Finite element analysis of bone stress after SARPE.

PURPOSE: This study investigated stress distribution in maxillas that underwent surgically assisted palatal expansion (SARPE).

MATERIALS AND METHODS: Five maxillary models were built: no osteotomy (M1), Le Fort I osteotomy with a step in the zygomaticomaxillary buttress (M2), Le Fort I osteotomy with a step in the zygomaticomaxillary buttress and the pterygomaxillary disjunction (M3), Le Fort I osteotomy without a step (M4), and Le Fort I osteotomy with pterygomaxillary disjunction and no step (M5). Displacement coherence and maximum stress (MS) analyses were used for all models.

RESULTS: Areas of tension spread to the maxilla and the region between the alveolar ridge and the palate and a critical point in the median suture for M2, M3, M4, and M5. In M2 and M4, MS spread farther toward and over the pterygoid process, contrary to what was found in M3 and M5. M3 had a better performance than the other models, and the tensile stress was interrupted by the posterior osteotomy, thus avoiding possible damage to the sphenoid bone or difficulties in expanding the posterior region of the maxilla.

CONCLUSIONS: The steps in the zygomaticomaxillary buttress and the pterygomaxillary disjunction seem to be important to decrease the harmful dissipation of tensions during SARPE.