Early endodontic diagnosis is often a challenge. Patients may present with symptoms, but radiographs don’t always show a clear lesion of endodontic origin (LEO), especially in the early stages. By the time a radiolucency becomes visible, tissue changes have already progressed.
A recent study looked at whether quantitative percussion diagnostics (QPD) can detect these changes earlier — specifically by identifying damage in the periodontal ligament (PDL) associated with endodontic pathology.
We know that pulpal infection does not start as a radiographic lesion. It begins with biological changes in the PDL and surrounding tissues. The limitation is that most of our routine diagnostic tools — radiographs, CBCT, sensibility tests — either detect changes late or rely on subjective interpretation.
QPD approaches this differently. It evaluates the mechanical behavior of the tooth under percussion, rather than relying on visual or radiographic changes.
What the Study Did?
The study evaluated a mandibular first molar with a confirmed apical LEO using:
Clinical examination Radiographs and CBCT Quantitative percussion diagnostics
To better understand the findings, the same tooth was also modeled using finite element analysis (FEA). The model simulated changes in the PDL by reducing its mechanical properties to reflect tissue damage.
What Was Observed
QPD produces an energy return graph (ERG), which reflects how the tooth responds to percussion.
A healthy tooth shows a single, smooth peak. A tooth with internal structural changes shows multiple peaks, indicating internal mobility
In this study:
The tooth with an apical LEO showed a distinct multipeak pattern. There was a reduction in the second peak amplitude, suggesting altered PDL behavior. The FEA model closely replicated these findings when the PDL stiffness was reduced
This correlation between clinical QPD data and the simulated model strengthens the interpretation that the changes detected were due to PDL damage associated with the lesion.
The key finding is not just that QPD detects a difference — but what it is detecting.
The altered signal appears to reflect oscillation within the damaged PDL, indicating loss of normal structural integrity. The study suggests that as the PDL weakens, its mechanical response changes — and QPD is able to capture that.
Clinical Relevance
From a chairside perspective, this has practical implications:
Early endodontic lesions may be present before radiographic visibility
PDL damage may be one of the earliest detectable changes
A quick percussion-based test could provide objective data on internal tooth integrity
The study also suggests that QPD testing can be performed quickly — within seconds per tooth — making it feasible as an adjunct in routine diagnosis.
This is not a replacement for radiographs or clinical testing. But it introduces a different dimension — mechanical diagnostics.
In cases where:
Symptoms don’t match radiographic findings
Early endodontic disease is suspected
There is uncertainty in diagnosis
Free for members
Keep reading — it's free
The rest of this article is open to DentalReach members. Create a free account, or sign in, and every article on the site opens in full.