Monocortical versus bicortical hard palate anchorage with the same total available cortical thickness: a finite element study.

Objective We aimed to compare the bicortical fixation of a palatal miniscrew in comparison to monocortical anchorage when total anchored cortical layer thicknesses are the same. Materials and methods Six models were designed: I, monocortical, 1.1 mm palatal cortical thickness, 8.5 mm bone height; II, bicortical, 0.4 mm palatal, 0.7 mm nasal cortical thickness, 8 mm bone height; III, bicortical, 0.7 mm palatal and 0.4 mm nasal cortical thickness, 8 mm bone height; IV, monocortical, 1.1 mm palatal cortical thickness, 7 mm bone height; V, bicortical, 0.4 mm palatal, 0.7 mm nasal cortical thickness, 7 mm bone height; VI, bicortical, 0.7 mm palatal and 0.4 mm nasal cortical thickness, 8.5 mm bone height. An 8 mm miniscrew was fully engaged in the bone and was subjected to vertical pull out until displaced 0.01 mm and 0.05 mm or horizontal traction load of 2 N. Results Monocortical fixation provides higher retention in comparison to bicortical fixations with the same total cortical thicknesses in terms of vertical pull-out test. Models with bicortical fixation and thicker nasal cortex sustained lower strain energy when subjected to horizontal traction load. Conclusion Bicortical fixation of hard palate exhibit different reactions to vertical and horizontal tractions.