ObjectiveThis study evaluates the expression of interleukin-18 (IL-18) and hypoxia-inducible factor (HIF)-1αin rat periodontitis model exposed to normoxia and chronic intermittent hypoxia (CIH) environments. The possible correlation between periodontitis and obstructive sleep apnea-hypopnea syndrome (OSAHS) was also investigated.MethodsThirty-two Sprague–Dawley (SD) rats were randomly assigned into four groups: normoxia control, normoxia periodontitis, hypoxia control, and hypoxia periodontitis groups. The periodontitis models were established by ligating the bilateral maxillary second molars and employing high-carbohydrate diets. Rats in hypoxia control and hypoxia periodontitis groups were exposed to CIH treatment mimicking a moderately severe OSAHS condition. All animals were sacrificed after eight weeks, and the clinical periodontal indexes were detected. The levels of IL-18 and HIF-1α in serum and gingival tissues were determined using enzyme-linked immunosorbent assay (ELISA). The correlation between attachment loss (AL) and the levels of IL-18 and HIF-1α in hypoxia periodontitis group was evaluated.ResultsThe levels of IL-18 and HIF-1α in hypoxia periodontitis group were significantly higher than that in normoxia periodontitis and hypoxia control groups (PConclusionCIH could aggravate the destruction of periodontal tissues, which is correlated with IL-18 and HIF-1α levels.