Background & Objectives: The midline is the fundamental reference for all esthetic deviations. Therefore, knowledge of the midline will invariably result in a better understanding of facial and dental esthetics. However, the literature is not clear regarding verifiable guidelines for the determination of midlines of the face or mouth. The aim of this study was to determine the hierarchy of facial anatomic landmarks closest to the midline of the face as well as midline of the mouth.

Objectives:  The objectives of the study were to define:

(1) The hierarchy of facial anatomic landmarks closest to the midline of the face;

(2) The hierarchy of facial anatomic landmarks closest to the midline of the oral commissures (mouth); and

(3) The relationship between the midline of the oral commissures and the midline of the face.

Material and methods:  

·                     This study was conducted among subjects of Dakshin Kannada population.

·                     Frontal full–face digital photographs of the subjects (in smile) were made under standardized conditions using a digital camera and

·                     A tripod stand was used to place and orient the camera in the standardized position (camera was positioned 5 feet away from the patient; and the lens of the camera was adjusted at the patients’ eye level).

·                     Imaging software (Adobe Photoshop CS5; Adobe Systems, Inc, San Jose, Calif.) was used to mark the anatomic landmarks and to digitally analyze the photographs.

Deviations from the midlines of the face and mouth were measured for the 3 clinical landmarks; the existing dental midline was considered as the fourth landmark. The entire process of midline analysis was done by a single observer.

Results:

The results indicated that each of the 4 landmarks deviated uniquely and significantly (P<.001) from the midlines of the face as well as the mouth.

Conclusion:

Within the limitations of the study, the hierarchy of anatomic landmarks closest to the midline of the face in smile were as follows: The midline of the oral commissures, dental midline, tip of philtrum, nasion and tip of the nose. The hierarchy of anatomic landmarks closest to the midline of the oral commissures was: tip of philtrum, dental midline, nasion and tip of the nose. These relationships were the same for both age groups studied.