Within-Device Exposure-Setting and Voxel-Size Changes in CBCT Alveolar Bone Measurement for Implant Planning: A Systematic Review

Background: This review examined whether within-device exposure-setting or nominal voxel-size changes in cone-beam computed tomography (CBCT) affect linear alveolar bone measurements for implant planning, separating accuracy from agreement. Methods: Database-specific search strategies and retrieval counts are reported for PubMed/MEDLINE, Ovid Embase, Scopus, and Web of Science Core Collection. Study selection is presented in the updated PRISMA flow diagram. The reported International Prospective Register of Systematic Reviews (PROSPERO) identifier is CRD420261361509. Studies were grouped by outcome, protocol contrast, and experimental model. The Quality Assessment Tool for In Vitro Studies (QUIN) appraisal was performed by one reviewer. A revision-stage source and analysis-unit audit led to withdrawal of the planned inverse-variance meta-analyses and their ±0.5 mm equivalence claims; structured study-level synthesis was used instead. Results: Eight studies addressed linear measurements; two additional reports were retained only as methodological context. Seven linear-measurement studies compared protocols within a device, and one compared different devices. All were experimental. In one five-skull study, mean absolute errors were 0.50, 0.46, and 0.51 mm at 40, 20, and 7 s, respectively. A cadaver study reported mean absolute errors of approximately 1.10–1.20 mm. Small mean between-protocol differences sometimes coexisted with impaired anatomical visibility. Repeated observations were not equivalent to independent specimens, and several required sampling variances could not be reconstructed. Conclusions: Selected within-device protocol changes may preserve average measurements under controlled experimental conditions. The evidence does not establish statistical equivalence, interchangeability of protocol classes, or clinical safety near critical anatomy. Validation in living patients is needed before broad implementation.