Gingival Recession After Combined Orthodontic–Orthognathic Treatment: A Systematic Review of Clinical Studies with Emphasis on Mandibular Incisors and Adjunctive Periodontal Therapies

<b>Background and Objectives:</b> Combined orthodontic-orthognathic treatment is the standard approach for managing severe dentofacial deformities. Nevertheless, its potential impact on periodontal tissues, particularly gingival recession (GR), remains a matter of clinical concern. This study aimed to evaluate the relationship between orthodontic-orthognathic procedures and GR based on available clinical evidence, with particular focus on potential risk modifiers, including orthodontic mechanics, surgical factors, and periodontal phenotype. <b>Materials and Methods:</b> This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. The review question was formulated using the PICO framework. <b>Results:</b> Seven observational clinical studies were included, with sample sizes ranging from 24 to 40 patients. GR outcomes varied considerably according to surgical procedure, orthodontic mechanics, adjunctive therapies, and patient-specific factors. Overall certainty of evidence was low-moderate. <b>Conclusions:</b> GR following combined orthodontic-orthognathic treatment is inconsistently reported and influenced by multiple clinical variables. Evidence suggesting roles for periodontal phenotype and adjunctive therapies, including PAOO, remains limited and context-dependent. Overall certainty of evidence is low-moderate, and findings should be interpreted cautiously.