Orthodontic RetainerNCT06283823
Morphological Changes of Removable Orthodontic Retainers During the Use
An observational study of Orthodontic Retainer, run by University of L'Aquila at 1 site in Italy.
Trial summary
The retention is one of the stages of orthodontic treatment that aims to keep the teeth in the correct positions after orthodontic treatment. Without a retention phase, there is a tendency for the teeth to return to their initial position (relapse). Read more about this study
- Who is it for?
- Ages 18 to 35 yearsHealthy volunteers can take part
- Conditions the study is for
- Orthodontic Retainer
- What is being tested?
- Thermoformed orthodontic retainer
- Type of treatment
- Medical device
- How many people
- 41 participants
- Where
- 1 siteItaly
- Study dates
- 21 Dec 2021to 30 Sep 2024
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 35 years
- All sexes
- Healthy volunteers accepted
- Adult
Study population: Undergraduate students
Who may be able to join
- young adult patients: 18-35 years;
- Caucasian ethnic group;
- good oral hygiene (evaluated by observing a plaque index < 20% understood as the sum of the indices of the individual dental elements divided by the number of dental elements considered multiplied by 100);
- patients with normal occlusion Class I occlusion with slight overcrowding and PAR Index less than or equal to 10;
- patients who have received previous orthodontic treatment, with or without stripping;
- patients who have received previous orthodontic treatment with < 20 orthodontic aligners;
- patients who currently use a thermoprinted mask as a restraint, or who do not use any restraint but who would like to receive one.
Who cannot join
- patients with chromosomal defects, specific neuropsychological disorder, epilepsy (1);
- patients with systemic diseases and comorbidities;
- bruxist patients;
- patients with hypertrophy of chewing muscles, occlusal parafunctions or joint disorders;
- patients with cognitive disabilities with IQ<70;
- patients undergoing drug therapy.
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Morphological Changes of Removable Orthodontic Retainers During the Use, a Prospective Study
The retention is one of the stages of orthodontic treatment that aims to keep the teeth in the correct positions after orthodontic treatment. Without a retention phase, there is a tendency for the teeth to return to their initial position (relapse). To prevent relapse, at the end of orthodontic therapy the use of retaining devices to keep the teeth in their ideal position is required. The aim of the study is to analyse whether intraoral aging of removable retention devices can lead to morphological or dimensional changes, and whether or not these changes are related to orthodontic relapse, expressed as a change in the Peer Assessment Rating (PAR) index. The PAR index is an index that allows us to evaluate the relapse after orthodontic treatment. In this study the PAR index will be measured at the start of the retention period (T0), at the three-months follow-up (T1) and at the six months follow-up (T2). In particular, two types of thermoformed retainers with different cutouts will be evaluated to determine whether the presence of higher margins in a type of retainers allows to maintain greater stability over time and, therefore, to confer a mechanical and clinical advantage.
Read the detailed description
This study was approved by the Internal Review Board of the University of L'Aquila, L'Aquila, Italy (prot. n. 41821/22). In order to observe a difference between the two groups and the three repeated measurements by ANOVA test equal to a large effect size, with a power of 80% and a probability of the error of the first type equal to 5%, 36 subjects in total will be needed, 18 for each group. Therefore, 36 patients will be selected from the undergraduate students in Dentistry and Oral Hygiene, implementing all the necessary precautions to avoid any problems due to subordination between students participating in the project and teachers.
The eligible patients who will sign a written informed consent, after having received the necessary verbal explanations, will be included in the study. The selected patients will be allocated to one of the two groups (normal masks and masks with modified cutout) by block randomization using Random Allocation Software.
The enrolled patients will be called for the acquisition of a digital impression of the dental arches through an intraoral scanner (CS3600, Carestream Dental LLC, Atlanta, USA). The obtained digital models will be used to create three pairs of identical thermoformed retainers that will be delivered to the patient at a later time. The retainers will be manufactured with custom landmarks at the level of the second molar, between first molar and second premolar, at the level of the canine, and between the two central incisors. Each retainer will be coated with a thin and uniform layer of white paint specially designed to make the material - in itself transparent - scanned with a 5-axis scanner (Zenotec S100, Wieland) obtaining digital copies. Afterwards, the paint will be removed and the retainers will be ready for delivery to the patient.
