Comparison of Two Miniscrew Bone-borne Expanders (2 vs 4 Screws) Versus Conventional Hyrax Expander in Adolescents

February 4, 2026 updated by: Michele Cassetta, University of Roma La Sapienza

Prospective Randomized Controlled Study Comparing Dentoalveolar, Skeletal, Periodontal and Nasal/Airway Effects of a Two-miniscrew Bone-borne Expander, a Four-miniscrew Bone-borne Expander, and a Conventional Tooth-borne Hyrax Expander in Adolescents.

Rapid maxillary expansion (RME) is used to correct transverse deficiencies of the maxilla. This randomized controlled trial compares three RME devices in adolescents (age 10-15) with at least 8 mm maxillary transverse deficiency: (1) bone-borne expander supported by two palatal miniscrews, (2) bone-borne expander supported by four palatal miniscrews, and (3) conventional tooth-borne Hyrax expander. Devices were placed using static computer-guided miniscrew insertion (where applicable). All participants received the same activation protocol to reach 8 mm expansion. Cone-beam CT scans were obtained pre-treatment (T0) and at 6 months post-treatment (T1). The trial assesses skeletal, dentoalveolar, periodontal, and nasal/airway outcomes. Enrollment: 36 subjects. Study sites: Sapienza University of Rome.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

This is a prospective, randomized, parallel-group clinical trial performed at the Department of Oral and Maxillofacial Sciences, Sapienza University of Rome (Nov 2021 - Sep 2024). Inclusion criteria included age under 16 years, late mixed or permanent dentition, and maxillary transverse deficiency ≥ 8 mm. Exclusion: poor oral hygiene; previous orthodontic treatment; craniofacial syndromes; cleft lip/palate; genetic/congenital diseases. After consent, eligible participants (N=36) were randomized (1:1:1) to: Group A - two-miniscrew bone-borne expander (paramedian screws near 1st-2nd premolar region); Group B - four-miniscrew bone-borne expander (two paramedian + two parapalatine); Group C - Hyrax tooth-borne expander banded to upper first molars. Miniscrews (Benefit system; PSM Medical Solutions) were placed using a CAD-CAM surgical guide planned from CBCT and digital models (Easy Driver). Activation: Hyrax click 10 mm screw; four quarter-turns at insertion then three quarter-turns/day for 12 days (0.20 mm/turn; ~0.6 mm/day) until 8 mm achieved. CBCT scan acquisition: Scanora 3Dx (Soredex). Measurements performed on Simplant v17 on defined landmarks (MaxBas, MaxAlv, MaxAlvPre, Ns, ZigMax, IntermCo, IntermoAp, molar angles, periodontal bone thickness measures, nasopalatine foramen width). Primary outcome: change in maxillary basal width (MaxBas) T0 to T1 measured on CBCT.

Study Type

Interventional

Enrollment (Actual)

36

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Italy
    • Rm
      • Rome, Rm, Italy, 00161
        • Sapienza University of Rome

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Age 10 to 15 years (under 16 at enrollment).
  • Late mixed or permanent dentition.
  • Maxillary transverse deficiency ≥ 8 mm (unilateral or bilateral).
  • Parent/guardian able to provide written informed consent; participant assent where applicable.

Exclusion Criteria:

  • Poor oral hygiene.
  • Prior orthodontic treatment.
  • Craniofacial syndromes.
  • Cleft lip and/or palate.
  • Genetic or congenital diseases likely to affect craniofacial growth or bone quality.
  • Inability/unwillingness to attend scheduled follow-up visits.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Arm 1 (Group A) - Two-miniscrew bone-borne expander
one-borne rapid maxillary expander anchored on two palatal miniscrews inserted in paramedian palatal vault (near first-second premolar area). Miniscrews: self-tapping titanium (Benefit system; PSM Medical Solutions). Placement planned via CBCT-guided CAD/CAM surgical guide (Easy Driver). Activation protocol: Hyrax click 10 mm screw: 4 quarter-turns at placement then 3 quarter-turns/day for 12 days (0.20 mm/turn) until ~8 mm expansion.
Device: Miniscrew supported expander application
Two palatal miniscrews with custom bone-borne expansion framework (device transmits forces to palatal bone; no tooth bands).
Experimental: Arm 2 (Group B) - Four-miniscrew bone-borne expander
Bone-borne rapid maxillary expander anchored on four palatal miniscrews (two paramedian + two parapalatine). Same guided insertion workflow and activation protocol as Group A.
Device: 4 miniscrews supported rapid maxillary expansion application
Four palatal miniscrews with custom bone-borne expansion appliances.
Active Comparator: Arm 3 (Group C) - Conventional tooth-borne Hyrax expander
Tooth-borne Hyrax expander banded on upper first permanent molars (conventional Hyrax). Same activation protocol as Groups A/B.
Device: Conventional tooth-borne Hyrax expander (comparator)
Hyrax-type tooth-borne expander with bands cemented on upper first molars (Hyrax click 10 mm).

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in maxillary basal width (MaxBas) from baseline (T0) to 6 months post-treatment (T1)
Time Frame: at 6 months
Measurement method: CBCT (Simplant software) distance between alveolar/basal points (points 5-6 as per Podesser/Garib protocol).
at 6 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Roma La Sapienza

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

November 1, 2021

Primary Completion (Actual)

September 1, 2024

Study Completion (Actual)

September 1, 2024

Study Registration Dates

First Submitted

February 4, 2026

First Submitted That Met QC Criteria

February 4, 2026

First Posted (Actual)

February 11, 2026

Study Record Updates

Last Update Posted (Actual)

February 11, 2026

Last Update Submitted That Met QC Criteria

February 4, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Other Study ID Numbers

  • URomLS_RME

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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