Differential Attachment of Engineered Oral Soft Tissues to Implant Surfaces

Background/Objectives: The formation of a soft tissue seal through mucosal integration around dental implants is critical for potentially achieving long-term peri-implant health and clinical success. Understanding how different implant and abutment surfaces interact with individual layers of the oral mucosa remains limited. This study aimed to compare the differential attachment of tissue-engineered oral epithelium, connective tissue, and full-thickness human oral mucosa to various implant and abutment materials and surface topographies. Methods: Sand-blasted, large-grit, acid-etched (TiZr-SLA), machined TiZr (TiZr-M), machined zirconia (ZrO₂-M), polished zirconia (ZrO₂-P), and machined PEEK rods, along with commercially available titanium and ZrO₂ healing abutments, were inserted into 3D oral mucosal models following a 4-mm punch biopsy. Inflammation was induced using Escherichia coli lipopolysaccharide. Analyses included histology, PrestoBlue viability assay, scanning electron microscopy, and ELISA quantification of cytokines IL-1β, IL-6, and IL-8. Results: Epithelial attachment was greater on TiZr-SLA, ZrO₂-P, and PEEK-M (p < 0.05 and p < 0.01) surfaces compared with TiZr-M and ZrO₂-M. TiZr-SLA exhibited the highest connective tissue attachment (p < 0.05). Commercial titanium and ZrO₂ healing abutments demonstrated the highest post-pull PrestoBlue viability and overall soft tissue attachment. SEM confirmed cell retention on all implant surfaces. Elevated IL-1β levels were detected in models exposed to ZrO₂-M and PEEK-M, whereas IL-6 and IL-8 levels were not influenced by any material or surface topography. Conclusions: In vitro epithelial and connective tissue responses are influenced by implant material, surface topography, and design. Rough TiZr-SLA surfaces promote superior connective tissue attachment, while smooth commercial abutments support optimal overall soft tissue integration. These findings highlight the importance of surface engineering in preclinical optimization of peri-implant soft tissue attachment.