Open bite malocclusion and orofacial dysfunction in patients with rare diseases

Aim To compare orofacial dysfunctions (OFD) in individuals with rare diseases, with and without open bite (OB) malocclusion, and to explore the associated symptoms. Patients and Methods In total, data for 788 individuals representing 164 different rare diseases, were collected from the MHC database for the period of 2013–2019. The inclusion criteria were having a rare disease and having completed the Nordic Orofacial Test—Screening (NOT-S). OB was categorized as anterior OB (AOB), lateral OB (LOB), and severe anterior OB (AOBS). The sample was divided into two groups: 142 with OB (mean age, 14.2 ± 13.0 years; 81 males, 61 females); and 557 with normal vertical relation (NVR) (mean age, 15.1 ± 12.9 years; 292 males, 265 females). OFD was compared between the groups. Items from the NOT-S test were analysed, and the Odds Ratio (OR) for OB was calculated. Results The OB prevalence was 18%, with AOB being the most-common sub-type (58%), followed by AOBS (15%) and LOB (13%). Nemaline myopathy was the disease with the highest prevalence rates for OB and AOBS. The OB group had a larger proportion of OFD than the NVR group in 6/12 domains of the NOT-S. Deviant tongue posture was most strongly associated with OB (OR 6.062). Conclusion Two-thirds of the individuals had OFD, and OB was a common finding (18%). Rare diseases with symptoms of orofacial hypotonia, craniofacial abnormalities and macroglossia show a higher prevalence of OB. A deviant tongue posture showed the highest odds for OB in this group of rare diseases.