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Seongmo Dental Clinic · Seongbuk-gu, Seoul

Q-ray · Quantitative Light-Induced Fluorescence (QLF)

Told "you're fine" one time and "you have a cavity" the next — you didn't know which to believe.

Now red fluorescence lets
you see it with your own eyes and decide.

Seongmo Dental Clinic operates the Q-ray system (QraycamPro, Qray Pen, Qscan Plus), which uses quantitative light-induced fluorescence technology. When a harmless blue light is shone on a tooth, areas with high bacterial activity glow red, letting us show you hidden problems right in front of your eyes.

Sungshin Univ. Seongmo Dental Clinic Quantitative Light-Induced Fluorescence (Q-ray)

EARLY CAVITIES
Early detection
COMPLEMENTS VISUAL/X-RAY LIMITS
DIAGNOSTIC METHOD
Blue-Light Fluorescence
No radiation
EXPLANATION
On-Screen Sharing
Reviewed together with you
We prove problems you couldn't see, in red light. A diagnosis free of overtreatment starts with looking together.
TECHNOLOGY
Quantitative Light-Induced Fluorescence (QLF)
COMPONENTS
QraycamPro · Qray Pen · Qscan Plus
RADIATION
None (Visible Light)
USED FOR
Checking cavities/cracks/gum inflammation
01
What is Q-ray

Sungshin Univ. dental Q-ray —
what does it actually detect?

Q-ray captures and analyzes the fluorescent response that appears when a specific-wavelength blue light is shone on a tooth. Areas with high bacterial activity and demineralized tooth tissue show up as red fluorescence, revealing early problems easily missed by the naked eye or X-ray.

QLF
Quantitative Light-Induced Fluorescence
red fluorescence
Areas of bacterial activity
No radiation
Based on visible light

The challenge in dental diagnosis is that early problems don't show up on the surface. X-rays are good for seeing cavities or bone conditions that have already progressed significantly, but they struggle to catch early surface demineralization or fine cracks.

Seongmo Dental Clinic introduced the Q-ray system to make up for this limitation. Shining a harmless blue light causes only the problem areas to glow red, showing you the hidden cause directly with your own eyes.

Q-ray Core Technology

Early Detection of Initial Cavities
Initial cavities that used to be easy to miss because they're symptomless and invisible are now revealed in red light. Catching them early can reduce how much tooth structure needs to be removed, or allow preventive management instead.
Diagnosing Hidden Secondary Cavities
Detects secondary decay progressing hidden in the gaps of existing crowns, inlays, or composite fillings.
Detecting Fine Cracks
Visually shows fine tooth cracks — a common culprit behind unexplained pain — along with the bacterial activity around them, enabling data-based diagnosis instead of guesswork.
Detecting Gum and Peri-Implant Inflammation
Detects inflammation hidden deep in the gums or around implants, allowing early identification of periodontal disease and peri-implantitis and management of its progression.
Transparent Care You See Together With Us
By explaining while looking at the red areas together on a monitor, you can directly understand and connect with why treatment is needed.

Q-ray, which finds even problems you can't see, is Seongmo Dental Clinic's commitment to honest diagnosis without overtreatment.

02
Early caries

Early and Secondary Cavities —
why are they so easy to miss?

Early cavities are at the stage where minerals are leaching out beneath the surface, so there's barely any visible color change, and secondary cavities are hidden under a prosthetic, making them hard to read even on X-ray. Fluorescence analysis reveals the difference in bacterial activity in these areas as color.

Beneath the Surface
Detects early demineralization
Around Prosthetics
Detects secondary decay
Progress Comparison
Re-imaged under the same conditions

A cavity doesn't appear suddenly — it begins as acid produced by bacteria slowly leaches minerals out of the tooth surface. Catching it at this stage leaves room to reverse it with management instead of removing tooth structure.

Seongmo Dental Clinic records Q-ray images and compares them under the same conditions at your next checkup. Being able to confirm progression with data lets us separate what to watch from what to treat, instead of defaulting to "let's just fill it."

Criteria for Watching Without Drilling

When We Watch
If it's judged to be early demineralization with the surface still intact, we monitor progress along with fluoride application and improved oral hygiene.
When We Treat
If fluorescence intensity and extent show signs of progression, or the surface has broken down, we treat it following a minimal-removal principle.
When Deciding on Prosthetic Remake
If secondary decay is confirmed beneath a prosthetic, we check its extent and respond with options like a same-day PrimeMill restoration.

Knowing exactly when to treat is the way to remove the least amount of tooth structure.

03
Crack & gums

Unexplained Sensitivity —
Even Cracks and Gum Inflammation

Q-ray can also detect bacterial activity around a tooth crack and inflammation around gums or implants through fluorescence, helping find the cause of pain that photos and X-rays alone couldn't explain.

Fine Crack
Identifies cause of pain
Periodontal Inflammation
Early detection
Implants
Manages peri-implantitis

Sensitivity only when chewing, or pain when force is applied in a specific direction, can indicate a fine crack. The crack itself often doesn't show up well in photos, but if bacteria settle into the crack, the fluorescence response can offer a clue.

