Implant Connection Types: Conical, Hex, Tri-Lobe — A Guide to Choosing the Right CAD Library
The implant-abutment connection type is one of the key factors determining prosthetic longevity, soft tissue stability, and CAD/CAM design accuracy. Each manufacturer uses proprietary interface geometry, which dictates exactly which scan body and abutment library you must load into exocad, 3Shape Dental System, or DentalCAD.
Let's review the four main connection groups and how they influence your digital workflow.
External Hex
The classic connection introduced by Brånemark in the 1980s. The hexagon sits above the implant platform and serves as the anti-rotation element. Used in Nobel Biocare Brånemark, MIS Seven, Zimmer Screw-Vent, and many budget analogs.
Pros: time-proven design, easy placement, universal compatibility with screw-retained prosthetics. Cons: micromovement and microgap at the platform level, higher screw-loosening risk, less stable soft tissue seal.
In the CAD library, the scan body has a distinctive recess matching the external hex, and the abutment geometry assumes a flat interface with the platform.
Internal Hex
The hex shaft sits inside the implant body. Used in Zimmer Tapered Screw-Vent, MIS C1, Adin Touareg, BioHorizons, and many others. Hex depth and dimensions vary by manufacturer — critical for library selection.
Advantages: better occlusal load distribution through the shaft walls, lower suprastructure profile, more stable fixation than external hex. Disadvantages: possible wall wedging under overload, sensitivity to positioning accuracy.
When working in exocad or 3Shape, always load the original manufacturer library — even implants with similar platform diameters have different hex depths and screw thread pitches.
Conical (Morse Taper) Connection
A Morse cone with a 1.5°–11° angle provides friction-fit between abutment and implant. The modern premium standard: Straumann Bone Level, Ankylos, NobelActive, Astra Tech EV, Neodent GM, Osstem TS III. Often combined with an index hex or octagon for positioning.
Strengths: near-zero microgap, minimized bacterial leakage, platform switching effect, excellent soft tissue stability and marginal bone preservation. Weaknesses: higher cost, difficulty removing a 'cold-welded' abutment, demanding CAM milling precision.
For conical connections, library choice is especially critical: even a small cone angle error renders a custom abutment unusable. Use only official manufacturer libraries or verified certified analogs.
Tri-Lobe and Tri-Channel Connections
Tri-Lobe is Nobel Biocare's proprietary Replace Select connection with three lobes providing intuitive abutment positioning in three indexed positions. Tri-channel interfaces, such as in NobelActive, use three internal grooves for indexing above the conical seat.
Tri-Lobe pros: fast, unambiguous abutment seating, clear orientation when working through the gingiva. Cons: limited cross-compatibility with other manufacturers; in the three-lobe version, increased lobe stress under lateral forces.
In CAD systems, Replace and NobelActive libraries are not interchangeable despite sharing a brand. Before scanning, verify that the scan body matches your specific connection type.
How Connection Type Drives CAD Library Choice
Interface geometry defines three key library parameters: abutment seating shape (Ti-Base or custom), screw channel position and size, and the anti-rotation feature. Using a 'similar' library from another manufacturer produces 50–150 µm gaps — critical for conical connections and unacceptable for long-term prosthetic service.
Practical tips: always cross-check the scan body article with the library ID; for multi-unit constructions use dedicated multi-unit libraries, not standard ones; keep libraries in exocad and 3Shape updated as manufacturers refine tolerances and add new platforms.
If the library you need isn't in the standard exocad, 3Shape, or DentalCAD package, or you need help installing and activating any software version — message us on Telegram or WhatsApp, and we'll help set up your workstation.