The process of a child replacing their primary, or deciduous, teeth with permanent teeth is a natural and staggered period of development. This transition, which is sometimes referred to as the mixed dentition phase, begins when the twenty baby teeth start to be shed and the thirty-two adult teeth begin to emerge. It is a multi-year process that typically starts in early childhood and continues until the beginning of the teenage years. While the general timeline is predictable, the exact speed and sequence can vary significantly from one child to another.
The Typical Eruption Sequence and Timeline
The first permanent teeth usually appear around age six, often before the first baby tooth has fallen out. The first set to emerge are the permanent first molars, which erupt in the back of the mouth behind the existing primary molars. These four molars are sometimes called the “six-year molars” and are important because they help establish the proper bite and alignment of the jaw.
Shortly after the first molars, the primary teeth begin to exfoliate, or shed, with the permanent teeth pushing them out. The lower central incisors—the two bottom front teeth—are typically the first baby teeth to fall out, usually between ages six and seven. They are quickly replaced by the permanent central incisors, followed by the lateral incisors between ages seven and nine.
The eruption of the remaining teeth, including the canines and premolars, occurs over the next several years, continuing until around age 12 or 13. Premolars replace the primary molars and generally appear between ages 10 and 12. Canines often emerge between ages 9 and 12. Once a baby tooth falls out, the permanent successor often appears in the gum within a few weeks to a couple of months, but the total completion of this phase, excluding wisdom teeth, takes approximately six to seven years.
Factors That Influence Tooth Eruption Speed
The timing of permanent tooth eruption is primarily dictated by genetic programming. A child’s dental timeline often mirrors that of their parents or siblings. If a child’s parents experienced late teething or a delayed start to the permanent dentition phase, the child is likely to follow a similar pattern. This inherited tendency is the most significant factor determining the overall speed of the process.
A child’s overall health and nutritional status also influence the speed of eruption. A diet lacking in essential nutrients, particularly calcium and Vitamin D, can slow the formation and emergence of teeth. Similarly, conditions like premature birth or low birth weight have been linked to a generally slower developmental timeline, which can include delayed tooth eruption.
The premature loss of a primary tooth, due to decay or injury, can also affect the eruption speed of the permanent tooth. If a baby tooth is lost very early, the permanent tooth may take longer to appear. Conversely, if there is a lack of space in the jaw due to crowding, the path of the emerging permanent tooth can be physically blocked, leading to a delay.
When to Consult a Dentist About Delays
While a variation in timing is normal, there are specific instances when a professional evaluation is warranted. A significant delay is generally considered a delay of more than six months between the loss of a primary tooth and the appearance of its permanent replacement. Parents should also be concerned if a tooth has erupted on one side of the mouth, but the mirror tooth on the opposite side has not appeared after several months.
A dental visit is also necessary if a permanent tooth begins to emerge while the baby tooth it is meant to replace is still firmly in place, a situation often referred to as “shark teeth.” This can lead to alignment issues. The presence of severe pain, swelling, or an infection in the gums around an area where a tooth is expected to erupt also requires immediate attention.
The dentist can take an X-ray to see the developing permanent teeth beneath the gum line, checking for issues like impaction or the absence of a permanent tooth bud. This imaging can determine if the delay is simply a normal variation or if it is caused by a structural problem. Early assessment ensures that any potential complications are addressed before they can negatively affect the child’s bite or jaw development.