Alveolar Bone Loss ; Dental Implants ; Humans ; Peri-Implantitis ; epidemiology ; prevention & control ; therapy ; Risk Factors

Retrograde peri-implantitis (RPI), a kind of rare biological complication in implant-supported prosthetic rehabilitation, has been reported more frequently in recent years. RPI is defined as the periapical lesion that occurs following implant placement while the coronal part of the implant achieves normal osseointegration. Due to the possibilities of asymptomatic clinical scenarios, RPI can easily be ignored if routine radiographic examination is absent postoperatively, which may postpone treatment and affect long-term outcome. The common cause is infection originating from the periapical lesion of the neighboring teeth, the residual bacteria at the implant site, the contaminated implant apex and etc. Treatment methods rely on the infection source and severity of defect. This article discusses the diagnosis, classification, etiology, and pathology as well as prevention and treatment of RPI in order to provide evidence for clinical decisions in the future.
Dental Implantation, Endosseous ; Dental Implants/adverse effects* ; Humans ; Osseointegration ; Peri-Implantitis/prevention & control*

OBJECTIVE: This study aims to use Arginine-gingipain A gene vaccine (pVAX1-rgpA) to immunize adult Beagle dogs and to evaluate its effect during peri-implantitis progression and development. METHODS: Plasmid pVAX1-rgpA was constructed. The second and third bilateral mandible premolars of 15 adult Beagle dogs were extracted, and the implants were placed immediately. After 3 months, the animals were randomly divided into groups A, B, and C. Afterward, the animals were immunized thrice with plasmid pVAX1-rgpA, with heat-killed Porphyromonas gingivalis, or pVAX1, respectively. IgG in the serum and secretory IgA (sIgA) in saliva were quantitatively analyzed by enzyme-linked immunosorbent assay before and after 2 weeks of immunization. Peri-implantitis was induced with cotton ligatures fixed around the neck of implants. Probing depth (PD) and bleeding on probing were recorded. All animals were sacrificed after ligaturation for 6 weeks. Decalcified sections with thickness of 50 μm were prepared and dyed with methylene blue to observe the bone phenotype around implants. RESULTS: Levels of serum IgG and sIgA in saliva were higher in groups A and B after immunization than before the process (P<0.05) and higher than those in group C (P<0.05). However, no difference was observed between groups A and B (P>0.05). At 4 and 6 weeks after ligaturation, PD of the ligatured side in group C was higher than that in groups A and B (P<0.05). On the other hand, no difference was identified between groups A and B (P>0.05). Bone loss in group A was significantly lower than that of the other groups (P<0.05). Abundant inflammatory cells and bacteria were present in the bone loss area around the implants in the three groups, as identified through hard tissue section observation. However, group C presented the most number of inflammatory cells and bacteria in the bone loss area around the implants. CONCLUSIONS IgG and sIgA can be generated by immunity with rgpA DNA vaccine, which can significantly slow down bone loss during experimental peri-implantitis in dogs.
Adhesins, Bacterial ; therapeutic use ; Alveolar Bone Loss ; Animals ; Arginine ; Cysteine Endopeptidases ; therapeutic use ; Dental Implants ; Dogs ; Peri-Implantitis ; prevention & control ; Porphyromonas gingivalis ; chemistry ; Vaccines ; therapeutic use