Apparatus and method for tooth pulp vitality detection
Inventors
Tang, Cha-Min • Schmitt, Joseph
Assignees
US Department of Veterans Affairs
Publication Number
US-11666223-B2
Publication Date
2023-06-06
Expiration Date
2038-02-22
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Abstract
An apparatus provided for detecting tooth pulp vitality includes a handle, a pivot and a caliper. A pair of fiber optic lines pass through an interior of the handle, the pivot and the caliper. One of the fiber optic lines is a source line with a connector at an end of the source line and another of the fiber optic lines is a detector line with a connector at an end of the detector line. The source line is single mode in the handle and the detector line is multi mode. A system is also provided for detecting tooth pulp vitality that includes the apparatus. Additionally, a method is provided for detecting tooth pulp vitality that employs the apparatus.
Core Innovation
An apparatus, system, and method are provided for detecting tooth pulp vitality using a pair of fiber optic lines passing through a probe configured to engage opposite sides of a tooth or sample. The system improves detection of motion, such as blood flow in the tooth pulp, by employing a source line that is single mode and a detector line that is multi mode. It uses an optical source emitting adjustable bandwidth light, a reference path with adjustable delay line, and a detector to measure interference signals caused by Doppler shifts from scatterers within a defined target volume, such as the pulp region.
The invention addresses limitations and problems seen in prior art techniques like laser Doppler flowmetry (LDF) and Doppler optical coherence tomography (DOCT). Existing LDF methods lack sufficient sensitivity to pulp flow, cannot isolate signals from the pulp region due to interference from surrounding gum tissue, and use single mode fibers that complicate use of reusable probes. DOCT devices, while offering imaging capabilities, are costly and complex. The present system mitigates these drawbacks by using a transmission-mode optical configuration with an optical reference channel, a tailored spectral emission profile, and a probe geometry that achieves both high sensitivity to pulp flow and specificity by excluding signals from gum tissue.
To enhance specificity, the system adjusts the coherence length of the output light via bandwidth control such that only scattered light from the target volume within the tooth generates an interference signal, while scattered light from outside the target, e.g., from gum tissue, does not. The adjustable delay line positions a zero delay plane in the target volume so that optical path lengths from the target and the reference path match at the detector. The probe includes a handle, pivot, and caliper, with fiber optic lines passing through these parts. A removable caliper allows sterilization or disposal of the probe tip. The invention also describes methods of engaging opposite sides of the tooth at or below the cemento-enamel junction to optimize signal quality and reduce interference from enamel and gum tissue.
Claims Coverage
The claims include one independent system claim and one independent method claim. These claims focus on the combination of a probe with specific fiber optic configurations, an optical source with adjustable bandwidth, a reference path with adjustable delay, and processing to position a zero delay plane and vary coherence length, enabling detection of motion in a designated target volume within a tooth sample.
Probe with single mode source line and multi mode detector line
The probe comprises a pair of fiber optic lines including a single mode source line with a connector and a multi mode detector line with a connector, arranged to engage opposite sides of a sample (e.g. tooth).
Adjustable optical source bandwidth and coherence length
An optical source emits output light with adjustable bandwidth to vary the coherence length, enabling selective interference from the target volume while suppressing signals from outside the target volume.
Adjustable reference path delay line for zero delay plane positioning
A reference path includes an adjustable delay line to position a zero delay plane equalizing optical paths between scattered light from the target volume and reference light, enhancing selective interference detection.
Detection and processing of Doppler-shifted interference signal
A detector coupled to the reference path and detector line receives light and a processor uses stored instructions to adjust the delay line and bandwidth, and to determine motion within the target volume based on Doppler shifts from the interference signal.
Probe geometry and removable caliper design
The probe includes a handle, pivot, and caliper through which fibers pass; the source line is single mode at least in the handle and multi mode in the removable caliper which allows for detachable, sterilizable or disposable probe tips.
Couplers for distribution and combining optical signals
Use of a single mode coupler to split output light between source line and reference path, and a multi mode coupler to combine scattered light and reference light before detection to improve signal-to-noise ratio.
Real-time adjustment of output light intensity
The system adjusts the intensity of the optical source output based on scattered light intensity to accommodate different tooth conditions and ensure sufficient signal strength.
Method steps for tooth engagement and measurement
The method involves engaging opposite sides of a tooth with the probe, emitting adjustable bandwidth light into the source line, receiving light at a detector from the reference path and sample, adjusting the delay line to position the zero delay plane in the pulp region, tuning bandwidth to differentiate pulp from gum tissue signals, and determining pulp motion from Doppler shifts.
Collectively, the claims cover a system and method employing tailored fiber optic probe geometry with single and multi mode fibers, adjustable optical source bandwidth and reference path delay, and processor-controlled adjustments to localize and detect motion in a tooth's pulp while suppressing interference from surrounding tissues, facilitated by a removable, sterilizable probe tip design.
Stated Advantages
Increased sensitivity to detect pulp blood flow while rejecting blood flow signals from surrounding gum tissue.
Improved specificity by isolating scattered signals from the pulp region and excluding those from gum tissue and periodontal ligament.
User-friendly and low-cost probe with detachable, sterilizable or disposable tips suitable for multiple individuals.
Reduced complexity and cost compared to existing techniques such as DOCT, while maintaining adequate sensitivity and reliability.
Real-time, non-invasive detection suitable for handheld use without moving parts.
Adjustable parameters (bandwidth, delay line) enable tuning the coherence length and zero delay plane position for optimal detection.
Documented Applications
Tooth pulp vitality detection to evaluate the need for root canal procedures due to tooth decay, infection, or trauma.
Detection of blood vessels during electrode insertion for stereotactic neurosurgery.
Detection and avoidance of large blood vessels during anesthesia injection, catheterization, cerebrospinal fluid collection, and interventional surgeries.
Vessel avoidance in the brain during deep brain electrode placement.
Verification of blood flow cessation in ligated vessels during open surgical procedures.
Monitoring in non-medical applications such as engines, microfluidic devices, and micro-electro-mechanical systems (MEMS) where flow detection is important.
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