Seongmo Dental Clinic also uses 3D CT and T-scan occlusal analysis alongside this. Checking whether excessive occlusal force is being applied to a suspected cracked tooth lets us plan management of the underlying cause as well.

Diagnostic Equipment Used Together

3D CT (HDX Dentri)
Checks periapical lesions, bone condition, and the 3D structure of a suspected cracked tooth.
T-scan Digital Occlusal Analysis
Measures which tooth bears force, when, and how much, to manage the cause of cracks and fractures.
EMS Powder Cleaning
Gums and implant areas with confirmed inflammation are managed with PERIOFLOW® cleaning, and progress is rechecked.

The cause of pain is usually revealed not by a single device, but by a combination of data.

04
Trust

Worried About Overtreatment —
It Disappears When You See the Screen With Us

Seongmo Dental Clinic explains why treatment is needed while viewing Q-ray fluorescence images together on a monitor, and keeps records to compare changes at your next checkup.

Looking Together
Explained on a shared monitor
Record Comparison
Tracks change between checkups
Radiation-Free
Low burden for repeat imaging

The moment patients feel most uneasy is when they can't verify something even after hearing an explanation. Fluorescence images let you distinguish red areas from normal areas without any specialized knowledge, giving the explanation something to point to.

Because Q-ray doesn't use radiation, repeat imaging for follow-up carries little burden. Located near Exit 2 of Sungshin Women's University Station, Seongmo Dental Clinic has built up diagnostic records through comprehensive dentistry specialist care since opening in 1998.

Diagnostic Process

01 — Fluorescence Imaging
We image the teeth and gums with QraycamPro/Pen. There's no pain or radiation exposure.
02 — Reviewing Together
We look at the red areas together on screen and explain their location and meaning.
03 — Treatment Plan & Record
We separate areas to watch from areas to treat, and record the images to compare at your next checkup.

Only an accurate diagnosis prevents overtreatment and makes exactly the treatment you need possible.

Comparison

Conventional Diagnosis vs. Quantitative Light-Induced Fluorescence

COMPARISONVisual/X-Ray AloneSeongmo Dental Clinic with Q-ray
EARLY CAVITIESHard to detect before color changeEarly detection via fluorescence
Secondary CavitiesReading limited, hidden by prostheticFluorescence check around prosthetic
Fine CrackDoesn't show well on imagingChecks bacterial activity around crack
Gums/ImplantsMainly probing/X-rayFluorescence check of inflamed area
RADIATIONExposure during imagingNone (Visible Light)
Patient ExplanationMainly verbal explanationExplained with shared images

Q-ray doesn't replace conventional diagnosis — it complements it, and the final diagnosis is made by combining clinical examination and imaging.

Glossary

Quantitative Light-Induced Fluorescence — Glossary

Quantitative Light-Induced Fluorescence (QLF)
A technology that checks and quantifies tooth demineralization and bacterial activity based on fluorescence differences produced by light of a specific wavelength.
Demineralization
The early cavity stage where minerals like calcium and phosphorus leach out of the tooth surface.
Secondary Cavities
Decay that progresses again around or beneath an existing prosthetic or filling.
Fine Crack
A thin crack in a tooth. Can cause a sharp pain when chewing.
Peri-Implantitis
Inflammation of the gum/bone around an implant. Pain is minimal, so early detection matters.
Fluoride Application
A preventive treatment that helps remineralize early demineralized areas.
FAQ

Sungshin Univ. Q-ray Diagnosis — FAQ

Does the Q-ray exam involve radiation?

Q-ray is a fluorescence imaging method that uses blue visible light and doesn't use radiation. It also carries little burden for monitoring progress through repeat imaging.

Is it painful or time-consuming?

It works by shining light on the teeth and imaging them, so there's no pain and no anesthesia needed. The imaging itself is quick.

Does that mean I don't need X-rays?

No. Fluorescence analysis shows surface and bacterial activity information, while X-ray/3D CT show internal and bone information, so they complement each other. Seongmo Dental Clinic uses both together to make a judgment.

If it shows red, do I have to be treated no matter what?

Red fluorescence is a signal of possible bacterial activity or demineralization, but it isn't a treatment order by itself. We look at surface condition, depth, symptoms, and progression together to separate what to watch from what to treat.

Can it also be used for children's checkups?

Since it's radiation-free and painless, it's very useful even for pediatric checkups where cooperation can be difficult. That said, X-rays are added when necessary.

How much does the exam cost?

The exam items and scope depend on the treatment. Non-covered items can be checked on Seongmo Dental Clinic's Fee Guide page, and we'll let you know after diagnosis.

References

References — Authoritative Medical Sources

Related Treatment Info

Results of any dental treatment can vary with individual oral condition, and whether a device applies depends on the case. Treatment method should be decided after a precise diagnosis and thorough consultation with your provider.