Figure 2. Results of lip-line measurements and model cast analysis, including an illustration of the method for determining the inclination of the maxillary central incisors. (A) Measurement of left upper central's inclination in relation to the occlusal plane on the prepared dental cast. (B/C) Relationships between lip line, upper central incisors, and pressure transducers in the Class I group (B) and the Class II, Division 2 group (C). (Table) Mean values and standard deviations of the upper central inclination, the level of the lip line, the frontal overbite, and buccal occlusion in the Class I group (n = 21) and the Class II, Division 2 group (n = 21). ^*Standard deviations. op₁, occlusal plane (defined by the tip of the cuspid and the most prominent cusp of the upper first molar); op₂, model base (trimmed parallel to the occlusal plane); gs₁, gingival sulcus at the lingual side of the left upper central incisor; gs₂, gingival sulcus at the labial side of the left upper central incisor; ca, crown axis of the left upper central incisor; c_r, center of resistance of the upper central incisor; and d_c/i, distance from the cervical sensor location (d_c) and the incisal sensor location (d_i) to the center of resistance of the upper central incisor. In our experiment, the ratio of d_i/d_c was 1.6 (according to Burstone and Pryputniewicz, 1980). ll_1/2 = level of the lip line (defined as the distance between the lip line and the incisal edge) in the Class I group (ll₁) and the Class II, Division 2 group (ll₂).