Basic and patient-oriented research
Closer Look at the Stability of Surgically Assisted Rapid Palatal Expansion

https://doi.org/10.1016/j.joms.2008.04.020Get rights and content

Purpose

To assess the amount of dental and skeletal expansion and stability after surgically assisted rapid maxillary expansion (SARPE).

Patients and Methods

Data from 20 patients enrolled in this prospective study were collected before treatment, at maximum expansion, at the removal of the expander 6 months later, before any second surgical phase, and at the end of orthodontic treatment, using posteroanterior cephalograms and dental casts.

Results

With SARPE, the mean maximum expansion at the first molar was 7.48 ± 1.39 mm, and the mean relapse during postsurgical orthodontics was 2.22 ± 1.39 mm (30%). At maximum, a 3.49 ± 1.37 mm skeletal expansion was obtained, and this expansion was stable, such that the average net expansion was 67% skeletal.

Conclusion

Clinicians should anticipate a loss of about one third of the transverse dental expansion obtained with SARPE, although the skeletal expansion is quite stable. The amount of postsurgical relapse with SARPE appears quite similar to the changes in dental-arch dimensions after nonsurgical rapid palatal expansion, and also quite similar to dental-arch changes after segmental maxillary osteotomy for expansion.

Section snippets

Patients and Methods

Twenty patients aged between 15 and 54 years, participating in a prospective, observational study of SARPE outcomes approved by the Laval University Ethics Committee, received dental casts and P-A cephalograms before SARPE (time-point [T] 1), at the completion of expansion (T2), at the removal of the expander approximately 6 months later (T3), before any second surgical phase (T4), and at the end of orthodontic treatment (T5). All had a transverse discrepancy of 5 mm or more, and were beyond

Results

Changes during expansion (T1 to T3), changes after expansion (T3 to T5), and net expansion (T1 to T5) are shown in Figure 2. All changes were significantly different from zero (P < .001), except those for the lower molar (not significant). Note that the amount of expansion at the molars was very similar to the expansion at the first premolar (P = .95). This shows the parallelism of the expansion of the posterior teeth.

The amount of skeletal expansion with SARPE and its stability are shown in

Comparison to Other Studies of SARPE

The mean expansion at the first molar observed in the SARPE group was similar to that in previous studies using a comparable research design. The 30% relapse is less than the 36% relapse reported by Byloff and Mossaz.6 Post-treatment retention is likely to be an important factor in any study of stability.15 In our study, the expander was left in place for 6 months (standard deviation, 5.98 ± 0.72 months) after the expansion had stopped, whereas Byloff and Mossaz6 left the distractor in for 3

Acknowledgments

We thank Jean-Paul Goulet, DDS, MSD, FRCD(C), and André Fournier, DMD, for their direction and co-direction of this Master's Degree project, Dany Morais, DMD, FRCD(C), Oral and Maxillofacial Surgeon, for careful surgical treatment, and Gaetan Daigle, PStat, for statistical consultation and statistical analysis. This project was supported in part by grant DE-05221 from the National Institute of Dental and Craniofacial Research of the National Institutes of Health (Bethesda, MD).

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