## 1 Introduction  
Implant-prosthetic rehabilitation has become a successful and highly predictable method used for restoring the functions of the stomatognathic system and improving the quality of the patient's life [1; 2; 3].  
However, in the partially edentulous mandible with bone atrophy, a favorable bone volume and density is a prerequisite for achieving a successful implant-prosthetic rehabilitation [3; 4]. In such cases, the placement of standard length implants is often prohibited by an insufficient height of the alveolar ridge [4]. Modern alveolar bone addition techniques can lead to the successful restoration of bone volume, creating the optimal geometry for the use of a larger dental implant [4]. Yet, in the posterior mandible, bone augmentation has been associated with a higher rate of peri-implant marginal bone loss, donor site morbidity, pain, increased costs, and duration of treatment [4; 5; 6].  
In this case, short implants can be a viable solution in implant-prosthetic rehabilitation of the edentulous mandible with bone atrophy [7; 8; 9]. The development of surface treatment technologies,high-performance materials, and design of microtopography of implants have helped to increase the reliability of short implants [7; 8; 9; 10].  
Oral rehabilitation becomes more challenging in the context of bilateral terminal dentulism. Further, as there are still insufficient data that could determine the optimal treatment, whether it would be rehabilitation using short implants or bone augmentation that would allow the use of longer implants, clinicians often face problematic situations [3]. However, some studies suggest that short implants may be more advantageous than longer implants placement following bone augmentation because of the reduced number of complications [7; 8; 11; 12]. In comparison with sandwich osteotomy and delayed implant placement, prosthetic rehabilitation of the partially dentulous atrophic mandible with short implants has been shown to have a comparable survival rate [11]. Moreover, short implants placed in an atrophic ridge and long implants placed after alveolar bone augmentation have been reported to present similar short-term peri-implant alveolar bone loss, regardless of the arch [7].  
While these clinical studies offer valuable information, in complex rehabilitation cases, there is yet to be a consensus or a guideline that would offer long term success of prosthetic implant rehabilitation. Therefore, the question is whether or not bone augmentation is necessary to enable larger implants to be used when smaller implants may perform comparably and avoid complications from preliminary surgical procedures in complex cases, such as bilateral terminal dentulism with mandibular bone atrophy.  
To the best of our knowledge, no previous finite element studies have yet to explore implant-proshetic rehabilitation in the posterior mandible with bilateral terminal edentation and bone atrophy.  
The scope of our study was to analyze the impact of implant prosthetic rehabilitation in bilateral terminal partial edentulism with mandibular bone atrophy and potential benefits of mandibular bone augmentation through finite element analysis (FEA).