The question of whether 27 teeth is a normal count for an adult is common, and the answer involves understanding the variability of adult dentition. While a full set is often cited as 32 teeth, having fewer is a frequent occurrence that does not automatically signal a problem. The number of teeth an adult has is influenced by genetics, dental history, and the natural development of the human jaw. Exploring the standard count and the reasons for missing teeth provides a clear perspective on why 27 is a count many adults possess.
The Typical Adult Tooth Count
The complete set of adult teeth, known as the permanent dentition, is comprised of 32 individual teeth, split evenly between the upper and lower jaws. These teeth are categorized by function: eight incisors for cutting, four canines for tearing, eight premolars for crushing, and twelve molars for grinding.
The final four teeth are the third molars, commonly called wisdom teeth. Because these teeth frequently cause problems with eruption, misalignment, or pain, they are often surgically removed. Consequently, the practical standard for an adult is 28 teeth, which is the full set excluding the four wisdom teeth. This count of 28 is the baseline against which a count of 27 teeth is most often measured.
Causes of Missing Teeth in Adults
A count of 27 teeth usually means the absence of the four wisdom teeth, plus one other tooth. Since the removal of all four third molars brings the total count down to 28, the single remaining missing tooth is the primary focus. This tooth can be absent for several reasons related to dental health or treatment.
One frequent reason for non-wisdom tooth extraction is severe damage from decay, advanced gum disease, or traumatic injury. A tooth that is too compromised to be saved must be removed to protect the health of the surrounding bone and tissue. Another common cause is orthodontic treatment, where a tooth—often a premolar—is intentionally extracted to create space and relieve severe crowding in the dental arch.
The missing tooth may also be absent due to a developmental condition known as hypodontia. This is a congenital condition where the permanent tooth bud never formed in the jawbone. Studies suggest that up to 20 percent of adults are born with at least one missing permanent tooth, making hypodontia a common cause for a single missing tooth. If a person is missing all four wisdom teeth and has one other tooth congenitally absent, their count would naturally be 27.
Functional Considerations of Having 27 Teeth
While a count of 27 is common, especially if the missing teeth include the wisdom teeth, the functional significance depends on the location of the single non-wisdom tooth. If a tooth other than a wisdom tooth is missing, the resulting gap can disrupt the balance of the bite. The surrounding teeth lose support and can begin to drift or tilt into the empty space over time.
This movement, known as dental migration, can lead to misalignment, which complicates oral hygiene and makes the remaining teeth vulnerable to excessive wear. A shifting bite can also impact chewing efficiency and contribute to jaw joint issues. Additionally, the jawbone that once supported the missing tooth’s root no longer receives stimulation and can begin to resorb, or shrink.
For a person with 27 teeth, a professional assessment of the gap is advised. A dentist can evaluate the bite alignment (occlusion) and determine if the space is causing or will cause problems. Replacing the missing tooth with a dental implant or bridge is often advised to prevent the remaining teeth from shifting and to preserve the jawbone structure. The concern is the potential for the single missing tooth space to destabilize the rest of the dentition.