Objective. Determine the parameter deviation of the upper dental midline is considered aesthetically acceptable by patients, and that these values are considered by orthodontists as a guide for the completion of their clinical cases. Material and methods. This descriptive study, prospective, cross-sectional and observational, and whose design is descriptive and transversal. Surveys were administered to patients attending the School of Dentistry at the University of San Martin de Porres between October 3 and November 14, 2011. photo of a woman and a man were recorded, both 26 years presented the LMDS centered with the facial midline, with a Sony Cybershot 8.1 megapixel and 10x optical zoom, both photos were taken in the area of Orthodontics USMP and modified in a hp centrino intel computer using the Microsoft program office picture manager to give an LMDS deviation of 1, 2.3 and 4 mm, obt...