UPDATE: Concerning Medpor and Jaw Angles
After coming across new scientific literature and re-reading a phenomenal medical journal, I wish to make a retraction regarding my predisposition towards using Medpor @ the jaw angles.
I knew there was a high rate of infection in the mandibular angle area but couldn't remember if it was ascribed to that area specifically
(due to being a tight space which encourage bacterial growth when contamination with saliva occurs etc...) and/or more so due to Medpor being the implant material laced in that area. Thanks to that aforementioned journal, it's the latter and now I have the exact figure of infection attributed to Medpor in the mandibular angle area.
According to the medical journal,
Ridwan-Pramana et al. reported a 27.3% infection rate when using porous polyethylene in the mandibular angle area. As porous ethylene is not osseointegrating, it may become infected because fibrovascular ingrowth takes 3 months. The implant can also migrate when not fixed with long enough screws, which may cause it to be exposed and extruded.
Source: Porous polyethylene implants in facial reconstruction: Outcome and complications.
Ridwan-Pramana A, Wolff J, Raziei A, Ashton-James CE, Forouzanfar T
J Craniomaxillofac Surg. 2015 Oct; 43( 8 ):1330-4.
27.3% is colossal for a infection rate. So, for the sake of brevity I will not be using Medpor for my jaw angles.
In light of this and upon further research, I believe that I have found an appropriate alternative (for my case):
Titanium implants made by selective laser melting - Titanium alloy (Ti-64). After I address PloskoPlus, I will detail my reasons why I believe Titanium to be exceptional and why I would currently choose this implant material over PEEK as well as osteotomies. Moreover, I will also be including other contemporary implant materials which are newly emerging.
Before I delve into my thoughts on different implant materials, let me preface by saying that the success and longevity of implants depend upon a multitude of various factors like material characteristics, design of the implant and the surgeon's skill.
Each of these materials poses certain complication risks based on their surface contour (smooth vs. porous), pliability, and reactivity with surrounding tissue. In addition, certain implant locations within the head and neck are at risk for different postoperative complications.
@PloskoPlusBTW, what about PEEK implants? They are supposed to have the lowest infection rate of them all.
Source for lowest infection rate?Small study but then again, PEEK is limited in scope:
RESULTS:The overall complication rate of PEEK cranioplasty was 28%. Complications included infection (13 %), postoperative haematoma (10 %), cerebrospinal fluid leak (2.5 %) and wound-related problems (2.5 %). All postoperative infections required removal of the implant. Nonetheless removed implants could be successfully re-used after re-sterilization.
Source: https://www.ncbi.nlm.nih.gov/pubmed/27524384Outcome in patient-specific PEEK cranioplasty: A two-center cohort study of 40 implants.
PEEK PEEK custom cranial implants are being used more in the current times. PEEK is a highly strong engineering thermoplastic, which retains its chemical and mechanical properties even at high temperatures. The material has high biocompatibility and biostability maintaining its physical and chemical characteristics on long-term exposure to body fluids. The modulus of elasticity of PEEK is similar to that of cortical bone, preventing any stress shielding making it a better choice over metallic implants that have high modulus of elasticity. PEEK is also radiolucent facilitating postoperative imaging procedures. Implants can be designed to replace exact anatomy even in bulky regions as the material is very light. The material can be repeatedly sterilized by common methods as autoclave, gamma or ethylene oxide. PEEK lends itself to machining of complex organic shapes very well. PEEK implants can be fixated to the adjacent bone with standard screws and plates of surgeons’ choice. All the above mentioned characteristics have made PEEK the sought after material for cranial implants by manufacturers and surgeons in the recent past.
In general, PEEK implants are made from a block of extruded material using a CNC machining. PEEK implants can be used in non-load bearing regions of the craniofacial skeleton. PEEK can also be sintered to produce implants similar to the machined PEEK.[32] CAD designed PEEK custom implants have been used to correct cranial, frontal, malar and mandibular defects.
• My current thoughts on PEEK: At this moment and time, PEEK seems supreme but not superlative in regards to implant material. While I believe PEEK is a good alternative to titanium implants for customized implants; as it may be easier to use and lighter; the following illustrate it's shortcomings & limitations:
-Will not integrate with bone (this increases the chance of long-term complications: infection etc...)
