“Zirconia on Zirconia” case study

Implant-retained zirconia dentures are playing an increasingly important role in implant rehabilitation.
This is happening for two main reasons: the first is due to patients’ requests to stabilize their prostheses through implant therapy.
This is happening for two main reasons: the first can be traced back to the requests of patients who want to stabilize their prostheses through implant therapy;
The second relates to the fact that this therapy has become increasingly effective, personalized, and minimally invasive.
The number of implants inserted, the type of anchorage required, whether screwed or cemented, the availability of patients determines the choice of rehabilitation.
CAD-CAM technology, combined with new materials, has made it possible to produce precise and stress-free screw-retained restorations.
precise and stress-free.
This rehabilitation option, long-neglected and relegated exclusively to the use of acrylics, is now the preferred choice.
This choice of rehabilitation, long-neglected and relegated exclusively to the use of acrylics, is now preferred by clinicians who recognize, in addition to a number of obvious clinical aspects, as well as ease of installation and removal when an inspection is required. need for inspection.
Cemented prostheses, on the other hand, are increasingly losing acceptance, and even at a time when and even when it seems to be the only possible solution, knowledge, technology, and associated materials still favor screw-retained restorations.
In this extract, the author will show a clinical case in which the above-mentioned is highlighted.

Clinical case

Rehabilitation request:
Zirconia denture-skeletal prosthesis retained through screws.
Patient of about seventy years of age from whom the clinician removed an old work on implants in the maxillary.
The rehabilitation therapy foresees keeping four old implants – positioned one posteriorly on the left and three posteriorly on the right with very inclined emergence – and the insertion of four new implants in the anterior region, different both in terms of the type of connection and manufacturer from the existing ones.
This choice is able to create a suitable architecture to support the new prosthesis.

The unfavorable emergence of the three pre-existing implants, together with the difference in the connection between the implants present and not properly indicated for a screwed prosthesis, has led the clinician to consider, through the indication of the temporary, a definitive rehabilitation of cemented type on custom titanium abutments. (Photo 2)

The long experience gained on this type of prosthetic restoration, the knowledge of technological systems associated with that of the materials has allowed the author to indicate to the clinician an alternative prosthetic solution, able to satisfy the rehabilitative retention through screws.
Consequently, a titanium bar with a continuous design is designed, fractionated however into three segments with the following purpose: to eliminate the tensions due to the different types of connection and different inclination of the implants present.
Photo 3

On the head of the bar, the author decides to make three threaded holes; each of them is placed on a segment of the bar itself, so as to constitute a tripod geometric design.
Photo 4

Titanium bonding links are screwed onto these threaded holes, enabling the design of a zirconia restoration intercalated with the bar and retained by the three screws. Design a zirconia restoration interlocked with the bar and retained by the three screws through the
bonding links. The reference technique is called “zirconia on zirconia”

 

The “zirconia on zirconia” fabrication technique allows a highly tough Katana HT ML zirconia to be combined with less tough multilayer zirconia. Katana HT ML by sintering 1200 MPa with a less tough, highly aesthetic Katana ST ML 750 MPa multilayer.
aesthetic Katana ST ML 750 MPa.
The use of the full-zirconia anatomical part enables the anatomy of the installed temporarily to be perfectly replicated.
the anatomy of the previously installed temporarily.

The beauty of Katana ST ML 750 MPa, coupled with its chemical and physical properties, makes it an excellent
this material an excellent reference for this choice of material.

The integration of the prosthetic restoration on the patient.
Photos 8,9

Conclusions
The prosthetic case treated, despite the objective difficulties encountered, has allowed evaluating how it is possible to give an innovative and unexpected vision through the use of new technologies and materials associated with them, together with the specific knowledge of the operators.

 

 

Written and performed by Marco Stoppaccioli DGSHAPE Expert

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