Collagen Membrane

The goal of this clinical trial is to evaluate clinically and radiographically effectiveness and products safety of the collagen membrane (FormaAid®) in the treatment of periodontal regeneration using guided tissue regeneration (GTR) performed by the trained periodontists. The main question it aims to answer are: * The difference of periodontal status: clinical attachment level (CAL), periodontal pocket depth (PPD), gingival recession (GR), gingival Index (GI) and plaque index (PI). * The difference of intrabony defect height. * The difference of gingival tissue thickness and gingival tissue volume. * The incidences of safety indicators. Participants will be randomized into either experiment group or control group, undergo guided tissue regeneration (GTR) surgery at week 1, and re-visited on week 3, 5, 13 and 27 after the GTR surgery. Researchers will compare if the test product is non-inferior to Bio-Gide.