The relationship of facial and dental midlines with various anatomic landmarks of face and oral cavity

The aim of the study was to find out the relative reliability of different clinical anatomical landmarks to determine the midline of face and the hierarchy of facial anatomical landmarks closest to the midline of the face. The facial anatomical landmarks such as - nasion, tip of nose, tip of philtrum, incisive papilla and dental midline were chosen as they are commonly used in clinical practice. 100 patients were randomly selected; full face digital images were made with clinical markings on selected anatomical landmarks. Esthetic frame was constructed on each image with digital lines passing through each marked point. Casts were made for maxillary arch of each subject. Two sets of readings were tested using intra class correlation coefficients (ICCs) reliability test. To determine whether the selected landmarks differed from midline of face and mouth, a series of one - sample t test were conducted with alpha value of 0.5. 5 Relative facial midline value (RFV) and 4 relative commissural midline value (RCV) values were obtained for each subject. Two hierarchal orders were obtained; one defining the relation of various landmarks to midline of face and second for midline of mouth. Observation from casts revealed that incisive papilla lined up with defined dental midline. Intercommissural midline ranked closest to facial midline followed by dental midline, tip of philtrum, nasion, and tip of nose. Landmarks closest to midline of mouth are tip of philtrum, dental midline, nasion and tip of nose. Incisive papilla lies in direct relation to dental midline. Centre of mouth is reliable midline anatomical landmark for determining midline of face. Key words: Esthetic frame, facial midline value (RFV), intra class correlation coefficients, intercommissural, philtrum, nasion, incisive papilla, maxillary arch.