[SDH and Periodontal Disease ①] The unease I feel at the phrase 'Let's increase the ratio of private practice'

I will start with something that is never discussed at dental seminars or academic conferences.

Introduction

This is not content where I teach you anything. It is for me to organize my own thoughts while studying together with the readers. I would be happy if you could look at my past Notes for my self-introduction.

I am a board-certified periodontist of the Japanese Society of Periodontology and a dentist who studied MBA at a graduate school of management. However, the SDH (Social Determinants of Health) that I will deal with from now on is outside my area of expertise, and I am still in the process of learning. Therefore, I cannot say anything arrogant. (I cannot say anything arrogant even in the fields I am studying, haha)

Rather, the more I study, the more anxious I become about my clinical practice as a dentist. I would like to think about this with you while sharing that unease and anxious feeling.

First, before talking about evidence or anything else, I will start with my personal unease.

1. What is SDH in the first place?

First, let's confirm the terminology.

SDH (Social Determinants of Health) is, roughly speaking, this way of thinking.

Income, education, work, where you live, and connections with people. These living conditions eventually reach the body. This is the view also adopted by the WHO.

When thinking about it in dentistry, it looks like this.

“Are they brushing properly?” “Do they smoke?” “Are they visiting regularly?”
The living conditions behind that determine the fate of that person's periodontal tissue.

The act of going to see these "things behind it" is SDH. There is only one thing I want you to remember: "causes of the causes". If plaque and smoking are the "causes," then the educational background, income, and working environment behind them are the "causes of the causes." Looking at this is what SDH is about.

2. A different story is heard in dentistry

From here on is not so much the main topic, but my unease.

The more I study management, the more clearly I hear a certain phrase.

"Let's increase the ratio of private practice"

Seminars on increasing the ratio of private practice are rampant in the world. "You can't make a living with insurance treatment," "How to increase the ratio of private practice," "Talk techniques to increase unit prices." Customer acquisition, closing, the order of presentation... Honestly, some of it is useful as know-how.

But among them, there are also things that make me wonder if this is truly correct medicine or how it stands ethically. That is how I feel.

Please do not misunderstand me; I myself provide private practice, and I am someone who has been looking at the ratio of private practice as a management indicator for many years. I have no intention of denying private practice itself. Good medical care requires compensation, and running a clinic requires revenue. Without that guarantee, it is impossible to continue providing good medical care.

What I am hung up on is not the existence of private practice itself, but the atmosphere in the industry that 'increasing the ratio of private practice equals good'.

Here, I will write down the unease I have been unable to put into words for a long time.

'Creating a treatment plan for a single patient that ignores both money and time to cure them perfectly'. This is an ideal. If there were no upper limits on costs or conditions, that might indeed be the best medical care. Periodontal tissue regeneration, prosthetics, orthodontic treatment, and ideal maintenance could all be done.

But in reality, that is medical care that perhaps only 1 out of 100 people can receive.

Then, where do the remaining 99 people go?

Neither in seminars on increasing the ratio of private practice nor in the flashy case presentations at academic conferences does the story of these 99 people appear. What is always talked about is 'how to deliver the best to the one person who can pay'.

There are doctors who pay out of their own pockets to provide ideal medical care. I also make efforts every day, and I think doctors who work hard every day to achieve ideal results are truly wonderful.

That is also important. But what I am facing every day in Nantan City is actually those 99 people.

3. Geoffrey Rose's Question — 'Sick Individuals' and 'Sick Populations'

Public health had already put this unease into words 40 years ago.

It is the paper written in 1985 by British epidemiologist Geoffrey Rose, "Sick Individuals and Sick Populations".

Rose distinguished between two questions. Let's rethink those questions from a dental perspective.

One is 'Why did this patient get periodontal disease?'. Finding high-risk individuals and treating them thoroughly is the high-risk approach. The other is 'Why does this population have more periodontal disease than the one next door?'. Shifting the risk distribution of the entire population itself is the population approach.

'Let's increase the ratio of private practice' is the high-risk approach pushed to its commercial limit. It is the idea of concentrating resources on the one person who can pay.

Rose also left behind a famous paradox: the 'prevention paradox'. The more a measure brings great benefits to a population, the less the individual receiving it feels the benefit. Conversely, even if you treat prominent severe cases thoroughly, the disease burden of the entire population does not move much.

This is because most cases arise from the 'vast majority at medium risk'.

My sense of discomfort that 'even if I cure one person perfectly, won't periodontal disease in Nantan City fail to decrease?' was exactly this.

4. So, is periodontal disease really linked to "society"?

"That said, periodontal disease is a matter of plaque bacteria and host response. Before talking about society, isn't it just a matter of individual differences in how well people brush?"

