Tooth 16: Your Upper Left Wisdom Tooth

Reviewed by the toothcheck Dental Team Independent dentist providing online second opinions.

If your dental record, X-ray or treatment plan mentions "tooth 16" or "#16", it is referring to your upper left wisdom tooth. It is the very last tooth on the upper left side of your mouth, and the final tooth in the upper arch in the Universal Numbering System used by US dentists.

Wisdom teeth are the teeth most often discussed for removal, and a number on a quote can make the decision feel more technical than it is. This guide explains exactly where tooth 16 sits, what its numbers mean in other systems, what commonly goes wrong with it, and how to judge whether a proposed extraction makes sense.

Quick Answer

Tooth 16 is the upper left third molar, also called the upper left wisdom tooth. In the Universal system the upper teeth are numbered 1 to 16 from the patient's upper right to upper left, so 16 is the last one. It is tooth 28 in the FDI system and the upper left 8 in Palmer notation. Many people never develop it, and many who do have it keep it without problems, but it is among the teeth most often impacted, decayed or extracted.

Where Tooth 16 Sits

Imagine looking in a mirror at your upper teeth. The numbering starts at your upper right wisdom tooth (tooth 1), moves forward along the right side to the front teeth (8 and 9 meet at the middle), then continues along the left side and finishes at the back left with tooth 16.

Tooth 16 sits directly behind tooth 15, your upper left second molar. It is typically the smallest and most variable of the upper molars. It may have a normal four-cusp crown, a smaller rounded crown, fused roots or a single short cone-shaped root. Some people have a fourth molar behind it, but that is uncommon.

One detail matters for planning: the roots of upper back teeth sit close to the maxillary sinus, the air space in the cheekbone above them. Upper wisdom teeth are also surrounded by relatively soft, spongy bone and a thick pad of tissue behind them called the maxillary tuberosity. This is why upper wisdom teeth are often (though not always) easier to remove than lower ones, and why your dentist will want to see a clear image of how close the roots are to the sinus before treatment.

Tooth 16 in Every Numbering System

The same tooth has different labels depending on who is writing the chart. If a report from another country or clinic uses a different system, this table translates it.

A common mix-up is confusing tooth 16 with FDI tooth 16, which is the upper right first molar. The two numbers are identical but refer to completely different teeth, so always check which system a document uses. For a full walkthrough of all 32 teeth, see our guide to dental tooth numbering explained.

Why Wisdom Teeth Like Tooth 16 Cause Trouble

Humans usually have the third molars erupt between roughly ages 17 and 25, and modern jaws often have limited space for them. That mismatch is behind most wisdom tooth problems.

Impaction. Tooth 16 may be partly or fully stuck under the gum or bone. Upper wisdom teeth commonly tilt forward toward tooth 15 or sideways toward the cheek. An impacted tooth is not automatically a problem, but it can trap food and bacteria against the tooth in front. Our article on what an impacted wisdom tooth looks like on an X-ray shows the common patterns.

Decay. Because tooth 16 is so far back, it is hard to reach with a toothbrush and floss. Decay can form on the wisdom tooth itself or on the back surface of tooth 15 where the two touch. Decay on the neighbouring tooth is one of the more convincing reasons to act, because it puts a tooth you do want to keep at risk.

Pericoronitis. When a wisdom tooth is only partly through the gum, a flap of tissue can trap debris and become infected, causing pain, swelling, a bad taste and sometimes difficulty opening the mouth. In the upper jaw the flap can also be bitten by the opposing lower tooth, making it worse.

Cheek irritation. Upper wisdom teeth sometimes erupt outward and rub the inside of the cheek, causing ulcers or soreness.

Gum disease. Deep pockets behind the last tooth are hard to clean and can be hard to treat, particularly if the tooth is awkwardly positioned.

Cysts and other pathology. Less commonly, the sac around an unerupted wisdom tooth can enlarge into a cyst. This is typically found on X-ray rather than felt, which is one reason dentists like to image wisdom teeth periodically.

Many wisdom teeth never cause any of these problems. A healthy, fully erupted, opposed (meeting a tooth below) and cleanable tooth 16 can be perfectly fine for life.

