## 4 Discussion
found in their review the population that attends dental office for regular maintenance have a lower incidence of peri-implant disease [40]. Our result of 5.3% of patients diagnosed with peri-implantitis is significantly less than the recent available literature describes. However, it should be noted that in our study, the included patients were generally healthy, heavy smokers, and patients with uncontrolled metabolic diseases were excluded. In addition, the group of patients analyzed in our study was under regular medical care from the time the implants were inserted, which, as [PERSON] et al. [40] point out, is not insignificant for the occurrence of peri-implant inflammation. Although peri-implantitis is thought to be caused mainly by dental plaque accumulation on the implant or abutment surface, many other risk factors have been reported, including cigarette smoking, noncontrolled diabetes, osteoporosis, history of periodontitis, presence of keratinized mucosa, occlusal overload, the surface of trans gingival abutment element, and the position of implant-abutment junction [40; 41; 42; 43]. Our results have shown a three-fold increase in peri-implantitis incidence, comparing the groups without and with bone augmentation (no GBR G1 = 2.27%, GBR G2 = 9.7%). However, the literature does not mention GBR as a risk factor for peri-implantitis [38; 44]. Similarly age structure of the patient with a diagnosed peri-implant disease, in our study, there were differences found between the age groups of patients, but there are still isolated cases of peri-implantitis that are, therefore, difficult to interpret. Proper width and thickness of the gingival connective tissue have been proven to be one of the success criteria in dental reconstructive surgery. The mean value of the thickness of keratinized tissue (TKT) analyzed together for both G1 and G2 was 1.87 mm. According to the literature, the influence of soft tissue remains not insignificant in terms of preserving the bone around the implant. [PERSON] [45] found that the gingival tissue thickness at the alveolar crest can significantly affect marginal bone loss (MBL) around implants. A value of 2 mm has been described in the literature as necessary to maintain the proper level of bone in the area of the implant [45; 46; 47; 14]. [PERSON] et al. [48], in a recent systematic review, have found that the soft tissue thickness is correlated with MBL except in cases of platform-switching implants when implants with thin tissues and screw-retained prostheses are used. In the case of our study, platform-switching implants were used, and soft tissue thickness was similar in both groups with no GBR G1 = 1.95 and GBR G2 = 1.74 with no statistically significant difference, so it can be assumed that tissue thickness did not affect the results of our comparison between G1 without augmentation and G2 with augmentation on the MBL. The characteristics of the dental implant have an influence on the surrounding tissue behavior among the position of the implant platform in relation to the height of the alveolar crest (supracrestal, equicrestall, subcreal); the type of connection between the implant and the superstructure, e.g., utilizing the platform switching [49; 50; 51]. [PERSON] et al. [52], in a systematic review, found that platform-switching implants placed in a subcreal position seem to have less marginal bone level changes when compared with implants placed equicrestall. However, [PERSON] et al. [52] pointed out that significant differences were only observed in animal studies. In our study, Conelog\({}^{\text{\textregistered}}\), Camlog bone level platform switching implants were used and placed equicrestally in all cases, so it can be assumed that the position of the implants did not affect the results of the comparison between the groups. The limitation of the presented study is its design as a retrospective study. The long-term analysis is based on the patients' medical records.