Nature reports: Evaluation of the effectiveness of 3D printed titanium alloy implants for bone growth

Introduction: Titanium and titanium alloys because of their goodbiologyCompatibility is widely used inorthopedics,dentistry,oral cavityand other medical fields, in combination with3D printingAfter the integrated construction capability of technology, titanium alloys can be processed into medical products with complex structures and personalized customization.Implants.3D printingThe new model of titanium alloy implants greatly reduces the waste of raw materials and saves labor and time costs. This is the ability that traditional processing does not have, and it will have a broader development space in the future.

On May 11, 2022, a group of researchers from a Korean hospital conducted a retrospective study to verify the efficacy and safety of customized 3D printed titanium alloy implants on patients’ maxillofacial bones.
A total of 16 patients were observed during the study, all of whom underwent reconstruction of various maxillofacial defects
Operation
. Patients were fitted with custom-made titanium alloy implants and followed up for a long period of time over a period of several months.
Of the 28 implant cases installed, only one failed to integrate successfully with the bone, while the others showed satisfactory results in treating various oral and maxillofacial defects.

△Titanium alloy reconstruction of mandibular defect caused by tumor. Image from “Nature”.

3D printed maxillofacial implants

For some time now, 3D printing has been used several times in surgical guidelines for the preparation of patient-assisted medical devices in order to improve treatment outcomes. More recently, researchers have begun experimenting with 3D printing to create facial implants that can be implanted into a patient’s skull. For example, scientists at Texas A&M University have developed a new type of 3D-printed scaffold that directly promotes bone cell growth after surgery.For more end-use applications, the Quebec Centre for Industrial Research (CRIQ) has deployed a GE Additive Arcam Q10 3D printerto expedite the preparation of patient-specific mandibular implants, while researchers at the University of Paulista have 3D printed a facial prosthesis for a Brazilian cancer survivor that included her entire right eye structure.Recently, Health Canada approved its first made-in-Canada 3D printingmedicalThe implant, which is a customizable mandibular plate, is primarily used for facial reconstruction surgery in patients with oral complications.

△ Dental implants on titanium mandibles. Image from “Nature”.

retrospective study

Autologous bone grafts or implants are the main methods used to treat oral and maxillofacial defects, and although they have broad biocompatibility, there may be concerns regarding donor site morbidity, surgical failure, and difficulty in reoperation.Rapid development of digital technology for oral and maxillofacialsurgicalThe field opens up new avenues,3D printing technologyMakes surgery faster and more accurate, especially in titanium alloy materials, which have proven biocompatibility as dental implants. The maxillofacial titanium implants used in the surgery documented in this study were 3D printed by electron beam melting (EBM) and selective laser sintering (SLS) processes. A total of 28 implants were 3D printed and then inserted into the maxilla (dominant part of the face), mandible (lower jaw) or zygomatic (cheek/nipple) of 16 different patients.

Of the patients, seven were women and nine were men, ranging in age from 9 to 78 years old. A total of 28 defect areas were operated on, including 5 mandibular segments, 9 zygomatic, 10 mandibular body, angle or chin, and 4 maxillary areas.
Long-term follow-up was then performed, ranging from 8 to 79 months per patient. The study primarily analyzed osseointegration of titanium implants, but also recorded postoperative infection, implant misalignment, functional outcomes, patient satisfaction, subsidence, peri-implant osteolysis, and any complications that occurred.
The study found that out of 28 implants, only one was not bonded to the bone. CBCT analysis showed that the bone fusion rate at 6 months after surgery was 96.5%. The study also observed no osteolysis (a progressive condition in which bone tissue is destroyed) or subsidence around the titanium implants.
According to the study, patients enrolled in the trial were generally satisfied with their surgical outcomes, both aesthetically and functionally. However, two of the five patients who underwent cheekbone reconstruction underwent revision surgery due to dissatisfaction with the appearance of the implants.

A photo of a patient with Treacher-Collins syndrome. Image from “Nature”.

Review implants

The bone-to-implant interface of the 3D-printed implant is designed as a mesh or solid, depending on whether stability is required. This implant was the first choice because the rough surface of the mesh titanium implant was found to be more likely to integrate into the patient’s bone.SLS enables additive manufacturing of metals such as titanium at high sintering temperatures, however this technology is currently undergoing process improvements to improve its properties due to limited dimensional accuracy and poor surface roughness. EBM uses electron beams instead of laser beams to sinter or fuse materials. Unlike SLS, EBM can fabricate complex geometries by selectively scanning each cross-sectional layer.

Implants 3D printed via EBM are more expensive than those 3D printed using SLS, but differences were found in implant interface type or 3D printing methodclinicalThere was no difference in the results.At follow-up, 3 out of 16 patients developed complications such as screw breakage and aesthetic dissatisfaction, however these issues were eventually resolved and all patients had satisfactory postoperative recovery.

△ One of the revision surgery case studies. Image from “Nature”.

Based on patient experience, the study proposes guidelines for the use of 3D printed titanium alloy patient-specific implants. In short, the study recommends that this implant should be used for continuous defects in the facial bone, limited to hard tissues that have already been reconstructed and no reconstruction options, and in patients with facial bone reshaping due to prior excessive bone preparation. Conditions with mild or moderate bone defects.
In addition, the guideline says, 3D printed titanium implants should also be used in aesthetically demanding situations, such as correcting skeletal asymmetry, in areas such as the mandible that require functional weight-bearing, and where dental implants are required. things are reconstructed at the same time.

More information about this study can be found in the journal Nature titled: “Reconstruction of maxillofacial bone defects using patient-specific long -lasting titaniumimplants” paper. Co-authors of the study are H. Lim, Y. Choi, W. Choi, I. Song and U. Lee.

Links to related papers:https://www.nature.com/articles/s41598-022-11200-0

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Nature reports: Evaluation of the effectiveness of 3D printed titanium alloy implants for bone growth

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