Tooth development is the complex process by which teeth form from embryonic cells, grow, and erupt into the mouth. Although many diverse species have teeth, non-human tooth development is largely the same as the process in humans. For human teeth to have a healthy oral environment, enamel, dentin, cementum, and the periodontium must all develop during appropriate stages of fetal development. Primary (baby) teeth start to form between the sixth and eighth weeks in utero, and permanent teeth begin to form in the 20th week in utero. If teeth do not start to develop at or near these times, they will not develop at all. A significant amount of research has focused on determining the processes that initiate tooth development. It is widely accepted that there is a factor within the tissues of the first branchial arch that is necessary for the development of teeth.

Read the rest of this article: http://en.wikipedia.org/wiki/Tooth_development

_______________________________ Today's selected anniversaries:

1265: Summoned by Simon de Montfort, the first English parliament held its first meeting in the Palace of Westminster. (http://en.wikipedia.org/wiki/Palace_of_Westminster)

1320: After reuniting Poland, Wladislaus the Short was crowned king in Kraków. (http://en.wikipedia.org/wiki/Piast_Poland)

1885: LaMarcus Adna Thompson patented the roller coaster. (http://en.wikipedia.org/wiki/roller_coaster)

1892: The first official basketball game was played at the YMCA in Springfield, Massachusetts. (http://en.wikipedia.org/wiki/basketball)

1942: Nazis at the Wannsee conference in Berlin decided the "final solution to the Jewish question", leading eventually to the Holocaust. (http://en.wikipedia.org/wiki/Wannsee_conference)

_____________________ Wikiquote of the day:

"I don't understand politics. I don't understand the concept of two sides. And I think that probably there's good on both sides, bad on both sides, and there's a middle ground. But it never seems to come to the middle ground. And it's very frustrating watching it, and seemingly we're not moving forward." -- David Lynch (http://en.wikiquote.org/wiki/David_Lynch)