What Is The Project?

Dental radiography is an essential tool for diagnostics of dental diseases. Analysis of radiographs is time-consuming and often error-prone due to a high variety of dental structures, positioning/orientation errors, and the substantial amount of radiographs that need to be analysed. An automatic solution for flagging abnormalities in dental radiographs is needed to improve detection accuracy and to reduce the cost of misdiagnosis. This project aims to use AI to bridge this gap to find and validate such a solution, by building a software prototype enabling computers to recognise normal anatomical structures and differentiate from subtle abnormalities in radiographs. The project has been sponsored by the EPSRC Impact Acceleration Account (IAA) and the Research England Higher Education Innovation Fund (HEIF) Strategic Fund.

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Milestone Completed

We have achieved a great milestone in this project through the strong support from volunteers who helped us identify dental diseases in over 6,000 radiographs in previous workflows.

In the next stage, we will explore how to automatically generate tooth numbers in our radiographs.

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Tooth Notation Adopted

The FDI notation system is a commonly used system for the numbering and naming of teeth and is adopted in this project. In FDI notation, the mouth is divided into Upper Right, Upper Left, Lower Left and Lower Right quadrants along the horizontal and vertical mid-lines. Orientation of the above chart is from "dentist's view", i.e. the subject's right corresponds to notation chart left.

For permanent dentition in adults, each tooth number is designated by 2 digits. The first digit is the quadrant number with: Upper Right = 1, Upper Left = 2, Lower Left = 3, Lower Right = 4. The second digit is the tooth number, starting from 1 from the mid-lines and increment towards the back of the mouth.

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Diseases We Are Looking For

Bone Loss (Periodontal Disease)

Periodontal disease is caused by gram-negative anaerobic bacteria, Which initially cause inflammation in the gums and progresses onto destroying the jawbone and the connective tissue. After the bacteria start to destroy the bone, there is no way to regain that bone naturally after it is lost, which makes periodontitis a very important disease to detect in the early stages.

There are 4 stages to periodontal disease:

Stage 1: gingivitis:
inflammation of the gums and is only diagnosed through visual inspection. It can be reversed via conventional dental hygiene.
Stage 2: initial:
The bone starts to be destroyed and the bone line recedes. Requires dentist intervention to stop and cannot be reversed.
Stage 3: Moderate:
The bone line has receded more creating more space in the gums for bacteria to enter. The bacteria can now enter the bloodstream and affect the immune system. Will need a dentist to perform a deep clean to get rid of and is irreversible.
Stage 4: Advanced:
Is classed as bone loss of more than 50%. Very high chance of losing your teeth in the affected area, severe chance of abscess and infection, and serious loss of jawbone. This stage also has a high chance to spread to other areas of the head and can only be stopped through surgery or laser treatment. This stage cannot be reversed and will most likely result in reconstructive surgery.

Dental Caries (Tooth Decay)

Dental caries or tooth decay is caused by gram-positive coccus bacteria and is the most common dental disease. Most of the time it can be spotted through visual inspection, however, if the affected area is in between teeth, it becomes almost impossible to detect via visual inspection alone. Coincidentally, The most affected area for dental caries is between the teeth, due to widespread poor flossing habits. Cavities caused by caries can be easily treated by cleaning the affected area and applying a filling. However, If the decay is not detected by the dentist, it can cause tooth loss, infections, abscesses, and even lead to periodontal disease.

Stage 1: Enamel De-Mineralisation:
The enamel becomes weaker and more translucent.
Stage 2: Enamel Decay (Early):
Decay starts eroding the hard enamel layer, this stage takes a long time to progress onto the next stage.
Stage 3: Dentin Decay:
Decay has made it to the dentin layer of the tooth. This stage progresses much faster than stage 2.
Stage 4: Pulp Decay (Advanced):
Decay has reached the pulp layer of the tooth which can cause infections.
Stage 5: Abscess (periapical radiolucency):
Decay has caused an infection that has travelled down to the bottom of the root, causing an abscess or cist.

Calculus Plaque (Tartar)

Calculus plaque occurs when plaque has become calcified after gingival crevicular fluid from plaque mixes with the minerals in saliva when the teeth have not been properly cleaned when brushing. Calculus can be supragingival or subgingival, above the gums or below the gums respectively. When viewing calculus on a radiograph, due to the similar densities of the plaque and teeth, it appears as the same shade as the teeth, making it hard to spot by shading alone. However, calculus does not follow the normal profile of the teeth so you can easily spot it by comparing the shape of the affected teeth with a healthy tooth.

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Automatic Generation of Tooth Numbers

Apart from detecting diseases as the major project objective, the automatic generation of tooth numbers for radiographs is the next step to complete an AI-assisted disease detection workflow. The automatic generation of tooth numbers can reduce the administrative workload of dental nurses and dentists when preparing disease diagnosis reports. We aim to generate tooth numbers in collected radiographs according to the FDI notation.

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How You Can Help

The process of labelling the radiographs needed to train the AI models is incredibly time-consuming, for a smaller number of researchers, due to the large number of labelled data needed to train an AI solution. This is why we need you to help us label dental radiographs with the bounding box tools in the classify section. Your contribution will lead to a more accurately trained AI workflow, which in turn could reduce the rate of misdiagnosis from dental radiographs and reduce the administrative workload of dental nurses and dentists.

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Additional Resources

If you want to learn more about dental radiography then feel free to visit these websites:

Tooth Numbering Notations
Diagnosing Caries
Diagnosing Bone Loss
Diagnosing Bone Loss 2
Diagnosing Calculus
Revision Flashcards