## 4 Discussion
Three-dimensional information can thus be obtained by means of a conventional imaging modality like the panoramic radiograph [27]. Despite the benefit of these changes, limiting the FOV to the ROI remains a significant factor in reducing the effective radiation dose [1,9]. [PERSON] et al. showed that a dose reduction of approximately 82% is possible with the selection of the smallest FOV (4 \(\times\) 4 cm) rather than the largest (17 \(\times\) 12 cm) [28]. The vertical limitation of the FOV in particular helps to protect radiation-sensitive organs such as the thyroid gland or the eye lenses and thus contributes to a reduction in the effective dose [29]. As a secondary approach for dose optimization, the modulation of tube voltage (kV) and tube current (mA) can reduce the dose used by standard protocols by up to 40% [1]. PL could be diagnosed much more frequently with CBCT than with conventional imaging methods such as panoramic and periapical radiography [30,31]. 3D imaging could be particularly relevant in cases where there is a discrepancy between the diagnostic findings of the intraoral X-ray and the clinical situation. In such cases, possible clinical causes like, e.g., untreated root canals (MB2) or root resorptions, are visualized [32]. As the FOV does not seem to have a significant impact on detectability with CBCT, it should be chosen to be as small as possible [25]. Indeed, our results indicate that a sufficient dose reduction can be achieved with the application of the low-dose protocol without any significant detriment to the detectability of periodontal lesions. A recent review has shown that CBCT can visualize periodontal lesions with fraction involvement and allows for the adequate examination of periodontal defects in the bucco-oral dimension [6,33]. However, the application of CBCT in the diagnosis of marginal bone resorption is still a second-level imaging method, following primary 2D radiological evaluation [33]; with the application of the low-dose protocol, the clinical examination can benefit from 3D information without risking significant radiation exposure. In support of this argument, [PERSON] et al. recently showed that dose-optimized CBCT is sufficient for the assessment of periodontal structures [15]. For the assessment of anatomical landmarks such as the buccal lamella and the maxillary sinus or the diagnosis of fractures, 3D information can be crucial for clinical decision-making. Low-dose CBCT has been shown to be sufficient for adequately diagnosing midfacial fractures as well as for pre-surgical implant planning [34, 35, 36]. Low-dose protocols also have potential application in the radiological follow-up of bone pathologies (e.g., fibro-osseous lesions), as 3D data may reveal changes earlier than 2D information collected with conventional radiography. In addition to the aforementioned limitation of having not employed a clinical study design, the present investigation may have also been limited by our means of evaluating the CBCT datasets; as the evaluators received the same training in recognizing the four lesion types, a learning effect may have influenced our findings, leading to better diagnostics in later performed CBCT analyses. However, as the evaluators in the present study had at least two years of experience with CBCT images at the time of evaluation, this learning effect during the study should have been negligible. Concerning the expected increased use of low-dose CBCT in the future, it should be noted that the reporting of 3D datasets is more complex compared to 2D datasets, and thus requires specific training [37].