Hello @dmjohnstone, Welcome to Connect. My Mayo Clinic surgeon didn't require me to get a dental clearance before I had my right knee replacement surgery. I think it depends on who is doing the surgery. Here's some information from Dec 2019.

"Conclusion:
With an aging population, the number of total joint arthroplasties is likely to continue growing. Periprosthetic infection remains a great concern and quality improvement problem despite improvements in sterile and prophylactic techniques. There is little evidence to support universal dental clearance before TJA, even for higher risk patients. There remains a need for future research to elucidate the mechanism of periprosthetic infections and more robust analysis of patients with high risk dental pathologies to help guide interventions."
-- Impact of dental clearance on total joint arthroplasty: A systematic review
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6937426/
Is your surgeon requesting a dental clearance before doing your knee replacement?