3D Printing Ceramic Implants

Category: Blog,From Academia
Dec 05, 2020

In this issue, we included three latest publications focusing on 3D printing ceramic implants from different angles. The first publication focuses on 3D printing ceramic bone implants using laser stereolithography. The second article describes a customized, purely synthetic, 3D-printed bioceramic implant to regenerate and restore large cranial defects with mature, well-vascularized bone, with a morphology, ultrastructure, and composition similar to those of native skull bone. The final article evaluates the accuracy and precision of in-office 3D printed dental implant surgical guides comparing three different commercially available systems. “From Academia” features recent, relevant, close to commercialization academic publications. Subjects include but not limited to healthcare 3D printing, 3D bioprinting, and related emerging technologies.

Email: Rance Tino ([email protected]) if you want to share relevant academic publications with us.

Design and Fabrication of Complex-Shaped Ceramic Bone Implants via 3D Printing Based on Laser Stereolithography

Authored by Alexander Safonov, Evgenii Maltsev, Svyatoslav Chugunov, Andrey Tikhonov, Stepan Konev, Stanislav Evlashin, Dmitry Popov, Alexander Pasko and Iskander Akhatov. MDPI Applied Sciences. 29 September 2020

The distribution of vertical strains at the surface of the BI002 specimen during testing at the 187.5 N load, obtained by digital image correlation (DIC). Copyright MDPI Applied Sciences
The distribution of vertical strains at the surface of the BI002 specimen during testing at the 187.5 N load, obtained by digital image correlation (DIC). Copyright MDPI Applied Sciences

Abstract: 

3D printing allows the fabrication of ceramic implants, making a personalized approach to patients’ treatment a reality. In this work, we have tested the applicability of the Function Representation (FRep) method for the geometric simulation of implants with complex cellular microstructure.

For this study, we have built several parametric 3D models of 4 mm diameter cylindrical bone-implant specimens of four different types of cellular structure. The 9.5 mm long implants are designed to fill hole defects in the trabecular bone.

Specimens of designed ceramic implants were fabricated at a Ceramaker 900 stereolithographic 3D printer, using a commercial 3D Mix alumina (Al2O3) ceramic paste. Then, a single-axis compression test was performed on fabricated specimens. According to the test results, the maximum load for tested specimens constituted from 93.0 to 817.5 N, depending on the size of the unit cell and the thickness of the ribs.

This demonstrates the possibility of fabricating implants for a wide range of loads, making the choice of the right structure for each patient much easier.

Compression test simulation results for the BI002 specimen: (a) Computational model; (b) distribution of vertical displacements (mm) at the load of 185.7 N; (c) distribution of maximal principal stress (Pa) at the load of 279.9 N; (d) initial fracture of the specimen during compression test. Copyright MDPI Applied Sciences
Compression test simulation results for the BI002 specimen: (a) Computational model; (b) distribution of vertical displacements (mm) at the load of 185.7 N; (c) distribution of maximal principal stress (Pa) at the load of 279.9 N; (d) initial fracture of the specimen during the compression test. Copyright MDPI Applied Sciences

In situ bone regeneration of large cranial defects using synthetic ceramic implants with a tailored composition and design

Authored by Omar Omar, Thomas Engstrand, Lars Kihlström Burenstam Linder,  Jonas Åberg, Furqan A. Shah, Anders Palmquist,  Ulrik Birgersson, Ibrahim Elgali, Michael Pujari-Palmer, Håkan Engqvist, and Peter Thomsen, PNAS. 12 October 2020 