That is a reasonable counterargument. But in fact, the etiology of periodontal disease itself has moved significantly away from "it can be prevented by brushing" over the last 100 years. Please let me briefly review this.

There was once the non-specific plaque hypothesis, which essentially held that the "amount" of plaque was the problem, and that if it accumulated, you would get sick. This is exactly the worldview of "it can be prevented by brushing = individual effort." Eventually, the specific plaque hypothesis (Loesche, 1976) emerged, which posited that it was not the amount, but specific periodontal pathogens (the Red Complex, such as P. gingivalis) that were the culprits.

The turning point was 1997, with Page & Kornman. They showed that even when exposed to the same bacteria, what determines whether the disease develops or how far it progresses is the host's immune and inflammatory response, which is modified by genetic factors and acquired/environmental risk factors (smoking, diabetes, etc.)—a framework still called the "classic model." The mere presence of bacteria could no longer explain the disease.

And in 2012, we moved to the Hajishengallis and Lamont dysbiosis (PSD) model. It is not a single bad bacterium that causes disease, but the collapse of the balance of the entire bacterial flora (dysbiosis). This view holds that a small number of "keystone pathogens" disrupt the host response and tilt the harmony of the commensal bacteria toward pathogenicity.

The meaning of this progression is clear. The arrow of etiology has moved from "amount of plaque (individual brushing residue)" to "host response and the environment that modifies it". And smoking, diabetes, stress, and nutrition, which modify the host response, are precisely things that are influenced by the environment surrounding the patient.

Next, let's look at research on the link between periodontal disease and society through systematic reviews from the past 20 years.

2005 (Klinge & Norlund) — One of the earliest full-scale reviews. While many cross-sectional studies supported the association between SES and periodontal disease, the conclusion was cautious: "When smoking is included in the analysis, socioeconomic variables appear less important than smoking." J Clin Periodontol. 2005;32(Suppl 6):314–325.

In fact, this very sentence is the point often brought up as the greatest counterargument to the SDH theory. But think about it carefully. Smoking rates are themselves strongly stratified by education and income. The lower the income and education, the higher the smoking rate. If so, smoking might be the pathway connecting "society → periodontal disease." The fact that the association disappears when adjusted for smoking is not proof that "society is irrelevant," but rather that society might be reaching periodontal disease through the path of smoking.

2011 (Boillot et al.) — A meta-analysis of over 40,000 people. The risk of periodontitis in the low-education group was OR 1.86 (95% CI 1.66–2.10), and even after adjusting for smoking, etc., it remained at OR 1.55 (1.30–1.86). This quantitatively showed that social factors remain even after subtracting smoking. PLoS ONE. 2011;6(7):e21508.

2012–2019 — Perspectives expanded to include income, occupation, and life course, showing that even "at what point in life one had low SES" affects oral health.

2024/2025 (Albandar) — Moving beyond "is there an association," the subject has become how inequalities in age, gender, income, education, and medical access shape disparities in periodontal disease. The current consensus is that periodontal disease is a condition that weighs disproportionately heavily on poor and marginalized people. Periodontol 2000. 2025;98:125–137. (Online ahead of print January 13, 2024)

However, the papers I have researched on this are biased, so there is still much I do not know.

5. Is the expansion of private practice creating a "new social gradient"?

If periodontal disease is linked to socioeconomic status,

and if we "increase the ratio of private practice" and concentrate the best medical care on those who can pay,

won't the gap between those who can afford treatment and those who cannot widen?

In other words, the expansion of private practice may mean that dentistry itself is creating a "new social gradient." The best care gathers in the upper strata, and 99 people are left behind. Even with universal health insurance, isn't the social gradient widening?

This was the true nature of the unease I had been carrying for a long time. The rallying cry of "Let's increase the ratio of private practice" is correct from a management perspective. However, the moment you apply the yardstick of oral health for the entire community, a different face emerges.

I still do not have an answer to this question. I am not denying private practice, nor do I intend to spout platitudes like "people's hearts are more important than money." Because if the clinic doesn't continue, we can't even save 99 people.

However, I want to keep another perspective within myself in a world where only "Let's increase the ratio of private practice" alone continues to resonate. That is the eye that sees the collective = population approach, and SDH.

6. The patient in front of me is someone who has overcome five walls

Here, I will shift the perspective from the "collective" back to the "individual in front of me" once again. However, with different eyes than before.

In 2013, medical sociologist Levesque depicted the path a person takes to reach medical care as five walls (= abilities required to overcome them).

