Affiliation:
1. Department of Oral Surgery University of Murcia Murcia Spain
2. Oral Surgery and Implant Dentistry, Oral Surgery Unit, Department of Stomatology, Faculty of Medicine and Dentistry University of Valencia Valencia Spain
3. Department of Histology and Pathological Anatomy University of Murcia Murcia Spain
4. Oral Medicine, Oral Surgery and Implantology Unit, Faculty of Medicine and Dentistry. Health Research Institute of Santiago de Compostela, ORALES Group. Materials Institute of Santiago de Compostela Universidad de Santiago de Compostela Santiago de Compostela A Coruña Spain
5. Department of Surgery, Dental Clinic of the Faculty of Medicine University of Salamanca Salamanca Spain
Abstract
AbstractBackgroundThis study aimed to analyze the influence of concave and cylindrical abutments on peri‐implant soft tissue. Dimensions, collagen fiber orientation, and immunohistochemical data were assessed.MethodsA multicenter, split‐mouth, double‐blind randomized clinical trial was conducted. Two groups were analyzed: cylindrical abutments and concave abutments. After a 12‐week healing period, peri‐implant soft tissue samples were collected, processed, and evaluated for dimensions, collagen fiber orientation, and immunohistochemical data. Inflammatory infiltration and vascularization were assessed, and the abutment surfaces were analyzed using scanning electron microscopy. The statistical analysis was performed using the SPSS version 20.0 statistical package.ResultsA total of 74 samples in 37 patients were evaluated. Histological evaluation of peri‐implant soft tissue dimensions revealed significant differences between concave and cylindrical abutments. Concave abutments exhibited greater total height (concave: 3.57 ± 0.28 – cylindrical: 2.95 ± 0.27) and barrier epithelium extension (concave: 2.46 ± 0.17 – cylindrical: 1.89 ± 0.21) (p < 0.05), while the supracrestal connective tissue extension (concave: 1.11 ± 0.17 – cylindrical: 1.03 ± 0.16) was slightly greater (p > 0.05). Collagen fiber orientation favored concave abutments (23.76 ± 5.86), with significantly more transverse/perpendicular fibers than for cylindrical abutments (15.68 ± 4.57). The immunohistochemical analysis evidenced greater inflammatory and vascular intensity in the lower portion for both abutments, though concave abutments showed lower overall intensity (concave: 1.05 ± 0.78 – cylindrical: 1.97 ± 0.68) (p < 0.05). The abutment surface analysis demonstrated a higher percentage of tissue remnants on concave abutments (42.47 ± 1.32; 45.12 ± 3.03) (p < 0.05).ConclusionsWithin the limitations of this study, concave abutments presented significantly greater peri‐implant tissue height, linked to an extended barrier epithelium, versus cylindrical abutments in thick tissue phenotype. This enhanced soft tissue sealing, favoring a greater percentage of transversely oriented collagen fibers. The concave design reduced chronic inflammatory exudation with T and B cells, thus minimizing the risk of chronic inflammation.Plain Language SummaryThis study looked at how 2 different shapes of dental implant abutments (the parts that connect the implant to the crown), specifically concave and cylindrical, affect the soft tissue around the implants. We wanted to see how these shapes influenced the tissue's size, structure, and health. We conducted a clinical trial with 37 patients, comparing the 2 types of abutments in the same mouth over 12 weeks.Our findings showed that the concave abutments led to a taller and more extensive layer of protective tissue around the implant compared to the cylindrical ones. This protective tissue had more favorable collagen fiber orientation, which is important for the strength and health of the tissue. Additionally, the concave abutments resulted in less inflammation and better tissue integration.In conclusion, concave abutments may provide better support and health for the soft tissue around dental implants, reducing the risk of chronic inflammation and potentially leading to better long‐term outcomes for patients with dental implants