The Effects of Initial Periodontal Therapy on the Serum Receptor Activator of Nuclear Factor-κβ Ligand/Osteoprotegerin System in Patients With Type 2 Diabetes Mellitus and Periodontitis

Background: The aim of the present study is to evaluate the serum receptor activator of nuclear factor-κβ ligand (RANKL)/osteoprotegerin (OPG) system in patients with chronic periodontitis (CP) and type 2 diabetes mellitus (T2DM) and its changes after periodontal intervention.

Methods: Thirty-five patients with CP + T2DM, 35 systemically healthy patients with CP, and 35 healthy controls were enrolled, and serum levels of RANKL and OPG were measured at baseline. Then the CP + T2DM group was divided into a well-controlled subgroup and a poorly controlled subgroup according to their hemoglobin A1c (HbA1c), and initial periodontal therapy was performed. After 3 months, patients in both subgroups were recalled, and serum RANKL and OPG levels were tested again and compared with the baseline.

Results: At baseline, serum levels of OPG in the T2DM + CP group were much lower than in the CP group and healthy controls (197.41 ± 57.05 pg/mL versus 232.60 ± 70.85 pg/mL [CP group] or 244.96 ± 85.13 pg/mL [healthy controls], P <0.05), whereas their RANKL levels were much higher than in the other two groups (324.35 ± 87.62 pg/mL versus 284.52 ± 90.35 pg/mL [CP group] or 163.01 ± 45.24 pg/mL [healthy control], P <0.05), as was the RANKL/OPG (R/O) ratio (1.68 ± 0.33 versus 1.26 ± 0.35 [CP group] or 0.72 ± 0.25 [healthy control], P <0.001). Serum levels of OPG in both disease groups had significant negative correlations with HbA1C, and serum levels of RANKL in all participants had significant positive correlations with periodontal parameters. After periodontal intervention, both the well-controlled and poorly controlled subgroups exhibited significant increases in OPG and decreases in RANKL in serum, and the R/O ratio was also notably reduced. Additionally, the poorly controlled subgroup exhibited a greater reduction in HbA1c and a greater increase in OPG than the well-controlled subgroup.

Conclusions: The changing trend in the serum RANKL/OPG system in patients with T2DM + CP was similar to that seen in CP patients and may be even more pronounced. Periodontal intervention effectively improved glucose metabolism and changed the serum RANKL/OPG system regardless of whether patients' HbA1c was well-controlled or poorly controlled over the 3-month observation period.