Effectiveness, Patient Acceptance, and Cost Estimation of 3D-printed Retainer Compared to Hawley Retainer in Expansion Case: a Randomized Controlled Trial

NCT07659041 | Not Yet Recruiting DMC

• 1 other identifier: JEP 2025-630
• Study Type: interventional
• Target: 28
• Locations: 1 country
• Sites: 3

Brief Summary

Expansion of the arches is generally considered highly unstable and prone to relapse regardless of the type of expansion. Retention appliances play a vital role in preserving these changes. Hawley retainer users often avoid wearing them due to speech difficulties and less aesthetic appeal. They are also more prone to breakage, costlier, and require more labour. Despite the relatively recent introduction of 3D-printed retainers, they offer potential advantages in orthodontics, including the accuracy of digitally scanned images, reduced labour and material costs, and improved patient comfort. While 3D-printed retainers are quite new, most studies focus on laboratory testing of their mechanical properties, there is limited evidence directly comparing their effectiveness in retaining arch width increases, patient acceptance, and cost estimation. This knowledge gap creates uncertainty about the optimal choice of retainer for long-term stability, necessitating a comparative assessment of their performance. This study addresses this knowledge gap by evaluating the retention of arch width increases achieved using Hawley retainers versus 3D-printed retainers

Conditions

Orthodontic Relapse; Retention in Orthodontic

Keywords

orthodontic; 3D printed retainer

Outcome Measures

Primary Outcomes (1)

• Retention of the maxillary expansion

  1. Subjects will be scheduled for follow-up at T1-T3 after the initiation of retention wear. During these visits, impressions will be acquired with alginate impression material, and ICW, IPMW, IFMW1, and IFMW2 will be measured intraorally and on dental casts. 2. Calibrated researchers will collect the study models, and the ID and intervention will be covered by opaque tape once they are ready for measurement. Only one dental cast at a time will be picked out of its box without showing any previous measurements. Two dental casts from the same patient will not be measured in connection. Due to the prospective nature of the study, it was inconvenient to anonymize dental casts from the start of the study. 3. Intraclass correlation coefficient (ICC) will be done within and between researchers one week after the T0.

  12 months

Secondary Outcomes (2)

• Patient acceptance

  12 months

• cost estimation

  6 months

Study Arms (2)

Hawley retainer

ACTIVE COMPARATOR

A screening will be done to select suitable patients for the study. Only patients who fulfil the criteria will be invited to participate in this study. Following informed consent, eligible subjects will be randomly allocated into one of two groups wither hawley retainer or 3D printed retainer. Fabrication of Hawley retainers will be done using a standardized design across all centres.

Device: Hawley retainer

3D printed retainer

EXPERIMENTAL

A screening will be done to select suitable patients for the study. Only patients who fulfil the criteria will be invited to participate in this study. Following informed consent, eligible subjects will be randomly allocated into one of two groups wither hawley retainer or 3D printed retainer. Fabrication of 3d printed retainers will be done using a standardized design at one main centres by one technician using Nextdent Orhtoflex Resin.

Device: 3D printed retainer

Interventions

3D printed retainer DEVICE

3D-printed retainer Using Nextdent Orthoflex resin Standard design of 3D printed retainer: * Monolithic design (no wires) * Thickness 0.8mm-1.0 mm * Fully cover the teeth and part of the gingiva (1-2mm) * Undercut block - 0.25-0.5mm

3D printed retainer

Hawley retainer DEVICE

Hawley retainers have served as the established standard for retention after maxillary expansion. Standard design of Hawley Retainer: - Labial bow (0.8mm hard stainless steel) from canine to canine - Adam clasp on the molar (0.7mm hard stainless steel) - acrylic baseplate (2-3mm thickness) .

Hawley retainer

Eligibility Criteria

• Age: 16 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17), Adult (18-64), Older Adult (65+)

You may qualify if:

• Patients aged 16 years or older at the time of debonding
• Treatment plan of extraction or non-extraction followed by straight wire appliances in the upper arch only or both arches
• Undergone expansion treatment in the upper arch causing an arch width increase of 3-10mm, either using a Quadhelix, expansion with archwires, or URA with midline screw
• Had pretreatment dental cast
• Had no chronic medical condition.

You may not qualify if:

• Cleft lip and palate
• Chronic medical conditions
• Broken teeth or bubbles on study model at site of measurement.

Sponsors & Collaborators

• National University of Malaysia: lead
• University of Malaya: collaborator
• Universiti Teknologi Mara: collaborator

Study Sites (3)

National University Of Malaysia

Kuala Lumpur, Kuala Lumpur, 50300, Malaysia

Location

University Malaya

Kuala Lumpur, Kuala Lumpur, 50603, Malaysia

Location

University Teknologi Mara Selangor branch

Sungai Buloh, Selangor, 47000, Malaysia

Location

Related Publications (10)

• Firlej M, Zaborowicz K, Zaborowicz M, Firlej E, Domagala I, Pieniak D, Igielska-Kalwat J, Dmowski A, Biedziak B. Mechanical Properties of 3D Printed Orthodontic Retainers. Int J Environ Res Public Health. 2022 May 9;19(9):5775. doi: 10.3390/ijerph19095775.

  PMID: 35565167 BACKGROUND

• Hichens L, Rowland H, Williams A, Hollinghurst S, Ewings P, Clark S, Ireland A, Sandy J. Cost-effectiveness and patient satisfaction: Hawley and vacuum-formed retainers. Eur J Orthod. 2007 Aug;29(4):372-8. doi: 10.1093/ejo/cjm039.