1. Ability to perceive — Can they even notice that "I have medical needs" in the first place?

2. Ability to seek — Can they find the necessary medical resources?

3. Ability to reach — Can they overcome distance and time to get there?

4. Ability to pay — Can they afford the costs?

5. Ability to engage — Can they interact with medical professionals and continue to use care?

And the crucial point is that SDH (Social Determinants of Health) are involved in all five of these abilities. Access to information, health literacy, means of transportation, household finances, the capacity to build relationships with medical professionals—all of these are influenced by the conditions of that person's life.

The fact derived from this is quiet, but powerful.

The person sitting in the chair in my clinic right now is someone who has overcome all five walls.

They have noticed potential needs, searched for resources, managed their time to visit the clinic, scraped together the costs, and are trying to engage with me. Behind that, they have overcome numerous social hurdles without even realizing it themselves. Especially the fourth one, ability to pay — including that wall I have written about extensively up to the previous chapter.

The doctor who showed this diagram in a lecture added this at the end.

This sentence has remained stuck in me. What am I doing to the people who have overcome walls to come this far? The next chapter is that question.

7. Two questions I am posing to myself

Having written this far, two questions remain within me for which I still have no answer. I will list them honestly, without being able to resolve them neatly.

First. Is good medical care, in the end, only for the wealthy?

Good medical care requires payment. This is a fact. But when you take it to its logical conclusion, the landscape becomes one where 'the best medical care is only available to those who can afford it.' Periodontal tissue regeneration, precise treatment, and ideal maintenance are all things that become accessible starting with those who have the luxury of money and time.

Is that really 'unavoidable'? I cannot bring myself to say it is 'unavoidable.' But I also cannot say 'just do everything through insurance.' If the clinic does not survive, I cannot save even one of the 99 people. I am still standing in this dilemma.

Second. Is it virtuous to provide values-based education to get patients to choose good medical care?

In dentistry, 'values-based education' is often discussed. It involves conveying the value of the oral cavity to patients, encouraging investment in health, and dispelling the misconception that 'cheaper is better.' I have done this too. It is the very essence of informed consent and an effort to improve health literacy. Therefore, I have believed it to be virtuous.

But sometimes, there are moments when my thinking stops.

Is that really 'education'?

Or is it persuasion to 'get those who can pay to pay more'?

Against the backdrop of information asymmetry and the authority of national qualifications.

Moreover, this values-based education usually only works on the segment that already has a little bit of leeway. For those without leeway, even if the value is conveyed, they have no means to choose it. If that is the case, what I have done with good intentions might be reaching only those who can afford it, and actually accelerating inequality.

As if to say, 'If you cannot receive good treatment, you have no choice but to give up.'

There is a possibility that what I am doing with good intentions is creating a social gradient.

I have not yet been able to fully deny this possibility.

I still cannot find the answers to these two questions. However, I want to continue standing with this discomfort in a world where people can say 'Let's increase the ratio of private practice' without hesitation. I believe that not closing off these questions is the sincerity I can offer right now.

References

1. Rose G. Sick individuals and sick populations. International Journal of Epidemiology. 1985;14(1):32–38.

2. Klinge B, Norlund A. A socio-economic perspective on periodontal diseases: a systematic review. Journal of Clinical Periodontology. 2005;32(Suppl 6):314–325.

3. Boillot A, El Halabi B, Batty GD, Rangé H, Czernichow S, Bouchard P. Education as a predictor of chronic periodontitis: a systematic review with meta-analysis of population-based studies. PLoS ONE. 2011;6(7):e21508.

4. (2012: Review of SES indicators and periodontitis - Bibliographic information to be reconfirmed upon official publication)

5. (2017: Systematic review of life-course SES and adult periodontitis - Same as above)

6. (2019: Critical Review of Income and Oral Health — Ibid.)

7. Albandar JM. Disparities and social determinants of periodontal diseases. Periodontology 2000. 2025;98:125–137. (Online ahead of print January 13, 2024, doi:10.1111/prd.12547)

[Transition of Etiological Theory] 8. Loesche WJ. Chemotherapy of dental plaque infections. Oral Sciences Reviews. 1976;9:65–107. (Specific Plaque Hypothesis) 9. Marsh PD. Microbial ecology of dental plaque and its significance in health and disease. Advances in Dental Research. 1994;8(2):263–271. (Ecological Plaque Hypothesis) 10. Page RC, Kornman KS. The pathogenesis of human periodontitis: an introduction. Periodontology 2000. 1997;14:9–11. 11. Hajishengallis G, Lamont RJ. Beyond the red complex and into more complexity: the polymicrobial synergy and dysbiosis (PSD) model of periodontal disease etiology. Molecular Oral Microbiology. 2012;27(6):409–419.

* This article was written by the author while studying public health and SDH by consulting original research papers. Any errors in interpretation are solely the responsibility of the author.