A beautiful, authentic smile is an involuntary form of self expression. Universal in its message, a smile can communicate joy, excitement, and caring, all without language.
From a dentist's perspective, the essence of smiles is in their anatomy as well as cosmetic artistry. However, instead of writing about veneers, whitening, or any of the other many services and techniques that can enhance a smile, I thought it might be interesting to present some research on the phenomenon of the smile itself.
In 1862, the French neurologist G.B. Duchenne studied the muscles that cause us to smile and arrived at some interesting conclusions. A necessary characteristic of any smile, he found, is that the corners of the lip pull up with the help of the cheek muscles (zygomatic major). However, true joy is expressed on the face by the combined contraction of the muscles around the lips and very importantly, muscles around the eyes (orbicularis oculi). Of the two types of smiles, one being voluntary, Duchenne said, "the first obeys the will, but the second is only put into play by the sweet emotions of the soul." Artificial smiles can be performed at will because the brain signals that create them come from the conscious mind, prompting contraction of (zygomatic major) muscles in the cheeks. Real smiles come from another part of the brain and in addition to the zygomatic major muscles, also cause the orbicularis oculi muscles to contract around the eyes, as mentioned in PsychologyToday. This might be why we use the expression "sparkle in the eyes" when we talk about someone who is truly happy.
There are two main types of smiles and an authentic smile correlates with overall health, emotional fulfillment, and longevity. Psychologists LeeAnne Harker and Dacher Keltner analyzed 141 college yearbook photos of women, then matched up the smile ratings with personality data collected during a 30-year longitudinal study. Women who displayed true, Duchenne-worthy expressions of positive emotion in their 21-year-old photos had greater levels of general well-being and marital satisfaction at age 52, than those whose smiles were not Duchenne-worthy.
In a more recent study published in the Journal of Psychological Science, Ernest Abel and Michael Kruger of Wayne State University extended this line of research from emotional outcomes to a biological one: longevity. Abel and Kruger rated the smiles of professional baseball players captured in a 1952 yearbook, then determined each player's age at death (46 players were still alive at the time of the study). The researchers found that smile intensity correlated to longevity, with those smiling the biggest living longer than those who didn't smile at all.
The Duchenne smile is perceived as more sincere, honest, friendly, and approachable. Cultivating such a smile would have a positive influence on a person's feelings, state of being, and may influence his or her interpersonal relationships. So regardless of your age or sex, if you want to live a long and happy life, the Duchenne smile may be the most valuable gift you can give another person -- or yourself.