Evidence on Mandibular Asymmetry in Patients with Unilateral Posterior Crossbite: A Systematic Review

Background Unilateral posterior crossbite (UPC) is a common malocclusion in pre-adolescents and adolescents and is often associated with transverse discrepancies and potential skeletal asymmetries. Mandibular asymmetry, particularly involving the condyle and ramus, may either contribute to or result from such malocclusions, thereby impacting diagnosis and treatment planning.Aim To systematically evaluate the association between mandibular asymmetry and unilateral posterior crossbite (UPC) in pre-adolescent and adolescent populations.Types of Studies Reviewed A comprehensive literature search was conducted across databases including, PubMed (MEDLINE), Scopus, Google Scholar, supplemented by manual and gray literature searches upto September 2024. All study types, except case reports and review articles, were included. The protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO CRD42025641032). Studies assessing condylar and ramal asymmetry in individuals with UPC compared to those with normal occlusion were included. Risk of bias was assessed using the ROBINS-I tool for non-randomized comparative studies.Result Fourteen studies met the inclusion criteria, predominantly comprising cross-sectional study designs. The majority of studies reported increased condylar and/or ramal asymmetry in patients with UPC, although not all differences reached statistical significance. Variations in measurement methods and outcomes precluded meta-analysis. These findings were supported by GRADE-based evidence assessments and descriptive synthesis.Practical Implication/ Conclusion These findings underscore the potential impact of UPC on mandibular development and reinforce the importance of early diagnosis and intervention. Future well-designed, longitudinal studies employing standardized imaging protocols and outcome measures are needed to confirm these associations and guide clinical decision-making.