Korean J Orthod.  2019 Nov;49(6):360-371. 10.4041/kjod.2019.49.6.360.

Predictors of midpalatal suture expansion by miniscrew-assisted rapid palatal expansion in young adults: A preliminary study

  • 1Department of Orthodontics, College of Dentistry, Yonsei University, Seoul, Korea. yumichael@yuhs.ac
  • 2Institute of Craniofacial Deformity, College of Dentistry, Yonsei University, Seoul, Korea.
  • 3Department of Oral and Maxillofacial Radiology, College of Dentistry, Yonsei University, Seoul, Korea.


We sought to determine the predictors of midpalatal suture expansion by miniscrew-assisted rapid palatal expansion (MARPE) in young adults.
The following variables were selected as possible predictors: chronological age, palate length and depth, midpalatal suture maturation (MPSM) stage, midpalatal suture density (MPSD) ratio, the sella-nasion (SN)-mandibular plane (MP) angle as an indicator of the vertical skeletal pattern, and the point A-nasion-point B (ANB) angle for anteroposterior skeletal classification. For 31 patients (mean age, 22.52 years) who underwent MARPE treatment, palate length and depth, MPSM stage and MPSD ratio from the initial cone-beam computed tomography images, and the SN-MP angle and ANB angle from lateral cephalograms were assessed. The midpalatal suture opening ratio was calculated from the midpalatal suture opening width measured in periapical radiographs and the MARPE screw expansion. Statistical analyses of correlations were performed for the entire patient group of 31 subjects and subgroups categorized by sex, vertical skeletal pattern, and anteroposterior skeletal classification.
In the entire patient group, the midpalatal suture opening ratio showed statistically significant negative correlations with age, palate length, and MPSM stage (r = −0.506, −0.494, and −0.746, respectively, all p < 0.01). In subgroup analyses, a strong negative correlation was observed with the palate depth in the skeletal Class II subgroup (r = −0.900, p < 0.05).
The findings of this study indicated that age, palate length, and MPSM stage can be predictors of midpalatal suture expansion by MARPE in young adults.


Adult treatment; Expansion; Miniscrew-assisted rapid palatal expansion; Predictors

MeSH Terms

Cone-Beam Computed Tomography
Young Adult*


  • Figure 1 Miniscrew-assisted rapid palatal expansion appliance. A, Before expansion. B, After expansion.

  • Figure 2 Midpalatal suture opening width in periapical radiographic images (A) at T0 and (B) at T1 in separation and at T2 in non-separation cases. The midpalatal suture opening width was defined as the difference in distance (a′–a) between the mesial cementoenamel junctions of both upper central incisors. T0, Initial; T1, when the midpalatal suture opening was confirmed in a periapical radiograph; T2, immediately after miniscrew-assisted rapid palatal expansion stopped.

  • Figure 3 Re-orientation in InVivo5® software. A, In the coronal view, the horizontal line connected with both infraorbital lower borders. B, In the sagittal view, the Frankfort horizontal plane was used.

  • Figure 4 Measurements of palate length and the maxillary first premolar (U4) palate depth. A, Baselines for palate length in a sagittal view: the horizontal line passing through incisive foramen and the vertical line passing through posterior nasal spine (PNS). B, The solid arrow indicates palate length, defined as a perpendicular length from the posterior border of incisive foramen to the horizontal line made by coronal plane through the PNS sagittally. C, In an axial view, the horizontal line passing through both U4 buccal tips. D, In a coronal slice including the horizontal line in C, a solid arrow indicates U4 palate depth, defined as the perpendicular length from the deepest point on the palate to the horizontal line connecting both palatal cementoenamel junction points of U4.

  • Figure 5 Schematic images of midpalatal suture maturation stages by midpalatal suture morphology, in accordance with the results reported by Angelieri et al.20 Stage A shows a straight high-density line of a midpalatal suture with little interdigitation; stage B shows a scalloped high-density line of a suture; stage C shows two parallel, scalloped, high-density lines both in the maxillary and palatine bones; stage D is characterized by the fusion of the midpalatal suture in the palatine bone; and in stage E, the midpalatal suture is not seen even in the maxillary portion.

  • Figure 6 Evaluations of grey scales for midpalatal suture density ratio. A, In the midpalatal suture. B, In the palatine process of the maxilla and soft palate, in accordance with the results reported by Grünheid et al.21

  • Figure 7 Correlations between midpalatal suture opening ratio and age (A), palate length (B), MPSM stage (C), MPSD ratio (D), SN-MP angle (E), and ANB angle (F). Best-fit lines with correlation coefficients, r by Pearson correlation analysis and rs by Spearman correlation analysis (A–C, p < 0.01; D–F, p > 0.05). MPSM, Midpalatal suture maturation; MPSD, midpalatal suture density; SN-MP, sella-nasion-mandibular plane; ANB, point A-nasion-point B.

Cited by  2 articles

Stability of bimaxillary surgery involving intraoral vertical ramus osteotomy with or without presurgical miniscrew-assisted rapid palatal expansion in adult patients with skeletal Class III malocclusion
Yoon-Soo Ahn, Sung-Hwan Choi, Kee-Joon Lee, Young-Soo Jung, Hyoung-Seon Baik, Hyung-Seog Yu
Korean J Orthod. 2020;50(5):304-313.    doi: 10.4041/kjod.2020.50.5.304.

Effectiveness of miniscrew assisted rapid palatal expansion using cone beam computed tomography: A systematic review and meta-analysis
Patchaya Siddhisaributr, Kornkanok Khlongwanitchakul, Niwat Anuwongnukroh, Somchai Manopatanakul, Nita Viwattanatipa
Korean J Orthod. 2022;52(3):182-200.    doi: 10.4041/kjod21.256.


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