In the previous issue of JOI, 37(3), an article titled, “The Effect of Interleukin-1 Allele 2 Genotype (IL-1a−889 and Il-1b+3954) on the Individual’s Susceptibility to Peri-Implantitis: Case-Control Study,” by Hamdy and Ebrahem was presented. For the researchers among our readers, I am certain they found this article to be of interest and of value; however, clinicians may not have quite the same appreciation for the potential significance of research concerning the expression of genotype polymorphisms.

Let us take a look at the interleukins (IL). Interleukins are a group of cytokines (proteins) that are expressed by many cell types (white blood cells in particular) involved with signaling cascades for the immune system and the inflammatory response in particular. Polymorphism refers to 2 or more distinct phenotypes of a particular gene. An allele refers to one of multiple forms of the gene. There are 35 different ILs involved in inflammation in the various tissues of the body, and each of these can be expressed as a distinct set of alleles inherited from our parents (codominance). The set of different alleles that we obtain from our parents is responsible for the polymorphisms in our IL proteins. This has clinical relevance because it has been suggested that some polymorphisms within IL-1α are associated with many disease states including rheumatoid arthritis, Alzheimer’s disease and peri-implantitis.

So why should this mean anything to the Implant Dentist on Monday morning? All clinicians want the best treatment outcomes possible. Unexplained, extremely destructive, hard and soft tissue inflammatory responses, in conjunction with dental implant treatment, do occur and this leads to disappointment. Armitage et al1 suggested that polymorphism might explain these atypical responses. Researchers are investigating the influence of multiple single and collective IL polymorphisms on inflammation relating to periodontitis and peri-implantitis. The question to be answered is, does the expression of a specific genetic polymorphism (single or in combination) affect dental implant health? Fortunately, the overwhelming majority of dental implant cases proceed as planned and the “checkered flag” of success can be waived; however, in those cases where unexpected failure occurs, the expression of a defined IL polymorphism should be considered.

Clinicians must be aware that for some patients, a defined set of IL polymorphisms might have a significant impact on the proposed treatment. Identifying these patients and polymorphisms preoperatively will be the key. I encourage all clinicians to be aware of the potential impact genetic research may have on our profession in the coming years.

James L. Rutkowski, DMD, PhD and Douglas Michael Smith, PhD

Di Giovine
Low prevalence of a periodontitis-associated interleukin-1 composite genotype in individuals of Chinese heritage
J Periodontol