The Potential Effect of the Local Administration of Vitamins C and E on Orthodontic Treatment: A Randomized Clinical Trial

This randomized clinical trial aims to investigate the effects of locally administered vitamins C and E on mandibular incisor crowding relief during the initial stage of orthodontic treatment. The study follows a multicenter, prospective, single-blind, parallel-group design with equal randomization (1:1:1) and is conducted at Bab Al-Muadham Dental Health Center and the Postgraduate Orthodontic Clinic, Department of Orthodontics, College of Dentistry, University of Baghdad. Participants were blinded to group allocation, while the principal investigator (A.M.H.) was aware of all group allocations throughout the study period.

Study Rationale Orthodontic tooth movement involves a complex biological process mediated by bone remodeling, which is regulated by mechanical forces and biochemical mediators. Oxidative stress and inflammatory responses play a significant role in the remodeling process. Vitamin C (ascorbic acid) and vitamin E (tocopherol) are known for their antioxidant properties and potential effects on bone metabolism, tissue healing, and inflammation modulation. This study aims to determine whether locally administered vitamins C and E can enhance orthodontic tooth movement, reduce adverse effects such as root resorption, and improve patient experience during treatment.

Study Objectives The primary objective is to compare the effectiveness of vitamin C and vitamin E injections versus a saline control in mandibular incisor crowding relief over 24 weeks.

The secondary objectives include:

Assessing the extent of apical root resorption using periapical radiographs. Evaluating pain perception using a 0-10 numerical rating scale (NRS) during the first seven days after each archwire placement.

Measuring patient perception of treatment experience through a structured questionnaire.

Analyzing levels of biomarkers associated with bone remodeling (RANKL, OPG, RUNX2) in gingival crevicular fluid (GCF) to determine the biological effects of the interventions.

Participant Selection Eligible participants are patients aged 12 years and older with moderate to very severe mandibular anterior crowding (Little's Irregularity Index [LII]). Exclusion criteria include systemic diseases, prior orthodontic treatment, or the use of medications that could influence bone metabolism or inflammatory responses.

Intervention Groups

Participants will be randomly assigned to one of three groups:

Control Group: Receives 0.6 mL of normal saline, divided among the six mandibular anterior teeth and administered every two weeks.

Vitamin C Group: Receives intraepidermal injection of vitamin C (120 mg in 1.2 mL, divided among six mandibular anterior teeth).

Vitamin E Group: Receives intraepidermal injection of vitamin E (15 mg in 0.1 mL, divided among six mandibular anterior teeth).

Injections are repeated biweekly for the vitamin C and control groups and monthly for the vitamin E group, for a total of six months (24 weeks).

A pilot phase included 10 participants. Four participants who received the initial vitamin E regimen of 60 mg in 0.4 mL every two weeks were excluded from the final analysis after the regimen was modified because of poor absorption of the oil-based formulation. The final vitamin E regimen was reduced to 15 mg in 0.1 mL and administered once monthly. The remaining participants in the vitamin C and control groups continued in the trial and were included in the final analysis.

Orthodontic Treatment Protocol

All participants undergo standardized orthodontic treatment using MBT brackets (0.022-inch slot). The leveling and alignment phase follows a sequential archwire progression with CuNiTi archwires in the following sequence:

0.014-inch CuNiTi (weeks 0-8) 0.016-inch CuNiTi (weeks 8-16) 0.018-inch CuNiTi (weeks 16-24)

Data Collection and Outcome Assessments

Data will be collected at multiple time points throughout the study:

• Mandibular Incisor Crowding Relief Direct intraoral scans obtained using the Heron™ intraoral scanner will be used to measure Little's Irregularity Index (LII) at baseline and every four weeks until week 24.
• Root Resorption Standardized periapical radiographs of both mandibular central incisors will be taken at baseline, 8 weeks, and 24 weeks. Root resorption will be assessed using corrected root-length measurements and the Malmgren scoring index.
• Pain Perception Participants will record the maximum mandibular tooth pain experienced once daily in the evening using a 0-10 NRS for seven days after each archwire placement.
• Patient Perception A 22-item bilingual questionnaire assessing pain, discomfort, swelling, numbness, functional difficulties, effects on daily activities, and overall perception of the intervention visit will be administered at 8 weeks.
• Biomarker Analysis Gingival crevicular fluid (GCF) samples will be collected at baseline, 1 week, and 4 weeks. Levels of RANKL, OPG, and RUNX2 will be analyzed to assess changes in bone remodeling activity.

Statistical Analysis

Data will be analyzed using SPSS version 26. Statistical methods will include:

Descriptive statistics (mean, standard deviation, frequency). Intraclass correlation coefficients and weighted kappa statistics for measurement reliability.

One-way analysis of variance, mixed-design repeated-measures analysis of variance, Kruskal-Wallis test, Wilcoxon signed-rank test, Pearson's chi-square test, and Friedman test.

A significance level of 0.05 will be used for hypothesis testing, with Bonferroni adjustment where applicable.

Study Oversight and Ethical Considerations The study is self-funded and complies with ethical guidelines for human research. Ethical approval was obtained from the Research Ethics Committee of the College of Dentistry, University of Baghdad, on 21 January 2025 (reference number 1014; project number 1014425). Written informed consent was obtained from adult participants. For participants younger than 18 years, written parental or guardian consent and participant assent were obtained before enrolment.

Potential Impact This trial may provide valuable insights into the role of antioxidant therapy in orthodontic treatment. If vitamins C and E positively influence tooth movement and root integrity, their use could enhance treatment efficiency while minimizing complications. Findings may also contribute to a better understanding of bone remodeling mechanisms in response to mechanical forces.

Inclusion criteria

• Patients aged 12 years and above, who are indicated for fixed appliance orthodontic treatment.
• Patients with moderate to very severe crowding of the mandibular anterior teeth as per the Little's Irregularity Index (LII).
• Treatment with or without two mandibular first premolars extraction. Presence of all the mandibular permanent teeth, except the third molars.

• The overbite and overjet should not impede bracket placement on the mandibular anterior teeth.

Exclusion criteria

• History of previous orthodontic intervention.
• History of trauma or root resorption in the mandibular anterior teeth.
• Presence of mandibular anterior teeth crowding of less than 4 mm (LII).
• Existence of blocked-out teeth precluding engagement with the aligning archwire.
• History of systemic diseases, especially diabetes and bone diseases.
• Patients with periodontitis and obvious loss of tooth attachment according to Plaque and Bleeding on Probing indices.
• Pregnant and lactating mothers.
• Mouth breathing patients and smokers.
• Healthy patients who have not used any medications (such as anti-inflammatory or antimicrobial drugs) or supplements (such as vitamins)