Design and characterization of the implants. (A) The experimental bioceramic (BioCer) implant used in the sheep skull was composed of calcium phosphate tiles reinforced and interconnected by an additively manufactured titanium frame with built-in, low-profile fixation arms (black arrows). (B) The titanium (Ti) implant (control) used in the sheep skull had a design and dimensions similar to those of the BioCer but was made entirely of additively manufactured Ti (grade 23). (C) The BioCer cranial implant used in the human skull was composed of calcium phosphate tiles interconnected by a Ti frame, with built-in fixation arms (black arrows) for anchorage to the recipient, native skull bone. (D) For both the experimental and clinical BioCer implants after autoclaving, the composition was anhydrous dicalcium phosphate (84.74%), β-TCP (8.34%), and dicalcium pyrophosphate (6.77%), whereas extremely limited fractions of the material were HA (0.11%) and brushite (0.04%) phases. (E and F) Scanning electron micrographs. Copyright PNAS
Design and characterization of the implants. (A) The experimental bioceramic (BioCer) implant used in the sheep skull was composed of calcium phosphate tiles reinforced and interconnected by an additively manufactured titanium frame with built-in, low-profile fixation arms (black arrows). (B) The titanium (Ti) implant (control) used in the sheep skull had a design and dimensions similar to those of the BioCer but was made entirely of additively manufactured Ti (grade 23). (C) The BioCer cranial implant used in the human skull was composed of calcium phosphate tiles interconnected by a Ti frame, with built-in fixation arms (black arrows) for anchorage to the recipient, native skull bone. (D) For both the experimental and clinical BioCer implants after autoclaving, the composition was anhydrous dicalcium phosphate (84.74%), β-TCP (8.34%), and dicalcium pyrophosphate (6.77%), whereas extremely limited fractions of the material were HA (0.11%) and brushite (0.04%) phases. (E and F) Scanning electron micrographs. Copyright PNAS

Abstract: 

The repair of large cranial defects with bone is a major clinical challenge that necessitates novel materials and engineering solutions.

Three-dimensionally (3D) printed bioceramic (BioCer) implants consisting of additively manufactured titanium frames enveloped with CaP BioCer or titanium control implants with similar designs were implanted in the ovine skull and at s.c. sites and retrieved after 12 and 3 mo, respectively.

Samples were collected for morphological, ultrastructural, and compositional analyses using histology, electron microscopy, and Raman spectroscopy. Here, we show that BioCer implants provide osteoinductive and microarchitectural cues that promote in situ bone regeneration at locations distant from existing host bone, whereas bone regeneration with inert titanium implants was confined to ingrowth from the defect boundaries.

The BioCer implant promoted bone regeneration at nonosseous sites, and bone bonding to the implant was demonstrated at the ultrastructural level. BioCer transformed to carbonated apatite in vivo, and the regenerated bone displayed a molecular composition indistinguishable from that of native bone.

Proof-of-principle that this approach may represent a shift from mere reconstruction to in situ regeneration was provided by a retrieved human specimen, showing that the BioCer was transformed into well-vascularized osteonal bone, with a morphology, ultrastructure, and composition similar to those of native human skull bone.

Investigations of clinical implant retrieved from the human skull after 21 mo (ultrastructure and composition). (A) A CT scan shows the implant in the recipient skull. The red-, green-, and yellow-coded tiles in A are examples of the peripheral, central, and transitional zones that were processed and analyzed. (B–D) Raman spectroscopy. (B) The mineral crystallinity (FWHM−1 ν1 PO43−), (C) the carbonate-to-phosphate ratio (ν1 CO32−/ν1 PO43−), and (D) the apatite-to-collagen ratio (ν2 PO43−/amide III) of peripheral and central intertile bone in the bioceramic (BioCer) implant are similar to those of the native bone (biopsy from the recipient skull). (E) High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image shows the union of new bone (NB) with the BioCer surface. (F) Elemental analysis, using energy-dispersive X-ray spectroscopy (EDS), across the interface reveals the continuity of Ca, P, O, and C signals from the NB into the BioCer, along the black arrow in E, with higher contents of calcium and phosphorus in the BioCer and a higher content of carbon in the bone. Copyright PNAS
Investigations of clinical implant retrieved from the human skull after 21 mo (ultrastructure and composition). (A) A CT scan shows the implant in the recipient skull. The red-, green-, and yellow-coded tiles in A are examples of the peripheral, central, and transitional zones that were processed and analyzed. (B–D) Raman spectroscopy. (B) The mineral crystallinity (FWHM−1 ν1 PO43−), (C) the carbonate-to-phosphate ratio (ν1 CO32−/ν1 PO43−), and (D) the apatite-to-collagen ratio (ν2 PO43−/amide III) of peripheral and central intertile bone in the bioceramic (BioCer) implant are similar to those of the native bone (biopsy from the recipient skull). (E) High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image shows the union of new bone (NB) with the BioCer surface. (F) Elemental analysis, using energy-dispersive X-ray spectroscopy (EDS), across the interface reveals the continuity of Ca, P, O, and C signals from the NB into the BioCer, along the black arrow in E, with higher contents of calcium and phosphorus in the BioCer and a higher content of carbon in the bone. Copyright PNAS