-Currently, mostly only used in cranial reconstruction of the skull and minor areas of the mid-face (not enough is known about the mental and mandibular areas)
-Is as expensive as 3D-printed titanium alloys
-Behavior when transorally implanted is not yet known
-Comparatively short term clinical use to other implant materials (not enough information on long term effects and stability)
-Only a handful of surgeons use PEEK at the moment
*Directly from my implant surgeon when asked why he doesn't offer or use PEEK: "difficult to bend, conform and place due to rigidity" (keep in mind that my surgeon prefers silicone & Medpor. However, he is an implant specialist with extensive knowledge on all alloplastic materials)
Titanium alloy (Ti-64) - Titanium implants made by selective laser meltingThis titanium alloy (Ti-64) is a commonly used alloy in load-bearing medical applications because of its strength, low weight and excellent biocompatibility. Using 3D Printing (Selective Laser Melting) to produce patient-specific implants from TI6Al4V creates the possibility of adding porosity throughout the material and allows virtually unlimited shape complexity. It is mainly used for mandible reconstructions and custom osteosynthesis plates. Furthermore, Titanium is the most commonly used material in medical implants because it is highly biocompatible and integrates very well into tissues.
The mechanical properties of SLM titanium products are also within the ranges of the properties of bone . These similarities are particularly important because implant materials that are much stiffer than the bone can generate stress shielding, which can potentially lead to bone resorption or hinder bone regeneration. Bone resorption caused by stress shielding is believed to contribute to the aseptic loosening of implants. In contrast, the porous surfaces of SLM titanium parts have been demonstrated to be favorable for cell adhesion, migration and ingrowth, and these properties result in strong bone-implant contact. When an implant is populated with osteogenic cells, these cells not only migrate on the surface of the implant but also inside the pores of the implant.
Medical Argument for Titanium Over PEEK: The choice of titanium over polyetheretherketone (PEEK) is based on the European belief that it is
better to prevent long-term complications caused by nonosseointegrated PEEK implants than to handle those complications associated with osseointegrated titanium (Federal and Drug Administration philosophy).
• My current thoughts on Titanium: Vastly superior to PEEK. The aforementioned states succinctly why. I'll highlight the points below:
-Osseointegrated unlike PEEK
-Porous surfaces are favorable for cell adhesion, migration and ingrowth, and these properties result in strong bone-implant contact.
-Well known and commonly used as a result of strength, low weight and excellent biocompatibility.
-Mainly used for mandible reconstructions and custom osteosynthesis plates
-titanium is resistant to bacterial colonization and causes less inflammation.
-“Satin” finished to prevent contamination from saliva
-Virtually unlimited shape complexity.
Titanium being superior other implant materials and augmenting methods: • Titanium > polymethylmethacrylate(PMMA), hydroxyapatite(HA) and polyethylene
Materials such as polymethylmethacrylate(PMMA), hydroxyapatite(HA) and polyethylene have proven to be biocompatible but have individual shortcoming. Compared to titanium,PMMA and HA are associated with an increased risk of infection. Polyethylene is not as strong]
• Titanium > general alloplastics
Furthermore, A disadvantage of alloplastic materials is its high susceptibility to infection. However, titanium is resistant to bacterial colonization and causes less inflammation.
Additionally, The bio-compatibility of titanium is well established compared to alloplastics. It is robust enough to resist secondary trauma while providing maximal stability of the cranial vault. As well, titanium implants generally cause less inflammation and conducts well with surrounding mineralized bone.
Source: https://e-acfs.org/upload/pdf/acfs-16-11.pdfArchives of Craniofacial Surgery
Copyright © 2015
• Titanium > Autologous (calvarial bone) onlays and sandwich osteotomies
In Whitaker’s[1] experience, autologous (calvarial bone) onlays and sandwich osteotomies yielded unpredictable results because of resorption and symmetry issues, and he discontinued their use. Triaca et al.[19] used an extended chin osteotomy using frequent bone grafts and posterior design corrections with the “chin-wing” technique. Results regarding symmetry, fracture, and infection complications are not yet available at the time of writing.
Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5343643Guidelines for patient-specific jawline definition with titanium implants in esthetic, deformity, and malformation surgery
Ann Maxillofac Surg. 2016 Jul-Dec; 6(2): 287–29
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Newly emerging contemporary implant materials & techniquesCT-Bone®CT-Bone is a 3D printed calcium phosphate that unifies with the patient’s bone. It can be used for bony augmentations (non-load-bearing) and is converted into real bone in the patient. Because it is 3D printed it can be made into complex shapes with controlled porosity.
Additive manufactured full mandibleThe world's first additive manufactured full mandible was implanted in a patient by Dr. Jules Poukens and his team in Belgium.
Source: https://www.xilloc.com/patients/stories/total-mandibular-implant/To surmise, I think the best we can hope for at this point, is the emergence of patient specific implants that will replicate not only form as it is today but also have mechanical, chemical and physiological properties similar to native tissues they replace and provide an environment for cell differentiation and growth. Currently there is no one material that can provide a complete solution. The future is regenerative medicine that allows for growth of natural tissues similar to the region of implantation.
-Ｒｅａｌｉｔｙ
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