EC Dental Science

Aim: The aim of this longitudinal study was to evaluate short-term changes in dental arches dimensions in patients who had been treated with rapid palatal expansion (RPE) followed by fixed orthodontic appliances.

Materials and Methods: The sample comprised of the casts of 29 patients (9 boys of a mean age of 9.6 and 20 girls of a mean age of 9.4 years), who had undergone orthodontic treatment using RPE with Hyrax type device and fixed orthodontic appliances. For every patient three pairs of casts were used: T1 before the treatment, T2 after the RPE and T3 after the end of the overall treatment. For every pair of casts 8 variables were measured at three-time intervals. Differences between all variables were calculated and compared using the t-test. The method error was determined using the intraclass correlation coefficient.

Results: The results indicated that the inter-molar, inter-premolar, and inter-canine maxillary widths as well as the perimeter of the maxillary dental arch increased at T2. The expansion at the molar region was found to be greater of the corresponding expansion in the premolars and canine’s regions. The maxillary arch perimeter after RPE (T2), presented increase of 6.6 mm. In the mandibular dental arch at T2 a significant increase of the mandibular inter-molar width by 2.1 mm and mandibular inter-canine width by 1.5 mm was found. During the treatment with fixed orthodontic appliances (T3) very small changes occurred in the calculations of the width of both maxillary and mandibular arches (T3-T2) in comparison with the changes that occurred at T2. Consequently, it was observed increase of the maxillary inter-premolar width by 2 mm and in both maxillary and mandibular inter-canine width by 1.3 mm and 0.8 mm, respectively. In contrast, a reduction was observed of the maxillary inter-molar width by 1 mm and of the mandibular inter-molar width by 0.2 mm. The only variables that were increased significantly during treatment with fixed appliances were the maxillary inter-canine width and the palatal height.

Conclusion: Treatment by RME followed by fixed appliances seems to be an effective way of creating space in dental arches with mild to medium crowding.

Keywords: Rapid Palatal Expansion; Dental Crowding; Narrow Maxilla; Orthodontic Treatment, Tooth-Size/Arch-Size Discrepancies; Arch Perimeter

