Sutural deformation during bone-anchored maxillary protraction

Area of Science:

• Orthodontics
• Craniofacial Biology
• Biomechanical Engineering

Background:

• Bone-anchored maxillary protraction (BAMP) is an emerging orthopedic treatment for maxillary deficiency in young patients.
• BAMP is hypothesized to induce greater circum-maxillary sutural separation and mandibular retrusion than reverse pull headgear (RPHG).
• The mechanical forces acting on circum-maxillary sutures during BAMP are not well understood.

Purpose of the Study:

• To compare the mechanical loading and sutural separation of BAMP versus RPHG.
• To quantify the deformation of key circum-maxillary sutures under BAMP and RPHG forces.

Main Methods:

• Ex vivo pig heads (n=20) were used to simulate clinical BAMP and RPHG application.
• Strain gauges measured deformation across the zygomatico-maxillary (ZMS), zygomatico-temporal (ZTS), and nasofrontal sutures (NFS).
• Differential variable reluctance transducers (DVRTs) measured ZTS separation, comparing forces up to 1000 gf.

Main Results:

• BAMP generated significantly higher deformation in the ZTS (36.6 ± 20.6με vs. 18.0 ± 12.4με) and ZMS (54.7 ± 28.5με vs. 12.5 ± 14.8με) compared to RPHG.
• NFS deformation was also significantly greater with BAMP (18.4 ± 12.9με vs. -0.8 ± 12.0με).
• ZTS separation was substantially higher with BAMP (6.3 ± 5.2μm vs. 1.7 ± 2.1μm).

Conclusions:

• Both RPHG and BAMP effectively separate the ZTS and ZMS.
• BAMP induces 2-fold and 5-fold greater separation at the ZTS and ZMS, respectively, compared to RPHG.
• These findings provide biomechanical evidence supporting BAMP's efficacy in maxillary protraction.