Adult patients receiving clear aligner treatment for an anterior open bite experience mild root volume reduction across all anterior teeth, according to a volumetric analysis published in PMC. Maxillary and mandibular canines show the greatest percentage decrease, though the reduction is generally considered clinically insignificant by researchers.
Orthodontically induced external root resorption is a recognized adverse effect of orthodontic treatment, occurring when teeth are moved through bone. While minor root shortening happens frequently, severe resorption exceeding six millimetres occurs in roughly 1.5 percent of patients, potentially compromising long-term tooth stability. Clear aligner treatment has gained popularity for adult malocclusions due to aesthetics, but its specific mechanical effects on open bite cases require careful radiographic evaluation.
In Plain English: The Clinical Takeaway
- Volumetric Reduction: Anterior teeth lose a small fraction of their root volume during clear aligner treatment for open bites, averaging between four and seven percent.
- Most Affected Teeth: Canines in both the upper and lower jaws show the largest percentage decrease in root volume compared to central and lateral incisors.
- Demographic Factors: Male patients exhibit a significantly greater reduction in root volume across anterior teeth, while patient age does not show a meaningful correlation.
Cone-Beam Computed Tomography Reveals Canine Vulnerability in Open Bite Aligners
Researchers analyzed fifty cone-beam computed tomography scans from twenty-five adult patients with anterior open bites ranging from one to four millimetres. The study utilized semi-automated segmentation via Blue Sky Plan software and three-dimensional superimposition in 3-matic software to measure root changes from pre-treatment to post-treatment time points. Both intra-examiner and inter-examiner reliability demonstrated high statistical consistency, with intraclass correlation coefficients ranging from 0.90 to 0.96.
Among the twelve anterior teeth evaluated, maxillary canines registered the most pronounced percentage decrease at minus 6.33 ± 2.58 percent, closely followed by central incisors at minus 5.91 ± 4.93 percent and lateral incisors at minus 5.50 ± 3.24 percent. In the lower arch, mandibular canines demonstrated the largest reduction at minus 6.75 ± 2.33 percent. Lateral incisors and central incisors in the mandible followed with decreases of minus 5.58 ± 3.20 percent and minus 4.86 ± 2.54 percent respectively. These findings indicate that while all anterior roots undergo some degree of resorption during open bite correction with aligners, the distribution heavily impacts canine structures.
| Tooth Group | Maxillary Mean % Change | Mandibular Mean % Change |
|---|---|---|
| Canines | -6.33 ± 2.58% | -6.75 ± 2.33% |
| Lateral Incisors | -5.50 ± 3.24% | -5.58 ± 3.20% |
| Central Incisors | -5.91 ± 4.93% | -4.86 ± 2.54% |
Mechanical Forces and Divergent Findings in Aligner Versus Fixed Appliance Literature
Clear aligner treatment utilizes staged activation, material elasticity, attachments, and auxiliary mechanics like intermaxillary elastics to correct malocclusions. These mechanical properties distribute forces differently than traditional fixed metal braces. According to a systematic review published in the Journal of Contemporary Orthodontics by Sachdev et al., clear aligner therapy frequently demonstrates reduced severity of external root resorption compared to fixed appliance therapy, though aligners do not completely eliminate the phenomenon.
The extent of root resorption is influenced by factors such as the total duration of therapy, the magnitude and type of mechanical force applied, the initial degree of malocclusion, and whether extractions are performed. However, Sachdev et al. noted that many existing investigations exhibit moderate to substantial risk of bias due to inconsistent measurement techniques and a focus primarily on non-extraction instances with mild crowding. Consequently, researchers continue to emphasize the necessity of rigorous three-dimensional imaging like cone-beam computed tomography to isolate confounding variables.
Contraindications & When to Consult a Doctor
As the adoption of clear aligners expands into more complex skeletal and dental malocclusions, understanding the precise volumetric impact on tooth roots remains vital for long-term clinical prognosis.
References
- Volumetric analysis of external root resorption after clear aligner treatment in anterior open bite patients – PMC National Center for Biotechnology Information
- Root resorption in orthodontic treatment with clear aligners: A systematic review – Journal of Contemporary Orthodontics via ResearchGate
- Apical root resorption during orthodontic treatment with clear aligners: A retrospective study using cone-beam computed tomography – American Journal of Orthodontics and Dentofacial Orthopedics
