Periodontal Soft-Tissue Root Coverage Procedures

Concise, evidence-based answers to the five clinical questions posed at the start of the 2014 AAP Regeneration Workshop review by Kim & Neiva (J Periodontol 2015;86(Suppl.):S56-S72), captured in Periodontal Root non-root coverage procedures AAP overview. The paper’s overall evidence level is weak (mostly SORT level B-C) because of a lack of RCTs and systematic reviews; the conclusions below rest largely on classic case series and clinical observation.

1. What circumstances require an increased zone of keratinized tissue (KT) — is KT important?

The current consensus is that ≥2 mm of KT (with ≥1 mm of attached gingiva) is desirable around teeth, and an adequate band becomes important specifically where the periodontium is challenged. Gingival augmentation is indicated for sites with minimal (<2 mm) or no gingiva that will receive an intracrevicular restorative margin, for RPD connector impingement, and for overdentures, because such sites are more prone to recession and inflammation (SORT level B). For plaque-free, non-restored sites without prominent roots, a minimal band of attached gingiva may be sufficient, so KT augmentation is driven by the restorative/clinical context rather than KT width alone.

2. What is the ideal thickness of an autogenous gingival graft? Is thick better than thin?

A palatal graft should be ≥1 mm thick, with most authors citing an optimal range of roughly 0.75-2.0 mm. Thick is not simply better than thin: thin grafts (~0.5-0.75 mm) revascularize and heal faster and give better colour blending, while thicker grafts provide more functional resistance but a less esthetic profile and a deeper donor wound. The trade-off is in shrinkage behaviour — thick grafts undergo more primary contraction, whereas thin grafts are prone to more secondary contraction (SORT level B).

3. What are the alternatives to autogenous gingival grafting to increase the zone of attached gingiva?

Viable donor-free alternatives exist that avoid palatal harvesting and reduce morbidity: the modified apically repositioned flap (MARF), acellular dermal matrix (ADM), extracellular matrix (ECM) membranes, xenogenic bilayer collagen matrices (BCM/collagen membrane), and living cellular constructs (LCC). These reliably generate attached KT in short-term, small-sample studies, but generally yield less KT gain and more shrinkage than FGG (e.g., ADM showed up to ~71% shrinkage vs ~16% for FGG in one trial). LCC is the only alternative supported by a multicentre RCT; all carry only SORT level C evidence and need long-term validation.

4. Does orthodontic intervention affect soft-tissue health and dimensions?

Appropriately applied orthodontic forces do not cause permanent harm to a healthy periodontium as long as teeth are moved within the alveolar housing; lingual movement can even thicken the facial soft tissue. However, facial/proclining movement outside the alveolar process and movement in thin biotypes carry a high probability of recession and KT loss. Therefore augmentation is recommended before initiating orthodontics in areas with <2 mm of gingiva, and teeth lacking KT pre-treatment will not spontaneously form new KT during therapy (SORT level C).

5. What is the patient-reported outcome for minimal KT vs an enhanced zone of KT?

Patient-reported outcomes are under-studied, but augmentation generally improves comfort: long-term data show reduced dentine hypersensitivity (e.g., 64% of grafted sites lost baseline sensitivity) and greater comfort during toothbrushing in treated versus untreated sites. When the source of the graft is compared, donor-free alternatives (ADM, MARF, ECM, BCM, LCC) produce less postoperative pain and better colour/texture match than FGG, and patients significantly preferred LCC over FGG (~72% vs ~28%). Standardized collection of these outcomes is still needed (SORT level C).