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Measurement of the length of the root canal for the purpose of performing root canals and related dental procedures, for use by a trained professional in general dentistry.

The Apex NRG is used to measure the distance to the apex during root canal procedures. A low frequency low volt AC signal is applied between the lip electrode and the endodontic file, which is inserted into the root canal. The impedance of the tissues between the electrodes change as the file advances toward the root apex and the measured signals are used to monitor the progress of the file in the tooth.

The Apex NRG operates on the measurement of a weak electrical current flowing between two electrodes. One electrode is a metal hook that rests on the patient's lower lip and the other is the endodontic file that is attached to the file clasp and inserted into the canal. Multi frequencies are used to minimize errors that may be introduced by the entrance of conducting materials such as blood into the canal.

The ratio of the impedance values measured in the canal and lip are calculated to provide a measure of the probe tip relative to the apical foramen. The device consists of a main body incorporating the display, a lip hook, a file clasp and an apron clasp. The device is powered by one 200mAH CR2032 battery

Here's an analysis of the provided text regarding the Apex NRG device, focusing on acceptance criteria and the supporting study:

1. Table of Acceptance Criteria and Reported Device Performance

The provided document does not explicitly state formal acceptance criteria with specific thresholds (e.g., "accuracy > 90%"). Instead, the clinical study's objective was to demonstrate substantial equivalence to predicate devices and agreement with radiographic working length. Therefore, the "acceptance criteria" can be inferred as showing comparable performance to the predicate devices and the radiographic method.

2. Sample Size Used for the Test Set and Data Provenance

• Sample Size: The study included 69 root canals from 30 teeth.
• Data Provenance: The study was conducted at the Department of Endodontic, School of Dental Medicine Hebrew University, Jerusalem, Israel. The data is prospective, as patients were evaluated using the device.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

• Number of Experts: The document states that the radiographic working lengths, which served as a ground truth, "were determined by the investigators." It does not specify the exact number of investigators or experts.
• Qualifications of Experts: The experts are referred to as "investigators" from the "Department of Endodontic, School of Dental Medicine Hebrew University, Jerusalem Israel." This implies they are qualified endodontists or dental professionals with expertise in determining root canal length via radiography. Specific years of experience are not mentioned.

4. Adjudication Method for the Test Set

The document does not explicitly describe an adjudication method (like 2+1, 3+1). It states that the radiographic working lengths "were determined by the investigators." This suggests that the investigators established the ground truth without a formal multi-reader adjudication process mentioned in the filing.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, If So, What Was the Effect Size of How Much Human Readers Improve with AI vs Without AI Assistance

• MRMC Study: This was not an MRMC comparative effectiveness study in the context of human readers improving with AI assistance. The Apex NRG is an electronic apex locator, not an AI software. The study compared the device's measurements to other electronic apex locators and to radiographic measurements.
• Effect Size: Therefore, there is no reporting of an effect size of how much human readers improve with AI vs. without AI assistance.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

• Standalone Performance: Yes, the clinical study essentially assessed the standalone performance of the Apex NRG device. The device provides an electronic reading, which was then compared to other electronic devices and a radiographic ground truth. Human intervention was in using the device and interpreting radiographs, but the device's core measurement ability was tested directly.

7. The Type of Ground Truth Used

The primary ground truth used for comparison was radiographic working length, which was "determined by the investigators." This is an expert consensus ground truth based on a diagnostic imaging method.

8. The Sample Size for the Training Set

The document does not mention any training set or details about how the device's algorithms (which likely involve impedance measurements and calculations) were developed or trained. This type of device, an electronic apex locator, likely relies on pre-programmed physics-based algorithms rather than machine learning models that require a 'training set' in the conventional sense.

9. How the Ground Truth for the Training Set Was Established

As no training set is mentioned for the Apex NRG, which appears to be a hardware device with inherent electronic measurement principles, the concept of establishing ground truth for a training set in the AI/ML context is not applicable here. The device's design is based on established electro-physiological principles for apex localization.

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