White Paper · Original Research
Serial Salivary qPCR Across Periodontal Care
An exploratory retrospective analysis of 165 patients tested more than once.
TL;DR
The short version
In a retrospective study, we analyzed 165 patients who had been tested two or more times, 366 saliva samples in all. Between their first and most recent test, measured periodontal microbial burden usually went down. The median Periodontal Pressure Score (PPS) roughly halved, from 31.2 to 14.9.
The most useful finding is about reporting. In about half the patients whose 1–5 risk tier didn’t change, the 0–100 burden score still fell by 5 points or more. A tier-only report would have read “no change.”
This describes what changed, not why. There was no comparison group, and the data can’t show that any treatment worked or that tissue got healthier.
Key findings
Five things the data show
-
Measured burden usually went down
Median PPS fell 11.5 points between the first and most recent test. 112 patients (67.9%) fell by 5 points or more; 4 (2.4%) rose by 5 or more. Patients in PRS tier 4 or 5 dropped from 51 to 21. The spread was wide: some barely moved, a few rose, several reached zero.
-
The continuous score caught what the tier missed
PRS and PPS never moved in opposite directions. But 47 of the 91 patients whose PRS tier stayed the same still had a PPS drop of 5 points or more (28 at a stricter 10-point line). A tier-only report would have read “no change.” This is the finding most specific to reporting both scores together.
-
All six core targets were detected less often
Detection fell for every target, for example F. alocis from 61 to 37 patients and A. actinomycetemcomitans from 35 to 15. The median patient carried three of the six targets at the first test and two at the last. P. gingivalis was the least likely to become undetectable (5 of 22).
-
In a small clinical subset, bleeding fell too, but not in step
17 patients from one practice had chart-level exam data, all treated on the same protocol. PPS fell in all 17 and median bleeding index fell from 32.1% to 4.9%. But how far PPS fell showed little association with how far bleeding fell (ρ = 0.10; 95% CI −0.43 to 0.58). PPS looks like a distinct microbial measure that may complement the exam rather than duplicate it.
-
Burden doesn’t only go down, and one retest can mislead
A few patients rose. In one case the first retest showed a new A. actinomycetemcomitans signal and a more severe pattern, and only the third test came in lower. Among 33 patients with a third test, the median change from second to third was zero, with movement in both directions.
Two scores, one sample
PRS and PPS read the same six measurements differently
Periodontal Risk Score
Sorts the six-organism profile into one of 11 named microbial patterns, each mapped to a risk tier. An organism only counts once it is above its pattern threshold.
Answers: what kind of pattern is this?
Periodontal Pressure Score
A weighted total of how much target DNA is detected across all six organisms. It is continuous, so it moves even when the pattern doesn’t.
Answers: how much burden, and is it moving?
Both scores are computed from the same six qPCR measurements, so agreement between them is not independent confirmation.
Read with care
What this paper does not show
The data support a narrow conclusion: among retested patients, measured salivary microbial burden usually declined. They can’t show the following.
Cause
There was no comparison group. The care given was recorded for only 17 patients, all on one combined protocol, so change can’t be attributed to any therapy, home care or the passage of time.
Clinical outcome
Exam data exist for 17 practice-selected patients only. A lower PPS is not shown to mean healthier tissue.
Score validity
PRS and PPS are internally defined indices. Their weights and cutpoints aren’t tested here, and neither is validated against disease progression.
Measurement noise
The repeatability of PPS hasn’t been reported yet, so some small changes may sit within measurement noise.
Regression to the mean
Patients tested at their worst tend to look better next time, whatever care they receive. The largest drops came from the highest starting scores.
Selection
Practices chose whom to retest, so patients engaged in ongoing care may be over-represented.
In practice
Reading a follow-up result alongside the exam
A follow-up saliva result is one more input to clinical reassessment, not a stand-alone treatment decision. The paper suggests these uses.
Document microbial change
Record what changed on the microbial side alongside your clinical reassessment.
Flag patients for a closer look
Burden that stayed high or rose is a reason to look closely at the next exam.
Show patients movement
PPS shows change that a five-tier score would round away.
Retest at three to six months
A practical interval for prospective evaluation. These data don’t show that any interval is optimal.
The full paper
Methods, tables, four case studies and patient-level data
The 12-page paper covers how the cohort was selected, how both scores are built, organism-level results, the 17-patient clinical subset, and a framework for discussing follow-up results.
Disclosure. IMMYLabs, LLC performs the tests described, developed both scores and markets the test under the OraPath brand. Dental Design Studio, which supplied the clinical subset, is a founding clinical partner of OraPath. The author is co-founder and President of OraPath. This analysis was prepared by the company and has not been peer reviewed.
The OraPath Balance Test is a laboratory developed test performed under CLIA (#37D2236199) in a COLA-accredited (#32679) laboratory. It is intended for adjunctive clinical use and is not FDA cleared. Results are semi-quantitative and support, rather than replace, a clinician’s examination and judgment.