Inflammation in Clear Aligners With and Without Attachments

Official title

Molar-Specific Inflammatory Biomarkers in Adolescents Using Clear Aligners With and Without Attachments

Overview

Problem: Clear aligner therapy is widely used in orthodontics due to improved periodontal outcomes compared to fixed appliances. However, composite attachments are frequently bonded to molars to enhance biomechanics, potentially creating plaque-retentive areas that may increase localized inflammatory responses. Currently, no studies have directly compared periodontal inflammatory biomarker levels in molars treated with clear aligners with versus without attachments. This gap limits understanding of the biological impact of attachments on periodontal tissues.Hypothesis:First molars treated with clear aligners and composite attachments will demonstrate higher levels of inflammatory biomarkers in gingival crevicular fluid (GCF) compared to molars treated with clear aligners without attachments. Biomarker levels are expected to be lower in the non-attachment group. Methods: This study will include 30 orthodontic patients divided into two groups (15 per group):1. Clear aligners with molar attachments 2. Clear aligners without molar attachments. GCF samples will be collected from first molars at a routine orthodontic appointment at the UNMC College of Dentistry Graduate Orthodontic Clinic. Primary biomarkers include IL-1β, IL-6, TNF-α, and MMP-8 measured via ELISA. Clinical periodontal parameters (Plaque Index, Gingival Index, Bleeding on Probing, Probing Depth) will also be recorded.

Detailed description

Detailed Study Protocol:

This pilot clinical study will recruit subject currently undergoing orthodontic therapy in the graduate orthodontic residency program at the UNMC College of Dentistry. Each subject will be screened for recruitment into the study by review of records by study personnel to determine qualifications regarding inclusion and exclusion criteria. Once the subject has been screened, the subject (if over 18 years old) or the subjects' parent (if subject is between 14-18 years old) will be introduced to the study and invited to participate. The consent form will be reviewed, all questions answered and informed consent obtained prior to data collection. Study groups will consist of 15 subjects per group. Group A will be comprised of 15 subjects undergoing clear aligner orthodontic therapy with bonded composite attachments on the first molars. Group B will be comprised of 15 subjects undergoing clear aligner therapy without attachments on the first molars. The decision whether or not to use aligners is not a study decision and is part of routine orthodontic treatment planning and care. Routine aligner protocol includes a 1 week change schedule (aligner trays are changed/switched weekly) and must be worn a minimum of 22 hours/day. At the single data collection appointment, data collection will include assessment of plaque presence/absence at the mesiobuccal site of the first molars, gingival crevicular fluid (GCF) collection at the mesiobuccal site of the first molars, Gingival Index (Loe \& Silness) assessment at the mesiobuccal of each first molar (visual determination of gingival inflammation), probing depth assessment at the mesiobuccal of each first molar, and bleeding on probing (BOP) assessment at the mesiobuccal of the first molars. These measurements are being done for study purposes only.

The GCF collection procedure includes isolation of the tooth with cotton rolls, followed by gentle removal of all supragingival plaque with a dental explorer instrument. A small paper point will be inserted into the mesiobuccal gingival sulcus and held for 30 seconds to absorb the GCF. Four samples will be taken from each patient, one sample from each first molar. All samples will be stored at -80 degrees Celsius until assay.

Statistical analysis will be completed via t-tests and modeling. Within-patient differences will be calculated by subtracting the inflammatory marker value from a tooth without an attachment from a tooth with an attachment. These differences within patients will be averaged across all patients and compared to a null value of zero using a one sample t-test to see if the difference is statistically significant (this is the same as a paired t-test). This will be done for multiple inflammatory markers of interest, with IL1beta as the primary outcome of interest. As secondary, exploratory analyses, these difference scores will be compared to variables of interest (e.g., age, sex, length of time in a clear aligner, etc.), to see if there are associations with the size of differences observed, using Pearson or Spearman correlations for continuous variables, or Wilcoxon rank sum or Kruskal Wallis test

The primary outcome will be measure of inflammatory biomarker levels in GCF from first molars; specifically IL-1B. IL-6, TNF-alpha, MMP-8 will be measured as secondary outcomes. All biomarkers will be measured in pg/µL.

