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(a) Specific surgical templates used to choose the appropriate soft tissue expander. Each template has two ends that reflect the initial and final expander volumes. Courtesy of Osmed GmbH (Ilmenau, Germany). (b) Subperiosteal pouch prepared under local anesthesia and controlled with the surgical template.
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The appropriate expander was selected using a specific surgical template corresponding to the initial and final volumes of the expander (Figure 1(a)). Briefly, expanders were inserted in a subperiosteal pouch prepared under local anesthesia and controlled with the specific surgical template (Figure 1(b)) to ensure the device is easily fit without tension into the prepared pouch.
Insertion of bone fixation screw at the flat end to prevent potential expander migration.
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To prevent any dislocation or potential migration, expanders were fixed with a bone fixation screw (Figure 2), at the flat end, which does not have an expansion capability.
(a) Full-thickness flap was elevated to expose the expander and its fixation screw for removal. (b) Expander was removed, and signs of bone resorption due to expansion pressure are evident. (c) Cylinder expander of 0.7 ml final volume is removed. Fluid inside the expander is evident.
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Bone surface was carefully examined for any signs of potential resorption due to pressure from the expander (Figures 3(a)-3(c)).
(a) Horizontal augmentation was done in this case, utilizing xenograft with autogenous bone. (b) Bone graft was covered with collagen absorbable membrane. (c) Primary, passive wound closure was achieved without deep periosteal releasing incisions.
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Ti-250, Osteogenics Biomedical Inc., Lubbock, TX, USA), while collagen membrane was used (Bio-Gide , Geistlich Pharma, Wolhusen, Switzerland), in the case of horizontal bone augmentation (Figures 4(a) and 4(b)). Tension-free primary closure was achieved in all cases without utilizing deep periosteal and/or vertical releasing incisions (Figure 4(c)).
(a) Dental implant placement at the area that was expanded and augmented. (b) Section from panoramic radiograph representing the target site after dental implant placement.
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In patients that completed the study, dental implants (MegaGen Implant Co., Ltd., Gyeongbuk, South Korea) were placed 6 months following bone augmentation (Figure 5(a)).
Volumetric analysis in the upper left maxilla. (a) Optically scanned preexpansion model. (b) Optically scanned postexpansion model. (c) Superimposed pre- and postexpansion models. Software used: Geomagic Studio 2013, Raindrop Geomagic, NC, USA.
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Tessellation Language). The STL files of pre- and postexpansion models were imported into CAD software (Geomagic Studio  2013, Raindrop Geomagic, NC, USA) (Figures 6(a) and 6(b)). After being imported, files of pre- and postexpansion models for each patient were accurately superimposed, by using the buccal surface of adjacent teeth as a reference point (Figure 6(c)), applying the best-fit algorithm.
Calculation of volumetric changes. (a) Expanded tissues are highlighted with CAD software, and volume change is calculated. (b) The expanded area in STL format (coronal view), which can be superimposed on preexpansion STL file for further confirmation of calculation. (c) The expanded area in STL format (lateral view). Software used: Catia V5, Rand Worldwide Inc., Maryland, USA.
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The expanded tissues were highlighted with this CAD software, allowing for volume change calculation (Figure 7). After completing the calculations, the expanded area was then extracted into STL format, allowing for superimposition of this area over the original pre-expansion STL file for further confirmation (Figures 7 and 7).