## 2 Materials and Methods
### Peri-Implant Treatment and Maintenance Protocols
#### 2.2.3 Surgical Treatment  
After removing the prosthesis, a 4% articaine solution with 1:100,000 epinephrine (Artinbisa, Inibsa, Llica del Valles, Barcelona, Spain) was injected, and a full-thickness flap was elevated, exposing the margin of the peri-implant defect. The granulation tissue was removed from the peri-implant defect with titanium curettes (AEIIN128-15X American Eagle; Missoula, MT, USA). After that, the implant surface was chemically decontaminated with 0.12% chlororexidine gluconate for 60 s. This additional process aimed to prevent microbiological contamination and increase surface cleanliness. Chlorheximide was chosen because of its documented antibacterial effectiveness and widespread usage in peri-implantitis protocols, as emphasized by [PERSON] (2015) et al. (2015), who demonstrated its importance as a practical adjuvant in both non-surgical and surgical therapy techniques. Implants with intrabony defects were treated with regenerative surgeries, while implants with mixed defects (suprabony and infrabony) were treated with a combined approach.
* Regenerative Approach: Deproteinized bovine bone mineral (DBBM, Geistlich Bio-Oss 0.25-1 mm, Geistlich Biomaterials, Wolhusen, Switzerland) was used to fill the defect, and a resorbable membrane (Geistlich BioGide, Geistlich Biomaterials, Wolhusen, Switzerland) was adapted around the implant neck. Non-resorbable polyamide (Supramid 4/0, St. With, Belgium) and PTFE (Cytoplast 4/0; Osteogenics Biomedical, Lubbock, TX, USA) sutures were used to close the wound, allowing for transmucosal healing (Figure 1).  
Figure 1: _Cont._* Combined Approach: The implant area located in the suprabony compartment of the defect was treated with implantoplasty, and the implant surface located in the infrabony defect was debrided with curettes. Threads were removed and polished with specific burs: an oval-shape tungsten carbide bur (H379 314 023; Komet Dental, Lemgo, Germany) was used to remove the implant threads, and the surface was sequentially polished with two silicon carbide polishers (9618 314 030 and 9608 314 030, Komet Dental, Lemgo, Germany) [40]. In cases of inadequate keratinized tissue or thin biotype, a connective tissue graft was added. Deproteinized bovine bone mineral (DBBM, Geistlich Bio-Oss 0.25-1 mm, Geistlich Bio-materials, Wolhusen, Switzerland) was used to fill the defect, and a resorbable membrane (Geistlich BioGide, Geistlich Biomaterials, Wolhusen, Switzerland) was adapted around the implant neck. Non-resorbable polyamide (Supramid 4/0, St. With, Belgium) and PTFE (Cytoplast 4/0; Osteogenics Biomedical, Lubbock, TX, USA) sutures were used to close the wound, allowing for transmucosal healing (Figure 2).  
Figure 1: Regenerative approach for peri-implantitis. **(a)** Preoperative clinical view showing peri-implant inflammation and soft tissue recession. **(b)** Flap elevation reveals a circumferential bony defect around the implant. **(c)** Bone defect filled with deproteinized bovine bone mineral (DBBM). **(d)** Resorbable membrane adapted around the implant neck. **(e)** Primary closure achieved with internal horizontal mattress and simple interrupted sutures. **(f-h)** Sequential healing at 7, 14, and 30 days postoperatively, demonstrating progressive soft tissue maturation.  
Figure 2: _Cont._