To investigate the associations between sella turcica bridging (STB) and skeletal malocclusion patterns in orthodontic patients with third molar agenesis (TMA).

Panoramic radiographs were taken from patients aged 8–18 years to identify TMA. All the patients were included between March 2023 and June 2023. Lateral cephalometric radiographs were obtained from both patients with TMA (agenesis group, AG) and those without TMA (control group, CG). Cephalometric measurements between the two groups were compared using the Mann-Whitney U test. The analysis of the sella turcica was carried out on lateral cephalometric radiographs based on Leonardi's classification. Linear regressions were performed between bridging, agenesis, cephalometric measurements, sex and age. Significance was set at P<0.05.

Four hundred patients were included in the study, 200 for the AG group and 200 for the CG. A statistically significant influence of agenesis on the sella depth measurement, which was on average higher in the AG compared to the CG, was found, particularly in cases of mandibular agenesis. Both ANB and A0B0 were significantly lower in the AG compared to the CG (P<0.05), especially in the mandibular agenesis subgroup. Although the results are statistically significant for the A0B0 and SNB values, they were not clinically relevant. The intermaxillary angle is generally reduced in AG, indicating a greater tendency towards a hypodivergent skeletal pattern. The values of the joint angles, the total gonial angle, and the upper and lower gonial angles are slightly increased on average in AG compared to CG. The percentage ratio between posterior and anterior facial height is higher in AG compared to CG. The most important finding is that the mandibular body length is significantly shorter in AG.

No significant association was found between TMA and the skeletal parameters of the sella turcica. A possible association was found between TMA and skeletal malocclusions, particularly Class III malocclusions.