Reference
How the Periodontal Risk Score is calculated
The Periodontal Risk Score is a 1–5 score on the Oral Balance Test report. It is derived from which periodontal organisms are detected together in a saliva sample and what detection-level tier each one reaches, rather than from any single organism's level. The logic is rule-based and documented. The score describes a microbial profile, not a patient's periodontal condition, and is interpreted by a clinician alongside an examination.
Why a combination, and not a threshold
The simplest way to score a panel is to take the highest number and grade it. The Periodontal Risk Score does not do that, because the organisms on the panel are not independent of one another.
Two profiles on the Oral Balance Test can carry the same three core periodontal organisms and receive scores at opposite ends of the range. Among the worked examples the report publishes, a profile with P. gingivalis, T. denticola and T. forsythia all present at trace levels scores 2, while a profile with those same three at moderate-to-high levels scores 5. The organisms are identical; what differs is how much of each is there.
The reverse holds too. A single organism at a high level does not automatically outrank several at moderate levels, because co-detection of organisms associated with each other in the literature is part of what the score responds to.
So the score is a reading of the profile as a whole: which organisms appear together, and what tier each one reaches.
The five detection-level tiers
Every target on the Oral Balance Test is reported at a Detection Level on a 0–30 scale, where DL = 40 − Ct and each additional level represents roughly twice the quantity of target DNA. For scoring, each organism's Detection Level is placed in one of five tiers.
Detection-level tiers
The tier boundaries are per-organism. The cutpoints differ between targets.
| Tier | Rule |
|---|---|
| Not detected | DL = 0 |
| Trace | Above 0, below 3 |
| Low | 3 up to the organism's moderate cutpoint |
| Moderate | The moderate cutpoint up to the high cutpoint |
| High | At or above the high cutpoint |
A. actinomycetemcomitans uses tighter cutpoints
Most periodontal targets on the panel — P. gingivalis, T. denticola, T. forsythia and F. alocis — reach the Moderate tier at Detection Level 10 and the High tier at 14.
A. actinomycetemcomitans does not. It reaches Moderate at 4 and High at 8.
The cutpoints are tighter because A. actinomycetemcomitans is associated with disease at substantially lower abundance than the other targets, so the same Detection Level does not carry the same meaning across organisms. A reading of 9 is below the Moderate tier for P. gingivalis and above the High tier for A. actinomycetemcomitans.
This is why the report is read by tier rather than by comparing raw numbers across rows.
The same pattern does not always score the same
This is the part most easily misread, and it follows directly from the tiers.
The report names the profile it identifies — “Isolated Aa Detection”, “Pg + Td Synergistic Pattern”, and so on. A name describes which organisms are involved and how they relate. It does not by itself determine the score.
Take the clearest case. A profile showing A. actinomycetemcomitans alone is an Isolated Aa Detection whether that organism sits in the Moderate tier or the High tier. At the Moderate tier the Periodontal Risk Score is 3. At the High tier it is 4. Same pattern, same single organism, different tier, different score.
So the score is a function of two things together: the pattern, and the tiers the organisms in it reach. A list pairing each pattern name with one score would be wrong, and this page does not publish one.
The five score bands
A band describes the microbial profile in the sample. It is not a stage, a diagnosis, or a measure of tissue damage.
| Score | Band |
|---|---|
| 1 | Low risk |
| 2 | Mild risk |
| 3 | Moderate risk |
| 4 | Elevated risk |
| 5 | Severe risk |
"Moderate" means two different things
The report uses the word “Moderate” on two different scales, and they are not the same thing.
A Detection Level tier describes one organism: its Detection Level sits between that organism's moderate and high cutpoints.
A score band describes the whole profile: a Periodontal Risk Score of 3.
A sample can contain an organism in the Moderate tier without receiving a Moderate band, and can receive a Moderate band with no organism in the Moderate tier. When reading the report, check which scale a word belongs to.
The thirteen named patterns
Thirteen patterns are named on the report:
No Pathogens Detected · Fn-a Bridging Pattern · Multi-Organism Trace Pattern · Early Dysbiosis Pattern · Isolated Aa Detection · Core Pathogen Dominant · Dual Pathogen Profile · Low-Level Multi-Pathogen Pattern · Pg + Td Synergistic Pattern · Aa-Amplified Inflammatory Profile · Multi-Pathogen Inflammatory Profile · High-Risk Synergistic Pattern · Severe Multi-Pathogen Profile
They are listed here without scores beside them, for the reason given above: a pattern name does not map to a single score. Worked examples, each showing a representative profile and the score that profile receives, are on the Pattern Recognition page.
High-Risk Synergistic Pattern describes P. gingivalis, T. denticola and T. forsythia together — the group described in the periodontal literature as the red complex.
Why the score is rule-based, not machine-learned
The Periodontal Risk Score is produced by documented, version-controlled, rule-based logic. The inputs are measured Detection Levels and the tiers they fall into. The logic applied to them is written down and reproduces the same score from the same inputs.
It is not artificial intelligence and not machine learning. No model is trained on patient data, and no score changes because of what other patients' samples contained.
What the score does not tell you
A Periodontal Risk Score describes the periodontal organisms found in one saliva sample at one point in time. It is not a diagnosis of periodontal disease, it does not measure attachment loss, pocket depth, bleeding or bone level, and it does not establish that the organisms detected are causing anything a patient is experiencing.
A score of 5 is not a finding of severe periodontitis, and a score of 1 does not rule periodontal disease out. Organisms are one input a clinician weighs against an examination, radiographs, probing findings and a patient's history.
The Oral Balance Test is a laboratory developed test performed by IMMYLabs under CLIA. It has not been cleared or approved by the FDA, and results are intended to support a clinician's assessment rather than replace one. Anything a score raises is a reason to discuss it with your dentist.