Because of their long-lasting results and natural-looking effects. PLLA fillers, such as Sculptra, gradually stimulate collagen production over time, leading to improved skin texture and volume that can last for up to two years. Similarly, calcium hydroxylapatite fillers, like Radiesse, provide immediate volume while also stimulating the body's collagen production, resulting in long-lasting rejuvenation of facial contours. These fillers are favored for their ability to address multiple signs of aging, including wrinkles, fine lines, and volume loss, while producing natural-looking and youthful results that enhance overall facial appearance. Additionally, the gradual collagen stimulation process ensures a smooth transition and avoids the overfilled or unnatural look that can sometimes occur with other types of fillers.