INTRODUCTION: Severe constriction of the maxillary arch, especially in the anterior part of the maxilla, is a common finding in cleft lip and palate patients. The usual treatment generally involves the expansion of the arch. OBJECTIVE: The aim of this study was to evaluate the expansion pattern obtained with three different fan-type expander screws. METHODS: Using Typodont, 18 expansions were executed, six for each group, according to the expander tested: G1- DentaurumTM; G2- LeoneTM and G3- MorelliTM. For each essay, 13 activations of 2/4 of a turn were done in each appliance, leading to a total activation of 5.2mm. Using a caliper, measurements were taken in the beginning of the testing (T1); in half the total turnings (T2) and in the end of the testing (T3). Different measures were considered: interpremolar width (IP1), intersecond premolar width (IP2), intermolar width (IM) and also the arch length (CA). The data obtained was analyzed through Kolmogorov-Smirnov, Tukey and Freeman tests as well as by ANOVA. RESULTS: It could be observed that all tested groups showed a "V" expansion pattern, with major expansion in the anterior region of the arch, that was even more expressive in G3 (IP1=29.85% and IM=9.73%). Increases in the CA measurements were similar for groups G1 and G3 (+12.65% and +12.13%, respectively), and lower for G2 (+8.23%). CONCLUSIONS: It could be concluded that all the fan-type expander screws tested in the present study can be used for treating transverse constriction of the maxilla. However, Morelli expander showed a greater expansion in the anterior region of the arch in relation to the posterior region, which is an important characteristic when treating cleft lip and palate patients. Clinical studies are also necessary to confirm the findings of the present study.
Cleft lip and palate; Expander screw; Rapid maxillary expansion
