A nomogram prediction of gingival recession in mandibular incisors of orthodontic-orthognathic treated skeletal class III malocclusion with or without PAOO: A retrospective cohort study

Background: To assess the alterations in gingival thickness and the occurrence gingival recession subsequent to orthodontic-orthognathic treatment of mandibular incisors in skeletal Class III and identify risk factors associated with gingival recession. Methods: In this retrospective cohort study, we enrolled 33 patients exhibiting skeletal Class III malocclusion, totaling 131 mandibular incisors, who were undergoing orthodontic- orthognathic treatment that did not involve extraction of mandibular teeth. The subjects were categorized into surgery group (S; n = 17; ANB = −5.55 ± 3.26; IOFTN = 4.60 ± 0.51, scores ranging: 4.3–5.3) and non-surgery group (NS; n = 16; ANB = −3.00 ± 4.08; IOFTN = 4.63 ± 0.50, scores ranging: 4.3–5.4), based on if they had history of Periodontally Accelerated Osteogenic Orthodontics surgery (S) or not (NS). Patients in S group received orthognathic surgery about 1–1.5 years after Periodontally Accelerated Osteogenic Orthodontics surgery. Alterations in gingival thickness, gingival recession, and keratinized gingival width were compared before and after orthodontic-orthognathic treatment. Logistic regression analysis was used to construct a gingival recession prediction model and draw nomograms. Results: After orthodontic-orthognathic treatment, the gingival thickness and keratinized gingival width in NS group decreased by 0.15 ± 0.21 mm and 0.74 ± 0.91 mm, whereas those in the S group increased by 0.32 ± 0.28 mm and 2.09 ± 1.51 mm (P