Board Certified Periodontist

52 — Flossing Research

Hi there. Ben Young here. You are listening to The Perio Patient Podcast, a podcast for my patients and anyone else who cares to listen. Today is a topic close to my heart. I just want to share with you a study that was recently published in the Journal of Dental Research this year (2020) by three authors: Marchesan, Byrd, and Moss entitled: Flossing is associated with improved oral health in older adults. First some background: They state that tooth loss is independently associated with the onset of disability and mortality among elderly people and may be an early indicator of accelerated aging in adults. This is citing a finding from another study in the Journal of the American Geriatric Society. If this is the case, then the author’s of this study conclude that it would be a good idea to keep teeth around and to do this it is important to, in scientific terms, “disrupt the dental biofilm.” In other words if you want to keep your teeth it is a good idea to clean them – and by cleaning, since some will interpret this as an intense activity – we are talking about disruption of colonies of bacteria – not something requiring a lot of brute force. They also cite a 2019 Cochran Database Systemic Review from 2019 entitled: Home use of interdental cleaning devises, in addition to toothbrushing, for preventing and controlling periodontal diseases and dental caries. Now if you have listened to my previous podcasts dealing with the water fluoride question, you have already encountered the Cochran Database. So, it’s nice to know that what you have been learning comes back to be useful later. Anyway, this was a review of studies dealing with flossing as it relates to plaque and gingivitis. Now to this study. It involved 686 community-dwelling people at least 65 years of age that were enrolled in a North Carolina Dental Study. Out of this data, 375 individuals were evaluated for tooth loss over five years. Results: They found that elderly people who reported flossing had better attachment levels – meaning their teeth were attached with more fibers to the surrounding bone and gums. Visually, it meant the gums were closer to the crowns of the teeth or less tooth was showing. The P-value between the two groups, those that flossed and those that did not floss relative to the strength of the attachment of teeth in the mouth as less than or equal to .005. What does this mean? Hang with me. This is useful to understand if you have to read scientific articles that analyze data using statistics. First there is what is called, the Null Hypothesis. Hypothesis – is a guess about something. All research involves guessing. We guess that there is a correlation between an event and some process we think happened. The Null Hypothesis is the idea that there is no correlation between two things. In other words there is no cause and effect. The P value is asking what is the probability that the results of the experiment or study is null? Or not related, in other words random. The higher the probability results are random the larger the number with the largest number possible being the number 1. So the range is between 1 being no correlation, we did not prove our hypothesis to 0 – which is an impossible number to reach because nothing in science is ever completely proven. There are many things that have astounding evidence or weight that

they are true, but we can never be absolutely sure – if we are, we are in the area of faith and not science. In this case the null hypothesis would be that flossing has no relationship with stronger attachments around the teeth or less periodontal disease. The P value is a number smaller than one where one is the null hypothesis. The smaller the P value the more likely the result is not an accident. In other words, the more likely that there is a significant relationship between the two things being studied the smaller the p value. The normal cut-off for a strong finding or relationship is .05. At .05 it is saying that there is less than a 5% probability the null is correct – therefore, we reject the null hypothesis. Does this mean the correlation is correct? No. It means that there is strong evidence it is correct. Science is never certain – it is always the process of questioning, of being skeptical. This is way science and politics may poor bedfellows. Enough said on that point. Remember, this was a five year study. So baseline, at the beginning of the study, the number of teeth the flosser group had was 8.6. If this included wisdom teeth (and I’m reading a summary of this report coming out of the Journal of the American Dental Associated November 2020 edition) then it’s not as bad as it sounds at first. Also, for many who had orthodontics earlier it is not uncommon that four bicuspids were removed along with the wisdom teeth – that would be 8 intentional teeth removed having nothing to do with decay or periodontal disease. What about for those who did not floss? Their baseline number of missing teeth was 11.5. Is this a significant difference? I will answer by giving you the P value and you can figure it out yourself. The P value is .0001. That would be that there is one/one-hundreth of a percent chance that the findings were accidentally derived and that there is no correlation. Over 5 years, how many additional teeth did the two groups lose and is the loss of teeth between the two groups significantly different – thus implying that flossing is helpful?

The flossers lost one tooth. The non-flossers lost four teeth. The P value was .0001. Molars showed the highest benefit from the use of floss – P = .0005. Overall, people who used dental floss had less periodontal disease, fewer caries (tooth decay), and fewer lost teeth over a 5-year period. Now, before you go floss, which you can certainly do in a few moments, please understand that most people floss using the most difficult and frustrating method possible. That is they wrap the floss around their first or pointing fingers. If this is you, wrap the floss around your middle fingers and this will free your first fingers and thumbs to more easily manipulate the floss. If you want to learn more then read my book. It’s a cheap kindle download, or buy it for you kids or grandkids and read it outloud to them. They are the ones who if they floss the rest of their lives will receive the greatest benefit. In addition to being a kindle download, it’s a soft-cover easy-to-read book with pictures – I bet it would make an interesting stocking stuffer this Christmas. Thanks as always for listening. Share with others and we will talk again soon.