Frankfort Horizontal Plane

The Red Line Represents the Frankfort Horizontal Plane.

The Frankfort horizontal plane is a term medical professionals often use, but many people often do not know what it is and why it matters.

The Frankfort horizontal plane is a plane that medical professionals use as a reference plane. The plane is the imaginary line that starts on the upper part of your ear canal opening to the lower part of the orbitale.

What Is the Frankfort Horizontal Plane?

The Frankfort horizontal plane is an imaginary cranial reference plane useful in craniometry. It is a plane that intersects both porions and left orbitale.

The plane is first determined by the highest point of the upper margin of your auditory canal’s opening. The second point is the low point on the lower margin of your orbit. It is parallel to the floor in panoramic imaging.

Therefore, the Frankfort horizontal plane’s correct position is the upper margins of your ear canals and lower margins of your orbitales, and they should lie in a single plane.

Why Does the Frankfort Horizontal Plane Matter?

This plane is helpful in craniometry. The plane usually orients a human head or skull to help unify and standardize craniometric and cephalometric measurements.

The Frankfort horizontal plane is the skull’s anatomical position, which is extremely crucial for doctors and researchers to help their patients. For instance, a medical professional will likely need to measure the Frankfort horizontal plane to assist in orthodontic planning.

However, it’s not a perfect plane of reference because of individual variation. People with identical facial profiles can still have different Frankfort planes. For this reason, a true horizontal plane with the patient standing in a natural head position is sometimes preferred in craniometry.

How Do I Measure the Frankfort Horizontal Plane?

In infants, a doctor may use a fixed headpiece to measure the plane. The plane should be parallel to the fixed headpiece once the infant’s head is positioned correctly.

If a doctor measures the plane, the position of the head before clinical evaluation is crucial. Incorrect position can lead to mistakes in treatment planning and diagnoses (Naina et al., 2013).

The proper way to measure a Frankfort horizontal plane is with a cephalometric x-ray. It is an x-ray that a dentist often uses to see a complete radiographic image of your profile, which includes the Frankfort horizontal plane.

These x-rays are extraoral, so a dentist does not need to insert film or plates into the mouth. Intraoral bitewing x-rays cannot display the sinus and nasal passages, which is why cephalometric and panoramic x-rays are useful.

You need a panoramic x-ray machine to get a cephalometric x-ray, so you would likely need to see a doctor or dentist to get one.

An adapted machine will have a cephalometric film holder on the mechanical arm. An x-ray image receptor will get exposed to ionizing radiation to create photos of the whole oral structure. A bonus of panoramic and cephalometric x-rays is that they expose the body to less radiation.

How Medical Professionals Take Celaphometric X-Rays

These x-rays are painless. The patient’s head will be put on a mechanical rotating arm. Then a film holder will be put on another arm.

The arm will rotate around the head to get images of the face, teeth, and mouth. The position of your body will determine how clear and sharp the photos are. The images often get magnified by 30% to see any sign of disease, injury, and decay.

The dentist will be able to visualize the entire head’s side profile after capturing the cephalometric x-rays. It will also show the jaw’s relation to the cheekbone, allow teeth measurement, etc.

Some x-ray systems are popular with dentists, like the ORTHOPHOS XG 3D system.

For instance, the ORTHOPHOX XG 3D system scans a patient’s skull for panoramic imaging. In this particular device, you can see a laser light on the patient’s face. The laser light creates a line that identifies the patient’s Frankfort horizontal line.

Alternative Way to Measure the Frankfort Horizontal Plane

You can try to estimate your Frankfort horizontal plane. While it may not be an accurate measurement, it can give you a rough idea. With a side profile, draw a line from your ear canal to the bottom of your orbital bone, which you can feel (or see) under your eyes.

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