Gemma Barker considers how the mouth can be a source of infection and whether it acts as an early warning system for problems in other parts of the body

There is a tongue-in-cheek adage among dental academics: ‘to every tooth there is a patient attached.’ In other words, oral conditions and their treatment may have consequences for the patient beyond the mouth (Barasch, 2018).

Offering further insight on this, Sudhakara et al (2018) wrote: ‘The major gateway to the human body is the oral cavity. Micro-organisms [sic] enter into the human cavity through food and air, which passes through the nose and then reaches the trachea and lungs through the mouth.

Oral microbiome causes a number of oral infectious diseases such as dental caries, periodontitis, endodontic infection, alveolar bone loss, and tonsillitis. Studies have proven that an oral infectious disease will affect the overall health of an individual, extending beyond the oral cavity…’

Indeed, it has been suggested that a connection between oral health and general health is well-established and continues to evolve (DiMatteo, 2017). In line with this, following the 2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions, Jepsen et al (2018) wrote: ‘A variety of systemic diseases and conditions can affect the course of periodontitis or have a negative impact on the periodontal attachment apparatus.

‘There are many diseases and conditions that can affect the periodontal tissues either by 1) influencing the course of periodontitis or 2) affecting the periodontal supporting tissues independently of dental plaque biofilm-induced inflammation.’

Studies have also indicated there is a bidirectional relationship; for example, in relation to glycaemic control and periodontitis. Some research supports the idea that periodontitis may develop in patients with poor glycaemic control, and that poorly managed periodontitis may lead to a deterioration in glycaemic control (Alpert, 2017).

Other systemic diseases that have an implied association with periodontal disease include diabetes mellitus, Alzheimer’s, cardiovascular disease and rheumatoid arthritis (Winning and Linden, 2015). While the FDI agrees such associations are ‘biologically plausible’, interventional studies do not automatically demonstrate causation (FDI World Federation, 2013). Indeed, periodontal therapy does not always lead to an improvement in systemic diseases (Dörfer et al, 2017).

Research results continue to support the concept that some oral conditions are associated with a number of systemic diseases, but, for now, their mechanism is not fully understood. The possibility of a ‘causal-and-effect relationship’ between oral and system diseases remains unresolved (Alpert, 2017).

Confounding and causality

One of the challenges facing dental professionals is that many of the risk factors for periodontal disease overlap with those associated with systemic diseases, such as age, gender, obesity, smoking and socio-economic status. These are known as ‘confounding’ factors and need to be kept in mind by the dental team when discussing the reasons behind a particular health condition (Winning and Linden, 2015).

Expanding on this concept, Winning and Linden (2015) stated: ‘Although plausible, based on the mechanisms outlined, the critical appraisal of studies completed to date cannot distinguish whether periodontitis and systemic disease develop due to similar shared disease pathways rather than because one actually causes the other.’

That stated, according to Sudhakara at al (2018), ‘Recent studies have paved a paradigm shift in emphasizing [sic] the oral ecosystem as vital to maintaining both the oral and overall health of the body.’

Nonetheless, given the limitations in the current evidence base, Winning and Linden (2015) suggest, ‘…when we discuss links between periodontitis and systemic disease with patients it is better to describe “association” rather than “causation”.’

A pragmatic approach

Presenting an overview of the present situation to help the dental team in deciphering and making use of the idea that oral health may be intrinsically linked to general health, Winning and Linden (2015) advised: ‘Whilst [sic] there is now good evidence for periodontitis associating with various systemic diseases (particularly atherosclerotic cardiovascular disease and diabetes), evidence for a causative role is still lacking.

Many of the reviews in this area report that “further studies are needed”, but that should not prevent us taking a pragmatic approach in promoting a patient’s good oral health benefiting their general health. Treating periodontal disease, where we also address shared modifiable risk factors, such as smoking, diabetes control, and diet, can only have a positive effect on related systemic disease and as dental professionals we are ideally situated as front line health staff to do this. It is acknowledged that the gaps in our knowledge remain large.’

As a final point, it may be worth keeping in mind the following notion from Kane (2017): ‘Although many of the studies on treatment of oral disease have not shown a statistically significant impact on these systemic conditions, neither profession [medical nor dental] will deny that maximising a patient’s health is advantageous.’

References

Alpert PT (2017) Oral health: the oral-systemic health connection. Home Health Care Management & Practice 29(1): 56-59

Barasch J (2018) Oral disease and systemic implications. J Dent Oral Res 1(1): 13

DiMatteo AK (2017) Periodontal disease & systemic health. Inside Dentistry 13(11)

Dörfer C, Benz C, Aida J, Campard G (2017) The relationship of oral health with general health and NCDs: a brief review. International Dental Journal 67: 14-18

Jepsen S, Caton JG, Albandar JM, Bissada NF, Bouchard P, Cortellini P, Demirel K, de Sanctis M, Ercoli C, Fan J, Geurs NC, Hughes FJ, Jin L, Kantarci A, Lalla E, Madianos PN, Matthews D, McGuire MK, Mills MP, Preshaw PM, Reynolds MA, Sculean A, Susin C, West NX, Yamazaki K (2018) Periodontal manifestations of systemic diseases and developmental and acquired conditions: Consensus report of workgroup 3 of the 2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions. J Clin Periodontol 45(20): S219-S229

Kane SF (2017) The effects of oral health on systemic health. General Dentistry 65(6): 30-34

FDI World Dental Federation (2013) Oral infection/inflammation as a risk factor for systemic diseases

Sudhakara P, Gupta A, Bhardwaj A, Wilson A (2018) Oral dysbiotic communities and their implications in systemic diseases. Dent J 6: 10

Winning L, Linden GJ (2015) Periodontitis and systemic disease. BDJ Team 2(15163)