Changes in respiratory and cardiac functions of patients with mandibular deficiency after treatment with a removable functional appliance

Background and aim: there is no study on respiratory or cardiac function of patients with mandibular deficiency before or after treatment. this preliminary trial was conducted for the first time to assess respiratory/cardiac parameters of such patients before and after treatment (compared to healthy controls) with a removable functional appliance. methods: this before-after clinical trial was performed on 20 patients with class ii division 1 malocclusion (mandibular deficiency with normal maxilla) and 20 matched control subjects at the peak of the mandibular growth spurt. bionator removable functional appliance was used for 9 months to treat class ii cases. capnography and pulse oximetry were used to record respiratory parameters [end-tidal carbon dioxide pressure (petco2), respiration rate (rr), oxygen saturation (spo2), and pulse rate (pr)]. groups were compared using paired and unpaired t-tests (α = 0.05). results: carbon dioxide (co2) and oxygen (o2) did not change significantly after treatment (p > 0.50, paired t-test). however, rr and pr reduced significantly after the treatment (p < 0.001, paired t-test). co2 in healthy subjects was not different from pre-treatment or post-treatment values in class ii patients (p = 0.100). o2 in healthy subjects was not different from pre-treatment or post-treatment values in class ii patients (p = 0.200, independent samples t-test). the rr in healthy controls differed from pre-treatment (p < 0.001) but not post-treatment values in class ii patients (p = 0.541). the pr in the healthy controls differed marginally significantly from pre-treatment (p = 0.067) but not post-treatment values (p = 0.752). conclusion: in patients with mandibular deficiency, treatment with a bionator functional appliance improves rr and pr back to normal levels. o2 and co2 levels were not affected in class ii patients.