Occlusal plane rotation and vertical control using high-pull palatal gear: A finite element study

This finite element study evaluated the biomechanical effects of 2 different miniscrew positions, anterior vs posterior, in high-pull palatal gear (HPPG) mechanics. The objectives were to analyze 3-dimensional tooth displacement, occlusal plane rotation, and the clinical applicability of each configuration.

Finite element analysis simulated HPPG mechanics with a midpalatal miniscrew placed at either the first premolar (anterior HPPG) or the first molar level (posterior HPPG). Approximately 200 g of force was applied from lingual buttons on the bilateral lateral incisors to the miniscrew for retraction. Tooth displacement and occlusal plane rotation were evaluated and compared between the 2 configurations.

Both configurations produced significant incisor intrusion. The anterior HPPG showed greater incisor intrusion with less molar intrusion, resulting in a pronounced counterclockwise rotation of the occlusal plane and distinct lingual root displacement of the incisors. Posterior HPPG demonstrated a similar intrusion of the anterior and posterior teeth, with consistent distal displacement of both the crowns and roots throughout the dentition, leading to whole-arch intrusion and distalization with minimal incisor axis change and occlusal plane rotation.

The HPPG technique is effective for vertical control of the maxillary dentition. The miniscrew position significantly influences the line of force relative to the center of resistance, producing different occlusal plane rotations. Anterior HPPG induces greater incisor intrusion and counterclockwise occlusal plane rotation, whereas posterior HPPG results in comparable anterior and posterior tooth intrusion with minimal occlusal plane alteration. Miniscrew position should be selected according to the desired occlusal plane modification for optimal esthetic and functional treatment outcomes.