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Published on: June 24, 2018
Peri-Implant Soft Tissue Response to Monolithic Zirconia Versus Porcelain-Fused-to-Metal Implant Crowns: Histological
Yifan Zhang1,2, Sven Mühlemann2,3, Aspasia Pachiou2
1Department of Implantology, Peking University School and Hospital of Stomatology, National Center of Stomatology, National Clinical Research Center for Oral Diseases, National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, Beijing, China.
Objective:
To assess the peri-implant soft-tissue and hard-tissue response to monolithic zirconia (ZrO2) compared to porcelain-fused-to-metal implant crowns (PFMs).
Methods:
This report constitutes a pre-specified secondary analysis of this RCT. Eighty-three patients rehabilitated with single-tooth implants in the molar region were originally randomly assigned to receive either a ZrO2 or a PFM restoration. At 6 months, clinical parameters (plaque control record, probing depth, bleeding on probing, width of keratinised mucosa and marginal bone level changes) were recorded at the implant site and the adjacent natural tooth. In addition, a peri-implant soft-tissue biopsy specimen was harvested between the implant site and the adjacent tooth. The number of inflammatory cells and fibroblasts/fibrocytes was evaluated within four regions of interest (oral epithelium, sulcular epithelium, junctional epithelium, connective tissue). Descriptive statistics were arrived at for all outcomes, and differences between prosthetic materials, sites and timepoints were analysed using linear mixed-effects models.
Results:
The present exploratory secondary analysis included 67 patients (37 ZrO2; 30 PFM) with complete 6-month clinical, radiographic and histological data. Clinical parameters at both implant and adjacent tooth sites remained generally stable from baseline to 6 months, with limited marginal bone level changes and comparable outcomes between groups. Histologically, mixed-effects model analysis showed that the tissue region significantly affected both the inflammatory infiltrate and the fibroblast density (p < 0.001). The crown materials did not substantially influence the histological outcomes. The distribution of inflammatory infiltrate differed between tooth and implant sites, with the highest values in the sulcular epithelium around implants and in the junctional epithelium around teeth. Fibroblast density was highest in the junctional epithelium at both sites.
Conclusion:
Monolithic zirconia and PFM implant-supported single crowns resulted in comparable clinical and radiographic outcomes. The peri-implant soft-tissue response to the two restorative materials showed a greater effect of the tissue region, while the material itself had only negligible effect.
Trial Registration:
ClinicalTrials.gov identifier: NCT02272491.
