Aim. To investigate the effect of changes in incisor tip, apex movement, and inclination on skeletal points A and B and characterize changes in skeletal points A and B to the soft tissue points A and B after incisor retraction in Angle Class I bimaxillary dentoalveolar protrusion. Methods. Twenty-two patients with Angle Class I bimaxillary dentoalveolar protrusion treated with four first premolar extractions were included in this study. The displacement of skeletal and soft tissue points A and B was measured using cone-beam computed tomography (CBCT) using a three-dimensional coordinate system. The movement of the upper and lower incisors was also measured using CBCT-synthesized lateral cephalograms. Results. Changes in the incisal tip, apex, and inclination after retraction did not significantly affect the position of points A and B in any direction (x, y, z). Linear regression analysis showed a statistically significant relationship between skeletal point A and soft tissue point A on the anteroposterior axis (z). Skeletal point A moved forward by 0.07 mm, and soft tissue point A moved forward by 0.38 mm, establishing a ratio of 0.18: 1 (r = 0.554, p < 0.01). Conclusion. The positional complexion of the skeletal points A and B was not directly influenced by changes in the incisor tip, apex, and inclination. Although the results suggest that soft tissue point A follows the anteroposterior position of skeletal point A, its clinical significance is suspected. Thus, hard and soft tissue analysis should be considered in treatment planning.
Our aim was to investigate the bone regeneration capacity of powder-type biphasic ceramic scaffold (BCP powder), block-type BCP (BCP block), and collagen-added block-type BCP (BCP collagen) with different concentrations of recombinant human bone morphogenetic protein 2 (rhBMP-2) in an animal model. Four rabbits were assigned to each of the following groups: no graft + rhBMP-2 (0.1/0.2 mg/mL), BCP powder + rhBMP-2 (0.1/0.2 mg/mL), BCP block + rhBMP-2 (0.1/0.2 mg/mL), and BCP collagen + rhBMP-2 (0.1/0.2 mg/mL), i.e., a total of 32 rabbits. Polycarbonate tubes (Φ 7 mm × 5 mm) for supporting scaffolds were fixed into a 7 mm round border. Subsequently, 0.1 mL of rhBMP-2 solutions with different concentrations was injected into the tubes. Both radiological and histomorphometric analyses showed that osteogenesis was not enhanced by increasing the concentration of rhBMP-2 in all groups at both 3 and 6 weeks. Radiological analysis showed that bone formation was higher in the BCP collagen group than in the BCP powder and BCP block groups at both rhBMP-2 concentrations at 3 weeks. rhBMP-2 enhanced bone formation; however, as the concentration increased, bone formation could not be enhanced infinitely. Collagen-added alloplastic graft material may be useful for mediating rapid bone formation in initial stages.
Silk mats have been approved for clinical trials by the Korean Food and Drug Administration as membranes for guided tissue regeneration (GTR). In this study, silk mat application was compared to high-density polytetrafluoroethylene (dPTFE) membrane application or no membrane group.To compare the silk mat group to the dPTFE group or the no membrane group, a retrospective sample collection was conducted. Bony defects were measured at the time of extraction (T0) and then at 3 months (T1) and 6 months after extraction (T2) on a digital panoramic view. Bone gain (BG) was calculated by subtracting from the bony defect at T0 to the bony defect at each follow-up.The BG at T2 was 2.44 ± 2.49 mm, 4.18 ± 1.80 mm, and 4.24 ± 2.05 mm in the no membrane group, silk mat group, and dPTFE group, respectively. Both membrane groups had significantly higher BG than BG in the no membrane group at T2 (P < 0.05).Both membrane groups showed higher BG than the no membrane group.
This study evaluated the mechanical properties and bone regeneration ability of 3D-printed pure hydroxyapatite (HA)/tricalcium phosphate (TCP) pure ceramic scaffolds with variable pore architectures. A digital light processing (DLP) 3D printer was used to construct block-type scaffolds containing only HA and TCP after the polymer binder was completely removed by heat treatment. The compressive strength and porosity of the blocks with various structures were measured; scaffolds with different pore sizes were implanted in rabbit calvarial models. The animals were observed for eight weeks, and six animals were euthanized in the fourth and eighth weeks. Then, the specimens were evaluated using radiological and histological analyses. Larger scaffold pore sizes resulted in enhanced bone formation after four weeks (p < 0.05). However, in the eighth week, a correlation between pore size and bone formation was not observed (p > 0.05). The findings showed that various pore architectures of HA/TCP scaffolds can be achieved using DLP 3D printing, which can be a valuable tool for optimizing bone-scaffold properties for specific clinical treatments. As the pore size only influenced bone regeneration in the initial stage, further studies are required for pore-size optimization to balance the initial bone regeneration and mechanical strength of the scaffold.
This study aimed to evaluate the bone regeneration capacity of a customized alloplastic material and xenograft with recombinant human bone morphogenetic protein-2 (rhBMP-2). We prepared hydroxyapatite (HA)/tricalcium phosphate (TCP) pure ceramic bone blocks made using a 3D printing system and added rhBMP-2 to both materials. In eight beagle dogs, a total of 32 defects were created on the lower jaws. The defective sites of the negative control group were left untreated (N group; 8 defects), and those in the positive control group were filled with particle-type Bio-Oss (P group; 12 defects). The defect sites in the experimental group were filled with 3D-printed synthetic bone blocks (3D group; 12 defects). Radiographic and histological evaluations were performed after healing periods of 6 and 12 weeks and showed no significant difference in new bone formation and total bone between the P and 3D groups. The 3D-printed custom HA/TCP graft with rhBMP-2 showed bone regeneration effects similar to that of particulate Bio-Oss with rhBMP-2. Through further study and development, the application of 3D-printed customized alloplastic grafts will be extended to various fields of bone regeneration.
'%3e%3cg id='b'%3e%3cpath id='a' stroke='%23000' stroke-width='2' d='M-6-25H6m-12 3H6m-12 3H6'/%3e%3cuse xlink:href='%23a' y='44'/%3e%3c/g%3e%3cpath stroke='%23fff' d='M0 17v10'/%3e%3ccircle r='12' fill='%23cd2e3a'/%3e%3cpath fill='%230047a0' d='M0-12A6 6 0 0 0 0 0a6 6 0 0 1 0 12 12 12 0 0 1 0-24z'/%3e%3c/g%3e%3cg transform='rotate(-123.69)'%3e%3cuse xlink:href='%23b'/%3e%3cpath stroke='%23fff' d='M0-23.5v3M0 17v3.5m0 3v3'/%3e%3c/g%3e%3c/svg%3e)
