Alternative methods of implant materials are under investigation for the risk of titanium. Typically, these include zirconia and polyetheretherketone (PEEK) dental implants. These materials are considered to be alternatives to the hypersensitivity of titanium and are aimed at improving esthetics. Currently, zirconia is a clinically applied material for dental implants. There have been many studies in the past, and improvements in physical properties, osseointegration, and clinical application have been made. These clinical applications have been made, and there have been reports of clinical prognosis after use. Pierall et al. investigated about 347 cases and reported a 95.6% survival rate after a 1-year follow-up in 2016. Marginal bone loss was shown to be around 0.79 mm during the follow-up. Although there is still insufficient data for a long-term follow-up, the result is still somewhat successful.

In the case of PEEK implants, they are currently being studied and are not yet clinically useful. PEEK implants possess a similar elastic modulus to that of bone and have the advantage of imparting less stress on bone than other materials, including titanium, which have a high rigidity. Currently, studies are being performed including animal experiments, and studies are underway to improve their physical properties and osseointegration. However, there is still a lack of physical properties and osseointegration capacity to be clinically applied. These alternative materials are still lacking in research and are not yet clinically applicable to PEEK implants. Currently, clinically applied zirconia implants are limited to clinical applications due to research limitations and long-term data compared with titanium-based implants; the currently commercialized systems are a one-piece system. Until recently, there has not been a system that could completely replace titanium dental implants. Current titanium dental implants have a high success rate except in some cases and will continue to have clinically successful results over a long period of time now that they are being used universally. However, attention must be placed with regard to the hazards of titanium dental implants that are so commonly used. Clinicians should be able to look at the implications of materials in terms of both biological and mechanical aspects when implants fail. It is also important to consider allergic reactions and yellow nail syndrome, which can occur when using titanium dental implants. Clinicians should be aware that, and therefore, it is necessary to explain that these symptoms can occur in any patients when implants are installed. Preventive measures should be considered, and when symptoms occur, patients should be diagnosed accurately and managed appropriately.