Features of New Multi-Unit Abutments or Why Custom Abutments Are No Longer Needed

Factory standardization of superstructures versus laboratory milling: technical and economic arguments for the use of XGATE Dental multi-unit abutments in total rehabilitation.

This article, using the XGATE Dental system as an example, examines the clinical and economic potential of standard multi-unit abutments. The main drawbacks of custom-milled solutions are their high cost and direct dependence on laboratory equipment. Standardization allows these limitations to be overcome without compromising quality.

Key technical characteristics of the XGATE Dental system

• Titanium Grade 23 (ELI) alloy: Reducing the concentration of impurities increases the ductility of the metal, minimizing the risk of fracture in thin-walled, ultra-short, and tapered components.
• MUA D-Type: Compensation for implant axis non-parallelism up to 130° and continuous Color ID height marking.
• MUA V-Type: The 40° small cone geometry increases the calculated thickness of the zirconia framework in the gingival area by 66%, preventing chipping of the veneering ceramic.
• MUA S-Type (Slim): Ultra-narrow platform diameter (3.5 mm) for positioning in conditions of limited interdental space.
• Ergonomics and safety: A standardized tooling system (1.27 mm prosthetic driver) for all stages and a built-in screw retention (anti-drop) design in the shaft.

Prerequisites for the use of custom superstructures and their technological limitations

When creating complex bridge frameworks and performing total rehabilitation of inclined implants, the prosthodontic protocol requires solving three main problems:

1. Compensation for axial divergence angles: Straight standard interfaces of previous generations did not allow the integration of non-parallel implants into a single path of insertion without compromising the screw access axis.
2. Emergence Profile Management: Creating a smooth anatomical transition from the narrow implant platform to the crown in an aesthetically significant zone.
3. Adaptation to gingival biotype: The need for precise selection of the abutment collar height in cases of soft tissue deficiency or hypertrophy.

Manufacturing custom abutments using laboratory milling solves these problems, but increases the cost of the prosthetic stage and overall labor costs. Using XGATE Dental monolithic multi-unit abutments allows for the transfer of the prosthetic platform from the bone level to the tissue level, standardizing subsequent stages.

Biomechanical advantages of multi-unit screw retention

The use of factory-made screw-retained solutions eliminates the risks associated with cement-retained restorations on custom titanium bases (in particular, cement-induced peri-implantitis due to incomplete removal of excess material from the subgingival space).

Clinical indicators of factory multi-units:

• Gingival cuff stability: The factory polishing of the titanium surface ensures a tight and atraumatic fit of soft tissues, forming a biological seal.
• Occlusal load distribution: Chewing forces are transmitted strictly along the longitudinal axis of the implant, which reduces peak stresses in the crestal bone.
• Precision fit accuracy: The congruence of the implant-to-multi-unit interfaces minimizes micromotion, preventing loosening and fatigue fractures of the retaining screws.
• Retrievability of the restoration: The ability to dismantle the prosthesis in a clinical setting for hygiene or modification without damaging the prosthetic framework.

Physical and mechanical properties of Titanium Grade 23 alloy compared to Grade 5

To eliminate the risk of deformation and microcracks in narrow or low-profile areas of superstructures, XGATE Dental uses Titanium Grade 23 (Ti-6Al-4V ELI) alloy instead of the standard Grade 5.

Comparative characteristics of titanium alloys

Design features of the XGATE Dental lines: D-Type, V-Type, S-Type

The XGATE Dental ecosystem offers end-to-end interface compatibility and integrates with leading global implant platforms: Internal Hex (2.42 mm), Osstem (11° cone), Straumann (Bone Level, Tissue Level), Nobel (Active, Replace), Megagen AnyRidge, and other brands that use standard interfaces.

All fixation steps are performed with a single prosthetic driver with a diameter of 1.27 mm. The factory tolerance of the screw shaft (1.25 mm) ensures a tight fit and precise torque transmission without the risk of stripping the screw head.

D-Type multi-units: Angle compensation and Color ID system

These are used as a primary solution for long-span prosthetic restorations.

• Prosthetic platform: The 4.9 mm diameter provides a sufficient support area for bridge prostheses.
• Angulated modifications: Available in 17°, 30° and 45° versions.
• Non-parallelism compensation parameters:
  • The 17° abutment compensates for axial divergence of up to 74°
  • The 30° abutment compensates for axial divergence of up to 100°
  • The 45° abutment provides compensation up to 130°

• Clinical significance: The range of angles allows for bypassing anatomical obstacles (maxillary sinuses, mental foramen) without performing a sinus lift, optimizing the path of insertion of the prosthesis and redirecting the screw access hole to a non-aesthetic area.
• Color ID of the gingival heights of straight and angled MUA D-type:
  • Height 1 mm – Gold marker
  • Height 2 mm – Light Blue marker
  • Height 3 mm – Pink marker
  • Height 4 mm – Green marker

V-Type multi-units: Low-profile cone and framework chipping protection

Designed for total restorations and bar-retained systems in conditions of insufficient vertical interarch space.

• Minimum occlusal height: The combination of a gingival portion of 0.5 mm and a base cone of 3.0 mm allows for prosthetics to be performed at an accessible height of 3.5 mm, freeing up space for restorative material.

• Low-profile cone architecture: The low-profile cone and increased contact area allow for increased zirconia thickness in the gingival area, eliminating critical thinning of the crown wall and ceramic chipping.

• Contact area: The working height of the mating zone between the titanium sleeve and the abutment is increased to 10 mm (compared to the standard 6 mm), which increases the contact area by 66% and stabilizes the passive screw connection.

