Periodontal soft tissue augmentation induced by periodontally accelerated osteogenic orthodontics surgery

Abstract Objectives: To quantitatively assess the changes of periodontal soft tissue including gingival thickness and the width of keratinized gingiva after periodontally accelerated osteogenic orthodontics (PAOO) surgery by digital measurements.Methods: This study enrolled 15 maxillaries with 89 anterior teeth and 16 mandibles with 94 anterior teeth from Chinese adult patients with skeletal Angle Class III malocclusion for whom the PAOO surgery was proposed during orthodontic treatment. Intraoral scanning and cone beam computed tomography (CBCT) examinations were performed before PAOO surgery and 6-month after the surgery. The width of keratinized gingiva was measured on the digital model acquired by intraoral scanning. The gingival thickness was measured by a digital three-dimension model based on the combination of digital intraoral scanning and CBCT data.Results: The average gingiva thickness before surgery was 0.91 ± 0.32 mm and 1.21 ± 0.38 mm at 6-month after PAOO. Patients showed periodontal soft tissue augmentation with an average gingival thickness gain of 0.30 ± 0.33 mm. At 1mm, 2mm and 3mm apical to CEJ levels, the gingival thickness increase of mandible was higher than maxilla (0.38 ± 0.30 mm vs. 0.24 ± 0.31 mm, 0.43 ± 0.35 mm vs. 0.26 ± 0.41 mm, 0.36 ± 0.27 vs. 0.25 ± 0.32 mm, respectively, P<0.05). Meanwhile, the sites of gingival thickness ≤ 1mm before surgery showed more thickness gain than the sites > 1mm (0.36 ± 0.32 mm vs. 0.18 ± 0.31 mm, P < 0.001). The average width of keratinized gingiva at T0 was 3.88 ±1.22 mm, and increased 1.05 ±1.24 mm 6-month after PAOO surgery. Meanwhile, a digital three-dimension model for gingival thickness measurement based on the combination of digital intraoral scanning and CBCT showed high reliability and accuracy with intra-class correlation coefficient (ICC) of 0.897.Conclusion: PAOO could improve insufficient periodontal soft and hard tissues in patients with skeletal Angle Class III malocclusion, including the gingival thickness and keratinized gingiva width. The digital three-dimension model based on the combination of digital intraoral scanning and CBCT data could provide a new digital measurement of gingiva thickness with high accuracy and reliability.