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Title: The use of CBCT as an aid to endodontic assessment of calcified canals
Author: Dodd, M. N.
ISNI:       0000 0004 7428 7403
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2018
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Introduction: Endodontic treatment requires access to the pulp canal by removal of coronal dentine above this space. Calcification of the pulpal space can result from the deposition of secondary dentine which occurs throughout life or tertiary dentine in response to caries, toothwear or trauma. This increases the difficulty of endodontic treatment. The use of 3-dimensional radiographic techniques such as CBCT are being increasingly adopted for endodontic treatment planning. The role of such imaging in the management of endodontically involved calcified teeth remains unclear especially in terms of the sensitivity and specificity of canal detection. The presence of restorative materials may influence the detection rate by the introduction of artefacts into the image but there is little evidence in the literature as to the extent of these effects. Finally, there is growing interest in integration of CBCT imaging with data from intraoral scanning that could potentially be used to fabricate guides that reduce the amount of dentine removed during access of calcified teeth and improve the efficiency of the treatment. Literature review. The literature was reviewed in relation to the physiology of secondary and tertiary dentine deposition and the aetiology of severely calcified or obliterated pulp spaces. Papers suggesting treatment strategies for severely calcified teeth are discussed and studies investigating the benefit of preserving the maximum amount of dentine during endodontic access were summarized. Finally, studies investigating the use of CBCT in canal detection and the integration of these images with other technologies to produced guided access were reviewed. Aims. The aims of this thesis were to develop a soft and hard tissue phantom to provide sufficient clinical realism; to determine the root canal dimension of extensively sclerosed teeth using micro CT; to investigate the ability of CBCT in detecting root canal anatomy in sclerosed teeth compared with PA. Methodology: The first study involved testing several materials and a radiographic phantom was produced from a real mandible and polyurethane. This was then validated as a viable soft tissue analogue of to conduct the subsequent CBCT study. A second study in which 48 calcified lower anterior teeth were selected from a tissue bank and scanned with µCT at 20 µm resolution, reconstructed and imported to Mimics software allow morphometric analysis of the canal dimensions and configuration. A final study combined the phantom and teeth from the µCT study which were then used of the to obtain clinically realistic CBCT and PA images of teeth used in the µCT study using the Morita Accuitomo 170 scanner and DIGORA phosphor plate system. Six interpreters were then asked to identify the more coronal portion of the canal on both the CBCT and PA images. Results: Analysis of the phantom in a conventional CT machine showed Hounsfield values for the soft tissue analogue that were equivalent to soft tissue. µCT results shows canals were almost always present at the level of the CEJ and fairly centred within the root. Canal diameter was highly variable but the average diameter at the most coronal point was 173 µm (SD = 157 µm). The most common canal configuration was Vertucci class I (n=17) followed by class III (n=11). Observers identified canals from the incisal edge to the first observed pulp space at a mean distance of 10.15 mm (SD = 3.94) in the PA group and 6.79 mm (SD = 2.38) in the CBCT. This was a mean difference of 3.36 mm between PA and CBCT groups (95% CI = 1.71, 5.02) and was statistically significant (p<0.001, paired t-test) Conclusions Polyurethane can be used as an acceptable soft tissue substitute in the construction of a radiographic imaging phantom. Calcified canals exhibit varying lumen diameters but do not tend to regress far from the CEJ. Observers using CBCT consistently identify calcified canals at a more coronal position when compared to phosphor plate digital radiography. Application: Improvement in the knowledge of the microanatomy of calcified canals CBCT and calcified canals will aid in the treatment of these case and aid in the development of reliable and practical methods that improve technical and healing outcomes. Within the limitations of the study it would appear that CBCT is able to locate canal at a more coronal position than PA radiography.
Supervisor: Jarad, Fadi ; Youngson, Callum Sponsor: Not available
Qualification Name: Thesis (D.D.Sc.) Qualification Level: Doctoral