Center of Resistance for Maxillary Protraction in Patent and Fused Palatal-Suture Configurations: A Three-Dimensional Finite Element Study

Objective: To determine and compare the center of resistance (Cres) for maxillary protraction in fused and patent palatal suture models using three-dimensional finite element analysis. Study design: A three-dimensional craniofacial model was constructed from CBCT data of a 10-year-old female with maxillary hypoplasia. Models with fused and patent palatal sutures were created. Finite element analysis evaluated displacement patterns following anteroposterior forces (10 N) at different vertical positions (H1–H4) and superoinferior forces (10 N) at different sagittal positions (V1–V5). The force application site producing the most uniform displacement with minimal rotation was identified as the Cres. Results: In the fused palatal suture model, the Cres was located at H3.3 (infraorbital rim level, 15 mm superior to the line midway between the occlusal plane and the infraorbital rim.) for anteroposterior loading and at V3.6 (slightly distal to the lower border of the zygomatic process, 15 mm anterior to the posterior nasal spine) for superoinferior loading. In the patent palatal suture model, the Cres remained at similar levels but shifted laterally, requiring force application 20 mm lateral to the midpalatal suture to achieve translational movement. Force application closer to the midpalatal suture caused the maxillary segments to diverge anteriorly and converge posteriorly, whereas force application at the lateral maxillary rim produced the opposite rotational pattern. Conclusion: The Cres of the nasomaxillary complex was consistently located near the infraorbital rim under anteroposterior loading and slightly distal to the zygomatic process under superoinferior loading in both suture configurations. In patent sutures, optimal translational movement required bilateral force application 20 mm lateral to the midpalatal suture. These findings provide subject-specific biomechanical information that may assist in the design and evaluation of maxillary protraction force systems.