Accuracy Assessment of Three-dimensional Surface Reconstructions of In vivo Teeth from Cone-beam Computed Tomography

Background： The accuracy of three-dimensional （3 D） reconstructions from cone-beam computed tomography （CBCT） has been particularly important in dentistry, which will affect the effectiveness of diagnosis, treatment plan, and outcome in clinical practice. The aims of this study were to assess the linear, volumetric, and geometric accuracy of 3 D reconstructions from CBCT and to investigate the influence of voxel size and CBCT system on the reconstructions results. Methods： Fifty teeth from 18 orthodontic patients were assigned to three groups as NewTom VG 0.15 mm group （NewTom VG; voxel size： 0.15 ram; n = 17）, NewTom VG 0.30 mm group （NewTom VG; voxel size： 0.30 ram; n - 16）, and VATECH DCTPRO 0.30 mm group （VATECH DCTPRO; voxel size： 0.30 ram; n = 17）. The 3D reconstruction models of the teeth were segmented from CBCT data manually using Mimics 18.0 （Materialise Dental, Leuven, Belgium）, and the extracted teeth were scanned by 3Shape optical scanner （3Shape A/S, Denmark）. Linear and volumetric deviations were separately assessed by comparing the length and volume of the 3D reconstruction model with physical measurement by paired t-test Geometric deviations were assessed by the root mean square value of the imposed 3D reconstruction and optical models by one-sample t-test. To assess the influence of voxel size and CBCT system on 3D reconstruction, analysis of variance （ANOVA） was used （α = 0.05）. Results： The linear, volumetric, and geometric deviations were -0.03±0.48 mm, -5.4 ±2.8%, and 0.117 ± 0.018 mm for NewTom VG 0.15 mm group; -0.45 ± 0.42 mm, -4.5±3.4%, and 0.116 ＋ 0.014 mm for NewTom VG 0.30 mm group; and 0.93 ± 0.40 ram, 4.8 ± 5.1%, and 0.194 ± 0.117 mm for VATECH DCTPRO 0.30 mm group, respectively. There were statistically significant differences between groups in terms of linear measurement （P 〈 0.001）, but no significant difference in terms of volumetric measurement （P 0.774）. No statistically significant difference were found on geometric measurement between NewTom VG 0.15 mm and NewTom VG 0.30 mm groups （P - 0.999） while a significant difference was found between VATECH DCTPRO 0.30 mm and NewTom VG 0.30 mm groups （P = 0.006）. Conclusions： The 3D reconstruction from CBCT data can achieve a high linear, volumetric, and geometric accuracy. Increasing voxel resolution from 0.30 to 0.15 mm does not result in increased accuracy of 3D tooth reconstruction while different systems can affect the accuracy.

Comparative evaluation of a biomimic collagen/ hydroxyapatite/β-tricaleium phosphate scaffold in alveolar ridge preservation with Bio-Oss Collagen

Bone scaffolds are critical in current implant and periodontal regeneration approaches. In this study, we prepared a novel composite type-I collagen and hydroxyapatite （HA）/β-tricaleium phosphate （TCP） scaffold （CHTS） by incorporating type-I collagen and bovine calcined bone granules, prepared as a mixture of 50% HA and 50% TCP, by freeze drying. We then characterized the CHTS and determined its cytotoxic effects. Additionally, ridge preservation experiments were carried out to evaluate the clinical effects of the CHTS. The results demonstrated that the composite scaffolds had good surface morphology and no cytotoxicity. Additionally, an in vivo experiment in an animal model showed that the CHTS performed equally as well as Bio-Oss Collagen, a widely used bone graft in ridge preservation. These findings revealed that the CHTS, which contained natural constituents of bone, could be used as a scaffold for bone regeneration and clinical use.