Abstract
ObjectivesA conometric concept was recently introduced in which conical implant abutments hold the matching crown copings by friction alone, eliminating the need for cement or screws. The aim of this in vitro study was to assess the presence of microgap formation and bacterial leakage at the Acuris conometric restorative interface of three different implant abutment systems.Material and methodsA total of 75 Acuris samples of three implant-abutment systems (Ankylos, Astra Tech EV, Xive) were subjected to microbiological (n = 60) and scanning electron microscopic (SEM) investigation (n = 15). Bacterial migration into and out of the conical coupling system were analyzed in an anaerobic workstation for 48, 96, 144, and 192 h. Bacterial DNA quantification using qrt-PCR was performed at each time point. The precision of the conometric coupling and internal fit of cemented CAD/CAM crowns on corresponding Acuris TiN copings were determined by means of SEM.Resultsqrt-PCR results failed to demonstrate microbial leakage from or into the Acuris system. SEM analysis revealed minute punctate microgaps at the apical aspect of the conometric junction (2.04 to 2.64 µm), while mean cement gaps of 12 to 145 µm were observed at the crown-coping interface.ConclusionsThe prosthetic morse taper connection of all systems examined does not allow bacterial passage. Marginal integrity and internal luting gap between the ceramic crown and the coping remained within the clinically acceptable limits.Clinical relevanceConometrically seated single crowns provide sufficient sealing efficiency, relocating potential misfits from the crown-abutment interface to the crown-coping interface.
Highlights
Anchorage of the prosthetic connection for implantsupported fixed dental prostheses (FDPs) is commonly achieved by means of luting cement or screws
The size of the luting gap and the marginal integrity of the CAD/CAM ceramic crowns on the extraorally cemented Acuris titanium nitride-coated (TiN) copings were evaluated in the same way at 6 defined reference points (K0 to K5) according to the respective design properties of the prefabricated copings (Fig. 4)
The qrt-PCR results for all Acuris test samples revealed values approaching the negative control for bacterial leakage out of the conometric system
Summary
Anchorage of the prosthetic connection for implantsupported fixed dental prostheses (FDPs) is commonly achieved by means of luting cement or screws. To ensure firm retention between multiple implants and the respective superstructure, the use of a conometric concept has been proposed alternatively [1, 2] In this approach, conical abutments retain matching crown copings solely by surface friction, eliminating the need for either cement or screws. The final crown-coping complex is fixed intraorally to the anti-rotation connection of the conical abutment with an axially directed load of a calibrated striker (Acuris Abutment, Conometric Fixation Tool, both Dentsply Sirona Implants, Mölndal, Sweden). This ensures a correct alignment and secure coupling of the crown. The conometric joint is a fixed retention, with the possibility of maintenance-related disengagement by the dentist
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