Stress estimation by serum cortisol release during rapid maxillary expansion in mice: validation of an experimental model.

INTRODUCTION: Rapid maxillary expansion (RME) is an orthopedic procedure used to correct maxillary transverse deficiencies by applying forces through specialized appliances. This intervention induces both dental and skeletal changes, which may potentially elicit physiological stress responses. OBJECTIVE: To validate a model for estimating stress by measuring plasma cortisol levels in mice subjected to rapid RME. METHODS: 5-6-week-old male mice (C57BL6/J) were submitted to RME performed by an opening loop distractor at the mid palatal suture calibrated as follows (n = 5 per group): no force (control); 0.28 Newtons (N), 0.42N and 0.56N for periods of 7 and 14 days. Histomorphometry analyses were performed to analyze RME effect and serum samples were collected to measure cortisol by enzyme-linked immunosorbent assay (ELISA). RESULTS: The forces applied at two different time points resulted in a successful RME pattern with the opening of the mid-palatal suture compared to the control group (P