Evaluation of dental midline position

Maxillary midline position relative to the facial midline is stressed as an important diagnostic feature in orthodontic treatment planning. Depending on the patient, however, movement of the dental midline to be coincident with the facial midline may be difficult to achieve. In addition, evaluation of dental midline position may be complicated if other midline facial structures are not well aligned. The two objectives of the current study were to determine how far the maxillary dental midline could deviate from the facial midline and still be considered aesthetically acceptable, and to determine how the position of various midline facial landmarks affect overall facial aesthetics. One hundred twenty individuals, including orthodontists, general dentists, orthodontic patients, and parents of patients, evaluated digitally altered images of two patient-subjects to rate the acceptability of dental midline deviations and to prioritize the importance of location of various midline facial structures. The mean threshold for acceptable dental midline deviation was 2.2 +/- 1.5 mm. There was a significant difference in deviation thresholds between the two patient-subjects (P < .05). Orthodontists and dentists were significantly less tolerant of midline deviations than were patients (P < .001), with the tolerance of parents in between. When deviations of various midline facial structures were evaluated, photographs with maxillary midline and/or nose deviations were considered less aesthetic (P < .001). There were no apparent differences noted among orthodontists, dentists, patients, and parents in this part of the study.