This retrospective investigation sought to propose a new linear indicator, Lower Incisor—Pg, and to examine how this measurement behaves across various vertical and sagittal skeletal configurations. A dataset of 1256 lateral cephalometric radiographs was retrospectively analyzed. Subjects were categorized according to SN^Go-Gn, ANPg^, and IMPA parameters. Differences in Lower Incisor—Pg among groups were tested through ANOVA and post hoc comparisons, while Pearson correlation was used to explore inter-variable associations. The mesofacial pattern appeared most frequently (61.0%), followed by dolichofacial (30.0%) and brachyfacial (8.6%) morphologies. For the sagittal relationships, Class I predominated (70.9%) compared with Class II (19.3%) and Class III (9.8%). The average Lower Incisor—Pg value was 3.2 ± 4.0 mm. Regression analysis yielded β coefficients of 0.45 for ANPg^ and 0.36 for SNGoGn^. The Lower Incisor—Pg can serve as a direct cephalometric index for assessing the anteroposterior position of the lower incisor. Each 1° increment in ANPg^ and SNGoGn^ corresponded to 0.45 mm and 0.36 mm increases, respectively, in Lower Incisor—Pg.
