Lower Incisor—Pg: A New Cephalometric Parameter to Evaluate the Anterior Limit of Dentition

Background: This present retrospective study aimed to introduce Lower Incisor—Pg and to assess how this new parameter varies with the skeletal sagittal and vertical relationships. Methods: A total of 1256 cephalometric analyses were performed using lateral cephalometric radiographs of a sample of subjects divided according to SN^Go-Gn, ANPg^, and IMPA measurements. The differences in Lower Incisor—Pg between the groups were assessed through ANOVA tests and posthoc analyses, while Pearson’s correlation analysis was used to assess the correlations between the measurements. Results: The mesofacial growth pattern (61.0%) was more common than dolichofacial (30.0%) and brachyfacial (8.6%) ones in the sampled population. Regarding skeletal sagittal relationships, Class I was more frequent (70.9%) than Class II (19.3%) and Class III (9.8%). The mean value of the Lower Incisor—Pg was 3.2 ± 4.0 mm. Linear regression showed that the β coefficient was 0.45 and 0.36 for ANPg^ and SnGoGn^, respectively. Conclusions: Lower Incisor—Pg is a linear cephalometric measurement to evaluate the lower incisor sagittal position. For each degree of increase in ANPg^ and SNGoGn^, the Lower Incisor—Pg increased 0.45 mm and 0.36 mm, respectively.