Prevalence of Ectopic Maxillary Third Molars Inferior to Second Molars in Patients with Cleft Lip and Palate: Retrospective Study.

ObjectiveTo determine the prevalence of maxillary third molars developing inferior to the second molars in patients with cleft lip and palate (CLP) and to describe associated clinical and radiographic characteristics.DesignThis retrospective chart review assessed maxillary third molar position using cone-beam computed tomography (CBCT).SettingTertiary cleft and craniofacial center within an academic institution.Patients/ParticipantsPatients aged ≥7 years with CLP who underwent CBCT imaging between 2019 and 2025. A total of 104 patients met inclusion criteria (79 unilateral cleft lip and palate (UCLP), 25 bilateral cleft lip and palate (BCLP)).InterventionsNo experimental interventions were performed.Main Outcome Measure(s)Prevalence of maxillary third molars positioned inferior to the second molars, defined radiographically by crown position relative to the adjacent second molar. Secondary measures included developmental stage, visibility on 2-dimensional (2D) versus 3-dimensional (3D) imaging, and associated second molar eruption disturbances.ResultsEctopic third molars were identified in 4 of 104 patients (3.8%), occurring in 3 UCLP and 1 BCLP patient. All ectopic teeth were in early developmental stages (Demirjian A-C), were poorly visible on 2D panoramic reconstructions, and were associated with delayed or failed eruption of the second molar.ConclusionsInferior positioning of maxillary third molars is an uncommon but clinically significant eruption disturbance in CLP. When CBCT imaging is obtained for clinical indications in patients with CLP, careful 3D assessment of third molar position may facilitate early identification of ectopic development and help prevent second molar impaction. Further study is needed to optimize timing and indications for early surgical removal.