To Örebro University

Objectives: To evaluate and compare the effects of tooth-borne (TB) and tooth-bone-borne (TBB) rapid maxillary expansion (RME) on nasal airflow and resistance. Material and methods: Fifty-four consecutive patients who met the eligibility criteria were recruited from September 2010 to December 2015. Of these 54 subjects, 40 agreed to participate in the part of the study involving evaluation of nasal flow and resistance. The 40 subjects were allocated to either the TB group, mean age 9.7 years (SD 1.5), or the TBB group, mean age 10.2 years (SD 1.4). All subjects performed rhinomanometric registration at baseline (T-0), but only 30 attended the post-expansion registration (T-1), of whom 16 had been randomized to the TB group and 14 to the TBB group. The study outcomes, nasal airflow and nasal airway resistance, were evaluated with linear regression adjusted for baseline variable of the outcome to compare the study groups with complete cases strategy as well as after multiple imputation (MI). Randomization: Participants were randomly allocated in blocks of different sizes, using the concealed allocation principle in a 1:1 ratio. The randomization list was computer generated to ensure homogeneity between groups. Blinding: Blinding was done only for outcome assessor due to clinical limitations. The care providers at the ENT unit who conducted all the rhinomanometry examinations were blinded to which group the patients were allocated to. Results: Complete case analysis showed significantly higher post-expansion nasal airflow values for the TBB group compared with the TB group, mean difference 51.0 cm(3)/s (P = 0.018). The evaluation after MI showed a similar significant mean difference, 52.7 cm(3)/s (P = 0.020) in favour of the TBB group when taking into account the missing values from the T-1 examination. Even reduction in nasal airway resistance showed similar pattern in favour of the TBB group. Limitations: Our results represent the short-term effects. A longer follow-up period would have been preferable. Conclusions: The TBB RME induced significantly higher nasal airway flow and lower nasal resistance values than TB RME. It might be wiser to use TBB RME in cases with constricted maxilla and upper airway obstruction.