edentulism is a complex biomechanical problem that is usually solved by making conventional complete dentures. They are retained exclusively by the valve effect and often do not provide sufficient retention and stabilization of the denture, resulting in patient discontentment with chewing function. Today, however, modern dentistry offers a solution in the form of fixed or mobile restorations retained by implants. An implant-retained overdenture is a mobile replacement that can replace the largest resorptions of the alveolar ridge, and numerous studies have shown that implant-retained overdentures are an excellent therapeutic procedure for edentulous patients due to the significant improvement of chewing function, retention and stability of the prostheses, and by that also the quality of life depending on oral health (OHRQoL) in comparison to the previous experience of wearing complete dentures. Most often, implants of standard dimensions are inserted for the retention of complete dentures, however, there are cases in which the alveolar ridge is resorbed to such an extent that there is no adequate ridge width for their insertion. Such narrow ridges leave only the choice of mini dental implants (MDI) with a diameter less than 2.5 mm. Their insertion is a minimally invasive procedure and they are more financially acceptable than standard size implants. Due to the numerous advantages and the growing number of published critical studies on their use, it is expected that interest in them will soon expand and that the indications and contraindications for their insertion will be more precisely defined.