Research Article: Oral dysbacteriosis in type 2 diabetes and its role in the progression to cardiovascular disease

Date Published: December , 2017

Publisher: Makerere Medical School

Author(s): Ziad Nabee, Rajesh Jeewon, Prity Pugo-Gunsam.


Salivary changes and proliferation of specific bacterial communities are known to result in oral disease which may adversely impact on systemic conditions like diabetes and cardiovascular diseases.

This study reports on the changes in oral ecology of healthy and diseased adults and the possible role in disease causation.

The study comprised 150 participants divided into control (healthy), diabetic and cardiac groups. After dental examination for (Decayed Missing Filled Teeth (DMFT) and Oral Rating Index (ORI), stimulated saliva was sampled to determine flow rate and buffering capacity. Salivary microbial load of Streptococcus mutans and Lactobacilli were subsequently quantified.

DMFT, ORI, buffering capacity and flow rate were inferior for both diabetic and cardiac patients, who had higher bacterial counts (p<0.05). Long standing diabetics harboured a higher load of Streptococcus mutans. The microbial load of Streptococcus mutans in cardiac patients was double that of diabetics. Disruption in the salivary environment and changes in microbial ecology with increased load of cariogenic bacteria were found in diabetic and cardiac patients. This study brings forward new evidence of a markedly higher load of Streptococcus mutans in cardiac patients which may underlie the progression of diabetes to cardiovascular disease in this population.

Partial Text

Oral health is dependent on the maintenance of stable microbial communities and oral disease occurs when pathogenic species outgrow the normal flora1. In the oral cavity, pathogenic bacteria are often associated with two major diseases; dental caries and periodontal disease2. Saliva, which constantly bathes the oral cavity reflects an imbalance in microbial communities under these disease conditions3. In dental caries, there is a shift towards community dominance by acidogenic and acid-tolerating species such as Streptococci mutans and Lactobacilli4. Among the 200 bacterial species isolated from dental plaque the two most pathogenic for dental caries are: Streptococcus mutans5 and oral Lactobacillus6. These bacteria are documented to produce organic acids in the oral cavity and are able to maintain its metabolism in strong acid medium, rendering them cariogenic7. In the mouth, salivary imbalances in flow rates and buffering capacity have been shown to impact on the development of dental caries8,9. The dynamics involved in dental caries progression, compounded by resulting inflammation produced by these cariogenic bacteria often lead to periodontal disease in subjects afflicted with dental caries.

SPSS, version 16.0 (SPSS Inc., Chicago, IL, USA) was used to conduct the statistical analyses. An alpha level of 0.05 was used. One-way analysis of variance was used to determine any significant difference among the three groups for oral hygiene practice scores, DMFT scores, salivary parameters and microbial load. Post hoc analysis was carried out to examine the significance of relationships between and within groups. Pearson’s correlation analysis was used to study the relationship between salivary parameters and DMFT. Multiple regression analysis allowed assessing multifactor impact on oral health while controlling for oral hygiene of the subjects.

The main implication of the present study is that diabetic and cardiac subjects suffered from poor oral health with drastic changes in the oral environment as far as salivary properties and cariogenic bacterial load are concerned. The altered salivary composition presents as an important factor that serves to modify the proportions of specific oral bacterial species, ultimately predisposing to cariostatic lesions. In addition, our study brings forward new evidence that long standing diabetics harbour increased bacterial load of Streptococcus mutans. This indicates that the common progression of diabetics to cardiovascular disease in Mauritius may well be mediated by specific inflammatory mechanisms modulated by specific pathogenic oral bacterial species. This is further supported by the markedly higher microbial load of Streptococcus mutans in cardiac patients. The drastic alteration in pathogenic oral bacterial populations therefore may directly constitute a chronic source of systemic challenge. However, a causal relationship will only be confirmed by studying the behaviours of live oral pathogenic bacteria in cardiac tissues which requires invasive, costly and life threatening investigations. Likewise, it would also be important to consider the bidirectional relationship between bacterial infections and chronic systemic conditions. This study warrants the need for in-depth research using larger sample populations.




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