Accuracy and precision of 3D-printed implant surgical guides with different implant systems: An in vitro study

Authored Matthew Yeung, Aous Abdulmajeed, Caroline K.Carrico, George R. Deeb, Sompop Bencharit. The Journal of Prosthetic Dentistry. 23 October 2019

Study workflow. CBCT, cone beam computed tomography. ∗Length of drill refers to depth of osteotomy preparation. Copyright. The Journal of Prosthetic Dentistry.
Study workflow. CBCT, cone beam computed tomography. ∗Length of drill refers to depth of osteotomy preparation. Copyright. The Journal of Prosthetic Dentistry.

Abstract: 

Implant guided surgery systems promise implant placement accuracy and precision beyond straightforward nonguided surgery. Recently introduced in-office stereolithography systems allow clinicians to produce implant surgical guides themselves.

However, different implant designs and osteotomy preparation protocols may produce accuracy and precision differences among the different implant systems. The purpose of this in vitro study was to measure the accuracy and precision of 3 implant systems, Tapered Internal implant system (BioHorizons) (BH), NobelReplace Conical (Nobel Biocare) (NB), and Tapered Screw-Vent (Zimmer Biomet) (ZB) when in-office fabricated surgical guides were used.

A cone-beam computed tomography (CBCT) data set of an unidentified patient missing a maxillary right central incisor and intraoral scans of the same patient were used as a model. A software program (3Shape Implant Studio) was used to plan the implant treatment with the 3 implant systems.

Three implant surgical guides were fabricated by using a 3D printer (Form 2), and 30 casts were printed. A total of 10 implants for each system were placed in the dental casts by using the manufacturer’s recommended guided surgery protocols.

After implant placement, postoperative CBCT images were made. The CBCT cast and implant images were superimposed onto the treatment-planning image. The implant positions, mesiodistal, labiopalatal, and vertical, as well as implant angulations were measured in the labiolingual and mesiodistal planes. The displacements from the planning in each dimension were recorded.

ANOVA with the Tukey adjusted post hoc pairwise comparisons were used to examine the accuracy and precision of the 3 implant systems (α=.05). Dimensional and angulation displacements of guided implant systems by in-office 3D-printed fabrication were within clinically acceptable limits: <0.1 mm in M-D, 0.5 to 1 mm in L-P, and 1 to 2 degrees in angulation. However, the vertical displacement can be as much as 2 to 3 mm. Different implant guided surgery systems have strengths and weaknesses as revealed in the dimensional and angulation implant displacements.

Measurements for planned and placed implant positions. A, Measurements for BH. B, Measurements for NB. C, Measurements for ZB. BH, BioHorizons; NB, Nobel Biocare; ZB, Zimmer Biomet. Copyright. The Journal of Prosthetic Dentistry.
Measurements for planned and placed implant positions. A, Measurements for BH. B, Measurements for NB. C, Measurements for ZB. BH, BioHorizons; NB, Nobel Biocare; ZB, Zimmer Biomet. Copyright. The Journal of Prosthetic Dentistry.

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