Tunnel Technique and Subepithelial Connective Tissue Graft, With or Without Cross-Linked Hyaluronic Acid, in the Treatment of Multiple Gingival Recessions: Prognostic Parameters for Clinical Treatment Outcomes of Randomized Controlled Trial

<b>Objectives:</b> This study aimed to investigate factors that influence the 12-month outcomes after the treatment of multiple gingival recessions (GRs) with a modified coronally advanced tunnel (MCAT) and a subepithelial connective tissue graft (SCTG), with cross-linked hyaluronic acid (HA, tests) or without (controls). <b>Materials and Methods</b>: Twenty-four patients with 266 GRs were treated. A logistic regression model was set to identify the baseline parameters that could predict the 12-month outcomes. The study protocol was registered at ClinicalTrials.gov (ID No. NCT05045586). <b>Results</b>: The evaluated clinical and esthetic parameters showed marked improvement in both groups without any statistically significant differences between the groups, with the exception of the soft tissue texture (STT). The STT was in favor of the HA group (0.96 versus 0.73, <i>p</i> = 0.0091). The likelihood of an MRC > 85%, of achieving CRC, and of gaining an RES = 10 was the highest for the incisors (reference group) and the lowest for the molars (OR = 0.046, <i>p</i> = 0.005). With each 1 mm increase in the baseline clinical attachment level, the odds of failure (MRC < 85%, not achieving CRC) increased, whereas each 1 mm increase in the baseline keratinized tissue width (KTW) improved the chances of an MRC > 85%, of achieving CRC, and of gaining an RES = 10. The application of HA increased the likelihood of a perfect RES more than twofold (OR = 2.683, <i>p</i> = 0.001). <b>Conclusions</b>: The application of HA improved the 12-month esthetic outcomes after the treatment of GRs with the MCAT technique. The baseline CAL, KTW, and tooth type predicted the 12-month MRC, CRC, and RES. An evaluation of the baseline characteristics of the surgical area might help clinicians develop individualized treatment plans.