A meta analysis of maxillary expansion: comparisons of intercanine/intermolar expansion and rapid/slow expansion

Ko, Chang Hee; Lim, Sung Hoon; Yoon, Young Jooh; Kim, Kwang Won

Abstract

As a research method that weighs and combines evidence, meta analysis produces evidence that is more powerful than the original studies. The purpose of this study was to compare the intercanine/intermolar expansion and rapid/slow expansion in the maxillary expansion treatment using meta analysis. Medline was searched from 1979 to 2000 for all studies examining the stability of transverse expansion of the human maxilla, and 388 articles were found. Then these articles were reduced to 7 based on the defined inclusion and exclusion criteria, and a cumulative Meta evaluation score was computed for each study. The results were as follows; 1. The mean expansion in intermolar width was 6.0mm. Of the 6.0mm, 4.8mm was retained and 20.0%(1.2mm) was relapsed while wearing retainers. 2. In intercanines width, the mean expansion was 3.7mm. Of the 3.7mm, 2.6mm was retained and 29.7%(1.1mm) was relapsed while wearing retainers. 3. The differences in the amount of expansion and relapse between rapid expansion group and slow expansion group were less than 6%(0.1-0.3mm). But, there might be differences in the skeletal/dental exapnsion ratios according to the expansion method.