  PMID: 17702797 BACKGROUND

• Naeem OA, Bencharit S, Yang IH, Stilianoudakis SC, Carrico C, Tufekci E. Comparison of 3-dimensional printing technologies on the precision, trueness, and accuracy of printed retainers. Am J Orthod Dentofacial Orthop. 2022 Apr;161(4):582-591. doi: 10.1016/j.ajodo.2021.03.016.

  PMID: 35337648 BACKGROUND

• Tsoukala E, Lyros I, Tsolakis AI, Maroulakos MP, Tsolakis IA. Direct 3D-Printed Orthodontic Retainers. A Systematic Review. Children (Basel). 2023 Apr 3;10(4):676. doi: 10.3390/children10040676.

  PMID: 37189925 BACKGROUND

• Saw ZK, Yuen JJX, Ashari A, Ibrahim Bahemia F, Low YX, Nik Mustapha NM, Lau MN. Forward-backward translation, content validity, face validity, construct validity, criterion validity, test-retest reliability, and internal consistency of a questionnaire on patient acceptance of orthodontic retainer. PLoS One. 2025 Jan 3;20(1):e0314853. doi: 10.1371/journal.pone.0314853. eCollection 2025.

  PMID: 39752631 BACKGROUND

• Nakornnoi T, Bunjerdjin P, Santiwong P, Sipiyaruk K, Neoh SP, Chintavalakorn R. The Influence of Thickness on the Mechanical Behaviors of 3D Printing Resins for Orthodontic Retainers. Int J Biomater. 2024 Jun 25;2024:7398478. doi: 10.1155/2024/7398478. eCollection 2024.

  PMID: 38957572 BACKGROUND

• Ashari A, Xian L, Syed Mohamed AMF, Wahab RMA, Kit YC, Tata MD, Sinnasamy S, Kuppusamy E. One-year comparative assessment of retention of arch width increases between modified vacuum-formed and Hawley retainers. Angle Orthod. 2022 Mar 1;92(2):197-203. doi: 10.2319/050921-363.1.

  PMID: 34797378 BACKGROUND

• Ashari A, Nik Mustapha NM, Yuen JJX, Saw ZK, Lau MN, Xian L, Syed Mohamed AMF, Megat Abdul Wahab R, Yeoh CK, Deva Tata M, Sinnasamy S. A two-year comparative assessment of retention of arch width increases between modified vacuum-formed and Hawley retainers: a multi-center randomized clinical trial. Prog Orthod. 2022 Aug 26;23(1):40. doi: 10.1186/s40510-022-00424-5.

  PMID: 36018418 BACKGROUND

• Stoev YY, Uzunov TT, Stoyanova NS, Grozdanova-Uzunova RG, Kosturkov DN, Taneva IK. Mechanical properties of materials for 3D printed orthodontic retainers. Folia Med (Plovdiv). 2023 Dec 31;65(6):986-992. doi: 10.3897/folmed.65.e107299.

  PMID: 38351789 BACKGROUND

• Neoh SP, Khantachawana A, Chintavalakorn R, Santiwong P, Srikhirin T. Comparison of physical, mechanical, and optical properties between thermoplastic materials and 3-dimensional printing resins for orthodontic clear retainers. Am J Orthod Dentofacial Orthop. 2025 Jan;167(1):95-109.e1. doi: 10.1016/j.ajodo.2024.06.010.

  PMID: 39709226 BACKGROUND

Study Officials

• Asma Ashari, MClinDent Lon

  National University of Malaysia

  STUDY DIRECTOR

Central Study Contacts

Asma Ashari, BDS Adel, MClinDent Lon, MOrth

CONTACT

+603 8921 5555; asmaashari@ukm.edu.my

ALIZAE MARNY FADZLIN SYED MOHAMED

CONTACT

+6038921 5555; alizaemarny@ukm.edu.my

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: Investigators know who the participants are but will keep that information hidden from everyone else. Investigators will anonymize personally identifiable data so that it cannot be linked to other data by anyone else. Physical, social, psychological, and all other types of harm are kept to an absolute minimum.
• Purpose: OTHER
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: DR

Model Details: This study will be a multicentre prospective randomized controlled clinical trial conducted at Universiti Kebangsaan Malaysia (UKM), Universiti Malaya (UM), and Universiti Teknologi MARA (UiTM). A screening will be done to select suitable patients for the study. Only patients who fulfil the criteria will be invited to participate in this study. Participants will be approached in the dental chair once deemed suitable and given 5-10 minutes to decide on study participation. Consent will be gathered from the patients or the carer if the patient is below 18. Following informed consent, eligible subjects will be randomly allocated into one of two groups: Group 1: Hawley retainer. Group 2: 3D-printed retainer Dental casts of patients will be measured at intercanine width (ICW), inter-premolar width (IPMW), inter-first molar mesiobuccal cusp width 1 (IFMW1), and inter-first molar distobuccal cusp width 2 (IFMW2) for both groups at debond(T0), 3 (T1), 6(T2), and 12months(T3).

Study Record Dates

• First Submitted: June 8, 2026
• First Posted: June 22, 2026
• Study Start: June 1, 2026
• Primary Completion (Estimated): December 1, 2027
• Study Completion (Estimated): December 1, 2027
• Last Updated: June 22, 2026

Record last verified: 2026-06

Locations

MY (3)