Dental implants are another biomedical application where ceramics are making significant inroads. With the success SINTX has had with the development of the MC2 silicon nitride material for spinal implants, the company is now looking to broaden the application of this unique material to other applications inside the body. A key area of focus for the MC2 material is for dental implants and dental surgery.
Requirements for dental implants are similar, but even more demanding than those for spinal implants. These requirements are:
Infections associated with dental implants – Peri-implantitis, can reduce the success rate of dental implants, particularly in patients predisposed to periodontal disease. Dental peri-implantitis, whose prevalence has recently been reported as high as 37% on a per patient basis [3,4], remains a persistent and common postsurgical complication that often requires subsequent treatment or revision.
Biomaterials that resist bacterial colonization may be the solution. SINTX’s silicon nitride (Si3N4) is a non-oxide ceramic with proven efficacy in spinal fusion, excellent osseointegration, and inherent resistance to bacterial biofilm formation. The material is effective against a wide variety of orthopedic bacteria [5-8], and against P. Gingivalis , the bacteria implicated in gingivitis. SINTX has conducted research on the use of Si3N4 to evaluate bacteriostatic outcomes for both single- and commensal-strain testing. Accumulation of pathogenic bacteria at the implant site is a major component of its complex etiology.
Antibacterial properties are most likely related to favorable surface properties such as hydrophilicity, a net negative surface charge, and the fact that Si3N4 produces silicic acid and ammonia via hydrolysis upon exposure to water. It is hypothesized that interfacial production of silicic acid and ammonia promotes local osteogenesis and leads to bacterial lysis.
While titanium is the “gold standard” for the fabrication of oral implants, ceramics (particularly zirconia) are making inroads. In a recent review by Osman and Swain, they compare titanium vs. zirconia for this application.  While zirconia has many positive features, such as being metal-free for patients with allergic reactions, the material is prone to cracking. Silicon nitride exhibits very high toughness for a ceramic and provides antibacterial properties. In addition to favorable surface properties such as hydrophilicity and a robust net negative charge, Si3N4 produces silicic acid and ammonia via hydrolysis upon exposure to water.  It has been hypothesized that interfacial production of silicic acid and ammonia promotes local osteogenesis and bacterial lysis.
Si3N4 monoliths and coatings performed well relative to Ti-alloy and 3Y-ZrO2 in terms of resisting bacterial colonization, enhancing osteogenic activity, and osseointegration. Si3N4 monoliths also exhibited radio translucency using conventional radiography. These favorable results support the application and use of Si3N4 as a dental implant material.
SINTX can manufacture monolithic silicon nitride implants or utilize coating technologies to surface functionalize metals, ceramics, and polymers with silicon nitride. Regardless of the approach, the end product will be anti-bacterial with enhanced osseointegration.
SINTX has completed two 510(k) pre-submissions on ceramic dental implants to the U.S. FDA.
Standard silicon nitride has a dark color but it can be whitened through changes in the process.
Several different coating technologies have been developed and are transitioning from the laboratory to production. These technologies can confer the beneficial effects of silicon nitride onto metal components, such as titanium.
Silicon nitride appears to be an ideal material for dental implants particularly in light of the issues associated with periimplantitis. SINTX in continuing research and development and now looking to commercialize this technology. To learn more about dental implants a great resource is the American Academy of Implant Dentistry.
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