Purpose: Lateral cephalograms are conventionally used for landmark identification and cephalometric analysis, butexpose patients to ionizing radiation. Magnetic resonance imaging (MRI) is increasingly employed to evaluate various tissue types, with dental-dedicated MRI (ddMRI) emerging as a promising modality in clinical dentistry. High-quality MRI could offer a radiation-free alternative for orthodontic diagnosis and treatment planning. This pilot study aimed to evaluate the reliability of ddMRI for 2-dimensional (2D) orthodontic cephalometric landmark identification and annotation. Materials and Methods: Thirteen volunteers (7 men, 6 women; mean age 33±5.2 years) underwent ddMRI. Threeindependent raters identified 2D cephalometric landmarks and annotated their positions on the same ddMRI datasetstwice. The 3D Slicer application was used to identify key orthodontic cephalometric landmarks on multiplanar reconstruction images in the sagittal plane. Intra-rater and inter-rater reproducibility were assessed using intraclass correlation coefficients (ICCs), and reliability was evaluated by nominal differences in linear distance (mm) between annotated points. Results: Intra-rater ICCs ranged from 0.909 to 0.999, and inter-rater ICCs ranged from 0.988 to 0.999, indicating excellent intra- and inter-rater reliability. Bland-Altman plots were used to display mean differences (mm) and limits of agreement (±1.96 standard deviations) between annotations to assess potential biases. Conclusion ddMRI is a feasible imaging modality for 2D orthodontic landmark identification. Based on intra- andinter-rater reproducibility values, ddMRI demonstrates high reliability in identifying key orthodontic cephalometric landmarks, providing a radiation-free alternative for orthodontic diagnosis and treatment planning.

Purpose: This study proposes an ex vivo imaging protocol using a dental-dedicated magnetic resonance imaging (ddMRI) system and qualitatively and quantitatively evaluates the effects of phosphate-buffered saline (PBS) washing on image quality. Materials and Methods: Four half-maxillae and 4 half-mandibles from human cadaveric donors were scanned using a ddMRI system with a dental-specific coil. Two pulse sequences (“anatomy” and “inflammation”) were applied. Each specimen was imaged at 4 time points: immediately after PBS immersion and after 24, 48, and 72hours of washing, totaling 64 images. Image quality was evaluated using signal-to-noise ratio (SNR), contrast-tonoise ratio (CNR), and conspicuity of anatomical structures: cortical bone, medullary bone, root contour, soft tissue,and the sinus floor/mandibular canal. Conspicuity was rated by 3 observers and analyzed using the Cochran Q test (α = 0.05). Results: Cortical bone, medullary bone, and the sinus floor were depicted in all images; root contours (91.1%) and soft tissue (85.9%) were visible in most images. PBS washing did not significantly impact conspicuity (P>0.05).Signal intensity was higher in “anatomy” than “inflammation.” In the “anatomy” sequence, both SNR and CNRinitially declined, then stabilized from 24 hours onward. CNR between medullary bone and soft tissue showed thegreatest improvement with extended PBS washing, especially for the “inflammation” sequence. Conclusion The proposed ddMRI protocol enabled consistent visualization of dentomaxillofacial structures in ex vivo samples. PBS represented a suitable carrier. Although PBS washing did not influence conspicuity, at least 24hours of washing may improve image quality, as reflected by SNR and CNR.