Implant-retained zirconia dentures are becoming more important in implant rehabilitation for two main reasons:
– The first reason is the increasing number of patients requesting to stabilize their prostheses through implant therapy.
– The second reason is that this therapy has become more effective, personalized, and minimally invasive.
The choice of rehabilitation depends on the number of implants inserted, the type of anchorage required (screwed or cemented), and the availability of patients.
CAD-CAM technology combined with new materials has made it possible to produce precise and stress-free screw-retained restorations.
This rehabilitation option, which was previously neglected and only used with acrylics, is now the preferred choice. Clinicians recognize its numerous clinical benefits, ease of installation, and the ability to easily remove it for inspection when needed.
Cemented prostheses are increasingly losing acceptance, even in cases where they seem to be the only possible solution. This is because knowledge, technology, and associated materials still favor screw-retained restorations.
In this excerpt, the author will present a clinical case that highlights the above-mentioned trend.
Clinical case
Rehabilitation request: Zirconia denture-skeletal prosthesis retained through screws. The patient is approximately seventy years old and the clinician removed an old work on implants in the maxillary. The rehabilitation therapy involves keeping four old implants – one positioned posteriorly on the left and three positioned posteriorly on the right with very inclined emergence. Additionally, it includes the insertion of four new implants in the anterior region, which are different both in terms of the type of connection and manufacturer from the existing ones.
This option can establish a suitable architecture to support the new prosthesis.
The clinician has decided that due to the unfavourable emergence of the three pre-existing implants, along with the difference in connection between the implants, a screwed prosthesis is not suitable. Instead, they are considering a definitive cemented type rehabilitation using custom titanium abutments, indicated by the temporary solution.
The author’s extensive experience in prosthetic restoration, coupled with a deep understanding of technological systems and materials, enables them to propose an alternative prosthetic solution to clinicians. This solution is capable of providing satisfactory rehabilitative retention through screws.
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.
Titanium bonding links are screwed onto threaded holes, allowing for the design of a zirconia restoration that is interlocked with the bar and retained by three screws. This technique is referred to as “zirconia on zirconia”.
The “zirconia on zirconia” fabrication technique involves combining the highly tough Katana HT ML zirconia with the less tough multilayer zirconia. This is achieved by sintering the 1200 MPa Katana HT ML with the highly aesthetic 750 MPa Katana ST ML multilayer.
Utilizing the full-zirconia anatomical part allows for the perfect replication of the previously installed temporary anatomy.
The beauty of Katana ST ML 750 MPa, combined with its chemical and physical properties, makes it an excellent choice of material.
The integration of the prosthetic restoration on the patient.
Conclusions
The prosthetic case that was treated, despite the objective difficulties encountered, allowed for the evaluation of how it is possible to provide an innovative and unexpected vision through the use of new technologies and associated materials, along with the specific knowledge of the operators.
Written and performed by Marco Stoppaccioli DGSHAPE Expert.
Marco Stoppaccioli
