Effect of extraction timing on alkaline phosphatase enzyme levels in the fluid around the gums during orthodontic treatment

ISRCTN	ISRCTN17615120
DOI	https://doi.org/10.1186/ISRCTN17615120
Secondary identifying numbers	DN-160925-H35

Submission date: 25/10/2025
Registration date: 30/10/2025
Last edited: 30/10/2025

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
This study aims to investigate the biological response of the periodontal (gum) tissues during orthodontic treatment with different extraction timing protocols. Specifically, it evaluates the activity of alkaline phosphatase (ALP) enzyme in the gingival crevicular fluid (GCF, the fluid that flows into the crevice around the teeth), which reflects bone and periodontal remodeling, during the alignment phase of treatment. Understanding how extraction timing affects ALP activity may help optimize the treatment of orthodontic patients.

Who can participate?
Healthy male and female patients aged 18–28 years with moderate crowding in the upper dental arch (Little’s Irregularity Index between 4–6 mm) who require extraction of the upper first premolars as part of their orthodontic treatment plan.

What does the study involve?
Participants were randomly allocated into three groups:
Group A: orthodontic leveling and alignment only (delayed extraction)
Group B: extraction only (no active tooth movement during the observation period)
Group C: simultaneous extraction with leveling and alignment
Gingival crevicular fluid samples were collected from the mesial and distal sites of the upper canines at seven timepoints (baseline and weekly up to 6 weeks) to measure ALP activity. All procedures were carried out under routine orthodontic care and with informed consent.

What are the possible benefits and risks of participating?
The study aimed to improve understanding of biological markers related to orthodontic tooth movement and to help design more efficient treatment protocols.
There were minimal risks beyond standard orthodontic procedures, such as mild and temporary gum irritation during sample collection.

Where is the study run from?
The study was conducted at the Department of Orthodontics, Faculty of Dentistry, Damascus University, Damascus (Syria)

When did the study start and how long did it run for?
January 2021 to December 2024

Who is funding the study?
Investigator initiated and funded

Who is the main contact?
Dr Yahya Ahmad Dakdouk, yahya1.dakdouk@damascusuniversity.edu.sy

Contact information

Dr Yahya Dakdouk
Public, Scientific, Principal investigator

Damascus
Damascus
10090
Syria

ORCID ID	0009-0005-8076-1487
Phone	+963 (0)91833272
Email	yahya1.dakdouk@damascusuniversity.edu.sy

Study information

Study design	Randomized controlled three-arm clinical trial with a parallel-group design
Primary study design	Interventional
Secondary study design	Randomised controlled trial
Study setting(s)	University/medical school/dental school
Study type	Treatment
Participant information sheet	Not available in web format, please use contact details to request a participant information sheet.”
Scientific title	Alkaline phosphatase activity in gingival crevicular fluid during orthodontic alignment and extraction protocols: a randomized controlled clinical trial
Study acronym	ALP-Ortho
Study objectives	Primary objective: To evaluate the effect of extraction timing on alkaline phosphatase (ALP) activity in gingival crevicular fluid (GCF) around maxillary canines during the leveling and alignment phase of orthodontic treatment. Secondary objectives: 1. To compare ALP activity among three treatment protocols: leveling and alignment alone, extraction alone, and simultaneous extraction with leveling and alignment. 2. To explore whether extraction timing can serve as a biological factor influencing orthodontic tooth movement efficiency.
Ethics approval(s)	Approved 15/09/2022, Research Ethics Committee – Faculty of Dentistry, Damascus University (Mazzeh Street, Faculty of Dentistry, Damascus University, Damascus, 10090, Syria; +963 (0)991833272; ethics.dentistry@damascusuniversity.edu.sy), ref: DN-160925-H35
Health condition(s) or problem(s) studied	Evaluation of gingival crevicular fluid alkaline phosphatase activity in patients with moderate maxillary dental crowding undergoing orthodontic treatment with different extraction timing protocols.
Intervention	Randomization was performed using sealed opaque envelopes to ensure allocation concealment. Blinding was applied to the laboratory examiner analyzing ALP activity, while operator and patients were not blinded due to the clinical nature of the interventions. Participants will be randomly allocated into three parallel groups (n = 20 each) using sealed opaque envelopes: Group A (levelling and alignment only – delayed extraction): fixed orthodontic appliances will be placed, and tooth alignment will be performed without extractions during the first 6 weeks. Group B (extraction only): bilateral extraction of the upper first premolars will be performed without initiation of orthodontic treatment during the observation period. Group C (simultaneous extraction with leveling and alignment): extractions of the upper first premolars will be carried out on the same day as the fixed appliance bonding, and alignment will begin immediately thereafter. Gingival crevicular fluid samples will be collected from the mesial and distal sites of the maxillary canines at seven time points (baseline and weekly up to 6 weeks) to assess alkaline phosphatase (ALP) activity. The study will be conducted at the Department of Orthodontics, Faculty of Dentistry, Damascus University, over a 6-week experimental period.
Intervention type	Procedure/Surgery
Primary outcome measure	Alkaline phosphatase (ALP) activity in gingival crevicular fluid (GCF) measured using a spectrophotometric enzymatic assay (Jenway 6330, 405 nm) at seven timepoints: baseline (T0) and weekly intervals up to 6 weeks (T1–T6) during orthodontic leveling and alignment.
Secondary outcome measures	Changes in gingival crevicular fluid alkaline phosphatase (ALP) activity over time, measured using a spectrophotometric enzymatic assay (Jenway 6330, 405 nm) at seven time points: baseline (T0) and weekly up to 6 weeks (T1–T6).
Overall study start date	01/01/2021
Completion date	30/12/2024

