Early histological, microbiological, radiological, and clinical response to cemented and screw-retained all-ceramic single crowns.

OBJECTIVES: To assess the early histological, microbiological, radiological, and clinical response to cemented and screw-retained all-ceramic single-tooth implant-supported reconstructions. MATERIALS AND METHODS: Patients with single-tooth implants were randomly allocated to receive a cemented lithium disilicate crown on a customized zirconia abutment (CEM) or a screw-retained crown with a directly veneered zirconia abutment (SCREW). At the screening visit, at crown insertion and at the 6-month follow-up, clinical parameters were measured at the implant and the contralateral tooth. Marginal bone levels, technical parameters, and esthetic outcomes were measured at the implants. At the 6-month follow-up, a microbiological test was performed and a soft tissue biopsy was harvested at the implants for histological analysis. Inflammatory cells and fibroblasts/-cytes were analyzed at the level of the sulcular epithelium, junctional epithelium, and connective tissue. The histological parameters were analyzed by means of a linear mixed model. RESULTS: Thirty-three patients completed the study, and implant and crown survival rates were 100% at 6 months. Histologically, the number of inflammatory cells tended to be higher in group CEM (p > 0.05). Moreover, significantly less inflammatory cells and fibroblasts/-cytes were found in the sulcular epithelium compared to the junctional epithelium and supracrestal connective tissue (p < 0.001). Four patients were tested positive for periodontal marker pathogens at the 6-month follow-up, and three of them belonged to group CEM. From crown insertion to the 6-month follow-up, median marginal bone levels changed only minimally and measured 0.31 and 0.32 mm in group CEM and 0.47 and 0.36 mm in group SCREW, respectively. Clinical and esthetic parameters remained stable over time and were comparable between natural teeth and implants as well as between the groups. CONCLUSIONS: Cemented reconstructions were associated with more inflammatory cells, and more patients were diagnosed with periodonto-pathogens. Both types of reconstructions resulted in similar radiological (marginal bone levels) and clinical outcomes (bleeding on probing and probing depth).