What is the best treatment approach for an adult patient with a unilateral crossbite?

Treatment of Adult Unilateral Crossbite

For adult patients with unilateral crossbite, orthodontic maxillary expansion assisted by unilateral corticotomy with low-level laser therapy on the crossbite side is the most effective treatment approach, achieving successful correction with functional occlusion in all treated cases. 1

Why Adults Require Different Treatment Than Children

Adult treatment of unilateral crossbites is fundamentally more challenging than pediatric cases because:

• Skeletal maturity limits conventional expansion: It is difficult to treat unilateral crossbites in adults without combining orthodontics and surgery, unlike children where simple expansion appliances are highly successful 2
• Sutural fusion prevents orthopedic expansion: Adults lack the open midpalatal suture that allows symmetric maxillary expansion in children 2
• Established compensations complicate treatment: Adults often have severe dental compensations and asymmetric arch forms that developed over years 3

Recommended Treatment Protocol for Adults

First-Line Approach: Corticotomy-Assisted Expansion

The evidence-based protocol involves:

1. Application of orthodontic appliances (palatal expander and self-ligating brackets) 1
2. Unilateral corticotomy performed on the buccal aspect of the crossbite side only 1
3. Monthly low-level laser therapy (LLLT) administered until crossbite correction is achieved 1

This approach achieves:

• Greater expansion on the crossbite side compared to the unaffected side, with statistically significant differences at first premolars, second premolars, and first molars (P < 0.05 for all) 1
• 100% success rate in achieving functional occlusion 1
• Asymmetric correction that addresses the true unilateral nature of the problem 1

Alternative Approach: Asymmetric Orthodontic Mechanics

For cases with mandibular asymmetry and dental compensations:

• Nonsurgical treatment using unilateral extractions and asymmetric mechanics can successfully correct the crossbite while minimizing side effects 3
• This approach is particularly useful when the malocclusion involves asymmetric maxillary arch form, crowding, and skewed mandibular arch 3

Critical Diagnostic Considerations Before Treatment

Assess for functional shift versus true skeletal asymmetry:

• Evaluate condylar position differences between centric relation and maximum intercuspidation 4
• Document any mandibular shift associated with the crossbite 2
• Measure the degree of asymmetric molar rotation and mesialization, as upper first molars show significantly greater rotation (66.7% of crossbite cases) and mesialization on the crossbite side 5

Imaging requirements:

• Panoramic radiography and lateral cephalogram are necessary for orthodontic diagnosis and treatment planning 6
• CBCT is not indicated for routine unilateral crossbite cases unless severe craniofacial dysmorphosis is present 6

Why Early Treatment Is Emphasized (But You Have an Adult)

The literature strongly advocates for early treatment in late deciduous or early mixed dentition because:

• Crossbites are not self-correcting 2
• They have association with temporomandibular disorders 2
• They cause skeletal, dental, and muscle adaptations over time 2
• Treatment success is significantly higher when started early 2

However, since your patient is an adult, these developmental windows have closed, necessitating the more aggressive corticotomy-assisted approach described above.

Common Pitfalls to Avoid

• Do not attempt symmetric expansion alone: Conventional symmetric maxillary expansion fails to address the asymmetric nature of true unilateral crossbites in adults and faces biomechanical limitations due to skeletal maturity 1
• Do not ignore sagittal molar relationships: Unilateral crossbites involve not just transverse discrepancies but also asymmetric mesial rotation and mesialization of upper first molars that must be corrected 5
• Do not assume surgery is always necessary: While combination orthodontic-surgical treatment is often required, the corticotomy-assisted expansion protocol provides a less invasive alternative with proven success 1, 2