Fig. 2. Front teeth–to–carina distance (FT-C)  versus height (  A ), weight (  B ), and age (  C ) in children aged 0–19 yr.  Filled circles = girls;  filled triangles = boys.  Unfilled symbols represent children with syndromes that could affect airway growth (see Results section, third paragraph). Linear regression lines, their equations, and 95% prediction interval bands are shown. Note that the FT-C–  versus –weight relation was best described by a power equation (Results, fourth paragraph). The  dashed line in  A represents intubation depth calculated from the Morgan formula.  2 For practical reasons, one patient (age, 18 yr; weight, 180 kg; height, 185 cm) is not shown in the FT-C–  versus –weight graph, but the data are included in the regression equation.