Just about the time when a woman starts to wonder if she might be pregnant, around 6 weeks into the pregnancy, primary teeth, (aka baby) teeth begin to form. Incredibly, by the 10th week, the permanent teeth begin to form. Developing teeth form into four lobes, which can be thought of as four balls of clay that blend together over time to create the classic tooth shapes that we are familiar with. Think of the shape of a molar. If you look straight down onto the biting surface of a molar, you will notice a four-leaf clover outline. This shape is due to the melding of the four spherical developmental lobes.
The crown of a tooth develops first and begins to erupt (break through the gums) before the roots are fully formed. Primary teeth (aka “baby teeth” or “milk teeth”) typically erupt around age 6 months, starting with the lower front central incisors. If a baby is early to get his first primary teeth, he will stay on that schedule and will be early with the following eruptions and exfoliation (loss of) primary teeth. The same is true of late eruption. Usually, all primary teeth have erupted by age 3 years and the first baby teeth are lost during kindgergarten. As the permanent teeth make their way to the surface, the roots of the baby teeth resorb away, leaving nothing but tiny crowns attached to the gum tissue. Sometimes the baby tooth’s root does not resorb, in which case, the dentist will wiggle it out to make way for the permanant tooth.
I am still surprised today to sometimes hear adults comment that baby teeth are not important and therefore do not need to be cleaned, restored, and maintained until the permanent teeth erupt. The opposite is true. First, consider the fact that baby teeth have nerves. Ouch! Poor oral hygiene, poor diet, and lack of dental care can not only lead to painful cavities, but also to infection. Infection is so commonly treated with antibiotics that the public has come to believe that antibiotics cure infections, but in the mouth, an infection treated only with antibiotics will only easy pain and swelling temporarily. In addition to antibiotics, the source of the infection must be removed. Often, this is achieved with root canal therapy or extraction. The baby teeth act as an alignment guide for permanent teeth, so premature loss of baby teeth leads to tipping and malalignment as well as increased risk of decay, gum disease and fracture. Baby teeth are important!
From kindergarten through puberty, a child is in the state of mixed dentition, during which they simultaneously lose baby teeth and gain permanent teeth. It’s sometimes called the Ugly Duckling Phase, but I think it’s adorable. During these growth years, a dentist evaluates the size and shape of the jaws. Ideally, the upper teeth slightly overlap the lower teeth in a tiny overbite. In case of an underbite at anytime, the dentist will make note and, depending on the child’s age, may refer to an orthodontist for early intervention. During growth, pressure can be applied on the jaws to encourage or slow growth. This was traditionally achieved with headgear but today it is more common to use intra-oral hardware that is cemented into place temporarily. The main goal is to eliminate jaw size/shape discrepancies. If this is not done during growth, surgery is required as an adult.
As we age, teeth begin to show wear on the biting surfaces. Older populations often have worn through the lighter outer enamel layer to expose the darker dentin layer. Also, our the jaw bones that support our teeth tend to exhibit bone loss over time. As the bone levels drop, the gum tissue levels will follow, resulting in the “long in the tooth” look. One benefit of ageing is that as we age, the inner root canal of a tooth tends to become occluded, resulting in less sensitivity. Ah, a benefit to ageing! With a healthy diet, good oral hygiene, and regular dental visits, it really can be a sweet life for your teeth.