I had horribly crooked teeth and my mother has them too. I was told that I used to touch my gums with my fingers that's why my teeth were crooked.
What are the facts and myths regarding crooked teeth and what are the preventive measures?
The truth seems to be that we don't fully understand all the reasons why one's teeth may grow in crooked.
There are a number of theories, including one that hypothesizes that the change from our early ancestors' hunter-gatherer lifestyle to the modern agrarian lifestyle has resulted in a gradual shortening of the jaw, resulting in less room for the teeth to grow (which, in turn, results in crooked teeth as teeth compete with each other for space).
As far as facts, the only authoritative references I found were in a release by the American Dental Association and the American Academy of Pediatrics Dental's 2013 Fast Facts document (please forgive the American resource bias; they just happen to be the first names I think of when looking for reputable scientific resources).
They both agree that the biggest factor is lack of early childhood dental care.
Both mention that Early Childhood Caries (a.k.a. Baby Bottle Tooth Decay), defined as dental caries (cavities) that occurs in the primary (baby) teeth of young children, is a major contributor to crooked teeth.
If a primary tooth is lost due to tooth decay, the teeth adjacent to the lost tooth may drift into the gap in the jaw, causing the adult teeth to subsequently grow in crooked (or even prevent them from erupting). Healthy primary teeth, on the other hand, help guide the newly erupted permanent teeth into a straight position within the jaw line.
The AAPD's source also mentions two other factors.
The first is poor sucking habits from a pacifier or thumb:
Prolonged sucking can create crooked teeth or bite problems. Early dental visits provide parents with information to help their children stop sucking habits before they affect the developing permanent dentition.
Additionally, early intervention by a pediatric dentist can assist in the development of permanent teeth, and prevent them from growing in crooked:
A pediatric dentist can identify crowded or crooked teeth and actively intervene to guide the teeth as they come in the mouth. Not only will this improve the look of the child’s smile, but early orthodontic treatment may prevent more extensive treatment later.
So, in short, the best preventative measure is early and regular visits to a pediatric dentist.
I have read that that main cause for crooked teeth is due to a narrow upper palate and narrow jaw. These two areas are widened by the kind of sucking during breastfeeding. To receive milk from a bottle us much different, less effort. It also creates a more pleasing looking facial structure. It is recommended to breastfeed for at least three years for straight teeth that fit easily. You can tell your child is on the right track to straight teeth if their baby teeth have spaces between them. It worked for our kids even though my husband and I had terrible teeth and braces.
I'll just add a couple more possibilities, since the causes are not fully known.
Crooked teeth are due to teeth that do not all fit into the jaw. That can in turn be caused either by a jaw that is too small, or by teeth that are too large.
Vitamin D is critical to bone growth, so inadequate vitamin D could contribute to inadequate jaw development.
Tooth size is a function of calcium intake, to a larger extend than bone size, so getting too much calcium - for example, drinking lots of milk - could cause the teeth to be too large.
Both of these may have contributed to my crooked teeth. Years of orthodontics did nothing, but removal of my tricuspids eventually allowed the rest of my teeth to straighten out. Unfortunately, the third molars in my lower jaw were impacted - they grew in sideways - crowding my lower teeth and causing them to become crooked again.