Patients will be recalled in three steps: T0 (day of delivery of the first retainer), T1 (3 months after delivery) and T2 (9 months after delivery). During the follow-up visits at T1 and T2 new digital scans will be acquired to obtain virtual models of each patient's dental arches. The digital models acquired at T0, T1 and T2 will be used to measure the PAR index according to the Richmond et al. protocol of 1992. This protocol provides for the assignment of a score to the various occlusal parameters that determine a malocclusion, then adding the individual scores to obtain a total score. A score of zero indicates correct alignment and stable occlusion, while positive scores are indicative of a relapse and misalignment.
Patients will be instructed to wear the thermoformed retainers overnight and will receive written instructions on how to clean and manage the retainers, to avoid possible biases due to incorrect procedures. At every subsequent follow-up visits patients will return the used retainers and will receive a new pair. In this way, the first pair of retainers will be used for a total time of three months, while the second pair of retainers will be used for a total time of six months.
To evaluate the morphological changes of the used retainers, their shape and dimensions will be compared to the scanning made before delivery.
After calculating descriptive statistics, the difference between the two retainers type and the three timepoints will be evaluated using a MANCOVA model, after checking for data homoscedasticity with a Levene test.
- Conditions
- Orthodontic Retainer
- Being tested
- Thermoformed orthodontic retainer
- Keywords
- orthodontic, retainer, stability, thermoformable retainer
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Thermoformed orthodontic retainerDevice
compare the outcome of the retaining phase of the orthodontic treatment with two different thermoformed retainers
| Study group | Role | What they receive |
|---|---|---|
| Retainer with high margins | Thermoformed retainers with modified cutout and high margins in the posterior region of the retainer Receives: Device: Thermoformed orthodontic retainer | |
| Retainer with low margins | Thermoformed retainer with conventional festooned cutout and low margins Receives: Device: Thermoformed orthodontic retainer |
What is being measured
The primary outcome is the main question the study is designed to answer.
Peer Assessment Rating (PAR) index
The PAR index will be measured on digital casts to evaluate the amount of alignment relapse.
Measured: 3 years
Volumetric superimposition of digital models
Digital models of pre- and post-usage thermoformed retainers will be superimposed and the distance between the two digital models will be measured
Measured: 3 years
Secondary outcomes (1)
Thickness
The thickness of the material composing the retainers will be measured at different locations.
Measured: 3 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted28 Feb 2024
- Study start21 Dec 2021
- Primary completion1 Apr 2024
- Study completion30 Sep 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (7)Papers the sponsor has linked to this study.
- Other trials for Orthodontic RetainerStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 41 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of L'Aquila
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Michele Tepedino, University of L'Aquila
- Investigators
- Michele Tepedino, Principal investigator, University of L'Aquila
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06283823
- Sponsor's protocol ID
- 41821
- Status last verified
- Mar 2025
- First submitted
- 21 Feb 2024
- Last updated
- 1 Apr 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided: Since the data are anonymized it would be acceptable to share it upon reasonable requests.
Publications
Bucci R, Rongo R, Levate C, Michelotti A, Barone S, Razionale AV, D'Anto V. Thickness of orthodontic clear aligners after thermoforming and after 10 days of intraoral exposure: a prospective clinical study. Prog Orthod. 2019 Sep 9;20(1):36. doi: 10.1186/s40510-019-0289-6.
PubMed 31495908Saghaei M. Random allocation software for parallel group randomized trials. BMC Med Res Methodol. 2004 Nov 9;4:26. doi: 10.1186/1471-2288-4-26.
PubMed 15535880Schuster S, Eliades G, Zinelis S, Eliades T, Bradley TG. Structural conformation and leaching from in vitro aged and retrieved Invisalign appliances. Am J Orthod Dentofacial Orthop. 2004 Dec;126(6):725-8. doi: 10.1016/j.ajodo.2004.04.021.
PubMed 15592222Gerard Bradley T, Teske L, Eliades G, Zinelis S, Eliades T. Do the mechanical and chemical properties of InvisalignTM appliances change after use? A retrieval analysis. Eur J Orthod. 2016 Feb;38(1):27-31. doi: 10.1093/ejo/cjv003. Epub 2015 Mar 3.
PubMed 25740599Lombardo L, Arreghini A, Maccarrone R, Bianchi A, Scalia S, Siciliani G. Optical properties of orthodontic aligners--spectrophotometry analysis of three types before and after aging. Prog Orthod. 2015;16:41. doi: 10.1186/s40510-015-0111-z. Epub 2015 Nov 18.
PubMed 26582007Thickett E, Power S. A randomized clinical trial of thermoplastic retainer wear. Eur J Orthod. 2010 Feb;32(1):1-5. doi: 10.1093/ejo/cjp061. Epub 2009 Oct 14.
