Gerkowicz, Lauren2020-09-082020-09-082020-06https://hdl.handle.net/11299/216083University of Minnesota M.S. thesis.June 2020. Major: Dentistry. Advisor: Thorsten Gruenheid. 1 computer file (PDF); 46 pages.Introduction: Unilateral posterior crossbite, if left untreated, may lead to mandibular and facial asymmetry. Aim: To assess differences in mandibular ramus height in patients with unilateral posterior crossbites before and after correction with orthodontic appliances. Materials and Methods: Ramus heights were measured as the linear distance between the most anterior point of the condyle and gonion inferius on pre-treatment (T1) and post-treatment (T2) cone-beam computed tomography scans of 59 adolescent patients (mean age at T1 = 12.4, age range 8 - 16 years) who underwent rapid maxillary expansion followed by comprehensive orthodontic treatment with fixed appliances. Paired and two-sample t-tests were used to determine if the change in ramus height from T1 to T2 was associated with the crossbite side. Results: The difference between ramus heights of the crossbite and non-crossbite sides at T1 was not significant (P = 0.86). On both the crossbite and non-crossbite sides, the change in ramus height from T1 to T2 was significant (P < 0.0001). However, the difference between crossbite and non-crossbite side change from T1 to T2 was not significant (P = 0.39). There was no difference between males and females for any variable tested. Conclusions: Unilateral posterior crossbite in adolescents was not associated with shorter ramus height on the side of the crossbite. Hence, crossbite correction did not lead to more symmetrical ramus heights. Despite the lack of long-term controlled studies, early treatment of unilateral posterior crossbite may allow for more symmetrical mandibular growth.enCBCTFull-fixed appliancesRamus heightRapid maxillary expansionUnilateral posterior crossbiteThesis or Dissertation