The goal of this study is to assess the reconstruction of interdental papilla following the injection of UC-MSCs or physiological saline in patients with interdental papilla deficiency. Participants will be randomised into 2 groups (intervention vs placebo) to receive the treatment.

This is a two-arm parallel, prospective, single-center randomised clinical trial, which will be designed based on the guidelines from the Consolidated Standards of Reporting Trials (CONSORT) statement and will be registered in clinicaltrials.gov. Participants will be screened according to the inclusion and exclusion study criteria, and recruited from Orthodontic Postgraduate Clinic, Universiti Malaya.

Total sample size will be set at 20 interdental papilla after considering all the sample sizes calculated using different objectives, due to the cost effectiveness, the practicability, and consideration on the risk and complications.

This research is divided into 3 phases: pre-operative, operative, and post-operative phase.

Pre-operative includes full mouth scaling, baseline data collection (intra-oral scanning for soft tissue; cone beam computed tomography (CBCT) for hard tissue, basic periodontal examination). Then, the black triangle from upper or lower arch will be randomly assigned to two groups: the intervention (Stem cells) group, and the control (saline) group.

Operative phase involves injection either with the experimental or control solution. One injection will be given at each papilla set with the volume of 0.1mL with 2.0 x 10⁶ cells per syringe at every visit. A total of 3 injections will be given at the interval of 6 weeks, with a total of 6.0 x 10⁶ cells for each interdental papilla at the end of the 3 injections. Every injection starts with locally application of local anesthetic. For the control group, participants will be injected with 0.9% sodium chloride after locally application of local anesthetic.

Post-operatively, at 6, 12, 24 and 36 weeks, data will be collected for analysis. Intra-oral scanning of soft tissue will be done at every visits. CBCT for hard tissue will be done at 36 weeks. At every follow up, basic periodontal examination will be scored for periodontal health supervision. Data collected will be entered and analysed using SPSS 26.0. Images from the scans (soft tissue scans, hard tissue scans) will be superimposed and the difference between the 2 images will be calculated and analysed.

Inclusion Criteria:

• Adults aged 20 - 40 years
• Non-smoker
• Able to understand English
• Subjects who are able to attend follow up during the clinical trial
• Subjects who are able to maintain oral hygiene (< 10% FMPS) with BPE score 0, 1, or 2 at the upper anterior or lower anterior sextant
• Subjects having at least one deficient interdental papilla in the upper or lower arch or both in the anterior region (from canine to contralateral canine) with papillary deficiency type I or II, according to Nordland and Tarnow classification
• No history of regular medication intake (nifedipine, calcium channel blockers, cyclosporine, phenytoin, etc)
• Teeth free from caries, proximal restorations, fixed prosthesis or orthodontic fixed appliances (except for fixed retainer that does not encroach on black triangle)
• No open contacts between affected teeth
• No history of periodontal surgical or non-surgical treatment (Root surface debridement) over the last six months at the area of interest
• Probing pocket depth ≤ 4mm without bleeding on probing at the area of interest

Exclusion Criteria:

• Passive smoker/ former smoker/ electronic smoker
• Alcoholic
• Pregnant or breastfeeding females
• Subjects with current or previous drug intake that may predispose to gingival enlargement (nifedipine, calcium channel blockers, cyclosporin, phenytoin, etc)
• Subjects with medical conditions that may affect periodontal healing/ Reconstruction (diabetes, cardiovascular disease, stroke, asthma)
• Subjects with physical impairment, orofacial deformities
• Subjects with documented drug allergic, or history of allergic reaction to any constituents of injection
• Subjects who had active or past history of neoplasia
• Subjects who are on active orthodontic treatment/ require active tooth movement at the area of interest
• Subjects with probing pocket depth of more than 4mm with bleeding on probing at the area of interest
• Subjects with full mouth plaque score >10%
• Subjects with a history of periodontal surgical or non-surgical treatment over the last six months at the area of interest