The primary molars, often called “baby molars,” are a temporary set of teeth designed to be shed. The entire set of 20 primary teeth, which includes four first molars and four second molars, will eventually be replaced by permanent teeth. This natural process of shedding and replacement marks the transition from a child’s mouth to an adult’s permanent dentition.
Understanding Primary and Permanent Molars
Children possess 20 primary teeth, and a total of eight of these are molars, with two on each side of the upper and lower jaws. These primary molars are smaller, whiter, and have roots that are more divergent than their permanent counterparts, which helps them accommodate the permanent teeth forming underneath the gums. Their primary function is to help the child chew food efficiently and to hold the space for the adult teeth that will follow.
A frequent source of confusion for parents is the eruption of the first permanent molars, often referred to as the “six-year molars.” These four molars erupt around the age of six, appearing behind the last baby molars without replacing any existing tooth. Because they do not succeed a primary tooth, they are permanent from the moment they emerge and will never fall out naturally. These permanent molars are non-succedaneous, meaning they add to the total number of teeth, increasing the count from 20 primary teeth to the 32 teeth of the complete adult dentition.
The Typical Timeline for Molar Shedding
The shedding of primary teeth follows a general sequence, usually beginning with the front incisors around age six. The molars are among the last of the primary teeth to be lost, which helps maintain the bite and chewing function throughout the mixed dentition period. The first primary molars are typically shed between the ages of nine and eleven years. These teeth are replaced by the first permanent premolars, which are bicuspids with two cusps.
The second primary molars are the last baby teeth to be exfoliated and usually fall out between the ages of ten and twelve years. These are replaced by the second permanent premolars. The process of shedding, known as exfoliation, is triggered by the permanent successor tooth growing beneath the primary tooth. As the underlying permanent tooth develops, it gradually dissolves the roots of the primary molar, a process called root resorption, causing it to loosen and eventually fall out.
The age ranges for molar loss are averages, and a slight variation on either side of the typical timeline is common. This gradual progression ensures the permanent teeth have the necessary space to erupt into their correct positions without significant discomfort.
When Molar Loss Requires Dental Attention
While the natural shedding process is usually straightforward, certain deviations may require professional dental oversight. Premature loss of a primary molar, often due to extensive decay or trauma, can create problems for the developing permanent dentition. When a primary molar is lost too early, the adjacent teeth can drift into the newly created space, reducing the necessary arch length and potentially blocking the permanent premolar from erupting correctly. In cases of early loss, a dentist may recommend a space maintainer, which is a custom-made appliance designed to hold the gap open until the permanent tooth is ready to emerge.
Conversely, delayed loss can occur if the primary molar is retained long past the expected timeline. This sometimes happens because the permanent successor tooth is congenitally missing or is erupting in the wrong direction, known as ectopic eruption. The retained primary tooth can physically block the eruption path of the permanent tooth, requiring a dental assessment to determine if extraction is necessary. Failure to address these issues can lead to crowding, impaction of the permanent tooth, or malocclusion, increasing the need for future orthodontic treatment.