Why brush twice a day? There are several answers to this question. We brush, floss, and rinse repeatedly every day to reduce the bacterial load in the mouth, prevent disease development, avoid halitosis, remove stains, and remove food particles, among others. All these answers are true, valid, and accurate, but they do not drill down to the bottom line, bare bones, one ultimate reason.
Understanding the real reason for repetitive home care begins with the mechanism of biofilm formation. Biofilm develops in a precise sequence of bacterial species stacking on top of one another. It happens the same way over and over, every time biofilm starts building up. The first bugs congregating on a newly forming biofilm are always the same gram-positive aerobes, Streptococcus and Actinomyces. The most important feature of these early colonizers is that they are not pathogenic.
In other words, they cannot cause periodontitis. In fact, they are considered favorable or beneficial and are associated with healthy gingiva. Remember, a healthy gingival sulcus is not sterile or devoid of bacteria. It is, rather, populated by the right types of bacteria, namely the early colonizers.
If a newly developing biofilm is not eliminated or at least adequately dismantled, the later-arriving periodontal pathogens have a chance to come on board the biofilm. The periodontal bugs are always among the later colonizers.
This is certainly an evolutionary adaptation, for if the highly virulent periodontal bugs were the initial colonizers, the body would have a lower likelihood of surviving. The bugs cannot land on the biofilm until the conditions are appropriate and it is their turn. Holding them back gives the immune system a fighting chance to keep the pathogens in check.
Prior to joining the biofilm, the periodontal pathogens are freely floating around in the mouth. In a free-floating state, they cannot cause disease. Bacteria must be attached to the gingival epithelium to cause gum disease. No attachment, no disease, period.
When the biofilm is not brushed away, the perio pathogens start piling on. In approximately three to 12 weeks, they will become the predominant species. If the patient is genetically susceptible to periodontitis, it may ultimately develop.
Putting this all together, the primary reason for repetitive daily home care has to do with the properties of biofilm formation. Since the early colonizers are not pathogenic, we want to have these in place as often as possible. We want the virulent, disease-causing periodontal pathogens to be in the nonattached, free-floating position as often as possible. Those early bugs cannot cause periodontitis.
Development of periodontitis requires a genetically susceptible individual, an active chronic inflammatory response, and a sufficient number of the gram-negative anaerobic periodontal pathogens in the gingival sulcus in direct contact with the gingival epithelium.
So, on a clinical level, how do we maximize the favorable, early colonizers and minimize the later-colonizing periodontal pathogens? We do this by forcing the biofilm to keep starting over. We accomplish this by removing it as often as reasonably possible.
Every time we knock down the biofilm with our home-care efforts, we make it start over. Every time it starts over, the early bugs are the same favorable, nondisease-causing ones — and they cannot cause periodontitis, ever.
The ultimate reason for brushing twice a day is to keep making the biofilm start over and over and over, because every time it starts over, we have just the early arriving good bacteria on the biofilm. When this situation exists on a daily basis, the later-colonizing periodontal pathogens are kept in a holding pattern, circling around in the mouth without a place to land. This is where we want them, since they cannot cause disease in a nonattached position.
Frequent, effective home care is critically important, since periodontal diseases have local effects in the oral cavity and global effects around the rest of the body. Failure to prevent periodontitis development condemns the patient to a lifetime of disease management, since it is a noncurable condition. The oral contribution to the total inflammatory burden is significant, and the total inflammatory burden increases the risk for systemic diseases.
Brushing twice a day protects the patient’s general health. And the patient’s well-being is the reason we go to work every day.