Abstract
BACKGROUND: Periodontal accelerated osteogenic orthodontics (PAOO) requires precise flap design for aesthetic preservation, functional stability, and rapid recovery. This study compared two additional flap incisions—vertical releasing incision (VRI) and horizontal extending incision (HEI) for PAOO in the anterior region. METHODS: Twenty-two orthodontic patients requiring PAOO were randomized into the VRI or HEI group. Immediately after surgery, the surgical time and graft material weight were recorded. Wound healing was evaluated at 1 and 2 weeks post-surgery. Soft-tissue parameters, such as probing depth (PD), clinical attachment level (CAL), keratinized gingival width (KGW), and gingival recession depth (GRD), were assessed at baseline, 3, 6, and 12 months. To assess hard-tissue changes, including root length, vertical bone level (VBL), and bone width measured at 2 mm (BW2), 4 mm (BW4), and 6 mm (BW6) below the cemento-enamel junction (CEJ), cone beam computed tomography (CBCT) scans were performed at baseline, 6, and 12 months. Lateral cephalometric analysis was performed to evaluate tooth movement before and after orthodontic treatment. RESULTS: Patient-level analyses revealed that the HEI technique had shorter surgical time (57.66 ± 5.01 min vs. 68.50 ± 13.50 min, p = 0.029) and a lower incidence of scarring (10% vs. 60%) than VRI. At the tooth-level, HEI achieved significantly greater labial bone width (BW2, BW4, BW6; all p < 0.001). Both groups showed comparable KGW increases (VRI: 0.71 ± 1.15 mm; HEI: 0.85 ± 1.13 mm) and VBL changes (VRI: 2.94 ± 2.79 mm; HEI: 2.69 ± 2.96 mm) at 12 months. No significant differences were observed between the groups regarding postsurgical pain or mucosal condition. CONCLUSIONS: Both flap techniques were effective in improving KGW and bone augmentation (VBL, BW2, BW4, BW6), with HEI showing advantages in terms of surgical time, reduced scar formation, and greater bone width in PAOO surgery. TRIAL REGISTRATION: Registered on clinicaltrial.gov; NCT05441683, 13/6/2022. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12903-025-07270-x.