Three-Month Radiographic Change in Premolar Cusp-Tip-to-Occlusal-Plane Distance Among Patients Who Underwent Extraction of Infraoccluded Primary Molars: A Retrospective Uncontrolled Case Series

Background: Infraocclusion of primary molars, frequently associated with ankylosis, may disrupt normal occlusal development and affect the permanent successor. Aim: To describe the short-term change in the two-dimensional radiographic distance between the permanent premolar cusp tip and the occlusal plane between a pre-extraction baseline (T0) and an approximately three-month follow-up (T1) in patients who underwent extraction of infraoccluded primary molars. Design: This small, retrospective, uncontrolled case series included 19 infraoccluded primary molars in 13 patients aged 9–14 years. Pre-extraction and approximately three-month follow-up panoramic radiographs were analyzed. The primary outcome was the change in premolar–occlusal plane distance between T0 and T1. Results: The mean distance was 11.43 ± 2.31 mm at T0 and 7.49 ± 1.84 mm at T1, with a mean paired reduction of 3.93 ± 1.74 mm (tooth-level sensitivity analysis, paired t-test, p < 0.001). At the patient level, all 13 patients showed a reduction in their mean tooth-level distance (exact two-sided sign test, p = 0.00024; exact 95% CI for the proportion, 75.3–100%). Conclusions: This exploratory case series documents a short-term temporal reduction in the measured two-dimensional distance in a cohort of patients who underwent extraction. Because of the uncontrolled design, small clustered sample, short follow-up, and potential measurement-related sources of error, the finding does not establish that extraction caused the change or predict complete premolar eruption.