This is a single centre, randomised, single-blind, parallel-group clinical trial that aims at evaluating the use of imaging (2D and 3D) in obtaining geometric and thermometric changes of postoperative healing patterns and comorbidities (facial swelling, oedema and inflammation) following two routine surgical procedures performed for the treatment of periodontal (gum) disease.

A surgery in a posterior sextant will be performed per patient. The surgical procedures being compared for their post-operative healing patterns are:

1. Simplified Papilla Preservation Flap (SPPF) which is a conservative flap aiming at preserving the tissues between teeth.
2. Resective Periodontal Flap with Osseous Recontouring (RPFO) which is a conventional surgery which involves hard and soft tissues resection.

Geometric (3D) surface imaging and thermal (2D) surface imaging will be used to assess the post-operative healing patterns and comorbidities (facial swelling, oedema and inflammation) following either of the surgical procedures.

Inclusion Criteria:

1. Systemically healthy males and females ≥ 30 years of age.
2. Participants must be willing to read, and sign a copy of the "Informed Consent Form" (ICF) form after reading the, "Patient Information Leaflet" (PIS), and after the nature of the study has been fully explained.
3. Participants must present with clinical and radiographic evidence of periodontitis, with one interdental area of Periodontal Pocket Depth (PPD) ≥6mm, Bleeding On Probing (BOP), and Clinical Attachment Level (CAL) ≥6mm in any posterior sextant of their mouth (excluding third molars and the distal aspect of the second molars), or multiple sites (≥9) with PPD ≥5mm, BOP, and CAL ≥5mm.
4. Participants must have completed a course of non-surgical periodontal therapy within 2 years prior to study commencement and have had maintenance including subgingival debridement within 6 months prior to assessment for eligibility.

Exclusion Criteria:

1. Medical history including diabetes or hepatic or renal disease, or other serious medical conditions or transmittable diseases e.g. cardiovascular disease or AIDS.
2. Antibiotic, anti-inflammatory or anticoagulant therapy during the month preceding the baseline exam.
3. History of alcohol or drug abuse.
4. Self-reported pregnancy or lactation.
5. Other severe acute or chronic medical or psychiatric condition or laboratory abnormality that may increase the risk associated with trial participation or investigational product administration that may interfere with the interpretation of the data.

The calibrated examiners will be blinded to the study treatment. Samples will be labelled anonymously with subject ID and without codes relating to treatment group; therefore, all sample analyses will be blinded.

Blinding of the statistician will also take place. Data will be coded during data entry according to treatment group with a number disallowing group identification during analyses. Code details of which each treatment group will be revealed only once analyses are complete.