Tridimensional Changes in Mandibular Arch after Rapid Maxillary Expansion Therapy: A Clinical Study

Area of Science:

• Orthodontics and Dental Anthropology
• Craniofacial Growth and Development
• Biomaterials and Dental Devices

Background:

• Transverse deficiency of the upper jaw is a prevalent orthodontic issue with genetic and environmental origins.
• Rapid maxillary expanders (RMEs) are the primary treatment for correcting upper transverse discrepancies.
• Understanding the effects of RME on the mandibular arch is crucial for comprehensive orthodontic treatment planning.

Purpose of the Study:

• To evaluate changes in the mandibular arch during RME treatment in growing subjects.
• To analyze tridimensional lower digital casts to quantify mandibular arch alterations.
• To compare mandibular arch dimensions before and after RME therapy.

Main Methods:

• A study group (SG) of 20 growing subjects (mean age 9.4 years) with posterior transverse interarch discrepancy (≥ 4 mm) was treated with RMEs.
• A control group (CG) of 20 untreated subjects with similar criteria was used for comparison.
• Lower dental casts were digitized at two time points (T0 and T1, 6 months apart) using 3D scanning, and mandibular arch points were analyzed.

Main Results:

• A statistically significant increase in intercanine diameter was observed in the SG compared to the CG (p < 0.05).
• A statistically significant increase in intermolar diameter was observed in the SG compared to the CG (p < 0.05).
• These findings indicate a direct effect of RME on mandibular arch dimensions.

Conclusions:

• Rapid maxillary orthopedic expansion can lead to a significant increase in mandibular intercanine and intermolar diameters.
• RME therapy may have beneficial secondary effects on the transverse dimensions of the lower arch in growing patients.
• This suggests that RME is an effective treatment for transverse discrepancies, influencing both maxillary and mandibular arches.