Soluble Receptor Activator of Nuclear Factor Ligand and Osteoprotegerin Levels in Gingival Crevicular Fluid among Cigarette Smokers and Non-smokers with and without Periodontitis.

Abstract

This study aimed to measure and compare the levels of soluble receptor activator of nuclear factor ligand (RANKL) and osteoprotegerin (OPG) in the gingival crevicular fluid (GCF), as well as their ratio, in smokers and nonsmokers with periodontitis. Gingival crevicular fluid samples were collected using PerioPaper strips, from 150 individuals, who were categorized into three groups: current smokers with periodontitis stage III grades C and B (n = 50), nonsmokers with periodontitis stages I and II grade A (n = 50), and control healthy individuals (n = 50). The concentrations (pg/mL) of sRANKL and OPG in the GCF were measured by enzyme-linked immunesorbent assays (ELISA). The smokers' group exhibited the highest sRANKL (pg/mL) concentration as a subsequent lead to a higher sRANKL/OPG ratio. The healthy control group exhibited higher OPG and lower sRANKL concentration, subsequently, the sRANKL/OPG ratio was reduced compared with the other study groups. However, there was no statistical significance of sRANKL and its relative ratio between periodontitis stage III grades C and B, periodontitis stages I and II grade A, and healthy control individuals. There was a statistically significant positive moderate correlation between smoking duration (years) and the sRANKL (pg/mL) concentration and a statistically significant negative moderate correlation between OPG (pg/mL) concentration and cigarettes smoked per day. As a result, compared to the other research groups, smokers with periodontitis stage III grades C and B had greater GCF concentrations of sRANKL, lower OPG, and a higher sRANKL/OPG ratio. The difference in OPG (pg/mL) level was statistically significant. However, there was no statistically significant difference in sRANKL (pg/mL) or its relative ratio, sRANKL/OPG, across the groups. A characteristic that sets periodontitis apart is alveolar bone loss. Resorption is induced by RANKL and inhibited by OPG, resulting in a relative ratio. In light of this, the levels of RANKL and OPG may be helpful indicators for monitoring the activity of periodontal disease in both smokers and nonsmokers with and without periodontitis.