The goal of this clinical trials is to learn about the effect of taking Prodentis on a long term basis following periodontal therapy. The main question it aims to answer is

1. what is the effect of long-term consumption of Prodentis on regulating periodontal health and systemic immune-response, when compare to only taking it for 3 months post RSD?

Following root surface debridement (RSD), subjects in the control group (group NP) will be instructed to take Prodentis® twice/day immediately for 3 months only then continue 3 monthly review until month 12th.

For subjects in the test group (group OP), following RSD, they will be instructed to take Prodentis® twice/day immediately for 3 months then continue Prodentis® once a day until month 12th. They will be reviewed 3 monthly.

1. The subject has given their written consent to participate in the trial.
2. All subjects must be aged >18 years old, not pregnant, and presented with number of teeth > 12
3. Diagnosis for periodontitis Stage III and IV, will be according to 2017 the American Academy of Periodontology (AAP) and European Federation of Periodontology (EFP) classification
4. Has had 1 round of periodontal therapy within 3-6 months' time from recruitment date, and currently presented with at least 4 residual pockets with pocket depth 5mm and above.