Purpose: To assess the distribution of subgingival flora after restoration of dentition defect with conical telescopic removable denture in patients with periodontitis., Methods: 36 spots of 18 patients were examined and recorded for periodontal depth (PD) and gingival index(GI). Samples from subgingival pocket were collected, cultured, evaluated and compared between abutment teeth group and nonabutment teeth group. Chi-square test was used to determine the difference in each of these positive detecting rates by SPSS 10.0 software., Results: 3 years after restoration, the GI and PD of abutment teeth were normal, while those of the non-abutment teeth were higher. The positive rate for anaerobe in subgingival pocket after restoration, were significantly higher than that before restoration in both groups (P<0.05)., Conclusions: Conical telescopic removable denture is efficient in controlling the accumulation and attachment of nosogenetic microorganisms, preventing periodontitis from recurring and is a preferred prosthesis for dentition defect with periodontitis.