This is a technique for augmenting the forehead that is used to make the forehead more attractive. Most of the patients in this study were cis women, but a few were men. It is not clear if the men were trying to feminize their foreheads.
The authors were surgeons who used the procedure on 547 patients over a 13 year period; 516 of them were included in the study (the others did not return for the three-month follow-up). 45 of the patients were male, 471 were female.
Most of the patients were satisfied with the procedure and there were no major complications. 60 patients (12%) were not satisfied with the result, 28 people (5%) returned for a reoperation to fix things. The authors use the reoperation rate to evaluate the procedure. The authors modified their technique over time and the reoperation rate in 2008-2011 was lower than the rate in 1999-2002.
The article does not say if the people who were dissatisfied with the operation were female or male.
As in many studies, the authors of the paper are the surgeons who performed the operations. They may be biased in favor of their own work.
Forehead Augmentation with a Methyl Methacrylate Onlay Implant Using an Injectin-Molding Technique by Dong Kwon Park, Ingook Song, Jin Hyo Lee, and Young June You in Arch Plast Surg. Sep 2013; 40(5): 597–602..