Skeletal and alveolar changes in conventional rapid palatal expansion (RPE) and miniscrew-assisted RPE (MARPE): a prospective randomized clinical trial using low-dose CBCT

Abstract

Background: This prospective randomized clinical trial aimed to evaluate the immediate and short-term skeletal, dentoalveolar, and periodontal effects of rapid palatal expansion (RPE) and miniscrew-assisted RPE (MARPE) in adolescent and young adult patients.

Methods: This study followed a two-arm, parallel, randomized clinical trial design that recruited patients with transverse maxillary deficiency in a 1:1 allocation ratio. Forty patients (14 men and 26 women) requiring maxillary expansion were randomly allocated to the RPE (n = 20, age = 14.0 ± 4.5) or MARPE (n = 20, age = 14.1 ± 4.2) groups. The assignment was performed via computer-generated block randomization, with a block size of four. Upon identical (35 turns) amount of expansion, low-dose cone-beam computed tomography images were taken before treatment (T0), immediately after expansion (T1), and after a 3-month consolidation period (T2). The primary outcome of this study comprised the assessment of midpalatal suture separation. Secondary outcomes included, skeletal, dentoalveolar, and periodontal measurements, which were performed at each time point.

Results: The frequency of midpalatal suture separation was 90% (18/20) and 95% (19/20) for the RPE and MARPE groups, respectively. A greater increase in nasal width in the molar region (M-NW) and greater palatine foramen (GPF) was observed immediately after the expansion (T1-T0) and consolidation periods (T2-T0) in the MARPE group compared to the RPE group (P < 0.05). The MARPE and RPE groups showed similar dentoalveolar changes except for the maxillary width (PM-MW, M-MW). The MARPE group presented greater bilateral first premolar (PM-MW) and molar (M-MW) maxillary width in relation to the RPE group (P < 0.05). Through the expansion and consolidation periods (T2-T0), lesser buccal displacement of the anchor teeth was observed in the MARPE group (PM-BBPT, PM-PBPT, M-BBPT [mesial and distal roots], and M-PBPT)( P < 0.05).

Conclusions: Midpalatal suture separation was observed in 90% and 95% of patients in the RPE and MARPE groups, respectively. Both RPE and MARPE groups exhibited significant triangular basal bone expansion and skeletal relapse during consolidation. Under identical amounts of expansion, the MARPE group showed lower decrease in the skeletal, dentoalveolar and periodontal variables after consolidation. The reinforcement of RPE with miniscrews contributes to the maintenance of the basal bone during consolidation period. Trial registration WHO Institutional Clinical Trials Registry Platform (IRB No. KCT0006871 / Registration date 27/12/2021).

Keywords: Alveolar bone loss; Cone-beam computed tomography; Cranial sutures; Orthodontic anchorage procedures; Palatal expansion technique.

Fig. 1

CONSORT flow diagram

Fig. 2

a, b, tooth-borne rapid palatal expansion (RPE) before and after expansion, respectively. c, d, miniscrew-assisted rapid palatal expansion (MARPE) before and after expansion, respectively

Fig. 3

Preliminary study. a Human dry skull; b CBCT images in standard mode; c CBCT images in low-dose mode

Fig. 4

CBCT images illustrating skeletal variables: a Frontozygomatic suture. b Zygomaticomaxillary suture. c Nasal width. d Nasopalatine and greater palatine foramen. e Mid palatal suture gap

Fig. 5

Re-orientation of CBCT images. Reoriented as parallel to the palatal plane (a sagittal section), passing through the root apices of both maxillary first molars (b axial section), and parallel to the hard palate (c coronal section)

Fig. 6

CBCT images illustrating dentoalveolar variables: a MW, maxillary width at hard palate; IDW, interdental width; b DI, dental inclination

Fig. 7

CBCT image illustrating periodontal variables: BBPT, buccal bone plate thickness; and PBPT, palatal bone plate thickness

Fig. 8

Diagram of transverse change of the maxillary first premolars at each timepoint in the coronal section. Values are the mean differences (mm). a RPE, b MARPE; RPE, rapid palatal expansion; MARPE, mini-screw assisted rapid palatal expansion; T0, before treatment; T1, immediately after expansion; T2, after a 3-month consolidation period

Fig. 9

Diagram of transverse change of the maxillary first molars at each timepoint in the coronal section. Values are the mean differences (mm). a RPE, b MARPE; RPE, rapid palatal expansion; MARPE, mini-screw Assisted rapid palatal expansion; T0, before treatment; T1, immediately after expansion; T2, after a 3-month consolidation period

Fig. 10

Diagram of periodontal changes of the anchor teeth at each timepoint in the axial section. Values are the mean differences (mm). a RPE. b MARPE; RPE, rapid palatal expansion; MARPE, mini-screw assisted rapid palatal expansion; T0, before treatment; T1, immediately after expansion; T2, after a 3-month consolidation period