Additional outcomes will include assessment of periodontal clinical parameters (plaque presence, Gingival index, BOP, probing pocket depth (PD).

Primary outcome measures

• IL-1B [Time frame: Day 1]

Eligibility criteria

Inclusion criteria

• orthodontic patient at the UNMC College of dentistry
• clear aligner therapy

Exclusion criteria

• pregnancy

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Observational model

Cohort

Study locations

United States · 1 center

• University of Nebraska Medical Center College of Dentistry — Lincoln

Publications

• Kredig C, Peuckert E, Schmidtmann I, Drechsler T, Erbe C. Oral health in adolescents: periodontal inflammatory biomarkers during orthodontic clear aligner therapy. Clin Oral Investig. 2025 Mar 5;29(3):168. doi: 10.1007/s00784-025-06212-9. PMID 40042542
• Shokeen B, Viloria E, Duong E, Rizvi M, Murillo G, Mullen J, Shi B, Dinis M, Li H, Tran NC, Lux R, Wu T. The impact of fixed orthodontic appliances and clear aligners on the oral microbiome and the association with clinical parameters: A longitudinal comparative study. Am J Orthod Dentofacial Orthop. 2022 May;161(5):e475-e485. doi: 10.1016/j.ajodo.2021.10.015. Epub 2022 Mar 2. PMID 35248417
• Perinetti G, Paolantonio M, D'Attilio M, D'Archivio D, Tripodi D, Femminella B, Festa F, Spoto G. Alkaline phosphatase activity in gingival crevicular fluid during human orthodontic tooth movement. Am J Orthod Dentofacial Orthop. 2002 Nov;122(5):548-56. doi: 10.1067/mod.2002.126154. PMID 12439484
• Rouzi M, Zhang X, Jiang Q, Long H, Lai W, Li X. Impact of Clear Aligners on Oral Health and Oral Microbiome During Orthodontic Treatment. Int Dent J. 2023 Oct;73(5):603-611. doi: 10.1016/j.identj.2023.03.012. Epub 2023 Apr 25. PMID 37105789
• Xu M, Li G, Tian J, Xie F, Zuo J, Hu J, Yin K, Wang W. Comparison of the effects of clear aligners and fixed appliances on the oral microbiota and reactive oxygen species: a prospective study. Front Cell Infect Microbiol. 2026 Jan 23;15:1738047. doi: 10.3389/fcimb.2025.1738047. eCollection 2025. PMID 41659811
• Sioustis IA, Martu MA, Aminov L, Pavel M, Cianga P, Kappenberg-Nitescu DC, Luchian I, Solomon SM, Martu S. Salivary Metalloproteinase-8 and Metalloproteinase-9 Evaluation in Patients Undergoing Fixed Orthodontic Treatment before and after Periodontal Therapy. Int J Environ Res Public Health. 2021 Feb 8;18(4):1583. doi: 10.3390/ijerph18041583. PMID 33567492
• Kamran MA, Alnazeh AA, Almagbol M, Almoammar S, Alhaizaey AHA, Alshahrani I. Role of six cytokines and bone metabolism biomarkers in gingival crevicular fluid in patients undergoing fixed orthodontic appliance treatment in comparison with aligners: a clinical study. Angle Orthod. 2023 May 1;93(3):335-340. doi: 10.2319/091722-649.1. PMID 36807401
• Gujar AN, Baeshen HA, Alhazmi A, Bhandi S, Raj AT, Patil S, Birkhed D. Cytokine levels in gingival crevicular fluid during orthodontic treatment with aligners compared to conventional labial fixed appliances: a 3-week clinical study. Acta Odontol Scand. 2019 Aug;77(6):474-481. doi: 10.1080/00016357.2019.1607548. Epub 2019 Apr 26. PMID 31027423

Identifiers

NCT: NCT07506993 · 0171-26-EP

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