Objective：This study aimed to evaluate the treatment of four different methods on root surfaces of teeth affected by severe periodontal disease，adhesion and proliferation of Porphyromonas gingivalis（P. gingivalis）and human periodontal ligament cells（hPDLCs）on root surfaces. Methods：Severe periodontal affected teeth（n=100）were extracted and treated with scaling and root planning（SRP），and root slices were prepared. These slices were randomly divided into four groups：SRP group，Periocline group，EDTA group and Nd：YAG group. Scanning electron microscopy（SEM）and atom force microscope（AFM）were used to determine the morphology and the roughness of the root slices. The proliferation of P. gingivalis and hPDLCs was evaluated by cell count kit-8（CCK-8）. Results：The obvious smear layer was observed in SRP group，whereas it was almost removed in other three groups. The roughness of the root surface of Periocline group was the lowest while the Nd：YAG group was the highest. After 4 hours and 1 day，the amount of P. gingivalis adhered to the root surfaces of Periocline group and Nd：YAG group was significantly less than that to other groups. The attachment of hPDLCs to the root surfaces showed a time dependent manner，and the number of attached cells was higher in Periocline group and Nd：YAG group. Conclusion：SRP combined with Periocline or Nd：YAG laser is more conducive to the attachment and proliferation of hPDLCs，and decrease the adhesion of P. gingivalis at the early stage.