Digital subtraction radiography for monitoring carious lesions using clinical radiographs

Dental caries (tooth decay) is still a common problem. It is caused by the action of acid from the bacteria in the biofilm (plaque) on teeth, dissolving mineral from the tooth and leading to cavities. It is a dynamic process as early demineralisation lesions can remineralise with Calcium and Fluoride from saliva. Many diagnostic tools are available, but radiographs are the most common.<br/><br/>Dental caries diagnosis using radiographs is carried out by dental professionals everywhere. One of the most challenging current problems is to determine whether a carious lesion is static, progressing or regressing.<br/><br/>Digital subtraction radiography (DSR) has been available for several years and has a possible application in monitoring progression and regression of carious lesions over time. DSR is the process of computerised subtraction of grey values of geometrically corresponding pixels in digital radiographs taken at different times. The effect is to subtract out the unchanging background and magnify any changes that might have occurred. It is possible to visualise or measure changes in radiodensity over time. This has clinical and research applications that include monitoring lesions in tooth or bone that are accompanied by mineralisation changes.<br/><br/>One of the biggest limitations to the use of DSR clinically, however, lies in obtaining exact reproducibility in radiograph orientation at different time points and therefore sufficient geometrical standardisation of the images to produce images of useful diagnostic quality after subtraction. The effectiveness of digital subtraction radiography for assessing demineralisation of occlusal cavities (mimicking the carious process) has already been established in vitro. This project will follow on from that research, by establishing if radiographs taken in a clinical setting with non-standardised radiographic holders generate images which would allow for clinically useful DSR.<br/><br/>Radiographs were collected from different sources: Dundee Dental Hospital PACs system; a study on caries from New Zealand and a study on the Hall Crown Technique in Scotland. The radiographs were screened for suitable image pairs that showed possible caries stasis/progression/regression and digital subtraction images were produced for each pair. The subsequent paired images and subtraction images were scored by 11 clinicians for demineralisation and they rated their confidence using a 5-point certitude scale.<br/><br/>The results show the overall Intraclass Correlation Coefficient (ICC) for paired images to be 0.52 and DSR to be 0.58. Further analysis of the overall ICCs showed an improvement in ICCs with DSR compared to paired images for radiographs from mesial, distal and occlusal surfaces and also with permanent teeth. When the ICCs from the individual sources of the radiographs (PACS, NZ and Hall) were examined an improvement in ICCs was noted with NZ and Hall radiographs.<br/><br/>Therefore, to conclude, the ICCs indicate that the DSR images produced a higher reliability reading than viewing the pairwise images separately. Images produced in a non-standardised way in a clinical practice setting are sufficient to generate satisfactory DSR images.

Name dc:type.qualificationname

Master of Dental Science

Level dc:type.qualificationlevel

Master's Thesis

Grantor dc:publisher.institution

University of Dundee

Year dc:date.issued

2021

Author dc:creator

• Esler, William Henry

Advisors dc:contributor.advisor

• Innes, Nicola
• Ricketts, David

Language dc:language

eng

Identifier

oai:discovery.dundee.ac.uk:studenttheses/c32ed379-f47f-4058-8908-f3ddc7fce07f

OAI identifier oai:identifier

oai:discovery.dundee.ac.uk:studenttheses/c32ed379-f47f-4058-8908-f3ddc7fce07f