Fine lines and wrinkles. They are so often linked together, one is practically synonymous with the other?but aren?t they different? Does it matter when researching products and treatments? We asked?Dr. Robyn Gmyrek, MD, widely affiliated with Columbia University Medical Center?s Department of Dermatology and practicing at Union Square Laser Dermatology, where she draws the line: ?Most dermatologists understand fine lines as being one to two millimeters in depth,? she explains. That?s about as thin, or even thinner, than a thread. These shallow folds are caused by lax, sagging skin and are associated with the earliest signs of aging or photo damage. When you?re reading about clinical studies of any given product or treatment, the ?improvement in the appearance? of fine lines is typically found by comparing plaster molds of the subject?s skin from the start to the end of the trial period. The change of depth in these faint folds measured under analysis machines determines the effectiveness of the treatment. Wrinkles are a bit more complex. Generally speaking, they are any lines that are deeper than 2mm. Wrinkles are predominantly caused by muscle contractions under the skin, which is why they show up were you make the most facial expressions, like squinting, frowning and smiling. Repeated facial muscle movements, contracting and releasing in the same way, over years create folds along those habitual lines. But, there are different types of wrinkles to understand as well. Dr. Gmyrek explains, ?A dynamic wrinkle is a wrinkle that occurs only with movement. If you frown and you make that number eleven between your eyebrows, that?s a dynamic wrinkle. If you relax and that wrinkle stays, then you have a?static wrinkle, or a a?wrinkle at rest.? How do you prevent a dynamic wrinkle from turning into a static wrinkle? ?If you are still moving your face, you are not going to be able to get rid of that wrinkle,? Dr. Gmyrek confirms. ?You?re constantly contracting that muscle. It?s like doing bicep curls at the gym and expecting not to have definition or build up your biceps. It?s impossible to put cream on your bicep and expect that muscle not to get stronger over time.? Fine lines usually best describe the earliest signs of aging?women in their 30?s and 40?s are their target market. As you age, the perfect storm of collagen breakdown and repeated muscle movements cause deeper wrinkles. It?s good to understand these differences when researching skincare products, but when you want to get a cosmetic treatment to deal with them, don?t worry too much about semantics. A reputable dermatologist will take one look at your lines and know exactly what to do, wether it?s freezing them with a little?Botox?or resurfacing your skin with a laser like?Fraxel. Consult?The Book?to find a?qualified cosmetic doctor?in your neighborhood.