Changes in the Pterygopalatine and Midpalatal Sutures After Rapid Palatal Expansion With Tooth‐Bone‐Borne ( MARPE ) and Tooth‐Borne (Hyrax) Appliances

OBJECTIVE: This retrospective cohort study aimed to compare the effects of tooth-bone-borne mini-implant-assisted rapid palatal expansion (MARPE) and tooth-borne (Hyrax) rapid palatal expansion (RPE) techniques on the pterygopalatine suture (PPS) and the opening pattern of the midpalatal suture (MPS). MATERIALS AND METHODS: A total of 31 patients requiring RPE were included and categorised into two groups: MARPE (n = 14; mean age, 16.2 ± 2.0 year) and Hyrax (n = 17; mean age, 14.7 ± 0.8 year). Cone-beam computed tomography scans were obtained before (T1) and after (T2) expansion. All images were standardised using the skull base as a reference in the Dolphin Imaging software. PPS disarticulation and MPS opening patterns were evaluated based on the displacement between the anterior nasal spine (ANS) and the posterior nasal spine (PNS). All measurements were conducted by a single calibrated examiner. RESULTS: Pterygopalatine suture disarticulation was observed in 58% of patients in the MARPE group and 35% of those in the Hyrax group; however, the difference was not statistically significant (p = 0.224). The mean PNS-to-ANS expansion ratio was 0.82 in the MARPE group and 0.77 in the Hyrax group, indicating a tendency of a more parallel suture-opening pattern in the first one, although this difference was not statistically significant. CONCLUSION: While both techniques demonstrated the ability to disarticulate the PPS, MARPE exhibited a greater tendency for parallel MPS opening. The presence of PPS rupture may facilitate a more parallel expansion pattern, suggesting that PPS resistance could be a limiting factor in achieving symmetrical MPS separation.