Does Cranial Base Angle Make a Difference in the Effectiveness of Functional Orthopedic Treatment? A Retrospective Cohort Study

<b>Background/Objectives:</b> The literature suggests that the cranial base angle is considered one of the contributing factors to sagittal jaw malpositions when its relationship with the viscerocranium is examined. Our study aims to compare and evaluate the outcomes of fixed functional orthopedic treatment in patients with mandibular retrognathia across different cranial base groups. <b>Methods:</b> Participants were treated at Erciyes University with fixed functional appliances and categorized by CBA into low (<130°), medium (130°-134°), and high (>134°) groups. A total of 39 patients were included: 13 in the low CBA group (7 males, 6 females; mean age 14.62 ± 1.12 years), 13 in the medium CBA group (3 males, 9 females; mean age 14.38 ± 0.96 years), and 13 in the high CBA group (4 males, 9 females; mean age 14.08 ± 1.04 years). <b>Results:</b> In the low CBA group, Ar-Go-N (<i>p</i> = 0.005) and SNA (<i>p</i> = 0.023) angles significantly decreased, while the ANB angle and Wits appraisal significantly decreased across all groups (<i>p</i> < 0.05). The high CBA group showed increases in ANS-Me, N-Me, N-ANS, and N-Gn lengths (<i>p</i> < 0.05). The medium and high CBA groups had significant increases in S-Go and ANS-Gn lengths, while Co-Gn length increased significantly in the low and high CBA groups (<i>p</i> < 0.05). Incisor measurements (IMPA, L1-APog, L1/NB, L1-NB) increased in all groups, with overjet and overbite reduced (<i>p</i> < 0.05). U1/PP (<i>p</i> = 0.039), U1/SN (<i>p</i> = 0.043), U1-NA (<i>p</i> = 0.030), and U1/NA (<i>p</i> = 0.025) parameters increased in the low CBA group, with the Upper Lip-E distance decreasing significantly in the low and high CBA groups (<i>p</i> < 0.05). A comparison between groups showed significant differences in U1/PP, U1-NA, and U1/NA parameters, which increased in the low and medium CBA groups but decreased in the high CBA group. <b>Conclusions:</b> CBA influences treatment outcomes. The low CBA group experienced decreases in Ar-Go-N and SNA angles, while the high CBA group showed increases in certain vertical facial dimensions. Incisor parameters rose in the low and medium CBA groups but decreased in the high CBA group, suggesting limited CBA effects on treatment results.