Humans develop two sets of teeth: the initial deciduous teeth, commonly known as primary or baby teeth, and the permanent teeth that follow. The expected number of teeth lost depends on the stage of life and the reason for the loss. A clear distinction must be made between the normal developmental process of shedding primary teeth and the pathological loss of permanent teeth due to disease or trauma.
The Expected Loss of Primary Teeth
The first set of teeth a person is expected to lose are the 20 primary teeth. This natural shedding process, called exfoliation, is necessary for development, allowing space for the larger adult teeth to emerge. The transition period, known as mixed dentition, typically begins around six years of age and concludes by approximately twelve years of age. The primary teeth fall out because the underlying permanent teeth gradually dissolve the roots as they erupt. By the time a child reaches their early teens, all 20 primary teeth should have been lost and replaced by their permanent successors.
Defining the Standard Permanent Set
The full set of adult dentition totals 32 teeth, divided evenly between the upper and lower jaws. These permanent teeth are categorized into four types, each serving a specific function in chewing and speaking. The set includes eight incisors for cutting, four canines for tearing, eight premolars for crushing, and twelve molars for grinding. The first 28 permanent teeth are considered the functional, essential adult set. The final four teeth to develop are the third molars, commonly known as wisdom teeth, which typically emerge between the ages of 17 and 21 years.
Understanding Non-Essential Tooth Removal
A significant portion of adult tooth loss is due to planned surgical intervention, most commonly involving the third molars. Wisdom teeth are frequently removed because they often fail to erupt properly, becoming impacted due to insufficient space. Impaction can lead to pain, infection, or damage to adjacent molars, and prophylactic removal of these four teeth is common. Another form of non-essential removal occurs in orthodontics, where premolars might be intentionally extracted to create space for aligning severely crowded teeth.
The Goal: Retaining Permanent Teeth
For the 28 essential permanent teeth, the ideal number to lose is zero outside of planned removals. The loss of any of these functional teeth is considered pathological, typically caused by advanced periodontal disease or severe decay. Periodontal disease, which involves chronic inflammation of the gums and supporting bone, is a primary cause of non-planned adult tooth loss. Losing an essential tooth has consequences: the lack of the root eliminates jawbone stimulation, leading to gradual bone density loss. Neighboring teeth often shift into the empty space, disrupting the bite and increasing the risk of further decay and gum disease.