Effectiveness of Two Different Flap Advancement Techniques for Vertical Bone Augmentation in the Anterior Maxilla: A...

Achieving tension-free flap closure is a critical challenge in vertical ridge augmentation of the anterior maxilla, where anatomical constraints limit flap mobility and soft tissue advancement. This study compares the split-thickness flap (control) and sub-orbicularis full-thickness flap (test) in cadaveric models to evaluate their impact on soft tissue thickness, flap integrity following periosteal release, and mucogingival junction (MGJ) displacement. The goal is to characterize and optimize surgical approaches for vertical bone augmentation in the anterior maxilla.

Twelve edentulous human cadaveric maxillae were randomized to receive either split-thickness or sub-orbicularis full-thickness flap preparation in a split-mouth design. Standardized alveolar ridge conditions were established. Primary outcome was postoperative soft tissue thickness measured with high-frequency ultrasonography (HFUS); secondary outcomes were flap structural integrity assessed with HFUS and MGJ displacement evaluated using 3D optical scan superimposition).

Ultrasound revealed significant soft tissue thickness differences at 0 mm (0.45 mm, P = 0.009), 2 mm (-0.31 mm, P = 0.015), and 4 mm (-0.42 mm, P = 0.024) apical to the crest. Flap trauma was greater in the control group, with hypoechoic zones near deep vascular structures. The test group showed minimal soft tissue and vascular damage. MGJ displacement did not differ significantly between groups.

Both groups achieved tension-free flap closure. However, the 0.45 mm reduction in soft tissue thickness associated with the split-thickness flap may compromise blood supply and elevate the risk of tissue compression. Additionally, inadvertent trauma to deeper vascular structures in this group could delay healing and increase the likelihood of postoperative complications.