## 1 Introduction  
For years, edentulous patients have had no other option than conventional dentures for re-establishing their oral function [1]. Loose and unstable dentures with a compromised function is a common complaint in complete denture patients. [2]. During the previous decades, there has been a revolution regarding rehabilitation treatments for edentulous patients. The progress in dental implants and osseointegration formulated a new set of possibilities other than the conventional treatment with complete dentures, even for individuals presenting parafunctional activities [3]. A conference group, after much debate, established that the ideal rehabilitation model for an edentulous patient should be a complete maxillary denture and a two-implant retained mandibular overdenture as an antagonist [4]. A major limitation to the procedure of implant placement is the deficiency of bone tissue to support and sustain the dental implant. As per Atwood classification, alveolar ridge atrophy and resorption take place in two dimensions: horizontal and vertical. The alternative in such scenarios is to carry out bone graft surgery for increasing bone height and volume. Mini dental implants (MDIs) are indicated in horizontally atrophied alveolar ridges having inadequate bone width and adequate bone height. Usually, elderly patients are not willing to undergo so many surgical procedures and may refuse dental implant-retained rehabilitation [5; 6; 7; 8; 9; 10; 11; 12]. MDIs (1.8-2.9 mm in diameter) have been indicated to be a surgical alternative to conventional dental implants for patients with narrow alveolar ridges [13; 14; 15; 16; 17; 18] The Glossary of Oral and Maxillofacial Implants (GOMI) has defined MDIs as \"dental implants fabricatedof similar biocompatible materials as other dental implants but of smaller dimensions\" [19]. They present a single body system with a ball-type attachment incorporated and usually are placed in a one-stage surgical procedure [20]. Originally, they were fabricated as transitional implants [21] or for orthodontic anchorage [22], however, their osseointegration outcomes, because of a rough surface, have exhibited to be comparable to conventional dental implants and were then considered as a permanent alternative [17; 23; 24; 25]. Additional benefits of MDIs include low-cost, less denture bulk, ease of technique, and simple surgical procedures without bone augmentation [26]. A few drawbacks are also associated with MDIs since their mechanical features favor deformation of the ball attachment, implant fracture, and the lack of an anti-rotational notch [6]. A greater incidence of implant fracture has been associated with the use of MDIs as compared to conventional dental implants and has been reported to be sensitive to high-insertion torque [6]. Hence, concern related to possible high fatigue fracture levels associated with MDIs in high-stress regions has resulted in their application is restricted to removable prostheses by many [26]. The previous reports that assessed the MDIs with prosthetic purpose evaluated their viability for retaining single provisional prosthesis in anterior areas, as attachment systems in partial removable dentures, and as support for retaining mandibular overdentures [27; 28; 29]. Promising outcomes have been reported so far; however, there is an absence of consensus regarding the utilization of immediate loaded MDIs for retaining mandibular overdentures in the published literature. Some reports have shown high survival rates for MDIs to support mandibular overdentures [15; 30] while other reports have demonstrated low survival rates as compared to SDIDs [31]. Hence, this systematic review aimed to verify the feasibility of utilizing immediate loaded MDIs to support mandibular overdentures for permanent prosthetic rehabilitation.