A novel system for classification for midpalatal suture ossification based on pseudocolored and multilayer reconstructed coronal slices: Indication for selection of maxillary expansion methods.

Introduction: A novel method was established for the staging of midpalatal suture (MPS) ossification based on a pseudocoloring stack of anterior and posterior MPS coronal slices obtained by cone-beam computed tomography (CBCT).

Methods: CBCT scans of 240 subjects aged 5-35 years were pseudocolor processed. The slice thickness of stacked anterior and posterior coronal observation planes was set at 5.0 mm. The ossification status of both anterior or posterior MPS was classified as the tunnel, partially ossified, or ossified type. MPSs were classified into 5 stages: stage I, anterior and posterior MPSs are the tunnel type; stage II, anterior and posterior MPSs are the tunnel and partially ossified type, respectively; stage III, anterior and posterior MPSs are the partially ossified type; stage IV, anterior and posterior MPSs are the tunnel or partially ossified type and ossified type, respectively; and stage V, anterior and posterior MPSs are the ossified type. The weighted κ value was used to assess the intraexaminer and interexaminer agreement of the MPS classifications.

Results: Intraexaminer and interexaminer reliability of the proposed staging method was substantial. The largest proportions of patients aged 5-15 years and 16-35 years were classified as stages I and III, respectively. Among adults, 31.0% of males and 7.1% of females were classified as stage I or II.

Conclusions: The pseudocolor imaging technique and the stack of CBCT slices provide relatively intuitive and comprehensive information on MPS ossification. The novel classification of MPS ossification is expected to serve as an indication of the necessity of surgical intervention for maxillary expansion treatment.