## 4 Discussion  
As some implant manufacturers recognize the implant-return policy no matter the reason or circumstances, those data could be very valuable. From the clinical reality, we can assume that implant failure in most cases was because of implant-loading failure, which means that the implant was unable to work functionally. In the past, when not so many implant designs were available, patients were simply categorized based on relative and absolute contraindications for implant placement; nowadays, we rather use a low-, moderate-, or high-risk scale. Additionally, with the increased awareness in the field of biomaterials and the biology of bone-implant interference, implant features, such as shape and surface, are taken into consideration as important success factors [7; 8; 9]. On the other hand, remaining factors, such as the type of implant-abutment connections (internal and external hex, conical, trilobe, etc. ), abutment neck diameter, time of loading, and many more, should be taken into consideration [10; 11; 12]. All of these can create a lot of confusion when it comes to a proper assessment of the reason for a treatment failure and how it can be corrected or improved. Moreover, this shows not only how diverse the patients are and how our approach has changed over the past years but also that an implant limitation in one case can be an advantage in another [13]. In the literature, there is still no consensus when it comes to the best implant surface for immediate loading [14]. According to [PERSON] et al., machined surface implants, in general, are presenting poorer results for immediate loading [14]. This statement may be accurate for implants inserted into spongious bone areas, but results from this study are not in agreement with the above, especially when it comes to implants with a cortical anchorage [15]. In the present study, the complaint rate for polished implants was the lowest among all designs; thus, our results are in agreement with studies conducted by other researchers focusing on the early or immediate loading of machined implants [16; 17; 18; 19]. Surprisingly, implants that are \"Straumann-compatible\" have a high proportion of complaints. These implants' design provides little macro-retention, and their cylindrical shape prevents spongy bone from being compressed while the implant is inserted [20]. The endosseous design of such devices has a significant impact on their success rate [21; 22]. The performance of implants with essentially little thread retention (Category 4, threads 0.15 mm thicker than the core) is inferior to implants with the same connection but greater compression threads and conical design (Category 10, threads 0.25 mm thicker than the core). Single-piece compression screw implants with rough surfaces (Category 1) achieve significantly better results than two-stage implants with the same type of surface (Category 10), which is not in agreement with the paper of [PERSON] et al. However, they did not focus exclusively on immediate loading but rather on marginal bone loss and survival rate [23]. It appears that many dental professionals specializing in implantology simply follow the mainstream without giving appropriate thought to, for example, the true qualities of an implant design or how different designs and loading protocols cope with guided bone-regeneration materials. Future research should focus on comparing the results of this study with previous studies that followed a specific cohort of implant recipients. The findings of this study demonstrate that the rates of problems can fit the statistics on immediate or early loading found in the existing literature [24]. According to our findings, it may be concluded that there is no \"good\" or \"poor\" dental implant manufacturer; instead, the complaint rate (and hence, the \"success\" rate) is directly related to the implant design. Standard healing times for two-stage systems, with the exception of TGP, are 3 months for the mandible and 5-6 months for the maxilla.