The reliability of frontal facial photographs to assess changes in nasolabial soft tissues

A simple, modified method to evaluate changes in the nasolabial soft tissues after orthognathic surgery is presented. Eighteen healthy volunteers were photographed in a standardized manner with a 2-month interval. Pictures were taken with the soft tissues in repose and 'maximum closed mouth smile'. Discrepancies for repose and dynamic excursions (x and y coordinates) were calculated for the landmarks alare, crista philtri and cheilion. Multiple analysis of variance revealed no significant interaction for intra-observer variance and time of recording. Coefficients of reliability (repose: 90-99%, dynamic excursion (cheilion): >95%), Spearman correlation coefficients (repose: >0.8, dynamic: >0.6) and squared correlation (repose: >75%, dynamic: >50%) showed this method to be reliable for repose and dynamic excursions. The error of measurement was less than 1.8 mm for both repose and dynamic excursions (SD(differences)=0.9 mm). This is smaller than mean differences in nasolabial soft-tissues excursions found between the pre- and post-Le Fort I osteotomy situation in a previous study using video imaging. The discrepancies found were in keeping with other earlier reports for 2D and 3D measuring methods. The method as proposed is simple, cost effective and can be used to evaluate soft-tissue changes after orthognathic surgery.