## 5 Discussion
In the study, all drills allowed us to obtain the desired hole characteristics; all drills require adequate rotations and an appropriate cooling temperature. However, in some cases (D2), the cooling temperature was not sufficient to prevent tissue carbonization. We observed carbonization signs under water cooling and at 4 \({}^{\circ}\)C, but not at room temperature. This problem perhaps is associated with the shape of drill and the resistance of water flowing back, which results in locally increased friction and a temperature rise, leading to carbonization. However, in this case, this is not a very significant problem, which should be considered, but as it occurs too intensively, may be a factor causing carbonized residues to remain in the drilled hole. Such remains may be the cause of non-specific inflammation, which is not recommended for dental implantation. Dangerous effects of excessive rotational speed can be observed in the case of drills with a larger diameter due to the effect of drill geometry (effect of drill radius on tangential speed). This entails the risk that after the caliber of the drill hole has been determined, the inserted implant will not achieve the desired primary stability. Insufficient implant stability could hamper the osteeconductive capacity of the implant [38], resulting in impaired healing and implant loss [39]. Many factors could affect primary stability, including bone quantity and quality, implant macro- and micro-geometry, and surgical technique [40]. On the other hand, the obtained drill hole may be too small, for example due to leaving a part of the material mineralized in the hole. Undersized drilling is one of the most common surgical procedures to improve implant primary stability. With this technique, the implant osteotomy diameter is substantially smaller than the diameter of the implant [41]. It has been reported that increased lateral bone compression during implant placement into an undersized site results in higher insertion torque (ITQ), which can be an indicator of improved primary stability [10]. Elevated lateral compression during preparation can also be dangerous. However, a recent systematic review [42] suggests that higher lateral bone compression does not always result in enhanced mechanical stability and enhanced osseometigration. One of studies pointed out that implant insertion in underprepared sites provokes ischemia, osteocyte necrosis, and generates micro-fractures in the bone. It is well known that damaged cortical bone is replaced in the remodeling process. In the resorption process, temporary pores are formed in the peri-implant bone known as the remodeling space [2]. Based on our own observations and those described in the literature, the aim of drilling an appropriate hole is to obtain the so-called maximum primary stability followed by its temporary weakening. At this point, rapid bone resorption occurs, and bone density decreases directly in the area of the implants, which is followed by the synthesis of new bone tissue, creating a permanent biomechanical connection. Then, a slow process of bone tissue remodeling will last for many years. Remodeling occurs at the bone-implant interface, with the bone implant presumably affected by static strain. However, the extent of the remodeling has never been assessed by comparing different drilling protocols using implants with the same macro- and micro-design. It could be assumed that an insignificant amount of cortical bone could be subject to substantial compression forces. Regardless of the obtained results, in vitro studies will only become more valid predictors of human reactions to exposuresand treatments if there is substantial improvement in both their scientific methods as well as in more systematic reviews of the animal or \"in vitro\" literature as it evolves.