RgpA DNA Vaccine Induces Antibody Response and Prevents Alveolar Bone Loss in Experimental Peri‐Implantitis

Abstract

Peri-implantitis is one of many reasons for dental implant failure. This study is designed to prevent experimental peri-implantitis by arginine-specific gingipain A (rgpA) DNA vaccine. The bilateral mandibular second and third premolars from 15 male beagle dogs were extracted, and 60 implants were immediately implanted. Three months after implantation, the animals were randomly divided into groups A, B, and C and immunized with plasmid vector-rgpA, heat-killed Porphyromonas gingivalis, and plasmid vector, respectively. Cotton ligatures infiltrated with P. gingivalis were placed in the submarginal position around the neck of the implants to induce peri-implantitis. Clinical measurements, including probing depth (PD) and bleeding on probing, were recorded every 2 weeks postoperatively, and P. gingivalis-specific immunoglobulin G (IgG) in serum and secretory IgA (sIgA) in saliva were quantitatively analyzed by enzyme-linked immunosorbent assay at the same time. Animals were sacrificed after 6 weeks, 50-μm undecalcified histologic sections were prepared using methylene blue dye, and bone loss around implants was measured. Higher levels of IgG in serum and sIgA in saliva could be measured in groups A and B but not in group C after immunization. There were statistical differences (P <0.05) between, before, and after immunization, but no difference was found between groups A and B (P >0.05). Both peri-implant PD and bone loss in group A were significantly less than in groups B and C. IgG and sIgA could be generated by immunization with rgpA DNA vaccine, which could significantly slow down bone loss in the experimental peri-implantitis canine model.