Abstract
The aim of this study was to assess the internal fit accuracy of a three-dimensional (3D)-printed biphasic calcium phosphate (BCP) block compared with a 3D-milled poly methyl methacrylate (PMMA) block by scanning electron microscope (SEM) analysis. In a total of 20 porcine rib bones, two different types of defects having two adjacent walls and a floor were produced: a defect with a flat floor (flat defect; N = 10) and a defect with a concave floor (curved defect; N = 10). Each defect was grafted with either the 3D-printed BCP block or the 3D-milled PMMA block fabricated following the computer aided design. The defects were then cut cross-sectionally and evaluated under the SEM. The extents of internal contact and gap were measured and statistically analyzed (p < 0.05). All blocks in both BCP and PMMA groups were successfully fit to the flat and curved defects. The internal contact ratio was significantly higher in the BCP group (flat defect: 0.47 ± 0.10; curved defect: 0.29 ± 0.05) compared with the PMMA group (flat defect: 0.21 ± 0.13; curved defect: 0.17 ± 0.04; p < 0.05). The internal gap area was similar between the two groups regardless of the defect types (p > 0.05). The internal fit accuracy of the 3D-printed BCP block was reliable in both the flat and curved defects when compared with the accuracy of the 3D-milled PMMA block.
Highlights
Since placing implants in an augmented site was found to produce long-term reliable outcomes in several studies, guided bone regeneration (GBR) has become a routine procedure in clinics [1]
To verify that the dimensions of the defects were statistically similar between the biphasic calcium phosphate (BCP) and poly methyl methacrylate (PMMA) groups, the total length of each flat defect and curved defect was compared between the two groups in the cross-sectional scanning electron microscope (SEM) images prior to the measurement of the internal contact ratio and gap area
In the intragroup comparisons between the two defects, the contact ratio measured in the flat defect was significantly higher (+0.18) than that measured in the curved defect in the BCP group (p < 0.05)
Summary
Since placing implants in an augmented site was found to produce long-term reliable outcomes in several studies, guided bone regeneration (GBR) has become a routine procedure in clinics [1]. Particulate bone substitute has weaknesses in terms of positional stability of the graft material and space maintenance, both of which are prerequisites for successful bone regeneration [3,4]. Attempts to overcome these disadvantages have involved using pins to secure the particulate bone substitutes underneath the barrier membrane or applying screws to fix the block bone grafts [5]. When using block bone substitutes, it is necessary to manually shape and adapt the material exactly into the recipient sites Otherwise, severe complications, such as graft material exposure, wound dehiscence, or postsurgical infection, may occur due to insufficient fixation of the bone blocks, which impedes new bone formation
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