Microgap between zirconia abutments and titanium implants.

PURPOSE: The aim of this study was to evaluate in vitro the microgap between different zirconia abutments and their titanium implants. MATERIALS AND METHODS: Four systems were evaluated: Procera zirconia (Nobel Biocare) (Nb), Cercon Balance Anterior (Dentsply Friadent) (Ba), ZirDesign (Astratech) (Zd), and Straumann Cares ceramic (Straumann) (Ca). Five assemblies were assessed for each system. The assemblies were embedded in epoxy, cut along their long axes, and polished. Scanning electron microscopic observations were made along the first 100 microm of the gap on each side at maximal magnification. Images were combined and gap measurements were made 10 microm apart. A two-way analysis of variance was performed on the data. RESULTS: Scanning electron micrographs showed a mean marginal microgap of 0.89 microm (SD 1.67) for all assemblies. Significant differences (P < .001) were observed between mean (+/- SD) microgap measurements of the four tested systems: Ba = 0.38 +/- 0.28 microm; Zd = 0.55 +/- 0.23 microm; Nb = 1.83 +/- 3.21 microm; Ca = 0.90 +/- 0.59 microm. The mean microgap of the first 20 microm of the outer region (1.66 microm) was significantly (P < .001) larger than the mean microgap (0.56 microm) of the inner region (30 to 100 microm). CONCLUSIONS: Within the limitations of this study, the mean microgap observed for all tested systems was less than 2 microm. For each system, the microgap decreased quickly from the outer region to the inner. The mean gap was larger for flat-to-flat connection systems, compared to internal-connection systems with a conical interface. These results demonstrate smaller microgaps compared to those described in the literature for titanium abutments. The precise fit of these abutments could lead to better biologic and biomechanical behavior.

Antibacterial Peptide-Based Gel for Prevention of Medical Implanted-Device Infection.

Implanted medical devices are prone to infection. Designing new strategies to reduce infection and implant rejection are an important challenge for modern medicine. To this end, in the last few years many hydrogels have been designed as matrices for antimicrobial molecules destined to fight frequent infection found in moist environments like the oral cavity. In this study, two types of original hydrogels containing the antimicrobial peptide Cateslytin have been designed. The first hydrogel is based on alginate modified with catechol moieties (AC gel). The choice of these catechol functional groups which derive from mussel's catechol originates from their strong adhesion properties on various surfaces. The second type of gel we tested is a mixture of alginate catechol and thiol-terminated Pluronic (AC/PlubisSH), a polymer derived from Pluronic, a well-known biocompatible polymer. This PlubisSH polymer has been chosen for its capacity to enhance the cohesion of the composition. These two gels offer new clinical uses, as they can be injected and jellify in a few minutes. Moreover, we show these gels strongly adhere to implant surfaces and gingiva. Once gelled, they demonstrate a high level of rheological properties and stability. In particular, the dissipative energy of the (AC/PlubisSH) gel detachment reaches a high value on gingiva (10 J.m-2) and on titanium alloys (4 J.m-2), conferring a strong mechanical barrier. Moreover, the Cateslytin peptide in hydrogels exhibited potent antimicrobial activities against P. gingivalis, where a strong inhibition of bacterial metabolic activity and viability was observed, indicating reduced virulence. Gel biocompatibility tests indicate no signs of toxicity. In conclusion, these new hydrogels could be ideal candidates in the prevention and/or management of periimplant diseases.