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Trabecular and cortical bone as risk factors for orthodontic relapse
Laura E Rothe1, Anne-Marie Bollen, Robert M Little
1School of Dentistry, University of Washington, Seattle, Wash 98195, USA.
Summary
Thinning of the mandibular cortex is a key risk factor for post-orthodontic relapse of lower incisors. Patients with thinner mandibular bone cortices show increased risk for dental relapse after treatment.
Area of Science:
- Orthodontics
- Dental bone biology
Background:
- Post-orthodontic relapse of mandibular incisors is common.
- Risk factors for relapse are not well understood.
- Mandibular bone characteristics may influence relapse potential.
Purpose of the Study:
- To investigate if mandibular bone amount and structure impact post-orthodontic incisor relapse.
- To identify bone-related risk factors for mandibular incisor relapse.
Main Methods:
- Case-control study comparing relapsed (II > 6mm) and stable (II < 3.5mm) orthodontic patients.
- Mandibular incisor irregularity index (II) measured at initial, post-treatment, and 10-year post-retention.
- Mandibular cortical thickness assessed via panoramic and cephalometric radiographs.
- Trabecular bone structure analyzed using fractal analysis on periapical radiographs.
Main Results:
- Relapse group had higher initial irregularity and longer post-retention time.
- Significantly thinner mandibular cortical bone in relapse group at all time points (T1, T2, T3).
- No significant differences in trabecular bone structure between groups.
Conclusions:
- Thinner mandibular cortices are associated with increased risk of post-orthodontic mandibular incisor relapse.
- Mandibular bone thickness, not trabecular structure, is a significant predictor of relapse.
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