***TASK***
the task is to simplify the input abstract of a biomedical literature

***INPUT***
the input is the abstract of a biomedical literature

***OUTPUT***
the output is the simplified abstract for the input abstract of a biomedical literature

***DOCUMENTATION***

***EXAMPLES***

Input: We included 15 studies, of which two were at low risk of bias, seven were at high risk of bias and six were unclear. Fixed appliances with mid-palatal expansion Nine studies tested fixed appliances with mid-palatal expansion against each other. No study reported a difference between any type of appliance. Fixed versus removable appliances Fixed quad-helix appliances may be 20% more likely to correct crossbites than removable expansion plates (RR 1.20; 95% CI 1.04 to 1.37; two studies; 96 participants; low-quality evidence). Quad-helix appliances may achieve 1.15 mm more molar expansion than expansion plates (MD 1.15 mm; 95% CI 0.40 to 1.90; two studies; 96 participants; moderate-quality evidence). There was insufficient evidence of a difference in canine expansion or the stability of crossbite correction. Very limited evidence showed that both fixed quad-helix appliances and removable expansion plates were superior to composite onlays in terms of crossbite correction, molar and canine expansion. Other comparisons Very limited evidence showed that treatments were superior to no treatment, but there was insufficient evidence of a difference between any active treatments. There is a very small body of low- to moderate-quality evidence to suggest that the quad-helix appliance may be more successful than removable expansion plates at correcting posterior crossbites and expanding the inter-molar width for children in the early mixed dentition (aged eight to 10 years). The remaining evidence we found was of very low quality and was insufficient to allow the conclusion that any one intervention is better than another for any of the outcomes in this review.
Output:

Authors from the Cochrane Oral Health Group carried out this review update of existing studies and the evidence is current up to 21 January 2014. It includes 15 studies published from 1984 to 2013. Nine of these studies compared fixed (always in the mouth) appliances either against different fixed appliances, or against the same fixed appliance but comparing different rates of expansion. Two studies compared a fixed appliance with a removable appliance. The remaining four studies evaluated other comparisons that were more difficult to classify. There is some evidence to suggest that the quad-helix (fixed) appliance may be more successful than removable expansion plates at correcting posterior crossbites and expanding the top back teeth for children with a mixture of baby and adult teeth (aged eight to 10 years). The remaining evidence we found did not allow the conclusion that any one treatment is better than another. The evidence presented is mostly of low to very low quality due to the small amount of available studies and issues with the way in which they were conducted.