1. Wertz RA. “Skeletal and dental changes accompanying rapid midpalatal suture opening”. American Journal of Orthodontics 58 (1970): 41-66.
2. Wertz R and Dreskin M. “Midpalatal suture opening: a normative study”. American Journal of Orthodontics 71 (1977): 367-381.
3. Rakosi T., et al. In Orthodontic Diagnosis (Color Atlas of Dental Medicine) by Robert E. Moyers (1993).
4. Bonett DG. “Sample size requirements for estimating intraclass correlations with desired precision”. Statistics in Medicine 21 (2002): 1331-1335.
5. McGraw H., et al. “Forming inferences about some intraclass correlation coefficients”. Psychological Methods 1 (1996): 30-46.
6. Neter J., et al. “Applied Linear Statistical Models”. Publisher: McGraw-Hill/Irwin, Inc. 4th Edition (1996).
7. Lagravere MO., et al. “Long-term dental arch changes after rapid maxillary expansion treatment: a systematic review”. The Angle Orthodontist2 (2005): 155-161.
8. Lagravere MO., et al. “Long-term skeletal changes with rapid maxillary expansion: a systematic review”. The Angle Orthodontist6 (2005): 1046-1052.
9. Adkins MD., et al. “Arch perimeter changes on rapid palatal expansion”. American Journal of Orthodontics and Dentofacial Orthopedics 97 (1990): 194-199.
10. Moussa R., et al. “Long-term stability of rapid palatal expander treatment and edgewise mechanotherapy”. American Journal of Orthodontics and Dentofacial Orthopedics 108 (1995): 478-88.
11. Lima AL., et al. “Long-term Clinical Outcome of Rapid Maxillary Expansion as the Only Treatment Performed in Class I Malocclusion”. The Angle Orthodontist 75 (2005): 416-420.
12. Mutinelli S., et al. “Dental arch changes following rapid maxillary expansion”. European Journal of Orthodontics 30 (2008): 469-476.
13. Grassia V., et al. “Comparison between rapid and mixed maxillary expansion through an assessment of arch changes on dental casts”. Progress in Orthodontics 16 (2015): 20-27.
14. D’Souza IM., et al. “Dental arch changes associated with rapid maxillary expansion: A retrospective model analysis study”. Contemporary Clinical Dentistry 6 (2015): 51-57.
15. Melgaço CA., et al. “Rapid maxillary expansion effects: an alternative assessment method by means of cone-beam tomography”. Dental Press Journal of Orthodontics – SciELO 19 (2014): 88-96.
16. Toklu MG., et al. “Periodontal, dentoalveolar, and skeletal effects of tooth-borne and tooth-bone-borne expansion appliances”. American Journal of Orthodontics and Dentofacial Orthopedics1 (2015): 97-109.
17. Luebbert J., et al. “Skeletal and dental effects of rapid maxillary expansion assessed through three-dimensional imaging: a multicenter study”. International Orthodontics1 (2016): 15-31.
18. Furtado Á., et al. “Soft-tissue cone-beam computed tomography (ST-CBCT) technique for the analysis of skeletal, dental and periodontal effects of orthopedic rapid maxillary expansion”. Journal of Clinical and Experimental Dentistry9 (2018): e883.
19. Araújo MC., et al. “Tomographic evaluation of dentoskeletal effects of rapid maxillary expansion using Haas and Hyrax palatal expanders in children: A randomized clinical trial”. Journal of Clinical and Experimental Dentistry10 (2020): e922.
20. Garib D., et al. “Orthopedic outcomes of hybrid and conventional Hyrax expanders: Secondary data analysis from a randomized clinical trial”. The Angle Orthodontist2 (2021): 178-186.
21. Haas AJ. “Rapid expansion of the maxillary dental arch and nasal cavity by opening the mid-palatal suture”. The Angle Orthodontist (1961): 73-90.
22. Barber AF and Sims MR. “Rapid maxillary expansion and external root resorption in man: a scanning electron microscope study”. American Journal of Orthodontics 79 (1981): 630-652.
23. Langford SR. “Root resorption extremes resulting resulting from clinical RME”. American Journal of Orthodontics 81 (1982): 371-377.
24. Langford SR and Sims MR. “Root surface resorption, repair, and periodontal attachment following rapid maxillary expansion in man”. American Journal of Orthodontics 81 (1982): 108-115.
25. Sperl A., et al. “Buccal alveolar bone changes following rapid maxillary expansion and fixed appliance therapy”. The Angle Orthodontist2 (2021): 171-177.
26. Altieri F and Cassetta M. “Comparison of changes in skeletal, dentoalveolar, periodontal, and nasal structures after tooth-borne or bone-borne rapid maxillary expansion: A parallel cohort study”. American Journal of Orthodontics and Dentofacial Orthopedics (2022).
27. Chaconas SJ and Caputo AA. “Observation of orthopedic force distribution produced by maxillary orthodontic appliance”. American Journal of Orthodontics and Dentofacial Orthopedics 82 (1982): 492-501.
28. Garib DG., et al. “Rapid maxillary expansion: tooth-tissue-borne vs. tooth-borne expanders: A CT evaluation of dentoskeletal effects”. The Angle Orthodontist 57 (2005): 548-557.
29. Huynh T., et al. “Treatment response and stability of slow maxillary expansion using Haas, hyrax, and quad-helix appliances: a retrospective study”. American Journal of Orthodontics and Dentofacial Orthopedics 136 (2009): 331-339.
30. Davami K., et al. “Long term skeletal and dental changes between tooth-anchored versus Dresden bone-anchored rapid maxillary expansion using CBCT images in adolescents: Randomized clinical trial”. International Orthodontics2 (2020): 317-329.
31. Innoue N. “Radiographic observation of rapid expansion of human maxilla”. The Bulletin of Tokyo Medical and Dental University 17 (1970): 249-261.
32. Lagravere MO., et al. “Meta-analysis of immediate changes with rapid maxillary expansion treatment”. Journal of the American Dental Association 137 (2006): 44-53.
33. Akkaya S., et al. “Comparison of dental arch and arch perimeter changes between bonded rapid and slow maxillary expansion procedures”. European Journal of Orthodontics 20 (1998): 255-261.
34. Cotton LA. “Slow maxillary expansion: skeletal versus dental response to low magnitude force in Macacca mulatta”. American Journal of Orthodontics and Dentofacial Orthopedics 73 (1978): 1-23.
35. Halazonetis DJ., et al. “Changes in cheek pressure following rapid maxillary expansion”. European Journal of Orthodontics 16 (1994): 295-300.
36. Haas AJ. “The treatment of maxillary deficiency by opening the mid-palatal suture”. The Angle Orthodontist 35 (1965): 200-217.
37. Gryson JA. “Changes in mandibular interdental distance concurrent with rapid maxillary expansion”. The Angle Orthodontist 47 (1977): 186-192.
38. Jafari A., et al. “Study of stress distribution and displacement of various craniofacial structures following application of transverse orthopedic forces: a three-dimensional FEM study”. The Angle Orthodontist 73 (2003): 12-20.
39. Bruder C., et al. “Evaluation of palate area before and after rapid maxillary expansion, using cone-beam computed tomography”. Dental Press Journal of Orthodontics 24 (2019): 40-45.
40. Mosleh MI., et al. “Comparison of transverse changes during maxillary expansion with 4-point bone-borne and tooth-borne maxillary expanders”. American Journal of Orthodontics and Dentofacial Orthopedics4 (2015): 599-607.
41. McNamara JA., et al. “Rapid maxillary expansion followed by fixed appliances: A long-term evaluation of changes in arch dimensions”. The Angle Orthodontist 73 (2003): 344-353.