The Removal Debate

Extraction of wisdom teeth is common, but the reasons for it are not equally strong, and professionals do not all agree about teeth that are free of disease and symptoms.

Reasons that are widely accepted as justifying removal include:

• Recurrent infection or pericoronitis
• Decay that cannot be restored, in the wisdom tooth or the tooth in front
• Cyst or tumor associated with the tooth
• Resorption or damage to the neighbouring second molar
• Wisdom tooth in the way of other planned treatment such as orthodontics or a restoration

Reasons that are more debated include removing a symptom-free, disease-free wisdom tooth purely to prevent possible future problems. Some dentists recommend this, especially when the tooth is hard to keep clean or when surgery is easier at a younger age. Others prefer to monitor with regular exams and X-rays and treat only if something develops. Both approaches can be reasonable, and the right one depends on your tooth, your age, your oral hygiene, and your health.

Upper wisdom teeth usually involve a simpler extraction than lower ones, but that is not guaranteed. Position, root shape, how far back the tooth sits and sinus proximity all affect the difficulty. Your dentist or oral surgeon should be able to explain why they think your specific tooth should come out, point to it on the X-ray, and tell you what could happen if you wait.

What Imaging Should Show

A panoramic X-ray gives a broad view of all four wisdom teeth, their orientation, the sinus and the surrounding bone. A smaller bitewing or periapical film may show decay or bone loss more precisely. For complex cases, a 3D scan (CBCT) may be used to check the relationship between roots and the sinus.

If extraction is proposed, you can reasonably ask:

• Which problem is the extraction solving? Is it present now or a possible future one?
• Can you show me the issue on my X-ray?
• What are the realistic alternatives, including monitoring? (See alternatives to tooth extraction for what is generally considered before removing a tooth.)
• What are the risks of surgery for this tooth, including sinus involvement?
• Will the fee differ if I remove all four wisdom teeth at once?

For more on what you can and cannot see on a dental X-ray yourself, read reading dental X-rays: what you can see.

When a Second Opinion Helps

Wisdom tooth removal is a good candidate for a second look. It is a recommendation that is often reasonable, but it is also an area where practices differ, and the number of teeth, the use of sedation and the total quote can vary a lot. A second opinion is most useful if:

• The plan is to remove several wisdom teeth and you have no symptoms
• You were told tooth 16 must come out but nobody showed you the problem
• The quote seems high or includes IV sedation that you are not sure you need
• You are planning around a trip, pregnancy, orthodontics or another treatment
• You simply want to know whether monitoring is a reasonable choice

A reviewing dentist can look at your X-rays and written plan, confirm that the numbering matches the tooth being discussed, and give a view on whether removal looks justified, whether watchful waiting is reasonable, and what to ask your treating dentist. Our page on wisdom tooth extraction second opinion walks through this in more detail. The American Dental Association (https://www.ada.org/) also publishes general patient information on wisdom teeth.

FAQ

Is tooth 16 a wisdom tooth? Yes. Tooth 16 is the upper left third molar, the upper left wisdom tooth.

Is tooth 16 upper or lower? Upper. Teeth 1 to 16 are in the upper arch and 17 to 32 are in the lower arch. Tooth 16 is on the left side as you look at the chart from the patient's point of view.

What is the FDI number for tooth 16? FDI 28. In Palmer notation it is the upper left 8.

Does tooth 16 have to come out? Not always. Disease, repeated infection, uncontrolled decay or damage to the neighbouring tooth are strong reasons. A healthy, cleanable tooth can often be monitored.

Is upper wisdom tooth removal easier than lower? Often, yes, because upper bone is less dense and the roots are usually shorter, but difficulty depends on the individual tooth and its position near the sinus.

Final Thoughts

Tooth 16 is just a label for your upper left wisdom tooth. Whether it should stay or go depends on its condition, not on the number. If your dentist has recommended removing it and you want a clear, independent view before agreeing, you can get an online dental second opinion from a licensed dentist. Upload your X-rays and treatment plan, and you will have a plain-English written review in about 72 hours for 59 dollars. You can also read about our X-ray review service if you have images but no plan yet.

Last medically reviewed: October 2026