Cone-beam computed tomography in assessment of alveolar clefts

<p dir="ltr">Children born with an alveolar cleft receive a higher radiation dose compared to other children at the same age. In addition, children are more sensitive to radiation in comparison to adults. The aim of this thesis was to investigate potential dose reduction strategies in radiological examinations of alveolar clefts and to evaluate the outcome of bone grafting of bilateral alveolar clefts.</p><p dir="ltr">Paper I evaluated whether the radiation dose could be reduced by applying a low-dose protocol instead of the standard protocol. The study assessed the visibility of anatomical structures adjacent to the alveolar cleft with a blinded study setup. The result showed no significant difference between the low-dose protocol and the normal dose protocol. Using a low-dose protocol in cone-beam computed tomography (CBCT) examinations of alveolar clefts reduced the dose by approximately 70%.</p><p dir="ltr">In paper II, the outcome of two-step bone grafting in bilateral alveolar clefts was evaluated by calculation of bone fill through comparison of preoperative and postoperative cleft volumes. After bone grafting, no significant difference was observed when comparing the first and second operated alveolar cleft. The mean bone fill was 40% in the whole cleft. The bone fill in the nasal part was 12% and 52% in the dental part of the alveolar cleft. The cleft volume on the passive side did not change after bone grafting the cleft on the contralateral side.</p><p dir="ltr">Paper III investigated possible dose reduction by decreasing the field of view (FOV) of the CBCT examination of unilateral alveolar clefts. The project assessed two FOV reduction protocols, one larger, which fully included the upper canines, incisors and the alveolar cleft. The smaller FOV reduction protocol fully included the central incisor and canine adjacent to the cleft, and the alveolar cleft. A FOV of 50 x 40 mm was suggested to depict the anatomical structures of the larger FOV reduction protocol with a 41% dose reduction. For the smaller dose reduction protocol, a FOV of 35 x 40 mm was suggested with a dose reduction of 56%.</p><p dir="ltr">Paper IV assessed detection of dental anomalies between CBCT and two- dimensional (2D) radiological examinations of the maxilla and the alveolar cleft. Dental anomalies were found among 92% of the children with an alveolar cleft. PAN radiographs, CBCT, and a combination of PAN + IO radiographs. To reduce the radiation dose, 2D radiological examinations are recommended for assessment of dental anomalies. The most found dental anomalies were hypodontia followed by atypical morphology, microdontia, displaced teeth, and supernumerary teeth. The lateral incisor adjacent to the cleft was the tooth most frequently registered as missing.</p><h3>List of scientific papers</h3><p dir="ltr">I. Lemberger M, <b>Regnstrand T,</b> Karsten A, Benchimol D, Shi XQ. Low- Dose Cone-Beam Computed Tomography for Assessment of Alveolar Clefts: A Randomized Controlled Trial in Image Quality. Plast Reconstr Surg. 2024 Apr 1;153(4):897-903. doi: 10.1097/PRS.0000000000010588. Epub 2023 Apr 25. PMID: 37092973.<br><a href="https://doi.org/10.1097/PRS.0000000000010588">https://doi.org/10.1097/PRS.0000000000010588<br></a><br></p><p dir="ltr">II. <b>Regnstrand T,</b> Bousiou A, Karsten A, Benchimol D, Jacobs R. Volumetric Assessment of Resorption Patterns of Bilateral Alveolar Clefts in Cone-Beam Computed Tomography in Two- Stage Bone Graft. Orthod Craniofac Res. 2025 Jun;28(3):527-533. doi: 10.1111/ocr.12902. Epub 2025 Feb 4. PMID: 39905629; PMCID: PMC12056464.<br><a href="https://doi.org/10.1111/ocr.12902">https://doi.org/10.1111/ocr.12902<br></a><br></p><p dir="ltr">III. <b>Regnstrand T,</b> Top SK, Karsten A, Jacobs R, Benchimol D. Dose Reduction by Field of View Optimisation in Cone-Beam Computed Tomography of Unilateral Alveolar Clefts. Orthod Craniofac Res. 2025 Oct;28(5):820-825. doi: 10.1111/ocr.12938. Epub 2025 Apr 22. PMID: 40261632; PMCID: PMC12418059.<br><a href="https://doi.org/10.1111/ocr.12938">https://doi.org/10.1111/ocr.12938<br></a><br></p><p dir="ltr">IV. <b>Regnstrand T,</b> Karsten A, Jacobs R, Benchimol D. Radiological detection of dental anomalies in the anterior maxilla of patients with alveolar cleft, comparing 2D and 3D imaging modalities. [Submitted]</p>