People are unaware that diabetes mellitus, either type 1 or type 2, goes hand in hand with increased susceptibilities to oral health problems. Even diabetics themselves know little about the risks of bacterial infections such as Porphyromonas gingivalis, a primary cause of periodontitis; the correct term for gum disease. Although P. gingivalis is not normally found in subjects with good dental health, the presence of other bacteria is far more common. Streptococcus mutans and Streptococcus gordonii are both found within the oral setting and form biofilms on the tooth surface. Regular brushing and flossing removes these unwanted visitors but if the accumulated bacteria remain undisturbed for a long period of time they can begin to destroy the gum tissue surrounding the teeth. Interestingly this is where the P. gingivalis comes in. A shift in normal ecological balance in the microenvironment allows the bacteria to act as a secondary invader of the gums, and more specifically the gingival sulcus, the part where the tissue contacts the tooth. Colonisation of P. gingivalis arises via its ability to adhere to salivary molecules, matrix proteins in the gum and other bacteria present in the mouth. It is clearly an opportunistic pathogen.
So, why do diabetics have an increased risk of developing periodontitis? Well, Advanced Glycation End Products (AGEs) arise from chronic hyperglycaemia and therefore are common in diabetes. It is these glycated proteins or lipids which have been shown to impact on periodontal deterioration. Although the exact mechanism behind the interactions of AGE with the disease are unknown there is general consensus suggesting a couple of important points;
- An accumulation of AGEs affects the host immunological response. The products can disrupt an important nuclear transcription factor called NF-κβ, one which is involved in many inflammatory responses. IL-6 and TNF-α are also just two important pro-inflammatory cytokines which have been shown to be upregulated in the presence of AGEs.
- AGEs will not only upregulate the production of certain cytokines, they also affect the chemotactic properties of mono and polynuclear cells. This enhances the inflammatory response at a given site of infection, in this case at the gums and surrounding tissue.
One final problem in diabetic patients is a drop in salivary pH. Xerostomia, or hypo-salivation is a main cause of the low pH. Maintaining the correct level of fluid in the body perhaps is the greatest problem for individuals with diabetes mellitus. The presence of AGEs and glycated haemoglobin, the latter being another result of high blood sugar levels, disrupts the balance of fluid and electrolytes in the blood stream. Diabetes is a condition that is associated with polyuria (frequent urination), which occurs because the excessive glucose found in the blood changes the normal osmolarity gradient within the body. Simple GCSE Biology states that water will move from an area of high concentration to low concentration. Therefore the increased movement of water into the bloodstream will effectively force the kidney to produce more urine. It’s a vicious cycle – high glucose levels mean more urine produced, causing the person to become dehydrated which leads onto hypo-salivation, leaving an environment perfect for bacterial infection.
The low pH and reduced salivary rate contributes to an increase in tooth decay and as a consequence bacterial/fungal infections are more common in individuals with diabetes mellitus. This is because most oral bacteria and yeast thrive in the acidic conditions of the mouth, the reason why dental experts warn against sugary diet rich in carbohydrates – the main source of food for all mouth dwelling species. This is an alarming problem for experts and scientists worldwide, with an estimated 1 in 3 individuals with either form of diabetes mellitus having some degree of periodontitis during their lifetime. Of course the deterioration of dental health concerns everybody, but more attention must be paid to those that are at a higher risk. Managing the condition as a whole will pay dividends but are there any further precautions which should be taken to preserve the oral wellbeing for diabetics? This remains the most difficult question. Antimicrobial management and regular periodontal treatment is common in the general population, but both should be more prevalent in controlling diabetes related infections.
This post, by author Jason Brown, was kindly donated by the Scouse Science Alliance and the original text can be found here.
Goyal, D. et al (2012) Salivary pH and Dental Caries in Diabetes Mellitus. International Journal of Oral & Maxillofacial Pathology. 3(4):13-16
Griffen, AL. et al (1998) Prevalence of Porphyromonas gingivalis and Periodontal Health Status. J Clin Microbiol. 36(11):3239-3242
Lamont, RJ. Jenkinson, H. (1998) Life Below the Gum Line: Pathogenic Mechanisms of Porphyromonas gingivalis. Microbiol. Mol. Biol. Rev. 62(4):1244-1263
Takeda, M. et al (2006) Relationship of Serum Advanced Glycation End Products with Deterioration of Periodontitis in Type 2 Diabetes Patients. J.Periodontol. 77(1): 15-20.