Ever looked at someone and thought their face just seemed a bit "collapsed"? Maybe you’ve noticed your own chin getting closer to your nose over the years, or perhaps you’re dealing with a jaw ache that simply won't quit. It’s not just aging. Honestly, it’s often about a measurement most people have never heard of: the vertical dimension.
In clinical terms, vertical dimension in dentistry is the distance between two selected points—usually one on the tip of the nose and one on the chin—when the teeth are touching or the jaw is at rest. It sounds simple. It’s not. It’s basically the "height" of your face, and when it’s off, everything from your smile to your ability to chew a steak starts to fall apart.
Why Vertical Dimension is More Than Just a Measurement
Think of your mouth like a kickstand on a bike. If the kickstand is too short, the bike leans too far and eventually tips. If it’s too long, the bike won't stay up. In your mouth, your teeth are the kickstand. When they wear down due to grinding (bruxism) or erosion, that vertical height shrinks. This is what we call a loss of OVD, or Occlusal Vertical Dimension.
It’s a sneaky process. You don't wake up one day with a shorter face. It happens over decades. But the impact is massive. When you lose that height, your facial muscles have to over-contract just to get your teeth together. This leads to that "sunken" look around the mouth, often making people look ten years older than they actually are. It’s not a skin problem; it’s a structural support problem.
The Two Sides of the Coin: OVD vs. VDR
We usually talk about two specific types of vertical dimension. There’s the Occlusal Vertical Dimension (OVD), which is the height when your teeth are biting together. Then there’s the Vertical Dimension of Rest (VDR). This is where your jaw sits when you’re just hanging out, watching TV or reading.
The space between these two is called the "freeway space." Normally, it’s about 2 to 3 millimeters. If a dentist gives you a new set of crowns or dentures and doesn't leave that gap? You’re going to be miserable. Your muscles will constantly feel strained because they never get to "rest." It’s like trying to hold a squat for 16 hours a day.
What Happens When the Vertical Dimension Collapses?
If you lose your vertical height, you aren't just losing tooth structure. You’re losing function. People with collapsed OVD often report:
- TMJ Issues: The jaw joint gets pushed back and up into a position it wasn't designed for.
- Angular Cheilitis: That’s the fancy name for those painful cracks at the corners of your mouth. Because the face is "shorter," saliva pools in the corners of the lips, leading to fungal infections.
- Muscle Fatigue: Your masseter and temporal muscles are working overtime.
- The "Witch's Chin": As the mandible rotates forward and upward, the chin becomes more prominent while the lips seem to disappear.
Dr. Frank Spear, a legendary figure in restorative dentistry, has often discussed how "masking" these problems with simple cosmetic fixes like veneers without addressing the underlying height is a recipe for failure. You can’t just put pretty teeth on a collapsed foundation. They'll break.
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The Mystery of "Increasing the Bite"
Can you just add height back? Yes. But it’s risky business. For a long time, the dental community was terrified of changing a patient's vertical dimension. There was this old-school belief that the "Rest Position" was unchangeable—fixed for life.
We know better now.
Studies, including classic research by Carlsson and others, have shown that the neuromuscular system is surprisingly adaptable. You can increase the vertical dimension, but you have to do it carefully. You don't just glue on some tall crowns and send the patient home.
Usually, a "test drive" is required. A dentist might use an orthotic or a temporary "overlay" denture. This lets the patient live with the new height for a few weeks. If the headaches go away and the patient stops biting their tongue, you know you’ve found the "sweet spot."
The Kois Deprogrammer and Finding "Centric"
Finding the right vertical dimension often starts with finding the right jaw position. John Kois, founder of the Kois Center, developed a tool called a deprogrammer. It’s a small plastic appliance that prevents the back teeth from touching. By breaking the "muscle memory" of a bad bite, the jaw can finally settle into its most relaxed, anatomically correct position. Only then can a dentist accurately measure how much height needs to be restored.
Dealing with Extreme Wear
Let's talk about the "nubs." We've all seen someone—maybe a lifelong smoker or a heavy grinder—whose teeth are worn down to tiny yellow squares. In these cases, restoring the vertical dimension in dentistry isn't an elective cosmetic choice. It's a medical necessity.
When teeth are that worn, there’s no room for restorative materials. If a dentist tries to put a crown on a tooth that’s only 3mm tall, it’ll pop off the first time the patient eats a bagel. By increasing the OVD, the dentist creates "restorative space." This gives the new crowns enough height to actually stay attached to the teeth.
It’s a massive undertaking. It often involves "full mouth reconstruction." Every single tooth is treated to harmonize with the new height. It’s expensive, it’s time-consuming, and honestly, it’s one of the most difficult things a dentist can do.
Misconceptions That Can Ruin a Treatment
One of the biggest myths is that a "collapsed" look always means you need to height. Sometimes, it’s just tooth position.
Another mistake? Thinking you can determine the perfect vertical dimension using a single formula. Some people use the "Golden Proportion" or various calipers. While the "Willis Gauge" is a classic tool for measuring the distance from the eye to the mouth corner versus the nose to the chin, it's not a rule. Human faces are asymmetrical. What works for a 6-foot-4 man won't work for a 5-foot-2 woman.
You also have to consider phonetics. The "S" sound is the ultimate test. If you increase the teeth too much, the patient will "clack" their teeth together when they try to say words like "sixty-six." If they can't speak clearly, the vertical dimension is wrong. Period.
The Role of Technology: 2026 and Beyond
We've come a long way from biting on wax rims. Today, we use digital jaw tracking and T-Scan technology to see exactly how teeth are meeting in real-time.
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Digital smile design allows us to show a patient what their face will look like before we touch a drill. We can virtually "open" the bite on a 3D model of the patient’s skull and see how it affects the airway. That’s a huge point—sometimes, increasing the vertical dimension can actually help with sleep apnea by creating more room for the tongue.
Actionable Steps for the Concerned Patient
If you suspect your bite has collapsed or you’re experiencing chronic jaw pain, don't just ask for veneers. Here is how you actually handle it:
- Ask for a "Comprehensive Exam": Not just a cleaning. You want a structural evaluation of your OVD.
- Check Your "S" Sounds: Look in the mirror. When you say "S," do your front teeth almost touch? If there’s a huge gap, or if they hit hard, your vertical might be off.
- The "Rest" Test: Close your eyes and let your jaw go slack. Does it feel natural, or do you feel a "pull" in your cheeks?
- Request a Wax-Up: Before committing to permanent work, have the dentist create a model of your teeth at the proposed new height. You need to see it in 3D.
- Consider a Specialist: This is the realm of Prosthodontists. They are the "architects" of the mouth and spend an extra three years of residency specifically studying things like vertical dimension.
Vertical dimension is the "hidden" architecture of the human face. It dictates how we eat, how we talk, and how we age. Ignoring it during dental work is like building a skyscraper on shifting sand. You might get away with it for a year or two, but eventually, the foundation always wins.