Tunnel technique with connective tissue graft versus coronally advanced flap with enamel matrix derivative for root coverage: a RCT using 3D digital measuring methods. Part II. Volumetric studies on healing dynamics and gingival dimensions

Aim The aim of this randomized clinical trial (RCT) was to compare the clinical performance of the tunnel technique with subepithelial connective tissue graft (TUN) versus a coronally advanced flap with enamel matrix derivative (CAF) in the treatment of gingival recession defects. The use of innovative 3D digital measuring methods allowed to study healing dynamics at connective tissue (CT)-grafted sites and to evaluate the influence of the thickness of the root covering soft tissues on the outcome of surgical root coverage. Material & Methods Twenty-four patients contributed a total of 47 Miller class I or II recessions for scientific evaluation. Precise study models collected at baseline and follow-up examinations were optically scanned and virtually superimposed for digital evaluation of clinical outcome measures including mean marginal soft tissue thickness (THK). Healing dynamics were measured in a defined region of interest at CT-grafted sites where volume differences between time points were calculated. Results At 12months, recession reduction as well as mean root coverage were significantly better at CT-grafted sites treated in the TUN group (1.94mm and 98.4% respectively) compared to the non-augmented sites of the CAF group (1.17mm and 71.8% respectively) and statistical analysis revealed a positive correlation of THK (1.63mm TUN versus 0.91mm CAF, p<0.0001) to both these variables. Soft tissue healing following surgical root coverage with CT-grafting was mainly accomplished after 6months, with around two-thirds of the augmented volume being maintained after 12months. Conclusions The TUN resulted in thicker gingiva and better clinical outcomes compared to CAF. Increased gingival thickness was associated with better surgical outcomes in terms of recession reduction and root coverage.