No one human trait can stand alone as a benchmark of health and esthetics, but many fields of science have concluded that quickly identifying healthy perspective mates has an evolutionary basis. Indeed, most of us can assess attractiveness only after a few seconds. 1  Age, symmetry, strength, skin tone, and healthy teeth imply good genes and lack of disease, so one might say that sizing up the opposite sex is a proxy for a physical exam and a My Ancestry report. Both sexes prefer physically attractive mates and have preferences for the level of attractiveness sought in a potential partner. Males have reported stronger preferences for attractiveness relative to females, but females are more selective. The reason for the different preferences between males and females is that males spend less time rearing children compared to females. They, therefore, look for traits that guarantee the maximal survival of offspring. Females, on the other hand, choose mates who are more likely to provide longer-term resources to ensure their children survive. 2

Sexual Attractiveness

We often hear that physical traits of attractiveness are learned through cultural dissemination. However, across different cultures, certain mate-choice traits are somewhat universal. Many studies have found a high degree of agreement between individuals within a particular culture and individuals from different cultures. 3 Preferences are more a difference in degrees of preference than absolute between the sexes. 4 In a recent study, females rated age, education, intelligence, income, trust, and emotional connection around 9 to 14 points higher than males on a scale of 100. 5 Because females lose their fertility and males don't, males are likelier to prefer young females at peak fertility. Other evidence shows that males consider more bodily traits when their mating goals are short-term and female facial features when the intentions are long-term. 6

Facial Features and Attractiveness

As I mentioned, men probably use facial features when selecting mates since estrogen alters certain features of the lips, cheeks, and jawline. In addition, estrogen inhibits bone growth in a woman's lower face and chin, making them relatively small and short, as well as the brow, allowing her eyes to appear larger. 7 Across many animal species, males compete for select females through fighting and displays like peacock tails. So, heterosexual women control mate choice through a similar sexual selection. For Instance, male peacock tails are difficult to grow and maintain, so females prefer larger, more prominent ones because the owner is stronger and healthier, having produced and survived with it. So women prefer masculine faces, especially today, where offspring survival is higher and economic conditions are more favorable. Therefore, the effects of high testosterone, stronger jaws, prominent brow ridges, larger midface, and thinner eyes are generally preferred. In addition, more masculine-looking men tend to have more muscular physiques, greater strength, dominance, and competitive ability.  

However, women also rate masculine men as less stable mates, so when long-term paternal support is important, women may prefer less masculine faces. In addition, reports that women's preferences for masculine features fluctuate with their menstrual cycle have been cast in doubt. 8 Finally, preferences for women change with age; perimenopausal women have different preferences. 

Sexiness and Smiles

In a recent study by the Invisalign company, 94% of respondents noticed the other person's smile upon meeting them for the first time. In addition, 84% thought that an attractive smile is important for considering marriage. Additionally, one-third would not consider matching their friends with someone with crooked teeth. Finally, 86% recognize that attractive teeth make us more desirable to the opposite sex. Interestingly, they were less likely to notice eyes, height, or physique. 9 

Smiles Reflect Health and Communicate Desire

I mentioned ornamental displays of peacock tails, and several lines of evidence point towards teeth functioning as a human ornamental display. In addition, smiling is a universal human behavior and is usually viewed positively by those receiving them. Additionally, smiling is one of the first indications of sexual interest. Lastly, mutually shared smiles are one of the first occurrences in a courtship. 

Tooth loss is scientifically associated with poor general health, nutritional deficits, cognitive disorder, cardiovascular disease, stroke, increased risk of death, and, more than likely, a turn-off. In addition, the absence of teeth may also indicate previous trauma or dental caries and gum disease, which reflect poor oral hygiene and negative psychological characteristics, which are poor attributes for a mate. 10

What Constitutes a Sexy Smile

Teeth and eyes, jawlines, cheekbones, eyebrows, and hair traits, are important factors and present the whole picture. But let's put them aside and concentrate on smiles. I mentioned smiles develop best when genetics are sound, disease is low, and trauma has been minimal. Additionally, with age, teeth can wear, decay, break, become darker, and be lost. Gums can recede, become red, swollen, and infected as well. I often talk about how our ancestors rarely had cavities and gum disease, but disease, violence, and starvation were prevalent. However, decay and gum disease looks similar to the detrimental effects of starvation, trauma, and poor genetics, making their presence highly notable as undesirable. So these poor traits repel mates.

The Smile Features That Matter Most

 In optimal conditions, natural female teeth should have a light shade, a high lip line, a large display of teeth, and symmetry. Men's smiles should have a light shade, a moderate display of teeth, a moderate lip line, and symmetry. A 2012 study looked at the spacing of teeth and their color. The researchers digitally manipulated and combined the parameters on male and female subjects and asked them to be rated by the opposite and same sex. As expected, straight teeth were preferred over crowded and spaced teeth. In addition, men rated straight women's teeth across all colors as more desirable. However, the darker teeth, more than likely because they indicate the bearer as older, were also less desirable. Unfortunately, the results suggest that ratings of the attractiveness of female faces are more sensitive to digital manipulation than male faces, regardless of which sex is doing the rating, which may explain why females are more concerned about the appearance of their teeth than men. Studies show that women smile more and try to draw attention to their smiles with lipstick. 11 Besides demanding more attention, lipstick enhances the lips, making teeth appear lighter in contrast. Additionally, red lips mimic sexual arousal. 12 

Whitening Teeth Has Its Limits

One of the manipulations in the study was making teeth appear lighter than normal. Interestingly, there was no difference in attractiveness. But whitening does enhance attractiveness because those who seek to do it usually have stained teeth. The bottom line is that normal lightness is adequate for mate selection, whereas ultra-white teeth may only attract the attention of model agencies and media casting directors. 11

How to Have a Naturally Sexy Smile

To enhance the sexiness of our smiles, we need to focus on producing straight, naturally colored teeth, which is best accomplished by providing optimal nutrition to ourselves during our childbearing years, especially during pregnancy. Breastfeeding is a must for optimal tooth, arch, and jaw growth. Providing hard foods around one year of age is also important for adequate jaw growth. Identifying tongue ties and poor tongue posture is also important. Lastly, it is key to ensure that our children keep their mouths closed while not eating, laughing, or talking. For more information on all of these important factors, see this post. 

How To Achieve a Sexier Smile

For those who missed out, there is always orthodontics and whitening. Additionally, crowns, veneers, and dentures all improve esthetics when done properly. Please remember that the research shows that we only need normal-looking tooth shades. According to science, making our teeth super white is not necessary to attract the opposite sex. More studies may prove otherwise. Remember, don't fret if your teeth are not straight and light. They are not the only requirement for attracting people. Our overall appearance and demeanors are much more important than any one trait. 

Conclusion

I have only scratched the surface regarding whether teeth are sexy. Lipline, tooth size, shape, profile view, and the shape of our smile are all important factors in cosmetics. However, I can confidently say that straight teeth with a naturally light color can help attract the opposite sex. So yes, teeth can help us be sexy, but I don't believe they are stand-alone sexy. If I showed you a picture of just teeth, you could judge whether they were nice; however, without seeing the rest of the face, I doubt you would think of them as sexy. As I mentioned, many other facial features, expressions, and behaviors are also very important; too many to include in this post. Remember, teeth are not the only requirement for attracting people. Our overall appearance and demeanors are much more important than any one trait.