In-vitro investigation: Conometric concept for implant-supported single crowns

In-vitro investigation: Conometric concept for implant-supported single crowns

Konometrisches Konzept

Conometric concept for implant-supported single crowns

The conometric concept enables a single crown to be fixed on the implant without cementing and screwing. Avoiding cement residues and dispensing with additional retaining screws are named as advantages.

In an in vitro study, a team of researchers examined the fit and the risk of bacterial translocation at the junction between the abutment and the restoration. The results were published in the “International Journal of Molecular Sciences” [1].

Research group

Peter Gehrke, Philip Hartjen, Ralf Smeets, Martin Gosau, Ulrike Peters, Thomas Beikler, Carsten Fischer, Carolin Stolzer, Jürgen Geis-Gerstorfer, Paul Weigl, Sogand Schäfer

Short summary

The conometric concept for single implant crowns

In the conometric concept, a cone-in-cone connection is used between the implant abutment and the crown for fixation [2]. The system consists of a conical cap that is cemented extraorally in an all-ceramic crown and then attached by friction to the conical abutment (Acuris Cap / Acuris Abutment, Dentsply Sirona Implants). The retention is achieved through the friction of the conical surfaces. The difference to previously known conometric connections is that the bonding between the cap and the ceramic crown can be done extraorally by the dental technician.

To be mentioned as advantages of the conometric concept:

  • Cement-free restoration and therefore no risk of cement residues,
  • No additional retaining screws and therefore no screw channels,
  • Support in developing the anatomical soft tissue profile,
  • Use of inexpensive prefabricated components,
  • Easy care.

Bacterial translocation at the junction between the abutment and the restoration

In this study [1], the research team looked at the fit and the risk of bacterial translocation at the connection between the abutment and the restoration. A mismatch and a resulting microgap at the level of the restoration margins could serve as a bacterial reservoir that promotes plaque formation.

Konometrisches Konzept
Scanning electron microscope (SEM) overview image of the ACURIS conometric cone fit and the crown cement gap, magnification 50x.

In-vitro investigation

The microbial tightness of the conometric-prosthetic connection was tested in a double-variable study setup. The in vitro investigation did not reveal any transfer of bacteria from or into the prosthetic connection. The SEM analysis showed a marginal cement gap between the Acuris TiN coping and the ceramic crown within a clinically acceptable range of approximately 100 μm, but no microgap at the cone-in-cone-Acuris connection. The holistic consideration of the bacterial colonization for the cone-in-cone coupling did not reveal any microbial leakage. The limitation of this study is that the influence of dynamic chewing loads on bacterial translocation has not been investigated.

[1] Gehrke P, Hartjen P, Smeets R, Gosau M, Peters U, Beikler T, Fischer C, Stolzer C, Geis-Gerstorfer J, Weigl P, Schäfer S. Marginal Adaptation and Microbial Leakage at Conometric Prosthetic Connections for Implant-Supported Single Crowns: An In Vitro Investigation. Int J Mol Sci. 2021 Jan 17;22(2):881

[2] Gehrke P, Fischer C., Weinhold O., Dhom G. Das konometrische Konzept für implantatgetragene Einzelkronen: die definitive Befestigung ohne Zement oder Schrauben. ZWR – Das Deutsche Zahnärzteblatt 2021; 130: 1–7