Fabricating a New Generation of Hybrid Dentures for Edentulous Patients

The Atlantis Conus concept has received significant amounts of attention as an alternative to screw-retained hybrid prostheses. It is based on patient-specific conical abutments that provide a friction-fit telescopic hybrid prosthesis. This treatment modality provides patients with the same benefits as the conventional screw-retained hybrid prosthesis, with the addition of greatly improved hygiene and more cost-effective maintenance.

The system consists of the fabrication of 5° tapered patient-specific conical abutments that will be parallel to each other, with the ability to correct up to 30° of implant angulation. These abutments will be torqued into the implants. Then, 5° housing caps (SynCone) will be used and captured into the prosthesis, thus creating a friction-retained telescopic prosthesis.

The patient presented with an existing denture and six OsseoSpeed TX implants already in place with healing abutments. The denture was soft-relined (Figure 1).

A. Fabrication of Abutments:

1. The implant analogs were placed into the impression and soft tissue material was injected around them.

2. The master cast was poured with ISO Type V stone.

3. The retentive SynCone tapered caps were placed on top of each implant, submerging them 1 mm below the highest portion of the gingival margin.

4. The cast was scanned with the SynCone caps. These caps would serve as a reference for the design of the abutments, without the need for double-scanning the denture (Figure 2). The caps were removed and the implant positions were acquired using Atlantis FLOs (Feature Locating Objects, also known as scan bodies).

5. The two scans were merged and submitted in Atlantis WebOrder for abutment design.

6. An email was sent when the patient-specific abutments were available for review. Modifications were requested, and then approval for manufacturing was submitted once the desired design was achieved (Figure 3).

7. The abutments were attached to the master cast and parallelism was verified using the SynCone parallel pins. At this point, a delivery jig could be fabricated for easier clinical insertion.

B. Fabrication of Smart Bar:

1. The external surface of a new set of non-retentive SynCone tapered caps was sandblasted, and they were gently tapped onto the Atlantis Conus abutments. The resultant cast was scanned.

2. A bar with a minimum of 0.1 mm abutment clearance for the cement space was designed and submitted. It was important to ensure that the bar was centered on top of the ridge with 2 mm of soft tissue clearance (Figure 4).

The entire surface of the bar was sandblasted with aluminum oxide and vent holes were drilled on the buccal and lingual aspects of the abutment housings (Figure 5).

3. The case was sent back to the clinician with the following items:
• Custom abutments placed on the master cast
• Delivery jig
• Milled bar (sandblasted)
• Non-retentive SynCone tapered caps

The clinician then delivered and torqued the Conus abutments and tapered caps, cemented the bar onto the SynCone caps using a resin cement, and made a final pickup impression of the arch.

Using stock SynCone abutments as laboratory analogs, the pick-up impression was poured in ISO Type III stone to create the final master cast. This was feasible because stock and custom abutments in this system have identical functional areas (Figure 6-7).

The conventional wax try-in and processing steps followed (Figure 8). It was very important to block out the space surrounding the most apical 1 mm of the tapered cap in order to allow it to function adequately (Figure 9).

Finally, the clinician performed the try-in and delivered the completed prosthesis to the patient, and provided instructions for proper maintenance and hygiene. It is recommended that the patient then be seen for follow-up appointments at 6-month intervals.

The Atlantis Conus concept offers several advantages for patients, such as easy cleaning, optimal chewing function and sense of taste, and desirable phonetic function and esthetic results. The prosthesis is fixed-detachable but still provides the comfort of a fixed restoration. In addition, it creates value for dental professionals by allowing for predictable and lasting implant treatment outcomes, resulting in enhanced quality of life for patients (Figure 10).

Julio Zavala, BS, Master CDT, is an Associate Professor in the Department of Prosthodontics, Awada Abdallah, DDS, MSD, is an Assistant Professor in the Department of Prosthodontics, and Marco Brindis, DDS, is an Assistant Professor of Dentistry, all at Louisiana State University’s HSC School of Dentistry.

Disclaimer: The statements and opinions contained in the preceding material are not of the editors, publisher, or the Editorial Board of Inside Dental Technology.

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