Comparative Evaluation of Soft Tissue Regeneration Rate Using Different Wound Closure Methods After Palatal Donor Site Harvesting: A Retrospective Cohort Study.

Background and Objectives: This study evaluated the effect of two wound closure methods-polypropylene sutures and a butyl-2-cyanoacrylate tissue adhesive-on the rate of soft tissue regeneration following palatal donor site harvesting. A bovine collagen sponge, used as a secondary-intention dressing, was evaluated descriptively. Materials and Methods: Data from 300 patients (n = 100/group) with palatal donor sites were analyzed. Primary analysis compared suture vs. adhesive using Early Wound Healing Score (EHS) at days 7 and 14. Secondary outcomes were granulation tissue (day 7) and complications. Statistical methods: Mann-Whitney U test for between-group comparison (suture vs. adhesive); Kruskal-Wallis with Dunn's post hoc for granulation across all three groups; Spearman's correlation and logistic regression for the relationship between granulation tissue and EHS within primary healing groups. Results: At day 7, median EHS was similar between suture and adhesive groups (7.0 [interquartile range (IQR) 5.0-9.0] vs. 7.0 [IQR 7.0-9.0]; p = 0.31). By day 14, both groups achieved excellent healing (median 10.0, IQR 9.0-10.0 in both; p = 0.82). The collagen sponge group showed slower healing (median EHS day 7 = 4.0 [IQR 3.0-5.0], day 14 = 6.0 [IQR 5.0-7.0]), reported descriptively as expected for secondary intention. Granulation tissue on day 7 was highest in the adhesive group (p < 0.001 vs. collagen; p = 0.024 vs. suture). A strong positive correlation between day-7 granulation tissue and day-14 EHS was found in the primary-healing groups (ρ = 0.78, p < 0.001). Receiver operating characteristic (ROC) analysis established a granulation score ≥ 2 as the optimal cut-off for predicting successful healing (EHS ≥ 9) by day 14 (sensitivity 89.4%, specificity 76.0%, area under the curve (AUC) = 0.80), pending external validation. Conclusions: Surgical adhesive may be considered a viable alternative to sutures for palatal donor sites closed by primary intention, offering comparable healing by day 14. Collagen sponges result in slower healing and should be considered only when secondary intention is specifically desired. Early assessment of granulation tissue may serve as a simple prognostic indicator, but external validation is needed before clinical application.