Comparative study of histological differences according to monopolar radiofrequency tip width.

Monopolar radiofrequency (RF) devices have improved since 2002, with a significant change in the widths of the tip that comes into direct contact with the skin. We compared the histometric changes between different tip irradiation areas. A total of 28 participants were divided into two groups (14 participants per group) and received a single session of monopolar RF on the face using a 3 × 3 cm2 tip (Group S) or 4 × 4 cm2 tip (Group L). Skin biopsies were performed before and 2 months after treatment. The densities of collagen and elastic fibers in the papillary, upper reticular, and lower reticular dermis were assessed using the ImageJ software. Group L had a higher collagen density in all dermal layers before and after treatment than Group S; this was particularly noted among those aged 20-39 years. Among those aged > 60 years, Group S had higher collagen density in the papillary dermis than Group L. A large-width tip resulted in deeper and more powerful skin tightening, and a small-width tip may be more suitable for older adults.