Phenotype modification therapy has emerged as one of the main treatment objectives of periodontal plastic surgery. However, long-term data on the stability of gingival thickness gains are not available. This study examined the kinetics of mucosal thickness gain as a measure of phenotype modification therapy following treatment of multiple gingival recession defects with vestibular incision subperiosteal tunnel access (VISTA). Six patients with 14 recession type (RT) II teeth were treated using VISTA and subepithelial connective tissue grafts (SCTG). Scanned images of study casts at pre- and postoperative periods (6 to 66 months) were digitally superimposed for quantitative evaluation of soft tissue dimensional changes. Mucosal thickness gains ranged from 1.0 ± 0.7 mm (1 mm apical to cement-enamel junction [CEJ]) to 1.4 ± 0.4 mm (5 mm apical to CEJ). The gingival thickness gains remained relatively stable, with thickness gains at 66 months of 0.5 ± 0.8, 0.9 ± 0.6, 1.1 ± 0.6, 1.0 ± 0.4, and 1.2 ± 0.6 mm at 1, 2, 3, 4 and 5 mm apical to the CEJ, respectively. Treatment of multiple gingival recession defects with VISTA and SCTG led to stable gingival thickness gains and shows promise as a strategy for phenotype modification therapy.