The 2017 classification of periodontal diseases provides a structured system for staging and grading periodontitis to guide diagnosis and therapy. Orthodontic care has increasingly been applied alongside periodontal treatment to manage malocclusion, drifting teeth, and bite instability. Yet, there is still limited literature that directly matches this updated classification. This systematic review aims to assess how orthodontic intervention affects periodontal health in patients categorized as Stage III and IV under the 2017 system. Following PRISMA 2020 guidelines, a systematic review was carried out. Databases screened included PubMed, Web of Science, Scopus, and Google Scholar. Publications from 2012–2024 were considered. After selection, 17 studies met the inclusion standards. Key outcomes were changes in clinical attachment level (CAL), reductions in probing depth (PD), and radiographic indicators of bone repair. When orthodontic therapy was combined with periodontal management, there was a substantial gain in CAL (4.35–5.96 mm on average), a marked reduction in PD (3.1–6.3 mm), and measurable vertical bone fill (mean: 4.89 mm). The most pronounced benefits were reported in Stage IV Grade C patients, particularly when orthodontics followed regenerative procedures early on. Follow-ups lasting as long as 10 years supported the durability of these improvements. Adding orthodontics to conventional periodontal therapy enhances outcomes in advanced disease, especially in Stage III and IV periodontitis. These findings reinforce the value of coordinated, multidisciplinary care and the necessity for clear treatment pathways that integrate orthodontics into periodontal protocols.
