Clear Aligners May Harm Gums Depending on Edge Design, New Research Shows
Scoping review of 25 studies finds aligner margin design significantly affects gum health, with some configurations worsening inflammation.
Summary
A comprehensive review of 25 studies examined how clear aligner orthodontic treatment affects gum health. Researchers found that the design of aligner edges matters significantly - aligners with margins that follow the gum line caused worse inflammation compared to those extending beyond it. While clear aligners generally allow better oral hygiene than traditional braces, the specific margin configuration can influence periodontal outcomes. However, most studies used different measurement methods and timeframes, making direct comparisons difficult.
Detailed Summary
Clear aligner therapy has become increasingly popular as an alternative to traditional metal braces, but its effects on gum health remain poorly understood. This scoping review analyzed 25 studies published between 2020-2025 to map the evidence on how clear aligners affect periodontal health, with particular focus on aligner edge design.
The researchers searched three major databases and found substantial methodological diversity across studies. Most investigations examined standard periodontal measures like plaque index, gingival inflammation, and bleeding on probing, but used different scoring systems and assessment timepoints ranging from 1 to 12 months. Only three studies specifically addressed aligner margin design - a critical gap given its potential clinical importance.
The most significant finding came from Favero et al., who directly compared two margin configurations in 43 adolescents aged 14-18 years over six months. Juxtagingival margins (following the gum outline) were associated with significantly worse periodontal outcomes: plaque index (p=0.011), gingival index (p=0.03), and gingival bleeding (p=0.014). In contrast, vestibular rim margins (extending 3mm beyond the gum line) showed no significant changes in any measured parameter.
Other studies provided mixed results on general periodontal effects of aligner therapy. Some reported improvements in gum health compared to fixed braces, while others documented variations in inflammatory markers and bacterial composition. Laboratory studies examined bacterial adhesion to aligner materials and inflammatory cytokine expression, but with limited clinical correlation.
The review highlights a major evidence gap: despite clear aligners' growing popularity, standardized protocols for assessing their periodontal effects don't exist. The heterogeneous methodologies across studies prevent definitive conclusions about optimal margin designs or long-term periodontal safety.
Key Findings
- Juxtagingival aligner margins significantly worsened plaque index (p=0.011), gingival index (p=0.03), and bleeding (p=0.014) vs vestibular margins in 43 adolescents over 6 months
- Only 3 of 25 studies specifically examined aligner margin design effects on gum health, revealing major research gap
- Clinical attachment level remained stable in 7 of 8 studies that measured it, suggesting no permanent gum damage
- Studies used heterogeneous periodontal assessment protocols with timepoints ranging from 1-12 months, limiting comparability
- Laboratory studies documented bacterial adhesion variations to different aligner materials but with limited clinical correlation
- Interdisciplinary studies (10 of 25) combining orthodontics, periodontology, and molecular biology showed inflammatory marker changes during treatment
- Most studies excluded systematic comparison between different aligner margin configurations despite clinical relevance
Methodology
This scoping review followed PRISMA-ScR guidelines and searched PubMed, Scopus, and Web of Science from 2015-2025, identifying 1,587 records. After deduplication and screening, 25 primary studies met inclusion criteria. Studies included prospective clinical trials, observational studies, laboratory investigations, and case reports examining periodontal outcomes in patients ≥12 years old undergoing clear aligner therapy. No risk-of-bias assessment was performed as this was an evidence-mapping exercise rather than effectiveness evaluation.
Study Limitations
The review found substantial methodological heterogeneity across studies, with different periodontal indices, scoring systems, and assessment timepoints preventing quantitative synthesis. Only three studies specifically examined margin design effects, limiting conclusions about optimal configurations. Most studies had short follow-up periods (≤12 months), and the review excluded non-English publications except Romanian. No risk-of-bias assessment was performed, and the evidence base remains insufficient for definitive clinical recommendations.
Enjoyed this summary?
Get the latest longevity research delivered to your inbox every week.