Functional appliances and mandibular growth — is there an effect?

Abstract

Data sources A MEDLINE search strategy for the years 1966 to 1999 was developed. The search was limited to randomised controlled trials (RCT) and meta-analyses, which were performed on humans and written in English.Study selection Articles retrieved were critically appraised for their validity. For inclusion, an article had to meet four of seven validity standards and also the following criteria: it pertained to functional appliance use in the early treatment of Class II malocclusions; it was an RCT; and it included measurable mandibular cephalometric values.Data extraction and synthesis Cephalometric values were used to assess mandibular growth in the horizontal and the vertical dimensions. The following linear measures were assessed: condylion–pogonion (Co–Pg), articulare–pogonion (Ar–Pg), condylion–gnathion (Co–Gn), articulare–gnathion (Ar–Gn), sella–gonion (S–Go), articulare–gonion (Ar–Go), and condylion–gonion (Co–Go). Two angular parameters, sella-nasion-B point (SNB) and lower incisal angle (LIA), were also measured. Three horizontal measurements were also used in some of the studies examined, namely: gonion–menton (Go–Me), pogonion–N (Pg–N), and gonion–pogonion (Go–Pg). Annualised changes (linear or angular) in specific cephalometric data were pooled from the selected articles and then compared and plotted. Statistical significance was tested through analysis of variance, the Student’s t-test for paired data and 95% confidence intervals.Results The search identified 17 articles of which six met the inclusion and validity criteria. There was a significant difference between the control and the treated groups for Ar–Pg and Ar–Gn. No other horizontal or vertical cephalometric measurements were statistically significant.Conclusions It is currently difficult to obtain definitive answers about efficacy of functional appliances on mandibular growth because of many inconsistencies in measuring the treatment outcome variables. There is still a need to conduct more RCT to reduce the methodological limitations. © EBD 2004.