Morphological changes in alveolar bone thickness and height after orthodontic proclination or labial movement combined with autogenous soft tissue grafting: a CBCT evaluation

Abstract

Background: Autogenous soft tissue grafting is indicated in thin gingival biotypes before orthodontic proclination or labial movements to increase the keratinized gingiva and prevent gingival recession. However, its effect on local alveolar bone remodeling is unclear. The aim of this study was to investigate the effects of autogenous soft tissue grafting on local alveolar bone after orthodontic proclination or labial movements.

Methods: Sixteen patients with a thin scalloped gingival biotype, narrow keratinized gingiva, or thin cortical bone requiring orthodontic proclination or labial movement of teeth were included. Cone-beam computed tomography (CBCT) images were obtained before grafting and at least 6 months after surgery. Sixty mandibular teeth were included, and the vertical bone level and horizontal labial bone thickness were measured. The results were compared using paired t-tests or Wilcoxon signed-rank test.

Results: The horizontal labial bone thickness increased, especially at 6 mm below the cementoenamel junction (CEJ) in the mandibular central and lateral incisors (P < 0.05). The total alveolar bone area of the canines, first premolars, and second premolars increased at 3, 6, and 9 mm below the CEJ, respectively, and the differences were statistically significant (P < 0.05). Additionally, vertical bone height increased minimally on the labial side, but the differences were not statistically significant (P > 0.05).

Conclusions: New bone regeneration was observed on the labial (pressure) side after autogenous soft tissue grafting, which may represent a mechanism to effectively prevent gingival recession and maintain periodontal health.

Irb approval: All the experimental procedures involving humans in this study were approved by the Medical Ethics Committee of Xiangya Stomatological Hospital, Central South University ( No. 20190048).

Keywords: Autogenous soft tissue grafting; Bone regeneration; Gingival recession; Mucogingival surgery; Orthodontics; Periodontal regeneration.

Fig. 1

Detailed procedure for locating. Blue lines represent the axial plane, red lines represent the sagittal plane, and green lines represent the coronal plane. These reference lines were adjusted through the axis of the tooth in the three views

Fig. 2

Landmarks and measurements. FVBL: facial vertical bone level, LVBL: lingual vertical bone level, HBT: horizontal labial bone thickness

Fig. 3

Measurements on CBCT scans

Fig. 4

A, B, C Mucogingival condition before surgery. The maxillary left premolar and mandibular canines have gingival recessions, and the orthodontic treatment requires arch expansion for alignment. Autogenous soft tissue grafting has been performed in maxillary left premolar and mandibular canine and premolars. D, E, F: Changes 2 years after surgery. No further recession is observed in the operated regions after orthodontic treatment completion

Fig. 5

Superimposition of the two images before and after periodontal surgery. White represents T0; green represents T1. The tooth has been proclined with new labial bone formation