PubMed 19828592Richmond S, Shaw WC, O'Brien KD, Buchanan IB, Jones R, Stephens CD, Roberts CT, Andrews M. The development of the PAR Index (Peer Assessment Rating): reliability and validity. Eur J Orthod. 1992 Apr;14(2):125-39. doi: 10.1093/ejo/14.2.125.
PubMed 1582457
Study at a glance
From the registry record, last updated by the sponsor on 1 Apr 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Morphological Changes of Removable Orthodontic Retainers During the Use, a Prospective Study
- ClinicalTrials.gov ID
- NCT06283823
- Acronym / sponsor ID
- 41821
- Conditions
- Orthodontic Retainer
- Keywords
- orthodontic, retainer, stability, thermoformable retainer
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 41 participants (actual)
- Lead sponsor
- University of L'AquilaUniversity, hospital or other
- Study start
- 21 Dec 2021 (actual)
- Primary completion
- 1 Apr 2024 (actual)
- Study completion
- 30 Sep 2024 (actual)
- First posted
- 28 Feb 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The retention is one of the stages of orthodontic treatment that aims to keep the teeth in the correct positions after orthodontic treatment. Without a retention phase, there is a tendency for the teeth to return to their initial position (relapse). To prevent relapse, at the end of orthodontic therapy the use of retaining devices to keep the teeth in their ideal position is required. The aim of the study is to analyse whether intraoral aging of removable retention devices can lead to morphological or dimensional changes, and whether or not these changes are related to orthodontic relapse, expressed as a change in the Peer Assessment Rating (PAR) index. The PAR index is an index that allows us to evaluate the relapse after orthodontic treatment. In this study the PAR index will be measured at the start of the retention period (T0), at the three-months follow-up (T1) and at the six months follow-up (T2). In particular, two types of thermoformed retainers with different cutouts will be evaluated to determine whether the presence of higher margins in a type of retainers allows to maintain greater stability over time and, therefore, to confer a mechanical and clinical advantage.
Detailed description
This study was approved by the Internal Review Board of the University of L'Aquila, L'Aquila, Italy (prot. n. 41821/22). In order to observe a difference between the two groups and the three repeated measurements by ANOVA test equal to a large effect size, with a power of 80% and a probability of the error of the first type equal to 5%, 36 subjects in total will be needed, 18 for each group. Therefore, 36 patients will be selected from the undergraduate students in Dentistry and Oral Hygiene, implementing all the necessary precautions to avoid any problems due to subordination between students participating in the project and teachers.
The eligible patients who will sign a written informed consent, after having received the necessary verbal explanations, will be included in the study. The selected patients will be allocated to one of the two groups (normal masks and masks with modified cutout) by block randomization using Random Allocation Software.
The enrolled patients will be called for the acquisition of a digital impression of the dental arches through an intraoral scanner (CS3600, Carestream Dental LLC, Atlanta, USA). The obtained digital models will be used to create three pairs of identical thermoformed retainers that will be delivered to the patient at a later time. The retainers will be manufactured with custom landmarks at the level of the second molar, between first molar and second premolar, at the level of the canine, and between the two central incisors. Each retainer will be coated with a thin and uniform layer of white paint specially designed to make the material - in itself transparent - scanned with a 5-axis scanner (Zenotec S100, Wieland) obtaining digital copies. Afterwards, the paint will be removed and the retainers will be ready for delivery to the patient.
Patients will be recalled in three steps: T0 (day of delivery of the first retainer), T1 (3 months after delivery) and T2 (9 months after delivery). During the follow-up visits at T1 and T2 new digital scans will be acquired to obtain virtual models of each patient's dental arches. The digital models acquired at T0, T1 and T2 will be used to measure the PAR index according to the Richmond et al. protocol of 1992. This protocol provides for the assignment of a score to the various occlusal parameters that determine a malocclusion, then adding the individual scores to obtain a total score. A score of zero indicates correct alignment and stable occlusion, while positive scores are indicative of a relapse and misalignment.
Patients will be instructed to wear the thermoformed retainers overnight and will receive written instructions on how to clean and manage the retainers, to avoid possible biases due to incorrect procedures. At every subsequent follow-up visits patients will return the used retainers and will receive a new pair. In this way, the first pair of retainers will be used for a total time of three months, while the second pair of retainers will be used for a total time of six months.
To evaluate the morphological changes of the used retainers, their shape and dimensions will be compared to the scanning made before delivery.