Eligibility

Participant type(s)	Patient
Age group	Adult
Lower age limit	18 Years
Upper age limit	28 Years
Sex	All
Target number of participants	70
Total final enrolment	60
Key inclusion criteria	1. Healthy male and female participants aged 18–28 years 2. Presence of moderate maxillary dental crowding as defined by Little’s Irregularity Index between 4–6 mm 3. Indication for orthodontic treatment with extraction of upper first premolars for space management 4. Good oral hygiene and healthy periodontium (probing depth ≤ 3 mm, no bleeding on probing) 5. No systemic diseases or medications affecting bone metabolism 6. No previous orthodontic treatment 7. Willingness to participate and sign informed consent
Key exclusion criteria	1. Presence of severe or mild dental crowding (Little’s Irregularity Index <4 or >6 mm) 2. Systemic diseases or conditions affecting bone metabolism (e.g., diabetes, osteoporosis, hyperparathyroidism) 3. Current or previous use of medications that influence bone turnover (e.g., corticosteroids, bisphosphonates, anticonvulsants) 4. Poor oral hygiene or active periodontal disease 5. Pregnant or lactating females 6. History of orthodontic treatment or trauma to the anterior maxillary teeth 7. Smoking or use of tobacco products 8. Refusal or inability to sign informed consent
Date of first enrolment	01/12/2022
Date of final enrolment	01/12/2024

Locations

Countries of recruitment

Syria

Study participating centre

Damascus University

Faculty of Dentistry
Department of Orthodontics
Mazzeh Street
Damascus
10090
Syria

Sponsor information

Damascus University
University/education

Mazzeh Street
Damascus
10090
Syria

Phone	+963 (0)11 2122112
Email	info@damascusuniversity.edu.sy
Website	http://www.damascusuniversity.edu.sy
"ROR"	https://ror.org/03m098d13

Funders

Funder type

Other

Investigator initiated and funded

No information available

Results and Publications

Intention to publish date	31/12/2025
Individual participant data (IPD) Intention to share	Yes
IPD sharing plan summary	Available on request
Publication and dissemination plan	The findings of this randomized controlled clinical trial are planned to be published in a peer-reviewed international orthodontic journal. Additional dissemination will include conference presentations and academic sharing within the Faculty of Dentistry, Damascus University. The final manuscript of the external article is currently in preparation for submission to an indexed journal following ICMJE recommendations.
IPD sharing plan	The datasets generated and/or analysed during the current study will be available upon reasonable request from the corresponding author (Dr. Yahya Ahmad Dakdouk, yahya1.dakdouk@damascusuniversity.edu.sy). The shared data will include anonymised individual participant values of alkaline phosphatase (ALP) activity in gingival crevicular fluid (GCF) and related timepoint information (T0–T6). Data will be made available after publication of the main results and for up to five years thereafter, for research purposes only. Participant consent included agreement for anonymised data sharing, and all ethical and legal requirements under Damascus University regulations have been observed.

Editorial Notes

30/10/2025: Study's existence confirmed by the Damascus University.