Surgical Correction of Keratinized Mucosa Deficiency Around Dental Implants: A Clinical, Histological and Immunohistochemical Study

Background/Objectives: Peri-implant inflammatory complications remain a major cause of late implant failure and are closely associated with the condition of peri-implant soft tissues. Insufficient keratinized attached mucosa has been identified as a potential risk factor for peri-implant inflammation; however, morphological and immunohistochemical validation of soft tissue remodeling following corrective interventions remains limited. The aim of this study was to perform a morphological and immunohistochemical evaluation of a reproducible surgical approach for increasing keratinized attached mucosa around dental implants. Methods: A comparative clinical–morphological study included 25 patients undergoing implant-supported prosthetic treatment. Patients were divided into a control group (standard prosthetic protocol without soft tissue augmentation, n = 10) and a study group (soft tissue correction using a previously developed technique, n = 15). Punch biopsies of peri-implant mucosa were obtained at baseline and prior to definitive prosthetic restoration. Histological examination and immunohistochemical analysis were performed using the semi-quantitative Astaldi–Verga method. Expression of inflammatory markers (MPO, CD3, CD20, CD68), vascular marker CD31, and remodeling markers MMP-9 and TIMP-2 was evaluated. Data were analyzed using the Mann–Whitney U test (p < 0.05). Results: The study group demonstrated significantly lower expression of inflammatory markers, including MPO, CD68, CD3, and CD20 (p < 0.001), and reduced MMP-9 expression (p = 0.001) compared with controls. The MMP-9/TIMP-2 balance was more favorable in the study group, suggesting more regulated extracellular matrix remodeling. Histologically, the control group exhibited epithelial disruption and microcirculatory alterations, whereas the study group showed preserved epithelial architecture and reduced inflammatory infiltration. Conclusions: Morphological and immunohistochemical assessment suggests that soft tissue correction of keratinized mucosa deficiency may be associated with more favorable early peri-implant soft tissue characteristics, including reduced inflammatory activity and modulation of matrix remodeling. Immunohistochemical markers such as MMP-9 and TIMP-2 may provide additional insight into early soft tissue integration around dental implants. However, these findings should be interpreted with caution due to the exploratory design and short follow-up period.