After calculating descriptive statistics, the difference between the two retainers type and the three timepoints will be evaluated using a MANCOVA model, after checking for data homoscedasticity with a Levene test.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Retainer with high margins | – | Device: Thermoformed orthodontic retainerThermoformed retainers with modified cutout and high margins in the posterior region of the retainer |
| Retainer with low margins | – | Device: Thermoformed orthodontic retainerThermoformed retainer with conventional festooned cutout and low margins |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
- Study population
- Undergraduate students
Key inclusion criteria (7 listed)
- young adult patients: 18-35 years;
- Caucasian ethnic group;
- good oral hygiene (evaluated by observing a plaque index < 20% understood as the sum of the indices of the individual dental elements divided by the number of dental elements considered multiplied by 100);
- patients with normal occlusion Class I occlusion with slight overcrowding and PAR Index less than or equal to 10;
- patients who have received previous orthodontic treatment, with or without stripping;
Key exclusion criteria (6 listed)
- patients with chromosomal defects, specific neuropsychological disorder, epilepsy (1);
- patients with systemic diseases and comorbidities;
- bruxist patients;
- patients with hypertrophy of chewing muscles, occlusal parafunctions or joint disorders;
- patients with cognitive disabilities with IQ<70;
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Thermoformed orthodontic retainercompare the outcome of the retaining phase of the orthodontic treatment with two different thermoformed retainers | Device | Retainer with high margins, Retainer with low margins |
Primary outcome
Peer Assessment Rating (PAR) index
Time frame: 3 years
The PAR index will be measured on digital casts to evaluate the amount of alignment relapse.
Volumetric superimposition of digital models
Time frame: 3 years
Digital models of pre- and post-usage thermoformed retainers will be superimposed and the distance between the two digital models will be measured
1 secondary outcome
Thickness
Time frame: 3 years
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 1 Apr 2025.
- Background: PubMed 31495908Bucci R, Rongo R, Levate C, Michelotti A, Barone S, Razionale AV, D'Anto V. Thickness of orthodontic clear aligners after thermoforming and after 10 days of intraoral exposure: a prospective clinical study. Prog Orthod. 2019 Sep 9;20(1):36. doi: 10.1186/s40510-019-0289-6.
- Background: PubMed 15535880Saghaei M. Random allocation software for parallel group randomized trials. BMC Med Res Methodol. 2004 Nov 9;4:26. doi: 10.1186/1471-2288-4-26.
- Background: PubMed 15592222Schuster S, Eliades G, Zinelis S, Eliades T, Bradley TG. Structural conformation and leaching from in vitro aged and retrieved Invisalign appliances. Am J Orthod Dentofacial Orthop. 2004 Dec;126(6):725-8. doi: 10.1016/j.ajodo.2004.04.021.
- Background: PubMed 25740599Gerard Bradley T, Teske L, Eliades G, Zinelis S, Eliades T. Do the mechanical and chemical properties of InvisalignTM appliances change after use? A retrieval analysis. Eur J Orthod. 2016 Feb;38(1):27-31. doi: 10.1093/ejo/cjv003. Epub 2015 Mar 3.
- Background: PubMed 26582007Lombardo L, Arreghini A, Maccarrone R, Bianchi A, Scalia S, Siciliani G. Optical properties of orthodontic aligners--spectrophotometry analysis of three types before and after aging. Prog Orthod. 2015;16:41. doi: 10.1186/s40510-015-0111-z. Epub 2015 Nov 18.
- Background: PubMed 19828592Thickett E, Power S. A randomized clinical trial of thermoplastic retainer wear. Eur J Orthod. 2010 Feb;32(1):1-5. doi: 10.1093/ejo/cjp061. Epub 2009 Oct 14.
- Background: PubMed 1582457Richmond S, Shaw WC, O'Brien KD, Buchanan IB, Jones R, Stephens CD, Roberts CT, Andrews M. The development of the PAR Index (Peer Assessment Rating): reliability and validity. Eur J Orthod. 1992 Apr;14(2):125-39. doi: 10.1093/ejo/14.2.125.
- Individual participant dataSharing planned: Undecided. Since the data are anonymized it would be acceptable to share it upon reasonable requests.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Michele Tepedino principal investigator
University of L'Aquila
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Orthodontic Retainer, run by University of L'Aquila at 1 site in Italy.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 1 Apr 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Italy. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Peer Assessment Rating (PAR) index (time frame: 3 years). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT06283823, which also lists 7 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 1 Apr 2025.