## 4 Discussion  
Our aim was to evaluate the long-term effectiveness of the applied GBR procedure in correcting small peri-implant bone dehiscence using the xenogeneic deproteinized bovine bone mineral material and a xenogeneic native bilayer collagen membrane. To assess the effectiveness of treatment with the GBR method, several factors affecting long-term treatment were evaluated. Among them are the implant survival rate in augmented and nonaugmented sites, the incidence of complications (particularly peri-implantitis), and the marginal bone loss in the peri-implant area. The implant survival rate was 100% in the 7 years of observation. However, the survival rate itself applies only to implants that have been integrated or lost and is not sufficient for a positive assessment of the treatment method. The stability of hard and soft tissues around dental implants is believed to be a key factor for long-term implant treatment. In our study, it was found that when the guided bone regeneration with a xenogeneic bone is used for implant dehiscence treatment, it does not influence the marginal bone loss around the implant in 7 years of observation. Taking into account the frequency of the need to perform GBR procedures presented by [PERSON] et al. [18] who, during a retrospective evaluation of the 1512 implants, placed found that bone graft was performed in estimated that up to 50% of all dental implant procedures, among the bone grafted sites, sinus lifting with lateral approach (22.1%) and guided bone regeneration (22.7%). An important aspect is the type of material used in the GBR procedure. Despite the widespread use of bone grafts and their substitutes, there are still limitations that remain associated with these commonly used dental surgical biomaterials. Starting with golden standard autogenous bone that needs to be obtained from intraoral and extraoral sites from the same individual. The disadvantages of autogenous bone are the lack of availability of graft tissue, associated pain, and morbidity at the site donor. Autogenous odontogenic materials are biocompatible and have the inorganic component of autogenous teeth; however, it is necessary to have and process patient teeth [19]. Then allogeneic bone provides many options for its use, ranging from guided bone regeneration of small defects to extensive reconstructions using 3D allogenic graft blocks for mandibular sagittal bone defect reconstruction, as described by [PERSON] et al. [20]. Allogenic materials can be prepared in three primary forms--fresh, frozen, or freeze-dried. Fresh and frozen allograft materials possess superior osteoinductive properties, but at the same time, they carry the greatest risks risk of a host immunogenic response [21]. The further processing of allogenic material through freeze-drying can decrease the immunogenicity at the cost of decreased osteoinductive potential [21]. Animal materials are also widely used, including the deproteinized bovine bone, which is commercially available as BioOss (Bio-Oss\({}^{\circled}\) \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **G1** & **G2** & \
\begin{tabular}{c} **G1, Excluded** \\ **Peri-Implantitis** \\ \end{tabular} &
\begin{tabular}{c} **G2, Excluded** \\ **Peri-Implantitis** \\ \end{tabular} \\ \hline mean TKT (in mm) & 1.95 & 1.74 & 1.95 & 1.73 \\ SD & 0.72 & 0.65 & 0.72 & 0.67 \\ minimum & 0.72 & 0.45 & 0.72 & 0.45 \\ maximum & 3.45 & 2.9 & 3.45 & 2.90 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Thickness of keratinized tissue (TKT) in studied groups of patients. Data are means \(\pm\) SD. Geistlich Pharma AG, Switzerland) and was used in our study. The porous structure of deproteinized bovine bone resembles the human bone and can provide mechanical support and stimulate bone healing through osteeoconduction [22; 23; 24]. The application of the bovine bone is very wide and covers most GBR indications. However, it is important to keep in mind the biggest limitation of this material, which is exclusively osteogenic potential.