Quality of orthodontic treatment with straightwire or standard edgewise appliances

ISRCTN	ISRCTN13048456
DOI	https://doi.org/10.1186/ISRCTN13048456
Protocol serial number	ABOZUROSL
Sponsor	University of Zurich
Funder	Universität Zürich

Submission date: 09/04/2018
Registration date: 29/05/2018
Last edited: 29/05/2018

Recruitment status: No longer recruiting
Overall study status: Completed
Condition category: Oral Health

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Record updated in last year

Plain English summary of protocol

Background and study aims
The type of orthodontic appliance (brace) used might have a direct effect on the results and duration of treatment. This study aims to compare two kinds of braces (one pre-programmed and one not) from treated patients' records to assess any differences in the quality of treatment.

Who can participate?
Patients treated with fixed orthodontic appliances (braces) for crooked teeth

What does the study involve?
The study involves assessing routinely-collected anonymized treatment records (stone cast models and x-rays of the teeth) taken before insertion of the orthodontic appliances and directly after their removal (around 18-60 months later).

What are the possible benefits and risks of participating?
All patients have been already treated in the two participating university clinics to have their teeth straightened and before treatment they have signed an informed consent form that their anonymized data can be used for research purposes. No additional risks are imposed on the patients other than risks that are normally included in the average treatment with dental braces. The benefits to be gained are in the form of increased treatment effectiveness with one of the two brace types, which is translated to patients being burdened for less time during treatment by the braces and the subsequent reduction of side effects.

Where is the study run from?
1. University of Zurich (Switzerland)
2. University of Oslo (Norway)

When is the study starting and how long is it expected to run for?
March 2017 to September 2018

Who is funding the study?
University of Zurich (Switzerland)

Who is the main contact?
Dr Spyridon Papageorgiou
snpapage@gmail.com

Contact information

Dr Spyridon Papageorgiou
Public

Clinic of Orthodontics and Pediatric Dentistry
Center of Dental Medicine
University of Zurich
Plattenstrasse 11
Zurich
CH-8032
Switzerland

ORCID ID	0000-0003-1968-3326
Phone	+41 (0)44 634 32 87
Email	snpapage@gmail.com

Study information

Primary study design	Observational
Study design	Retrospective non-randomized comparative multi-center observational cohort study
Secondary study design	Cohort study
Study type	Participant information sheet
Scientific title	Clinical outcomes of orthodontic extraction treatment with pre-adjusted versus standard edgewise appliances: a retrospective cohort study
Study objectives	There is no difference in the occlusal outcome of comprehensive orthodontic extraction treatment, as measured with the American Board of Orthodontics (ABO) Objective Grading System (OGS), with either pre-adjusted edgewise appliances and standard edgewise appliances.
Ethics approval(s)	1. Regional Committees for Medical and Health Research Ethics, 26/10/2017, ref: 2017/1885 2. Kantonale Ethikkommission Zürich, ID: 2018-00631 - approval pending
Health condition(s) or problem(s) studied	Most orthodontic malocclusions can be effectively treated with comprehensive fixed appliance treatment, due to the ability of the latter to perform controlled tooth movements in all three planes of space. Often, severe arch length discrepancies or several dental/skeletal malocclusions necessitate the incorporation of dental extractions in the orthodontic treatment plan.
Intervention	Patient clinical documentation is consistently taken by all orthodontists both before insertion of the orthodontic appliances and directly after their removal (around 18-60 months after insertion). This documentation consists of intraoral/extraoral photographs, impressions made with metal trays and alginate to construct dental cast models of the patient’s dentition, and radiographs. These documentation, including each patient’s written log of treatment will be used as material for this study.
Intervention type	Device
Phase
Drug / device / biological / vaccine name(s)
Primary outcome measure(s)	The ABO OGS score will be evaluated using all its 8 components: alignment, marginal ridges, buccolingual inclination, overjet, occlusal contacts, occlusal relationships, interproximal contacts, and root angulation. This is measured from the patients’ post-treatment documentation (stone cast models of the occlusion and x-ray) using a specific checklist/form provided by ABO. The overall cumulative score for all ABO OGS categories will be used as primary outcome. The principal investigator (S.N.P.) has prior to initiation of the study completed the necessary calibration process as instructed by the ABO. All measurements will be obtained using the special ABO gauge provided with the calibration kit. The principal investigator has extensive experience in cephalometric analyses and their assessment for research purposes. The primary outcome of this study will be the overall ABO OGS score in a continuous scale (expected to be normally-distributed). Reliability of the method Descriptive and inferential statistics will be performed to detect both random and systematic errors of the method. Initially, Dahlberg's formula will be used to assess intra examiner repeatability. With the aid of a table of random numbers, 10 patients will be randomly selected and will be re-evaluated 10 days later by the same examiner (S.N.P.) and also by a second examiner. Next, the intraclass correlation coefficient and the Bland-Altman limits of agreement [Bland and Altman, 1986] will be used to evaluate interexaminer agreement.
Key secondary outcome measure(s)	The secondary outcomes will include each of the separate components of the ABO OGS score that is used as a summary in the primary outcome. Additionally, the treatment duration will be also extracted from the patient files and be used together with the ABO OGS to assess treatment efficacy. As treatment durations are expected to differ between the two centers, we might consider normalizing treatment durations within each center with the average duration of each center.
Completion date	01/09/2018

Eligibility

Participant type(s)	Patient
Age group	All
Sex	All
Target sample size at registration	50
Key inclusion criteria	1. Any ethnicity or race 2. Male or female 3. Class I, Class II, or Class III malocclusion 4. Full complement of teeth excluding the third molars 5. No previous orthodontic treatment 6. No dentofacial deformities or clefts 7. Complete set of diagnostic records With the following treatment characteristics to control for factors that might influence treatment outcome or duration: 1. One phase treatment with labial fixed appliances in both arches (no two-phase treatment) 2. Bilateral extraction of a premolar in one or two jaws (either 2- or 4-premolars extracted) 3. No temporary anchorage devices of any form 4. No orthognathic surgery 5. No dental trauma 6. No impacted canines 7. Complete set of treatment records
Key exclusion criteria	Does not meet inclusion criteria
Date of first enrolment	01/05/2018
Date of final enrolment	01/08/2018

Locations

Countries of recruitment

Norway
Switzerland

Study participating centres

University of Zurich

Zurich
8032
Switzerland

University of Oslo

Oslo
0455
Norway

Results and Publications

Individual participant data (IPD) Intention to share	Yes
IPD sharing plan summary	Stored in repository
IPD sharing plan	After study conduct, submission, and acceptance of the paper from a scientific journal, the anonymized dataset of the study will be made openly available through the Zenodo repository (https://zenodo.org/).

Study outputs

Output type	Details	Date created	Date added	Peer reviewed?	Patient-facing?
Participant information sheet	Participant information sheet	11/11/2025	11/11/2025	No	Yes