## 2 Materials and Methods
The position of the teeth and the alveolar process were drawn on CBCT scans and supplemented with the perfect size of the arch. The height of the bone block was assessed using two measurements: in the direction of the crown and the apex, while the level of the crestal bone was positioned at the CEJ level minus 2-3 mm which is the biological width of teeth with healthy periodontitis. The gingival biotype evaluation was performed using the puncture technique, which was followed by reading the values from the periodontal probe scale. Then came the phase of computer-aided design and manufacturing (CAD/CAM). A virtual model of the mandible was created by converting CBCT scans and intraoral scans into digital models. A bone block design was placed on the model, and the actual and target value points were placed into one unit. A suitable live donor was selected according to predetermined aspects: an adequate amount of cancellous and/or cortical bone (in this case only cancellous bone), proper bone density-D2-D3 according to Misch. After milling, the block was cleaned, packed, sterilized, and sent to the surgeon. A detailed description of bone block planning, including diagrams of the procedure, has been previously described [16]. The bone reconstruction was performed under local anesthesia with a 4% solution of articaine and epinephrine 1: 100,000 (Ubistsein forte, 3M\({}^{\text{TM}}\) eSPe\({}^{\text{TM}}\), Wroclaw, Poland), and also with an antibiotic--0.6 g of clindamycin administered p.o. 1 h before the procedure (Clindamycin MIP, MIP Pharma GmbH, Blieskastel, Germany). The entire surgical procedure was carried out following a previously established scheme. Photos of the key moments of the surgery show the procedure of another patient who had the same operation. The only difference is the type of bone block fixation. In the presented case, resorbable pins made of amorphous poly-(d,l)-lactide were used, while the photos show a procedure that uses titanium screws. Both variants are acceptable and effective for fixing the block. When titanium screws are used, they are gently removed after 6-8 weeks. First, an intrasulacular incision was made two spaces mesially and distally wider than the planned treatment area and the envelope mucoperiosteal flap was elevated beyond the mental eminence to create a receiving bed without an excessive tension of the flap. Due to this, bone dehiscences and concavities of the mandibular alveolar part were exposed [Figure 5]. Root surfaces were then mechanically cleaned of deposits, without the use of additional substances. Afterward, a drill was used to decorticate the cortical layer in the interdental spaces to improve vascularization, and advanced platelet-rich fibrin (A-PRF) membranes were prepared from then peripheral patient's blood and placed on its surface (PRF Duo, Process for PRF, Nice, France) [19]. Allogeneic bone particles obtained from the Bone Bank in Poland were introduced into the deepest bone defects, followed by the placement of an individualized three-dimensional block of allogeneic bone [Figure 6]. In order to immobilize the bone block, and for its appropriate adaptation to the base, two 11 mm long resorbable polylactaic pins were ultrasonically introduced using the SonicWeld \(\text{R}^{\otimes}\) technique (KLS Martin, Jacksonville, FL, USA). Titanium screws can be used instead of resorbable pins, but should be removed after 6-8 weeks. Screws of about 8 mm long are usually used, i.e., Surgical Co (Daegu, Korea) [Figure 7]. Figure 5: Exposed tooth roots and bone dehisecences. Picture taken after mucoperiosteal flap elevation in the area of planned bone reconstruction. Figure 6: Individualized allogeneic bone block soaked in injectable platelet-rich fibrin before placement.