Star Matrix vs Autogenous Graft for Gingival Augmentation: Split-Mouth RCT

Healthy gums include a "band" of firm, pink tissue (keratinized gingiva) that helps people brush comfortably and protects the area where the tooth meets the bone. Studies suggest that when this band is narrower than about 2 mm, plaque control becomes harder and the risk of recession rises; in one maintenance study, nearly one-fifth of such sites lost further tissue over time.

Since the 1960s the standard way to widen this band has been a free gingival graft-moving a strip of the patient's own palatal tissue to the thin area. The technique works, but it also creates a second surgical wound, offers only a limited amount of donor tissue, causes notable postoperative pain, and the graft can look or feel different from nearby gum.

Researchers have explored substitutes such as preserved sclera, freeze-dried skin, and acellular dermal matrix, yet none has matched the predictability of a patient-derived graft. For example, acellular dermal matrix shrank by about 71 percent and often healed as scar-like tissue with inflammatory reactions.

Star Matrix is a new cross-linked collagen membrane made from highly purified porcine type I collagen. It combines a smooth outer coating that shields the wound with a porous inner layer that welcomes cell ingrowth and is placed porous side down to encourage the patient's own cells to replace it over time. Because it is supplied sterile and ready-to-use, Star Matrix eliminates the donor-site injury and could shorten surgery. However, its effectiveness has never been directly compared with the current gold-standard graft in a controlled clinical trial-providing the rationale for the present study.

Our study will test a new, ready-to-use collagen membrane called Star Matrix as an alternative for the conventional surgery that takes a strip of a patient's own tissue from the roof of the mouth (an autogenous gingival graft) to augment thin or missing gum. We will enroll twelve adult patients who need gum thickening on both sides of their lower jaw; each person will receive Star Matrix on one side and their own tissue on the opposite side, so every patient acts as their own control. Our goals are:

• Primary aim - gingival augmentation

o Find out whether Star Matrix can widen the firm, protective gum (keratinized gum tissue) around teeth by at least the same amount as the patient-derived tissue six months after surgery.

• Comfort aim - early healing experience

o Compare how much pain patients feel during the first week after each procedure, using a simple daily pain scale (0 = no pain, 10 = worst possible pain).

• Appearance aim - color and texture match

o Judge how well the new gum created by each method blends in with nearby gum (color and surface feel) six months after surgery, using standardized photographs and a validated rating sheet.

• Efficiency aim - surgery time

o Record and compare the time the periodontist needs to complete each type of procedure, to see if Star Matrix shortens time in the chair for patients and clinicians.

• Exploratory aim - tissue quality (optional) o In volunteers who give permission, collect a very small gum sample (2x2 mm2) at six months to look under the microscope and describe how Star Matrix has been replaced by the patient's own tissue.

These aims will show whether Star Matrix can provide equal or better gum growth with less pain and surgical time, potentially giving patients a single-site, more comfortable alternative to current care.

Inclusion criteria

• Adults 20 - 80 years old who need gingival augmentation on both sides of the lower jaw.
• Able and willing to sign the consent form, follow study instructions and return for all visits
• Generally healthy (no significant illnesses or medicines that could interfere with healing).
• Demonstrates good daily oral hygiene (low plaque levels at baseline).

Exclusion criteria

• Does not meet any of the inclusion points or is unlikely to follow the schedule
• Previous gingival graft at the study site that failed
• Needs a root-coverage (recession-repair) procedure instead of simple width augmentation
• Active, untreated gum disease, cavities, infection, or chronic inflammation near the study teeth
• Used cigarettes, e-cigarettes, or other nicotine products within 3 weeks
• Insulin-dependent diabetes or hemoglobin A1c > 6.5 %
• Cancer (other than minor skin cancers or in-situ cervical cancer) within the past 5 years
• Currently pregnant or breastfeeding
• Taking (or soon to begin) drugs that change bone turnover (e.g., bisphosphonates, steroids)
• Diseases that disturb bone metabolism (except common osteoporosis)
• Auto-immune disease or known allergy to porcine collagen or study materials
• Active infection at the planned graft site
• Current use of systemic blood thinners (anticoagulants or antiplatelet agents; e.g., warfarin, heparin/LMWH, DOACs such as apixaban/rivaroxaban/dabigatran/edoxaban, or P2Y12 inhibitors such as clopidogrel/prasugrel/ticagrelor)