## 1 Introduction
focused on implant site preparation with a randomized controlled clinical trial-split-mouth design that assessed the superiority of piezosurgery compared to conventional drills in terms of bone quality and implant stability [22]. Moreover, it also demonstrated the effects and the advantages of piezosurgical devices over conventional rotary osteetomes in terms of bone healing in an animal model, which is indeed important to obtain suggestive data for clinical practice [2; 10]. Following these experiments on animal models, it was decided to investigate the morphological effects of osteotomy instruments on human specimens for the first time ex vivo. It was decided not to investigate thermal damage effects in this study due to the lack of reproducibility in real clinical practice. In fact, heat production in ex vivo samples does not necessarily correlate to in vivo conditions. On the contrary, the morphological results related to the different osteotomy devices used are clinically reproducible and can be associated with real surgical evaluations. Regarding the selected sample type, the diaphyseal fibula bone has been chosen due to its density, biomechanical properties, and practical implications since it is routinely used in major maxillofacial, plastic, and orthopedic reconstructive interventions [23; 24; 25]. Despite these features, there is a paucity of data on this topic, especially on the morphological aspects of the cutting surfaces obtained with piezosurgical osteotomies on human bone tissue. In particular, these morphologic modifications can play a key role in the success of implant site preparation. The use of ex vivo human specimens is critical, thus maximizing the real setting of the osteotomy procedure and lowering the risks of disadvantages for the patients. In this specific study, it has to be said that human fibula samples that were already collected from the patients and that would have been discarded after the preparation of a free fibula flap were used. A fibula flap is an osteeosptomuscular flap that can be harvested together with a skin paddle. The indications for surgery included oncological diagnosis, osteoradionecrosis (ORN), medication-related osteonecrosis of the jaw (MRON)), pathological fractures, and atrophy of the jaws. The main consequence is that the patients involved did not experience any risk and/or adverse event. Likewise, it was possible to collect fresh human fibula samples to be cut and evaluated. To summarize, while the specimens were collected in a real clinical scenario, the osteotomy procedures were performed in a laboratory setting, thus enhancing the advantages of this human ex vivo experiment. Here, there is a comparison between the use of piezoelectric bone-cutting devices and a reciprocating saw on human fibula segments harvested during the microvascular reconstruction of jawbone defects. This study aimed to qualitatively evaluate ex vivo the morphology of the cutting surfaces in human fibula obtained with different osteotomies using environmental scanning electron microscopy, allowing us to observe the whole surface with a tridimensional perspective. This approach would allow us to clearly identify the presence of debris, scratches, and microcracks on the cutting surface.