[Assessment of dentofacial growth changes using quadrilateral analysis].

This study was investigated to demonstrate the normal standards of the quadrilateral analysis and thereafter to clarify the mode of growth change by assessment of skeletal, dental and soft tissue proportion by the means of quadrilateral analysis. The materials used in this study consisted of cephalograms of 30 girls with normal occlusion. Cephalograms were taken longitudinally from first year grade of elementary school to third year grade of middle high school. For the group of each year grade, mean facial diagram, mean values of conventional cephalometric analysis and those of quadrilateral analysis were made, and compared and discussed for each other. The results were as follows: 1) The mandible grows forward with the decrease of gonial angle and forward rotation of mandibular plane. 2) In quadrilateral analysis, both jaws grow proportionally to the 6 year grade of elementary school, and after then mandible grows more forward than maxilla. 3) Though occlusal plane tended to rotate counterclockwisely to the palatal plane, it fell at right angle with A'B'. 4) Upper centrals tended to incline labially to the cranial base from first year grade to 6 year grade of elementary school and after that stage it remained stable. Lower centrals varied to third year grade of elementary school, but after that stage it remained stable. 5) Distances of upper and lower incisors to A'B' showed comparatively constant increase after the full eruption of permanent incisors. 6) Distance of nose tip to A'B' increased the most in the soft tissue landmarks. Subnasale soft pogonion line was considered to be effective base line of soft tissue profile because the angle with A'B' was stable along the growth and the distances of that to upper and lower lips were stable.