The Mouth-Joint Axis: Why Your Dentist Visit Belongs on Your Pre-Surgery Checklist

The study, published in 2025 in the European Journal of Orthopaedic Surgery & Traumatology, examined patients operated on at a single hospital between January 2020 and December 2022. The team measured three standard markers of oral health before surgery — plaque control records (PCR), bleeding indices, and the share of probed periodontal pockets ≥ 4 mm — and tracked wound infections through postoperative day 90. After adjusting for other variables, two factors emerged as independently associated with elevated infection risk: higher body mass index and a higher PCR rate, the latter a direct measure of how much bacterial plaque is clinging to a patient's teeth on the day of assessment, according to the authors' multivariate analysis.

The effect size is modest but consistent. Each one-point increase in the plaque control record was associated with a 4% rise in the odds of early wound infection (OR 1.04; 95% CI 1.01–1.07), while BMI carried an OR of 1.27 per unit (95% CI 1.10–1.49), as reported in the primary results. These are not the kind of numbers that rewrite surgical guidelines overnight. But for an elective procedure where infection is the complication patients fear most, a variable that is cheap, measurable, and modifiable deserves a seat at the prehab table.

The biological premise is not new. The mouth is a dense, persistent reservoir of bacteria, and periodontal disease creates a chronically inflamed surface through which oral microbes can enter the bloodstream during routine activities like chewing and brushing. In a patient whose immune system is already managing the insult of major orthopedic surgery — and whose body now contains a large foreign object in the form of a prosthesis — that low-grade bacteremia is a plausible vector for trouble at the surgical site.

What the new analysis adds is a quantitative hook on a routine clinical metric. PCR is not exotic; any dental hygienist can produce one in a standard cleaning visit. The implication of the Kaneko et al. cohort is that this number, captured weeks before surgery, carries information that orthopedic teams are not currently using.

The evidence here is best characterized as moderate and suggestive rather than definitive. This is a single-center, retrospective observational study in a relatively older Japanese cohort (mean age 75.3 years), and the authors themselves frame their conclusion as an emphasis on the importance of preoperative oral optimization, not a mandate. Retrospective designs cannot prove that cleaning teeth before surgery would have prevented infections; they can only show that patients with cleaner mouths had fewer of them, after adjusting for measured confounders. The authors note that the role of preoperative oral health in joint-replacement infection risk has been poorly understood, which is precisely why a single cohort, however well-executed, is a starting line rather than a finish line.

It is also worth noting what did not reach independent significance in the multivariate model. Bleeding indices and the rate of deep periodontal pockets were measured but did not emerge as independent predictors in the adjusted analysis — only plaque load and BMI did. That nuance matters: the finding is specifically about plaque burden, not about every facet of periodontal disease.

For a reader with an elective hip or knee replacement on the horizon, the operational translation is straightforward and low-risk. A dental cleaning and periodontal assessment are already standard preventive care; sequencing one into the pre-surgical window — well in advance of the operation, not days before — is a reasonable extension of existing prehab logic that already includes nutrition, conditioning, and weight management. The BMI association in the same model is a reminder that infection risk is multifactorial, and that no single modifiable variable carries the whole load.

None of this is a substitute for the conversation that should actually drive the decision: the one with your surgical team and your dentist, who can weigh your individual periodontal status, the timing of any planned dental work, and the prophylactic protocols specific to your procedure. The study points at a lever; clinicians decide when and how to pull it.