ABSTRACT
OBJECTIVE: To describe the frequency of hypodontia and left-right symmetry of hypodontia in the permanent dentition of children with Pierre Robin sequence (PRS). PATIENTS AND METHOD: The sample consisted of 78 children born with PRS between 1980 and 2006 and referred to the Oslo Cleft Lip and Palate Team (OCLPT). Data were collected retrospectively from the archives of the OCLPT. Panoramic radiographs were evaluated to document hypodontia; third molars were excluded. RESULTS: Of the 78 children with PRS, hypodontia was found in 33 (42%). Of the 33 children with hypodontia, 27 (82%) showed hypodontia in the micrognathic lower arch, 24 (73%) were missing two or more permanent teeth, and 2 (6%) had oligodontia. The teeth most often missing were the mandibular second premolar (72%), followed by the maxillar second premolar (29%). Most cases of hypodontia 21 (64%) occurred bilaterally. Bilateral hypodontia of the mandibular second premolar occurred in 27 (73%) of the patients. CONCLUSION: Hypodontia was found in 33 (42%) of the children with PRS, which is seven times higher than the prevalence among children without PRS (6%). Unlike in the general population, bilateral hypodontia was more common than unilateral hypodontia in the micrognathic mandible of children with PRS.