Nasal bone modification compared to normal growth after rapid maxillary expansion anchored onto deciduous teeth: a CBCT retrospective study.

Background: The present study was designed to evaluate the enlargement of the nasal bone as side effect when a treatment with a Haas rapid maxillary expander is performed in early mixed dentition.

Methods: The CBCT imaging of 36 children (mean age 8,4; SD,1,5) were retrospectively selected and then traced in order to evaluate the change in the nasal bone (primary outcome) and in the maxilla (secondary outcome). Five distances and one angle were measured: upper and lower nasal bone width (UNBw and LNBw) as well as its inclination (NBi), and the maxillary bone at the level of infraorbital foramen (IOFw), the nasolacrimal duct (NLDd), and greater palatine foramina (PFd). The sample was divided in a treatment group (26 subjects; 14 males; 12 females; mean age 8,0; SD 0,9), comprising children who underwent to a rapid maxillary expansion, and a control group (10 subjects; 7 males; 3 females; mean age 9,3; SD 2,3) including untreated children homogeneous for dental age to the treated subjects. Measurements were performed at baseline or before the treatment (T0), and after 2 years (T1).

Conclusion: The transversal modification induced with a rapid maxillary expansion was limited to the maxilla without involving the nasal bones when the treatment was performed in early mixed dentition. The changes recorded in the nasal bones seem to be the same of what happens during normal growth.