Abstract
Design The paper describes a continuing 5-year prospective randomised controlled trial (RCT).
Intervention The trial investigated the use of a customised face mask with a banded/ soldered jackscrew palatal expansion appliance in the two treatment groups under study, compared with control; in one treatment group, the appliance was activated twice daily (0.5 mm/day) for a minimum period of 7 days (the expansion group) and in the other was maintained passively (the nonexpansion comparative treatment group). Both groups received 300–500 g elastic force to the face mask on a fulltime basis. Patients in the control group were observed for at least 12 months then randomly assigned to one of the two treatment groups.
Outcome measure The outcome measure was the clinical evaluation of an overcorrected class I molar relationship approaching an end-to-end relation with a positive overjet of 4–5 mm. Cephalometric assessment was made with traditional measurements to describe the changes occurring between pretreatment, post-treatment and control lateral cephalograms; the changes in 55 landmarks were evaluated relative to an x–y coordinate system. The treatment effects were quantified using the Johnston analysis.1
Results Forty-six children of age 5–10 years were recruited into the study and were randomly assigned to group A (expansion; n=15), group B (nonexpansion; n=14) or group C (control; n=17). There was no statistically significant difference between the clinical outcomes nor cephalometric variables in treatment groups A and B. The total class III correction achieved was 4 mm, according to the Johnston analysis, 3.69 mm in group A (expansion), and 4.35 mm in group B (nonexpansion). Only one-third of the skeletal change was attributable to maxillary protraction with two-thirds of the change being attributed to mandibular rotation. The combined movement of the maxilla and the mandible produced an ANB angle of +3.87° and +3.99°, and a Wits change of +3.89 and +3.74 mm.
Conclusions Face mask protraction therapy provides effective correction in early class III malocclusion. The need for palatal expansion in the absence of a transverse discrepancy or a skeletal/ dental crossbite is not supported by the results of the study. Correction results from a combination of skeletal and dental change with an overall improvement in the dentofacial complex.
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References
Johnston LE . A comparative analysis of class II treatments. Monograph 19. Craniofacial Growth Series. Ann Arbor: Center for Human Growth and Development, University of Michigan; 1986; pp 103–148.
Kim JH, Viana MA, Graber TM, Omerza FF, BeGole EA . The effectiveness of protraction face mask therapy: a meta-analysis. Am J Orthod Dentofacial Orthop 1999; 115:675–685.
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Address for correspondence: Dr Gregory A Vaughn, 215 First Avenue W, Suite 100, Seattle WA 98119, USA. E-mail: greg@landvortho.com
Vaughn GA, Vaughn B, Moon HB, Turley PK. The effects of maxillary protraction therapy with or without rapid palatal expansion: a prospective, randomized clinical trial. Am J Orthod Dentofacial Orthop 2005; 128:299–309.
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Kalha, A. Face mask protraction therapy in early skeletal class III malocclusion. Evid Based Dent 7, 16–17 (2006). https://doi.org/10.1038/sj.ebd.6400384
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DOI: https://doi.org/10.1038/sj.ebd.6400384
