Comparison of naturally occurring and ligature-induced peri-implantitis bone defects in humans and dogs

Objectives: The aim of the present study was to evaluate and compare naturally occuring and ligature‐induced peri‐implantitis bone defects in humans and dogs. Material and Methods: Twenty‐four partially and fully edentulous patients undergoing peri‐implant bone augmentation procedures due to advanced peri‐implant infections were included in this study (n=40 implants). Furthermore, peri‐implantitis was induced by ligature placement and plaque accumulation in five beagle dogs for three months following implant insertion (n=15 implants). The ligatures were removed when about 30% of the initial bone was lost. During open flap surgery, configuration and defect characteristics of the peri‐implant bone loss were recorded in both humans and dogs. Results: Open flap surgery generally revealed two different classes of peri‐implant bone defects. While Class I defects featured well‐defined intrabony components, Class II defects were characterized by consistent horizontal bone loss. The allocation of intrabony components of Class I defects regarding the implant body allowed a subdivision of five different configurations (Classes Ia–e). In particular, human defects were most frequently Class Ie (55.3%), followed by Ib (15.8%), Ic (13.3%), Id (10.2%), and Ia (5.4%). Similarly, bone defects in dogs were also most frequently Class Ie (86.6%), while merely two out of 15 defects were Classes Ia and Ic (6.7%, respectively). Conclusions: Within the limits of the present study, it might be concluded that configurations and sizes of ligature‐induced peri‐implantitis bone defects in dogs seemed to resemble naturally occurring lesions in humans.