Recent research in the field of health and medicine is advancing our knowledge of the digestive system and its surprising bacterial universe. Over the last few years, research on the oral and intestinal microbiota has turned the understanding of the human body and its health upside down, mainly by providing a new way of looking at and understanding what lies behind many diseases.
Do all bacteria in our mouth cause disease?
No, bacteria in the mouth also play an important role in our well-being. In fact, 10% of the population never has caries because the oral cavity is protected by the Streptococcus dentisani bacteria. Therefore, in the mouth, we can find both beneficial and harmful bacteria.
The numbers are striking: in our mouth, we find more than 700 different species of bacteria, and in each millimetre of saliva there can be between 10 and 100 million microorganisms. A true ecosystem on whose balance our health depends.
What bacteria cause periodontal diseases?
Since the last century, a great deal of evidence has been accumulated on the origin of periodontitis, but few microorganisms have so far been termed periodontal pathogens, which are related to the initiation and progression of the disease.
Although there are more than 300 species of bacteria isolated from periodontal pockets, only a small percentage of them are considered etiologically important. The following is a list of the harmful bacteria that exist in our mouth and belong to the group of Gram Negative Anaerobic Bacilli, mostly related to the causes of periodontal disease:
1. Genus Porphyromonas.
The species of the genus Porphyromonas are characterized by being pleomorphic or coccobacilli, non-motile, non-sporulating bacilli. P. gingivalis, which has been considered a periodontopathogenic bacteria par excellence, is isolated from the gingival sulcus especially when periodontal health is poor and has been associated especially with the progression of chronic periodontitis. P. gingivalis is the most pathogenic microorganism within the group of Gram Negative Anaerobic Bacilli.
They point out that the pathogenic power of this bacterium in colonization, destruction of periodontal tissue and evasion of host defences is related to a number of virulence factors. This bacterium is capable of producing a variety of enzymes that cause alterations directly in the tissues of the periodontium. These include collagenase, which acts on the collagen of the periodontal ligament and alveolar bone.
The species that make up the genus Prevotella are short, pleomorphic, immotile, non-sporulating bacilli. The species most implicated in periodontitis are P. intermedia, P. loescheii and P. melaninogenica, in which fimbriae, such as adhesins, involved in bacterial adhesion and coaggregation have been described. Its capacity to degrade immunoglobulins, its toxic action on fibroblasts, its fibrinolytic activity, and the stimulation of its growth by hormones such as estradiol and progesterone have also been demonstrated.
Likewise, it has been demonstrated in vitro that P. loescheii and P. melaninogenica have an immunosuppressive effect by inhibiting the proliferation of B lymphocytes and immunoglobulins.
This genus includes a great variety of species located in the Bacteroides fragilis group, frequently isolated in infections of clinical importance in humans. These species are part of the autochthonous microflora of the gastrointestinal tract, but are rarely found in the mouth. In the oral cavity, only the species B. capillosus, B. heparinolyticus, and B. forsythus, which frequently inhabit the gingival sulcus, are of interest.
The bacteria that make up the genus Fusobacterium are characterized by being long spindle-shaped, immotile, non-sporulating and generally non-fermentative bacilli. The production of butyric acid as the main metabolic product allows differentiating Fusobacterium from Prevotella, Porphyromonas and Bacteroides.
What can cause these types of bacteria?
Chronic periodontitis involves the destruction of tooth-supporting tissues and is one of the most important cases of tooth loss. The existence of dental plaque is fundamental in this process. The colonization of periodontal tissues by these harmful bacteria is the first step in the development of this disease.
This destructive process is due to the entry of bacteria or their bacterial products into the periodontal tissues. Consequently, the destruction of the bone and gingiva surrounding the tooth derives from bacterial products that directly or indirectly cause damage to the teeth.
However, it is a mistake to kill all bacteria, as many are good bacteria. For example, they prevent the entry of certain pathogens, such as those that cause yeast or fungal infections. Therefore, periodontitis must be treated by means of specific disinfection techniques and mechanical plaque removal, respecting the beneficial bacteria in the mouth.
In addition, we must bear in mind that when we take antibiotics or use antiseptics continuously and abusively, the balance of the oral microbiota is also broken and these bacteria that prevent the settlement of opportunistic pathogens, i.e. harmful types of bacteria, disappear.