May 2011 in “Archives of Plastic Surgery” This study found that the inverted U-shape hairline is the most common among Korean male adults in their 20s and 30s, with an increased prevalence of the M-shape in their 30s.
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March 2011 in “Dermatologic Surgery” This study classified hairline contours in Asian women and concluded that their refined hair transplantation techniques may help correct wide foreheads with M-shaped or rectangular hairline contours.
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January 2014 in “Annals of Dermatology” This study surveyed hairline preferences and found that the M-shaped contour was most preferred overall, with lower forehead heights favored by men and those without a history of hair transplantation.
July 1998 in “Dermatologic Surgery” Various techniques and tools for hair restoration were presented in 1998, including a mathematical model for donor area, use of lasers in surgery, methods for controlling grafted hair direction, and ways to increase graft yield. Satisfaction rates were around 39%, and studies showed trauma and dehydration can damage hair follicles.
July 2026 in “Innovations in Pharmaceutical Sciences & Care” In this case report, a 31-year-old man with frontal hairline recession saw a marked improvement in hair density and scalp appearance after undergoing six mesotherapy sessions alongside twice-daily application of 5% minoxidil, attributed to the treatment protocol combining nutrients, bioactives, and topical minoxidil.