• Extended height range and Color ID: The V-Type line supports end-to-end color coding and offers extremely low gingival heights from 0.5 mm, extending the maximum range to 5 mm.

• Application in bar-retained prostheses: The reduced taper allows for a reduction in the thickness of the milled bar, which optimizes the volume of the structure in the oral cavity and accelerates patient adaptation.

• Angle correction on straight bases: The V-Type geometry ensures a passive fit of the bridge prosthesis with implant axes misaligned up to 40° without the use of angled abutments. The platform diameter is 4.6 mm.

In real practice, multi-unit abutments are often and very successfully combined in protocols for full-arch restorations on 4/6 implants.

Multi-units S-Type (Slim): positioning in limited interdental space

Designed for the restoration of the anterior region (in particular, when replacing lower incisors) in conditions of insufficient space between the roots of adjacent teeth.

• Prosthetic platform: The reduced diameter of 3.5 mm allows for the integration of the superstructure without compression of the surrounding soft tissues, preserving the interdental papillae.
• Mechanical properties: Thanks to the properties of Titanium Grade 23 alloy, this thin-walled component maintains torsional rigidity and resistance to chewing loads, outperforming custom-made structures of similar thickness. Gingival heights range from 0.8 to 4.0 mm.

XGATE Dental Multi-Unit Abutment Type Comparison Table

Anti-drop screw retention system

The internal diameter of the through-holes in temporary and permanent sleeves, as well as in impression copings, is precisely tapered. The head of the fixing screw physically cannot pass through the coronal constriction of the access hole. The screw rotates freely within the bore but is retained within the component, eliminating the risk of it falling out into the patient’s mouth or being lost during try-ins.

Unified instrumental standard

All clinical and laboratory stages of work with the D-Type, V-Type, and S-Type series are standardized using a single instrument type—a 1.27 mm universal prosthetic driver. The minimal mating tolerance eliminates backlash in the internal connection, preventing deformation of the titanium screw head when tightened to the standard prosthetic torque.

Integration into digital and analog protocols

End-to-end digital CAD/CAM protocol

XGATE Dental’s official open libraries are integrated into Exocad, 3Shape, RealGUIDE, and PALM software packages.

Stages of the digital prosthodontic protocol:

1. Scan abutments are fixed onto the platforms of installed multi-units.
2. Intraoral scanning is performed to determine the exact spatial position and angles of the platforms.
3. Using a digital impression, a CAD program is used to model a bar framework or bridge prosthesis with automatic compensation for platform non-parallelism and the placement of screw access holes on the lingual or occlusal surface.
4. The milling machine is used to mill the prosthetic framework, which is mated with XGATE Dental titanium sleeves while maintaining a passive fit.

Precision comparison: Factory production vs. lab milling

When fabricating a custom abutment using a standard laboratory milling machine, the precision of the milled interface (cone or hex) is limited by natural bur wear and axis vibration. Micron-scale geometric deviations lead to micro-gaps due to component rotation, implant cavity infection, and fatigue fracture of the prosthetic screw.

The lower interface of XGATE Dental multi-unit abutments is milled in a specialized factory with submicron tolerances and strict computer control. Laboratory equipment models and mills only the upper portion of the prosthesis, which is secured to the stable factory multi-unit platform, guaranteeing a biological seal.

The One-Abutment-One-Time concept

The use of XGATE Dental multi-unit abutments allows for the “One-Abutment-One-Time” protocol. The superstructure is fixed into the implant body once (on the day of surgery during immediate loading or during the second surgical stage) with the specified torque and is not removed. The photo below shows the completed restoration with integrated sleeves. The prosthesis is inserted and removed as needed with these sleeves, while the abutments remain in place.

The soft tissue heals around the polished Titanium Grade 23 alloy collar, forming a dense gingival margin. All subsequent procedures (impressions, framework try-ins) are performed supragingivally, on the multi-unit platform. This eliminates trauma to the gingival margin, infection of the subgingival area, and subsequent crestal bone resorption, which is typical with frequent replacement of temporary custom elements.

Compatibility with analog impression protocol

For classic analogue impressions, XGATE Dental offers specialized factory impression copings designed specifically for the D-Type and V-Type lines.

Economic analysis and risk management

Optimization of cost and chair time

• Cost calculation: Using custom solutions increases costs for titanium bases, material blocks, milling machine wear, and dental technician labor. The cost of a custom component exceeds that of a factory-made multi-unit. For full-arch restorations on 4–6 implants, this difference significantly increases the overall estimate.
• Reduction of chair time: Compensation for non-parallelism using D-Type angulated models (up to 130°) or V-Type cone geometry (up to 40°) ensures a passive fit of the framework from the first try-in. The number of patient visits is reduced from 4-6 to 2-3 (impression/scanning and final delivery).

Maintainability and certification

The quality of XGATE Dental interfaces made of Titanium Grade 23 alloy is confirmed by international certificates: CE MDR (European Medical Devices Regulation) and FDA (U.S. Food and Drug Administration).

The passive retrievability concept ensures the system’s repairability. If the fixing screws naturally loosen under cyclic chewing loads, the prosthodontist removes the prosthesis with a 1.27 mm driver, performs cleaning, and replaces or tightens the screw to the specified torque without damaging the prosthetic framework.

Conclusion

The factory-precision standardization of XGATE Dental multi-unit abutments replaces the laboratory fabrication of custom abutments based on clinical, biological, and cost-effective factors. Using the system reduces the dentist’s chairside time, reduces the risk of mechanical defects (thanks to the Grade 23 alloy), and ensures crestal bone and soft tissue stability according to the Tissue Level protocol.