Three-Dimensional Printed Patient-Specific Vestibular Augmentation: A Case Report

Abstract

Background: The anterior maxilla is challenging regarding aesthetic rehabilitation. Current bone augmentation techniques are complex and 3D-printed bioceramic bone grafts can simplify the intervention. Aim: A four-teeth defect in the anterior maxilla was reconstructed with a 3D-printed synthetic patient-specific bone graft in a staged approach for dental implant delivery. Methods: The bone graft was designed using Cone-Beam Computed Tomography (CBCT) images. The bone graft was immobilized with fixation screws. Bone augmentation was measured on CBCT images at 11 days and 8 and 13 months post-surgery. A biopsy sample was retrieved at reentry (10 months post-augmentation) and evaluated by histological and micro-computed tomography assessments. The definitive prosthesis was delivered 5 months post-reentry and the patient attended a visit 1-year post-loading. Results: A total bone width of 8 mm was achieved (3.7 mm horizontal bone gain). The reconstructed bone remained stable during the healing period and was sufficient for placing two dental implants (with an insertion torque > 35 N·cm). The fractions of new bone, bone graft, and soft tissue in the biopsy were 40.77%, 41.51%, and 17.72%, respectively. The histological assessment showed no signs of encapsulation, and mature bone was found in close contact with the graft, indicating adequate biocompatibility and suggesting osteoconductive properties of the graft. At 1-year post-loading, the soft tissues were healthy, and the dental implants were stable. Conclusions: The anterior maxilla's horizontal ridge can be reconstructed using a synthetic patient-specific 3D-printed bone graft in a staged approach for implant placement. The dental implants were stable and successful 1-year post-loading.

Keywords: 3D printing; biomaterial; bone grafting; case report; horizontal ridge augmentation; patient-specific; synthetic.

Figure 1

Virtual surgical planning (VSP) before the vestibular bone augmentation surgery. (A) Segmented and 3D-reconstructed bone tissue of the patient; (B) designed bone graft (dark blue) virtually fitted in the surgical site; (C) fixed bone graft with fixation screws in a representative anatomical model of the patient’s bone.

Figure 2

Clinical images demonstrating the vestibular bone augmentation (positions # 11, 12, 21, and 22) with a patient-specific bone graft. (A) Opening of the coronally advanced trapezoidal flap in the vestibular area; (B) exposed bone perforated with intramedullary holes; (C) hydration of the bone graft by immersion in saline solution; (D) placement of the bone graft in the surgical site; (E) perforation of the bone graft and the pristine bone; (F) fixation of the bone graft to the pristine bone with fixation screws; (G) fixed and immobilized bone graft; (H) covering of the bone graft with resorbable collagen membranes; (I) tension-free closure of the soft tissues (prior to closure, an incision in the periosteum was performed to obtain a coronally advanced flap).

Figure 3

Clinical images showing the reentry with the dental implant placement 10 months post-surgery. (A) Removal of the fixation screws placed to immobilize the bone graft during the bone regeneration period; (B) regenerated area with removed fixation screws; (C) extraction of a biopsy with a trephine burr; (D) perforation in the regenerated area for dental implants insertion; (E) subcrestal dental implant placement; (F) placed implants in positions # 12 and 22, insertion torques are shown in Figure S1, Supplementary information; (G) placed closure caps; (H) closed flap with loose and simple sutures; (I) immediate placement of the provisional prosthesis (i.e., a bridge supported by adjacent teeth).

Figure 4

Representative CBCT images to show how the measurements of the bone thickness were performed. The pink line indicates the contour of the pre-designed graft, and the green lines indicate the position and projection where measurements were performed. (A) Axial projection with pre- and post-surgery CBCT images superimposed; (B,C) a sagittal projection indicates how the different measurements were obtained, (B) pre-surgery (i.e., initial bone and pink line indicating planned augmentation), (C) post-surgery (i.e., initial bone and grafted area): i = initial bone thickness, a = bone thickness augmentation (i.e., gained bone) and t = total bone thickness; t = (i + a).

Figure 5

Two-dimensional segmentation and 3D reconstruction of the μ-CT acquisitions obtained from the biopsy extracted at the reentry (10 months post-surgery). (A) Two-dimensional segmentation in sagittal, coronal, and axial projections: (Ai–Aiii) slice images of the stack before segmentation, (Aiv–Avi) segmented images with the four model sub-populations distinguished by different masks: in grey: metal trephine, in pink: bone, in green: bone graft, in orange: soft tissue, and in purple line: the contour and limits of the volume of interest (VOI); (B) 3D reconstruction of the segmented image stack (in grey: metal trephine, in pink: bone, in green: bone graft, in orange: soft tissue, and in purple: VOI): (Bi) complete volume of the segmented parts, (Bii) volume of each region inside the VOI.

Figure 6

CBCT images acquired pre-surgery, 11 days, 8 months, and 13 months post-surgery (3 months after reentry and dental implant placement). (A–D) Axial projection; (E–H) sagittal projection, used for bone thickness measurements: (A,E) pink lines indicating the pre-designed bone graft and planned bone augmentation, (B,F) revealing a gap between the bone graft and the pristine bone, (C,G) demonstrating new bone ingrowth and bridging of the previous gap, (D,H) dental implant position after successful bone augmentation and implant placement.

Figure 7

Histological assessment of a biopsy collected 10 months post-surgery (during reentry) from the interface of the pristine bone and the regenerated area. In black: metal trephine, in purple: mature bone = B, in pink: bone graft = BG, and in white: bone marrow. (A,B) Overviews of the complete trephine sample; (i–vi) insets showing specific areas of the histological images in a greater magnitude and more detail: (i–v) new bone growing on the surface of the bone graft and following its contour together with bone marrow regions; (vi) signs of local graft and bone remodeling.

Figure 8

Clinical images of the prosthesis delivery. (A) Initial state, before starting the rehabilitation treatment; (B) provisional prosthesis (i.e., a bridge supported by adjacent teeth) placed immediately after the bone augmentation surgery; (C) definitive prosthesis delivered 5 months after reentry and dental implant placement; (D) 1-year follow-up post-loading.