Evaluation of condylar morphology following orthognathic surgery on digital panoramic radiographs. Could methodology influence the range of "normality" in condylar changes?

ABSTRACT

OBJECTIVES: To evaluate the morphological condylar changes following orthognathic surgery by using a rapid and reliable computational method on panoramic radiographs. METHODS: Digital panoramic radiographs of 45 patients who underwent bilateral sagittal split osteotomy (alone or associated with a Le Fort I osteotomy) between 2007 and 2010 were analysed. Calculation of the area, perimeter and height of 90 condyles was performed by using a specific computational method. Measurements were taken before surgery (m1), 1 day after surgery (m2) and 1 year after surgery (m3). The evolution of each index was analysed using paired t-tests between measures before and 1 day after surgery (m1 - m2) and measures before and 1 year after surgery (m1 - m3). The changes in the condylar area, perimeter and height were examined using the Bland and Altman plotting method. RESULTS: There were no statistically significant changes in the mean condylar area, perimeter or height between m1 and m2 or between m1 and m3. The Bland and Altman plots for each index showed that a very limited number of condyles increased or decreased in area, perimeter and/or height outside the boundaries of the measurement error. Given the impossibility for a condyle to increase in size, these results are considered to represent the limits of the computational method used. CONCLUSIONS: This study demonstrated that there were no significant morphological condylar changes at the 1-year follow-up following surgery and that the range of normality in condylar changes could be influenced by the methodology used.