Long-Term Effects of Rapid Maxillary Expansion Followed by Fixed Appliances

Abstract

Objective: To evaluate the long-term changes in maxillary arch widths, overjet, and overbite in patients who were treated with rapid maxillary expansion (RME) followed by edgewise appliances. Materials and Methods: The material for the study consisted of study casts taken from 41 patients (19 males, 22 females) on four different occasions (before treatment, T1; after RME, T2; after treatment, T3; and during follow-up period, T4). The upper intercanine, interpremolar, and intermolar widths and overjet and overbite were measured on each set of study casts. Mean age of the subjects was 13.2 Ϯ 1.3 years (range, 11.2-16.9 years) at T1, 13.3 Ϯ 1.3 years (range, 11.3-17 years) at T2, 15.5 Ϯ 1.4 years (range, 13.1-18.8 years) at T3, and 20.4 Ϯ 1.6 years (range, 17.9-24.8 years) at T4. Results: The net increase in intercanine width, interpremolar width, intermolar width, overjet, and overbite was 1.4 Ϯ 2.4 mm, 4.6 Ϯ 2.6 mm, 4.3 Ϯ 2.5 mm, 0.1 Ϯ 0.6 mm, and 0.2 Ϯ 0.6 mm, respectively, and the relapse rates were 37% for intercanine width, 19% for interpremolar width, and 17% for intermolar width at the end of the follow-up period. Conclusions: A significant amount of relapse occurred in maxillary arch widths at the postretention assessment, the greatest being in intercanine width. RME significantly decreased overbite and increased overjet, and a statistically significant decrease was observed in both overbite and overjet at the postretention assessment. (Angle Orthod. 2010;80:5-9.)

Longitudinal stability of rapid and slow maxillary expansion

“…Average expansion (transverse dimension with greater increase in each patient) was 4.91 ± 1.54. The appliance remained passive in place as a retainer for at least three months,6 , 21 , 22 after which a removable retention plate was installed and used for three months associated with Edgewise appliances.…”

Stretch force guides finger-like pattern of bone formation in suture

“…They were characterized by accumulation of a large magnitude of stretch force in a short time to open the non-fused sutures and obtain new bone formation. However, there are some problems encountered in clinical treatments, such as pain, limited expansion outcomes and post-expansion relapse [5]. …”

Rapid Maxillary Expansion Treatment may Maintain Long-term Dental Changes in Patients with Constricted Arches

“…Other authors have used the same sequence. 8 Although all the studies included the same protocol (expansion followed by an edgewise appliance therapy phase) that make them comparable, there is the question on how the edgewise therapy may have affected the long-term results of RME, such as better intercuspation or increase in arch width and perimeter after edgewise appliance therapy. For instance, the McNamara et al study 6 found a considerable increase in the mandibular intermolar and intercanine width and maxillary and mandibular arch perimeter.…”