Perception of the maxillary incisor position with respect to the protrusion of nose and chin.

OBJECTIVES: The aim of this work was to evaluate whether the protrusion of nose and chin influence the perception of the ideal tooth anterior limit line. The orthodontic, or combined orthodontic-surgical diagnosis, and the following treatment plan are in close correlation with a patient's requirements for aesthetic facial balance. This requires consideration of the position of the maxillary incisors which is often modified by treatment; it is obvious how important it is to clarify which are the facial features which determine the aesthetically ideal anteroposterior position of the incisors.

MATERIALS AND METHODS: Photographs of a female and a male patients' smiling profiles, carried out in natural head position (NHP), were modified progressively with respect to the protrusion of nose and chin. The altered images (17 images for each subject) were viewed and analysed by a panel made up of 19 resident orthodontists and 12 orthodontists who had more than 10 years experience.

RESULTS AND CONCLUSIONS: The hypothesis that the perception of the tooth anterior limit line is not influenced by the protrusion of nose and chin was statistically confirmed. The judgement of the tooth anterior limit line was independent of the protrusion of the nose and chin. We were not able to pinpoint a correlation between the entity of the protrusion or retraction of nose and chin and the changes of the ideal position of the maxillary incisor.