Using a claims database, 5117 adults with no periodontitis history were stratified by pre-defined criteria, and those negative for three risk factors (smoking, diabetes, IL-1 genotype) were not less likely to lose teeth over 16 years with two cleanings/year compared to one (p = 0.092), but patients with ≥1 risk factor benefited from two cleanings/year compared to one (p = 0.002) 22. This evidence concerns the gene IL1B and diabetes mellitus.